Superstol XL • on Superstol A

Adventure is Good for the Soul KITPLANES

JANUARY

2016

® SuperSTOL XL • On SuperSTOL a

Whim • ULPower

Engines XL • Fuel Systems 2 • Gear Collapse • Exhaust Systems • LED Lighting • Switch Stretching Layout • Pre-Trip The Envelope Maintenance Exhausting! JANUARY 2016 BELVOIR Expelling the Remains In the Shop:

PUBLICATIONS Fuel System Design • Downdraft Paint Booth Components 101 • Switch Layout • LED Nav Lights Hangar Mishaps

Gear Collapse www.kitplanes.com

January 2016 | Volume 33, Number 1 Flight Review 6 Stretching The Envelope: Flying the SuperSTOL Stretch XL with a 180-hp ULPower engine. By Dan Horton. Builder Spotlight 14 the New Old Aero Engine! ULPower takes a different approach to air-cooled, horizontally-opposed, direct-drive engines. By Steve Ells. 20 on a Wing and a Whim: Flying a scratch-built Sonex is good for the soul. By Kerry Fores. 28 light Aircraft Fuel System Design: Part 2—Every 20 component is there for a good reason! By Ken Krueger. 34 error Chain: Gear collapse—not all mishaps happen in the air. By Russ Erb. 38 engine Theory: Exhaust—expelling the remains. By Tom Wilson. 68 A sk the DAR: Combining parts from multiple kits, N-numbers, using an amphibian for land-only training. By Mel Asberry. 74 c ompletions: Builders share their successes. Shop Talk 46 Aircraft Wiring: Instrument panel switch layout for Experimental aircraft. 54 The New Guy: Ten universal tips for Experimental aviation. By David Boeshaar. 56 Maintenance Matters: Maintenance for an extended journey. By Dave Prizio. 78 Aero ’Lectrics: Winging it with LEDs. By Jim Weir. Shop Tip 64 Temporary Downdraft Paint Booth: By Larry Larson. Designer’s Notebook 50 Stressing Structure: Buckling of panels. By David Paule. 75 Wind Tunnel: Horns and spades. By Barnaby Wainfan. 6 Exploring 2 Editor’s Log: Shaving time with Occam’s razor. By Paul Dye. 60 the Dawn Patrol: The dropped tool disastrophe. By Dick Starks. 65 checkpoints: Oshkosh 2015 musings. By Vic Syracuse. Kit Bits 4 Letters 69 list of Advertisers 70 Builders’ Marketplace 80 kit StufF: Drawing on experience. By cartoonist Robrucha. 14 On the cover: Just Aircraft SuperSTOL Stretch XL with 180-hp ULPower engine. Photographed by Richard VanderMeulen near Lakeland, Florida. For subscription information, contact KITPLANES® at 800/622-1065 or visit www.kitplanes.com/cs. KITPLANES January 2016 1 Editor’s log Shaving time with Occam’s razor. Troubleshooting is an art—an art the servo or carburetor and turn on the based on experience, knowledge— fuel pump—does it flow? Airflow is even and sometimes a little luck. I have been easier to determine—is there anything building and fixing things all my life, obstructing the inlet? Does the throttle and there are still times that I run down plate open? If yes, check that off the list. a primrose path that leads me to a des- Spark, of course, needs to be pres- ert devoid of answers. And that is when ent—and at the right time (although I remind myself of Occam’s razor. No, it is astounding how far out of time an you don’t buy it in a drugstore—it’s the engine can be and still “run.” I use quotes name of a process. because it won’t run very well). I had an According to Wikipedia, Occam’s razor unfortunate experience with a used fly- is a principle of parsimony, economy, or wheel once that had me time the mags succinctness used in problem solving 120° off—and it still started! Ran fine at that was devised by William of Ock- about 1500 rpm, but backfired like crazy ham (c. 1287–1347). It states that among when we throttled back. competing hypotheses, the one with the How about if it won’t crank? Well, you fewest assumptions should be selected. need a charged battery, a starter that will Other, more complicated, solutions may engage and then turn, and if there is a ultimately prove correct, but—in the solenoid in between, it has to go “click” absence of certainty—the fewer assump- and conduct massive amounts of juice. To keep small tasks from becoming tions that are made, the better. There aren’t many things that can go large tasks, the first tool you should The razor has many different descrip- wrong, and they are easy to check—so reach for is Occam’s razor. tions, but the way I like to think of it, the why start thinking that you have been simplest possible solution is the one to attacked by cosmic rays, or some com- cylinder walls, so we make up all sorts of pursue. This works especially well with plicated failure has occurred in your bat- excuses like the ring gaps all being lined simple systems or mechanisms—like a tery that allows you to listen to the radio, up, or maybe it was just too cold to do a Lycoming-type engine. So long as the but not crank the engine (that’s not very good compression check. Lycoming says crank is turning freely, the pistons are complicated), or a witch doctor has put you can button it up and go fly an hour going up and down, and the valves are a curse on your machine? Look at the or two, and that’s a good idea. But when opening and closing, the only thing you simple things first. you come back and get the same results, need to get a Lycoming to run is air, fuel, Sometimes, we know in our hearts you might as well get out the cylinder- and spark. If it’s not firing, assume that it that the problem is serious, but we hope base wrenches—the ring gaps lining up is missing one of those three items and against hope that the problem is actu- is just not going to cut it as an excuse. look for the simplest solution. ally minor. A good example is when you Electrical problems are where we Has it got fuel? Well, that’s easy to fig- do a compression check and find a low always try and get creative—electricity ure out—make sure there’s something cylinder, with air coming out of the dip- is, after all, pretty much magic to many, in the tank and the valve is open. Want stick. No one wants to pull a jug and find so why not assume that the problem is to still be sure? Take off the fuel line at that you have a broken ring or glazed magical? When someone tells me that

Paul Dye retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the space shuttle. An avid homebuilder, he began flying and working on airplanes as a teen, and has experience with a wide range of construction techniques and materials. He flies an RV-8 that he built in 2005, and an RV-3 that he built with his pilot wife. Currently, they are building a Xenos Paul Dye motorglider. A commercially licensed pilot, Paul has logged over 4800 hours in many different types of aircraft and is an EAA tech counselor, flight advisor, and member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.

2 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes all of the LED indicators in their cockpit light up when they transmit, I don’t start talking about ferrite beads, separat- ing antenna wires from signal wires, or reloading software—I ask if they have a cheap wire-whip antenna in their all- metal airplane. The answer is usually yes, in which case I then point out that they left too much of the core unshielded next to the antenna. No one wants to hear that if the end of the antenna is under the floor, but nevertheless, that is going to be the answer. If you find yourself constructing a complicated rationale to describe a problem, you are violating Occam’s razor and heading down a path that will probably not take you anywhere. Landing gear seem to be loose? Most likely a hole has wallowed out, or a bushing has failed. Problem getting your RV to cool right? Look at what you have changed from the factory drawings; thousands of them are working just fine, built to plans. If you changed something, that is the most likely culprit—not some strange interaction of flow and the Vernatherm. You may not like the answer you are going to get when you take the simple path—it sometimes leads to a major structural rework, or an engine overhaul—but Occam doesn’t say you’re going to like his answer—only which is most likely. When a light that has been working stops working, suspect the bulb or a wire that has come undone, or you blew a fuse. I had a crimp come undone on a landing light wire on one of our planes recently. Rather than taking the whole wingtip off to start my troubleshooting, I looked under the panel, assuming that the wire was continuous from the fuselage to the tip. Sure enough, the bad crimp was in a splice six inches from the switch. That saved taking off 60 screws. Use your head—and Occam’s razor— the next time you have a problem. Don’t reach for the wrenches first. You’ll save time and look like a genius to your friends when you go right to the trouble spot without first going down some dead ends. Look for the simple, not the complicated. Remember, if you hear hoof beats, think horses—not zebras. Unless, of course, you happen to be in Africa. J

Photo: Richard VanderMeulen KITPLANES January 2016 3 EDITORIAL Editor in Chief paul Dye [email protected] Sharing with Others form, the aircraft cannot be registered as Managing Editor mark Schrimmer What a ride we got reading Michael Rob- an ELSA. Even though some manufac- Art Direction Dan Maher inson’s “Aeronautical Decision Making” turers have obtained SLSA certification, Editorial Director paul Bertorelli [“Error Chain,” October 2015]. He had they are not willing to provide Form Contributing Editors larry Anglisano, Marc Ausman, me on the edge of my sofa. I’m glad they 8130-15 to their kit-built customers due roy Beisswenger, Chuck Berthe, David Boeshaar, LeRoy Cook, survived, and that others can learn from to liability reasons. The manufacturer robert Hadley, Dan Horton, the experience. does not want their name listed as “man- louise Hose, Amy Laboda, Dave martin, Sid Mayeux, David Paule, Al Barrigar ufacturer” on the aircraft registration! Dave Prizio, Dean Sigler, Dick Joe Gores starks, Eric Stewart, Vic Syracuse, barnaby Wainfan, Jim Weir, We appreciate all pilots like Michael who tom Wilson. are willing to share their building or flying Mel Asberry responds: It is certainly true Web Editor Omar Filipovic mistakes with our readers via the “Error that a manufacturer may not offer their Cartoonist Robrucha Chain” feature. The only true mistake is not kit customers a certificate of compliance ADVERTISING sharing things that will help others build or (8130-15). That is their prerogative. I Sr. Advertising Manager Chuck Preston fly with less risk.—Ed. would sincerely hope that they would be 805/382-3363 [email protected] upfront with that information. If they offer Oxygen Availability? an ELSA kit, they must offer the 8130-15. BUSINESS OFFICE I greatly enjoyed “How to Use Your Belvoir Media Group, LLC Otherwise it’s not truly an ELSA kit. 535 Connecticut Avenue Oxygen System” in the November 2015 Now having said that, they may with- Norwalk, CT 06854-1713 issue. One thing not mentioned is where hold the certificate if all components are EDITORIAL OFFICE to refill bottles as needed. Do you have not purchased from them because they 535 Connecticut Avenue any insight on this? cannot certify that parts bought separately Norwalk, CT 06854-1713 Ron Banks meet their SLSA example. 832/851-6665 [email protected] Oxygen refills can usually be obtained at Time Keeps on Ticking… CIRCULATION airports (the most expensive choice) that are I read “Who’s Got the Time” [Octo- Circulation Manager Laura McMann listed in the Airport Guide—but if you’re ber 2015], and it made me think about SUBSCRIPTION DEPARTMENT looking for less costly alternatives, many how an EFIS could generate a proper, 800/622-1065 FAA-defined pilot flight time num- www.kitplanes.com/cs pilots rent a large bottle to keep in their P.O. Box 8535, Big Sandy, TX 75755-8535 hangar for less than $100 per year, and use ber. It seems to me that a GPS-enabled For Canada: Box 7820 STN Main, London, ON N5Y5W1 a transfiller hose to fill their aircraft bottle. EFIS could record the time of the first REPRINTS FOR PUBLICATION Medical supply companies can also fill, but forward motion after engine start and AND WEB POSTING AVAILABLE often require a prescription.—Ed. then record the time of the last move- Minimum Order: 500 ment before engine stop. Calculating Contact Jennifer Jimolka, 203/857-3144 ELSA vs. E/A-B the elapsed time between those two Mel Asberry did a great job explaining should yield a figure that meets the FAA Change of address? the difference between ELSA and E/A-B guidelines. The only exception would be Missing issue? [“Ask the DAR,” November 2015]. An if you were taxiing without the intent for Subscription Question? additional consideration for prospec- flight. Just one thought. Visit www.kitplanes.com/cs. tive builders who intend to register their RAndy King Or call 800/622-1065 from the U.S. and Canada. aircraft as ELSA is whether or not the manufacturer is willing to provide Form We agree—now we just need an EFIS pro- Foreign 903/636-1112 or fax 8130-15 to the builder. Without that 203/857-3100. grammer to take up the cause.—Ed. J

Web site Information: General homebuilt aircraft information, back issue availability, online directories ordering info, plus a Kitplanes® article index and selected articles can be found at www.kitplanes.com. Unsolicited manuscripts: are welcome on an exclusive basis, but none can be acknowledged or returned unless accompanied by a stamped, self-addressed envelope. No responsibility is assumed for loss or damage to unsolicited material. Kitplanes® (ISSN 0891-1851) is published monthly by Aviation Publishing Group, LLC, an affiliate of Belvoir Publications, 535 Connecticut Avenue, Norwalk, CT 06854-1713, Robert Englander, Chairman and CEO; Timothy H. Cole, Exec. Vice Pres./ Editorial Director; Philip L. Penny, COO; Greg King, Exec. Vice Pres./Marketing Dir.; Ron Goldberg, CFO; Tom Canfield, Vice Pres., Circulation. Periodicals postage paid at Norwalk, CT, and at additional mailing offices. Copyright ©2015 Aviation Publishing Group, LLC. All rights reserved. Reproduction in whole or in part is strictly prohibited. Printed in USA. Revenue Canada GST Account #128044658. Canada Publishing Agreement #40016479. Subscriptions: One year (12 issues) is $29.95 U.S. $41.95 in U.S. funds in Canada, includes GST. $41.95 in U.S. funds for Foreign Surface Mail or $57.95 in U.S. funds for Foreign Air Mail. Single copy price $4.99 U.S., $5.99 Canadian. POSTMASTER: Please send address changes and subscription inquiries to: Kitplanes®, P.O. Box 8535, Big Sandy, TX 75755-8535, or Canada Post: Return undeliverables to P.O. Box 2601, 6915 Dixie Rd, Mississauga, ON L4T 0A9 or call 800/622-1065. Kitplanes® is a registered trademark of Aviation Publishing Group, LLC.

4 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Before you need to recover, we’ll have you covered.

Introducing Garmin Electronic Stability & Protection for the G3X® and G3X Touch. ESP-X monitors your attitude while you hand-fly your airplane, and if you inadvertently exceed pilot-programmed bank- and pitch-angle limits—or you approach overspeed or stall speeds—it provides a correcting nudge to your flight controls to help you stay in control and get back to straight and level quickly.1 Especially when you’ve been distracted. And after 15 seconds, it’ll even automatically activate your autopilot to level you off. Best of all it’s a standard feature of the G3X autopilot.

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25836 G3X Touch ESPX Ad-Kitplanes.indd 1 4/8/15 9:52 AM Stretching The Envelope

Flying the SuperSTOL Stretch XL with a 180-horsepower ULPower engine. By Dan Horton

6 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes It was Editor Dye on the phone. “I have a Sun ’n Fun assign- Factory pilot Harrison Smith beckons toward the left seat. ment for you. Just Aircraft will have an airplane there with The doors are top-hinged and wide, so it’s easy to duck under a ULPower six-cylinder. Make arrangements to fly it, and them and climb aboard. The lift struts for the folding wings write your impressions of both the engine and airframe.” My are behind the doors, and don’t interfere with cockpit access at response, of course, was “Yes sir, I’ll get right on it.” I even kept all. I’m bubba-sized (6-2, 215), so it’s a pleasant surprise to find a straight face, although inside I was grinning like a mule eat- plenty of room. The seat adjusts fore and aft with a locking pin, ing briars. Let’s see now, who to call first? and slides back far enough for full leg extension. Size 14 shoes Early morning, a few weeks later; I’m standing on the green have plenty of toe clearance, and the rudder pedal/brake pedal grass at Paradise City, Sun ’n Fun’s lightplane strip. In the geometry is spot on. The doors bow out, adding elbowroom, ’80s and ’90s it was a beehive, but things got slow following and I have 3 or 4 inches of headroom to the skylight tubes. It the migration of most Light Sport vendors to the main flight fits, without control constraints. Score one for the big guys! line. Now people are returning, many to see the tall bush plane There are two short levers between the seats, in addition to parked in front of the Just Aircraft tent. No one can miss it. the flap lever. One is trim, as you might expect, but the other It’s red, really red, with big balloon tires, long black is a tailwheel lock. The tailwheel is mounted on a long-travel legs, and a prop hub more than head high. swingarm with a shock, just like the maingear, and thus can’t While the standard SuperSTOL is powered be easily steered. So, it’s full swivel to taxi…or to spin around, with a Rotax 912, this one mounts the new UL520i tail high, doing the bush plane dance in the rocks. The tail- rated at 180 horsepower (see page 14). The ULPower instal- wheel is locked for pavement or training, but doesn’t have to lation manual says the 6-cylinder weighs about 250 pounds be, as there is plenty of rudder authority. with all accessories: the exhaust, the oil cooler, the wiring Smith runs me through the start procedure. The UL520i looms, the coils and ECU, and even the oil. A Rotax 912 is has both electronic ignition and multiport electronic fuel roughly 100 pounds lighter, apples to apples, so to keep weight injection, so there’s no setup or priming. This particular air- and balance within the acceptable range, the Stretch XL’s aft plane was built with two of everything, so the drill is mas- fuselage is 2 feet longer. Naturally, the cowl is a little longer ter on, main and crossover battery on, both ECU’s on, both too. The proportions are very pleasing, less stubby than the injector drivers on, one fuel pump on, and then hit the start original, and less chunky than a Cub. button. The actual start is like a car…a few rotations and it’s The lean look is entirely the result of the fuselage stretch, running. We set 1200 rpm and let it warm. The throttle is the as the cockpit, wings, and tail feathers are identical to those only control, as the ECU controls mixture, there is no carb proven on the standard SuperSTOL. The damped shock struts to ice, and this aircraft is fixed pitch. When wired for dual are slightly more robust, but they will be shared with the lighter ECUs, the “mag check” consists of turning off one ECU at Rotax-powered versions in future production. It’s a practical a time. If the engine stays running on one ECU, you’re good design choice that further toughens the original while main- to go. Full throttle static rpm is 2800 with this particular taining a low parts count. custom-made Catto propeller.

Photos: Richard VanderMeulen and Dan Horton KITPLANES January 2016 7 Comfortable seating for two. The long flap lever provides leverage, KIS principle at work; nothing extra here, and the analog airspeed as it is pulled smartly during short takeoff. only requires a glance at needle position for STOL ops.

Time for fun the pilot know the slats are fully out in like an O-300 6-cylinder Continental, As quickly as you can read this sentence, the breeze. Operation is entirely aerody- an engine I’ve always found to be very Smith goes to full throttle, pushes for- namic, with all extension and retraction pleasant. Speed at 2500 rpm is 80 knots. ward on the stick to raise the tail, pulls in the speed range between 50 and 60. The oil temperature is 214° F, which, one notch of flaps, and rotates sharply They’re not connected, and can deploy given the short climb, seems a wee bit to something past 45 degrees. The ini- asymmetrically, which doesn’t seem high to my Lycoming-trained mind tial climb is helicopter-like, assuming to make any difference in control feel. (note: a subsequent inspection found a you normally fly your helicopter while Except for the thunk and a little motion broken oil thermostat spring). On the reclining with your feet higher than in the corner of the pilot’s eye, there are other hand, CHT is low at 283° F. That your head. Even when Smith relaxes the no operational clues…if you don’t count doesn’t surprise me, given the huge cool- stick for a sustained climb at 50 knots the outrageous angle of attack they allow ing fin area I saw on the display engines. IAS, the angle remains at an estimated when extended. I ask about stalls, and Smith just grins 30 degrees or so, slats out. We have a low overcast, with a storm and says, “Go ahead.” I pull the power Oh yeah, the leading edge slats. They brewing to the west. The Paradise City off, raise the nose, and wait. Other than swing outboard and forward on short pattern is only 300 feet agl, so we can’t slat extension, nothing happens. I raise arms, a mechanically robust arrange- climb far anyway. Smith points the XL the nose some more, then more again. ment, and just one of designer Troy toward South Lakeland (X49), settles Finally, at what seems like a ridiculous Woodland’s many clever choices. The into cruise, and says, “Your airplane.” attitude for idle power, the nose bobs extension stops are rubber bumpers, I take the controls and give the panel a faintly. It’s not a stall in the conventional which make a pleasing “thunk” to let scan. The UL520i feels and sounds just sense, but rather a big sink rate with the

The slatted wings fold to only 81/2 feet wide. The tailwheel has its own long-travel swingarm and hydraulic damper.

8 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Just Aircraft SuperSTOL Stretch XL

Kit price (U.S. dollars, excluding QB option) . . $44,300 Estimated completed price . . . . . $75,000–$95,000 Estimated build time ...... 500–1000 hours Powerplant as tested ...... ULPower 520i (180hp) Propeller ...... Catto 76-in diameter, 36-in pitch Powerplant options . Lycoming/Superior/Titan 320/340

AIRFRAME Wingspan ...... 31.27 ft, 8.50 ft wings folded Fuel capacity ...... 27 gal Cruise fuel consumption ...... 6.2 gph @ 78 kt Maximum gross weight ...... 1550 lb Typical empty weight ...... 870 lb Wing tanks fill a header tank hanging in the 32-cubic-foot baggage compartment, which Typical useful load ...... 680 lb in turn feeds the UL520’s electronic fuel injection. Recirculated fuel returns to the header. Full-fuel payload ...... 518 lb LSA typical useful load ...... 449 lb stick against the stop. There’s no ten- choices), a terrain-trapped pilot might LSA full-fuel payload ...... 287 lb dency to fall off to the side. The airspeed ride this one into the ground, upright Seating capacity ...... 2 Cabin width ...... 44 in is something less than 35 indicated. and fully stalled, with a good chance of Baggage area ...... 32 cubic ft At South Lakeland Smith shows me walking away. a short landing. It starts with power off, I get one takeoff and landing before PERFORMANCE then hauling the nose up to kill speed the weather dumps on us. We scoot Maximum cruise speed . . . . 90-95 kt/105 mph with and pop the slats, then extending the back to Paradise City in the rain, nar- ...... 29-in Alaskan Bushwheels and Catto propeller Stall, power off, no flaps ...... Less than 35 mph flaps and adjusting pitch to maintain 45 rowly missing two big orange flamingos Takeoff distance at 1550 gross ...... 300 ft indicated. I can’t see over the nose, but it scud-running toward Tampa. This time Landing distance at 1550 gross ...... 300 ft is possible to look around it on the side, Smith sets up with power at 2000 rpm, Takeoff distance at 1320 gross ...... 175 ft and there’s a plentiful view of the rap- assumes a steady nose-up attitude that Landing distance at 1320 gross ...... 175 ft idly rising green grass through the clear looks like 25 degrees or so, and simply All numbers are approximate. doors. At around 10 feet, Smith gives it flies a normal approach into the ground Specifications supplied by manufacturer. a short burst of power, raises the nose to at 45 with minimal flare, much like a what seems like a ridiculous angle, stabi- Naval aviator arrives on a carrier. He RV-8, heading for Clemson, South Car- lizes, and allows it to drop in tailwheel pulls power at touchdown, applies mod- olina. Smith will pick me up there, and first. The big tires and the long-travel erate braking in the wet grass, and we we’ll fly the XL over to the Just Aircraft struts negate the impact nicely. It feels a roll maybe 200 feet. factory, on a wooded hill outside Wal- lot like hitting a big bump while sitting halla. Ever been picked up in a limo? in the air-ride seat of a Class A truck, or LimoSTOL, Round Duex Well, I’m starting to think of the Stretch large agricultural tractor; just a comfort- Poor, poor me. The weather didn’t offer XL as the LimoSTOL. Rides good, and able smoosh into the hydraulic damping. much opportunity to play in Lakeland, at my age it’s probably as much fun as a Given the low stall speed (and no other so it’s two weeks later and I’m in my stretch Lincoln full of party girls.

KITPLANES January 2016 9 Big Bushwheels and long-travel hydraulic struts soak up near-vertical landings. Beringer wheels and brakes are a premium option, but they save weight and work very well. We saddle up, and I try to duplicate We check climb rate on the way over rpm for the 520i, a fuzz under 170 hp Smith’s short field departure. It’s not diffi- to Walhalla. Weight is a little over 1400 at sea level and not much more than 155 cult, but I’m a little slow as my right hand pounds, as this airplane is licensed E/A- with these conditions. We reach 3500 hunts for the flap lever. I don’t pull the B, not Light Sport. It’s a hot day too; in 2:43, for a rate of 727 fpm. For con- nose up so much either; that will require density altitude is nearly 3000 feet when trast, Smith flew a repeat at 55 knots, a bit more familiarity. Climbing at 60 or we start a climb at 1500 msl. Smith starts with the leading edge slats in, and the 65 knots provides normal over-the-nose by pulling the nose to 50 knots, slats out, result was 863 fpm. Although the gang vision anyway. Other than the short roll while I mind the stopwatch. Although on the FBO porch may not see these as and using the grass beside the runway, the 5-minute maximum power is 180 bragging numbers, they’re actually quite The Limo is perfectly comfortable in a hp at an electronically limited 3300 respectable, and illustrate a point about conventional airport environment. rpm, we set 2800, the max continuous climb rate vs climb angle. The Stretch Just Aircraft…Overnight Success in Only 14 Years When Troy Woodland and Gary Schmitt brought the prototype ribs. To maintain the desired price and weight, Wilson selected two- SuperSTOL to Oshkosh in 2012, it was a sensation. With its small stroke power, and to ease storage costs, the new “Avid Flyer” had a airframe, long legs, and giant tires, it looked like a friendly cartoon simple folding wing system. Wilson opened Light Aero, Inc. in Caldwell caricature of a bush plane, and seemed to land at a walking pace. to produce Avid kits. It was named the EAA’s Best New Design in 1983, Everyone went away shaking their head, and later, after a few rounds and became an immediate hit. of Spotted Cow, many swore to have one. The first Idaho spinoff was Wilson’s partner, Dan Denney, who set up Quite a few followed through with their checkbooks. While prepar- Denney Aerocraft in Boise to build what was initially an Avid copy with ing this story, Schmitt told me Just Aircraft had delivered 104 kits in a few minor styling changes. He called it a Kitfox, and it too was a huge 2014, with fully 85% of production (89 units) being the SuperSTOL. hit. Each firm continued to one-up the other with new models, but there That’s a fine performance for any current kit manufacturer, and more was a lively trade in employees, so nothing stayed secret for long. In due than double Just’s previous sales rate. Any way you shake it, the Super- course, some of those employees started kit companies of their own, and STOL has been a big winner. So how did it happen? most stayed in the Boise-Nampa area. Each specialized in a market niche Airplanes have a DNA of sorts. It is carried in the minds of the they found attractive (ultralight, heavy haulers, tandems, side-by-sides, designers, who often attend the same schools and work their way up with all kinds of landing gear and engines), but most stayed with the with the same employers. In the years after WW-I, a long line of young fundamental Wilson pattern: a light welded-steel fuselage, folding men (think Jack Northrop, Donald Douglas, and Dutch Kindelberger) wings, and tubular aluminum spars. Designs evolved, and manufacturing made their bones in the Southern California aircraft industry, and later methods became more efficient. It was survival of the fittest. produced the warplanes and transports that won WW-II and the Cold Ken Schrader was one of those guys; he worked for both Avid and War. Kansas connected Walter Beech, Clyde Cessna, and Lloyd Stearman, Kitfox before founding Flying K Enterprises. He was subcontracting and became a center of general aviation design. At one time, the quickbuild wings for Avid when a mutual friend brought a sharp kid fledgling light-aircraft kit industry had its CG too, although the named Troy Woodland for a shop visit. Woodland was no stranger to location may surprise a few readers. Arguably, it was Western Idaho, fabrication, having grown up around his dad’s sawmill equipment around Caldwell, Boise, and Nampa. It all started in the early 1980s business, and he was crazy about flying. Pretty soon he was working with Dean Wilson and the Avid Flyer. nights with Schrader, then full time. When not working, Schrader Wilson, already a successful designer, was asked to design an and Woodland liked to fly the backcountry, and not surprisingly, Sky ultralight. Wilson instead created a very light kit aircraft around a Raiders earned a reputation as personal-sized fun-flying bush planes. conventional steel tube fuselage, aluminum tube spars, and plywood Sadly, Ken Schrader died in a flying accident, an event Woodland calls

10 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Large surfaces allow flying the tail, even A new bush plane and a few acres of grass…what could be more fun? with the aircraft at a standstill.

XL is a low-speed airplane, and as such plant’s parking lot. Smith does the same hops into his personal short-body Super- it doesn’t travel a great distance forward short field setup I saw back at X49, first STOL (very light, and equipped with a or upward in a given period of time. It getting slow, then using power to raise modestly-pumped-up Rotax 912), does can, however, fly an obstacle clearance the nose a lot before landing like a fly on a warmup, then spins around, tail high, angle pretty much like a cat climbing a a wall. He then nonchalantly adds more and disappears over the edge of the park- screen door. It’s an airplane optimized power to taxi uphill to parking. ing lot at full power. He quickly reap- for a particular mission. Troy Woodland, Smith, and I loaf on pears, climbing steeply in a tight circle I see that mission in all its glory when the front porch a while, talking about to stay over the clearing. Smith taxis to we reach the Just Aircraft plant. The, airplanes, the Stretch XL, and company the edge, shoves in the throttle, and we umm, runway is a bulldozed slash in the history. After a plant tour (see sidebar), too dive off what now seems like a cliff. trees running straight up the hill to the Woodland suggests a flying lunch. He We don’t roll far; given the UL520i’s

the worst day of his life. In due course the business was sold. Woodland the environment. With a Helio in the family, it was only a matter of was left facing a classic choice; could he in turn make it on his own? He time before Woodland would evolve it further by trying a wing with decided to go for it, and started Just Aircraft in 2001. a slatted leading edge on a personal Highlander test mule. What Hard work and brains are essential for success, but it never hurts to he found was that the new wing would fly at a truly epic angle of be lucky. Woodland’s luck meter pegged the stop when Gary Schmitt attack, so much so that a full-stall landing had the tailwheel always walked into Just’s new Oshkosh display. Schmitt wasn’t from Idaho. contacting the earth feet before the mains. The result was a slam- His family had been in the construction business since 1965, in the down landing that made the partners worry about the Highlander mountain country of the western Carolinas. Schmitt had learned to fly gear structure. Woodland started thinking about long travel (for almost by accident, after having been talked into a skydiving adven- truly vertical, very short arrivals), which led to thoughts about ture, and deciding that flying the plane looked like fun too. He flew damping (to kill the resulting bounce), which led to the shock- jumpers for eight years in his C-182, bought a Helio Courier to explore equipped gear you see today. the hills, and decided to nose around the Red Barn area on a trip to The SuperSTOL and SuperSTOL XL depart from the Wilson pattern AirVenture because the light stuff looked like fun. The two hit it off, in one major detail: an entirely new, all-aluminum wing. Woodland and Schmitt asked if Woodland could build a custom side-by-side bush says the aluminum wing was a design effort started years ago, but plane for him. It wasn’t long before they were business partners. shelved for lack of time. The latest version incorporates spoilers in the Just built about 90 kits in Idaho before Schmitt found an empty outboard panels to complement the ailerons at very low speeds and 32,000 square foot plant building outside Walhalla, South Carolina. The high AOA. There should be quite a few spoiler wings flying in customer big move came in 2004, with Woodland and a few key employees pack- hands by the time this reaches print. ing and moving the entire company. By then the product line included The new slatted wing and its complementary long-travel landing the Escapade, a trigear side-by-side optimized for an export market, gear earned Woodland the EAA’s 2014 August Raspet Memorial Award and the very popular Highlander, a STOL bush plane optimized for the for the advancement of light aircraft design. It’s an impressive honor, type of flying Woodland and Schmitt like to do. The Walhalla plant sits given that Woodland is entirely self-taught; he does his own design on a hill, and it didn’t take long for the pair to decide they wanted to fly and prototyping, then has structure reviewed by a consulting engineer their Highlanders to work. The result was the now famous uphill-down- before production. It’s doubly impressive when you consider the previ- hill strip, with parking at the top and a lake at the bottom. ous 54 recipients, which include names like Wittman, Pitts, Rutan, The Highlander is fairly described as an evolution of the basic VanGrunsven, and yes, Dean Wilson. Wilson model, but like any evolved creature, much improved to suit —D.H.

KITPLANES January 2016 11 The House on the Hill Walking around the Just Aircraft plant is a lot of fun. The company currently employs about 20 people in a single day shift. As you would expect, they mostly build and stockpile components, but they also do a lot of customer assistance. Just owners have always been welcome to assemble their kits at the plant, if they commit to progress and keep it moving. Just does all their own welding in-house. They use pro-level MIG systems, with a little TIG work where It may not be Boeing Everett, but Troy Roll spoiler system, inside the wing, appropriate. The welds I examined at random were Woodland is justifiably proud of Just which is upside down in this view. Push- truly excellent, a point of pride to both Woodland Aircraft’s plant operation. rod rotates torque tube, which moves gray arms, extending the red spoiler and Schmitt. The fabrication methods are old school, panels up through the top of the wing. as there are only so many ways to construct a tubular structure. Precut tubes are clamped into a jig and tacked. Fuselages are then placed on a rotisserie fixture for finish welding. After surface prep, the structures are powder coated. Woodland strongly encourages buyers to choose quickbuild wings. With tubular spars, it’s easy to accidently build in some unwanted twist. Assembling the basic structure in a factory jig eliminates that risk, and it saves time. Builders still have plenty to do. The favored fabric system is Poly-Fiber, from Spoilers in extended position. They rise Racks of welded and powder-coated Poly-Tak adhesive through the Poly-Spray silver up through a slot. components, ready to go. coats. Factory applied color is usually Superflite polyurethane. Woodland and Schmitt don’t top- coat the underside of the fuselage on their own airplanes. Bare Poly-Spray allows easy repairs to torn fabric, a handy detail, because these guys are not kidding when they talk about landing off-airport. Besides, silver is an attractive complement to almost any paint scheme. A future evolution of the SuperSTOL was lying on the shop floor; an old O-320 Lycoming. Woodland sees the Stretch XL as a fine home for The master fuselage jig. Every Super- Quickbuild wings, ready to ship. good 320 cores currently hiding in hangars, the STOL starts life here. result being an affordable, reliable STOL combination for the regular Joe Homebuilder. That’s not to say customers can’t have a fire breather. When I visited, there were several ULPower engines on order (including a 200 hp UL520iS), a Titan 340, and at least one Aero Sport Power IO-375. If Walhalla develops a pilot shortage, call me…please. —D.H.

12 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes a comparable load (here two guys and 12 gallons of gas), the XL’s wing is carrying about 11/2 pounds more per square foot. The ailerons also have less control system friction, so coordination is simply less work. There’s plenty of adverse yaw, but that’s expected to change. Woodland is already building wings with a new spoiler system intended to improve roll response at very low speeds. The spoilers are panels that pop up vertically from a slot at the crest of the airfoil, and by nature, they counter adverse yaw by pro- The cowl is conventional, and goes together with 1/4-turn fasteners. viding drag on the wing opposite the downward deflected aileron. 320 cubic inches (5254cc) and a gravity distance. This is Southern bush plane Back on the ground, it is depressing assist, we’re at flying speed in the blink heaven…simply awesome. to walk away. I really like the Stretch XL of an eye. Smith and I head for the Clemson and the UL520i. They both seem to be Woodland’s lunch destination is the airport after lunch. The afternoon is hot, products refined beyond what anyone top of a rolling, grassy hill, at Chattooga the terrain is rolling, and at low altitude has reason to expect, given they are rela- Belle Farm, a pleasant 10-mile flight we should be wallowing and bouncing in tively new designs. In each case their cre- over the ridges. The manager retrieves us the thermals, wishing we hadn’t eaten so ators are serious men…and it shows. J with a four-wheeler, and drops us at the much. The Stretch XL, however, displays farm restaurant. We dine outside, on a very good manners in rough air. The Want more? Read Dave Prizio’s flight review deck overlooking the vineyards, with the wing is smaller than a Super Cub (147 of the standard SuperSTOL in our October north Georgia mountains rising in the square feet vs 178 square feet), so given 2013 issue or online at www.kitplanes.com.

KITPLANES January 2016 13 The New Old Aero Engine!

ULPower takes a different approach to air-cooled, horizontally-opposed, direct-drive engines. By Steve Ells

If small airplane pilots were to get so frustrated with ULPower is gaining a foothold in the Experimental fleet today’s engines that they “rioted” for new engines, they because they deliver these wants. The company builds a total might well be chanting: of eight different engines with power ratings from 97 to 200 “What do we want?” “Easier starting!” horsepower. These are clean-sheet, air-cooled, direct-drive “What do we want?” “Better power-to-weight ratios!” engines that were designed and built using 21st century tech- “What do we want?” “Full FADEC!” nologies. All of them weigh less than existing engines of the “What do we want?” “Multi-fuel engines!” same power, and they automatically adjust the spark timing “What do we want?” “Easy maintenance!” and fuel/air mixture to optimize performance. They are so

14 KITPLANES Januaruy 2016 www.kitplanes.com & www.facebook.com/kitplanes adaptable that they fit almost any appli- the engine since the ring-to-barrel seal cation, and they incorporate subtle, but is maintained throughout the process. proven, features gleaned from decades of Another advantage is that the torque developing automotive racing engines. values for the cylinder case halves are not Each design includes five crankshaft relaxed during head work, which main- main bearings, a large roller-type thrust tains main bearing crush and fit. bearing, positive-pressure oil lubrica- Another difference between tradition to the cylinder valve operating tional engines and ULPower engines is mechanisms, solid-valve lifters with dia- cylinder head and upper cylinder valve mond-coated faces, and other user- and train component lubrication. Each maintenance-friendly features. ULPower upper cylinder is constantly lubricated through an external oil line. Take Your Pick This flow not only lubricates the valves The line of ULPower engines includes and valve guides, but also cools the heads. 4- and 6-cylinder models. Every engine Pressure oil also squirts at the underside is delivered to the buyer with an exhaust of each piston and cylinder wall. Lionel D’ Hondt, owner of DL Racing and system, an incorporated alternator with designer of the ULPower line of engines at rectifier and voltage regulator, electric The Squish the ULPower display at Sun ’n Fun in 2015. fuel pump and regulator, and a starter. All ULPower engines are multi-fuel The 4-cylinder engines start with the engines. They are designed to run on portion of the piston and the cylinder UL260 line. These include the UL260i mogas, including mogas blended with head. Squish creates turbulence, causing (97 hp) and the UL260iS (107 hp). up to 15% ethanol, as well as on 100LL a more homogeneous fuel/air mixture Displacement is 2592 cc (158.17 cu in), leaded avgas. The “i” models use mogas that results in a better-controlled and and the installed weight is reported at with an anti-knock index (AKI) of 91, faster combustion event. 159 pounds. while the “iS” models require an AKI of The higher-power 4-cylinder engines at least 93. Pre-Takeoff Full-Power Check are the UL350 line. These include the When asked how ULPower is able to The fuel injection system utilized with UL350i (118 hp) and the UL350iS (130 safely use mogas in its engines with com- ULPower engines is a closed loop system. hp). Displacement is 3503 cc (213.77 cu pression ratios of 9:1, Lionel D’Hondt, Fuel flows from the tank(s) to a pres- in). Installed weight is 172 pounds. the designer of the engine, explained that sure pump—a second pump is available The 6-cylinder engines start with the it is possible due to the “squish” designed as an option—and then to the two fuel UL390 line. These include the UL390i into the cylinder head/combustion cham- injector blocks mounted on each side of (140 hp) and the UL390iS (160 hp). ber. As the piston nears top dead center the inlet collector atop the engine. The The displacement for these engines is (TDC) on the compression stroke, a por- fuel pressure at the blocks is regulated 3888 cc (237.2 cu in). Installed weight tion of the fuel/air mixture is “squished” to maintain 43 psi (3 bar) above the is 220 pounds. between a portion of the piston and the existing atmospheric pressure. Changes The bigger-displacement 6-cylin- head. Squish design utilizes a very nar- in atmospheric pressure automatically der engines are the UL520 line. These row gap of less than 1 mm between a result in changes in the fuel/air mixture. include the UL520i (180 hp) and the UL520iS (200 hp). The 520 line has 5254 cc (320.6 cu in) displacement and The Mogas Formula an installed weight of 238 pounds. The following simplifies the sometimes confusing octane numbers found in the ULPower All ULPower engines have a 105.6 cc operating manuals. Octane numbers are provided in three formats: RON, MON, and AKI. (4.1 inch) bore. The 260 and 390 have A 95 RON octane engine requires mogas from your local U.S. gas station that has an anti- a stroke of 74 mm (2.9 in); the 350 and knock index (AKI) of at least 91. Each 98 RON octane engine requires mogas with an octane 520 have a stroke of 100mm (3.9 in). rating of at least 93. The rating published on gas station fuel pumps in the United States is All ULPower engines are direct-drive, what’s known as an anti-knock index (AKI). The AKI is derived by adding the research octane wet-sump engines, just like a Lycoming number (RON) and the motor octane number (MON) and dividing the total by 2. or Continental. But unlike the tradi- It may be difficult to find 93 AKI fuel in some states, but 91 octane is available tional engines, ULPower cylinder heads almost everywhere. are not screwed onto the cylinder bar- If 100LL is the predominant fuel used, ULPower reminds owners that lead deposits can rels to form a one-piece cylinder/head. accumulate on the tops of pistons, on combustion chambers, and in the lubricating oil. ULPower heads are bolted to the bar- ULPower also warns against using fully synthetic engine oil—since these oils don’t scavenge rels. This feature makes valve and head lead well—and advises users to shorten engine oil change intervals. work much easier and less intrusive to —S.E.

Photos: Steve Ells and courtesy of ULPower KITPLANES January 2016 15 Since maintaining this pressure is critical for safe engine operation, the ULPower operating manual requires a full-power engine run of at least 5 seconds prior to takeoff to determine if the fuel pump(s) is/are functioning correctly. Cool Runnings The redline (maximum) cylinder head temperature (CHT) for ULPower engines is surprisingly low at 356° F (180° C), especially for pilots and technicians familiar with the 460° F (238° C) and 500° F (260° C) CHT red lines for Con- tinental and Lycoming engines, respec- tively. Maximum continuous CHT is Each ULPower engine is delivered with a complete exhaust system, a wiring harness, 320° F (160° C). an ECU, the ignition coil pack, an alternator rectifier, a voltage regulator, the left and right ram-air housings (not shown) and an air/oil separator. There are three reasons for these surprisingly low numbers. The first is the water tube manometer is open to the ensure there’s a sufficient pressure drop sheer number and large size of the cyl- pressure of the ram air above the cyl- across each oil cooler installation. inder head cooling fins, especially in the inders, while the other end is open to exhaust port area of each cylinder. air pressure below the cylinders near Mounting Options Each ULPower engine is also shipped the cooling air exit from the cowling. Each ULPower engine is shipped with with a left and right cylinder head ram A differential of at least 20 mm (0.78 a straight (not Dynafocal) four-lug air box. The design of these boxes is not in) at 120 km/hr (64.7 kts/hr) TAS is mounting plate bolted to the back of left up to the airframe manufacturers; required across both the cylinders and the engine. There’s also an option to ULPower designs them. In addition the oil cooler. add a two-lug mount at the front of the to supplying these boxes, part of the The third reason, although it’s one engine to utilize a cradle mount system. post-installation testing and evalua- not touted by ULPower, is the transfer Engines are shipped with a standard- tion procedures consists of measuring of cylinder head heat due to the continu- length 55 mm (2.166 in) prop flange, the air pressure differential across the ous flow of lubricating oil flowing to the but since the flange can be removed cylinders and across the oil cooler (if valve mechanism in the head and being without splitting the case—try that installed). When testing cylinder cool- sprayed on the bottom of the aluminum on your Lycoming or Continental ing effectiveness, one end of a simple pistons. That’s the reason it’s critical to engine—three optional lengths can

(L): Each cylinder head is separate from the cylinder barrel. This permits valve and guide work without disturbing the ring-to-cylinder wall fit. The squish area generates turbulence to increase atomization and mixing of the fuel-air mixture. (R): Crankshaft connecting rod journals are large to lessen loading forces. Crankshafts in the four-cylinder engines are supported in five main bearings.

16 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Satisfied Customers Rick McGarity replaced the engine in his Searey with a UL350iS and has never looked back. He lists why he likes ULPower over the original engine: less expensive, instant start, instant throttle response, air-cooled, light weight, and simple installation. McGarity’s pre-purchase research convinced him that ULPower was a superior design in every regard to his old engine and a perfect fit for his Searey. “I have flown my [ULPower] engine more than 200 hours to date, and my prac- The gerotor-type oil pump is externally mounted on the front of the engine to permit tical experience has very much validated easy servicing and inspection. my pre-purchase research,” he explained. Dave Ferrell, who lives near Durham, be used if desired: 35 mm (1.38 in), 90 Manuals and Tools North Carolina, installed a UL350iS in his mm (3.54 in), and 110 mm (4.33 in). The ULPower web site(www.ULPower. Zenith 650 two years ago. He’s logged over Propellers are available from companies com) provides a full complement of 250 hours. such as Sensenich, WhirlWind, Catto, installation, operation, parts, and main- “You turn the key and it starts. Turn the Prince and Airmaster. tenance manuals, as well as service bul- key and it stops. There’s no shaking,” said Due to the large roller-type thrust letins on every engine. All of these files Ferrell. He also told me that the engine bearing, all ULPower engines can be are available for download in pdf format. is very smooth in all conditions and that installed in tractor (prop in front) or In addition to the manuals, all of the it hardly uses any oil. “The oil stays really pusher (prop in back) configurations. engine service bulletins are also on the clean. I might add half a quart of oil in 50 All that’s required to adapt the engine web site pages. hours,” he said. for pusher use is to rotate the inlet air The only part of the engine that is not Ferrell noted that in two years, he had collector, the exhaust system, and ram fully illustrated in an exploded view is the missed only one flight due to an engine air collector boxes 180° to accommo- engine control unit (ECU), the ignition problem; he found a broken weld at the date the change. ULPower also offers a coils, and the starter motor. Every part muffler-to-tailpipe joint. Robert Helms fan and ducting kit to convert any of its of the engine, as well as every part of the immediately shipped a replacement muf- engines to helicopter use. alternator, is shown in the parts manual. fler that was an upgraded version of the original part. In an effort to round out this story, I called the ULPower factory in Belgium. A spokesman told me that there have been some problems and some changes have been incorporated to increase quality. For example, the design of the oil lines to the cylinder heads was changed due to small leaks; the exterior coating on the cylinders was upgraded to prevent rusting; a new lock was designed for the prop hub; the camshaft was lengthened slightly, and the coating on the cam fol- lowers was changed. The factory charges 6,000 euros (about $6,750 depending on exchange rates) for a factory overhaul that includes tested and refurbished reciprocating parts. It costs 8,000 euros (about $9,000) for an overhaul The compact ULPower components fit onto any firewall. This installation shows the that includes all new reciprocating parts. optional second fuel pump. —S.E.

KITPLANES January 2016 17 U.S. owners will need to buy a set of metric-sized internal wrenching sockets, as well as a conversion chart for converting European torque specifications to U.S. torque specs, since all specs in the manuals are in Newton/meters. For those that want to get started right away, it’s helpful to know that 1.35581794833 N-m equals 1 foot-lb. For example, the torque specifica- tion for the four engine-mount bolts that secure the 350 series engines to the mount is written as 25Nm. Conversion to 18.4 foot-pounds is easy by using any of the online conversion sites. Slots machined in the starter ring gear send crankshaft position data to the ECU for ignition timing. There are other metric notations such as thread sizes (M12 x 1.5) and wire worked with ULPower to develop an to Robert Helms, general manager sizes (2.5 mm), but these are relatively aerobatic version of its 107-hp UL260iS of ULPower North America (www. easy to convert. engine, the UL260iSA. Working in ulpower.net) in Lake Ozark, Missouri, conjunction with the ULPower design approximately 150 ULPower engines Real-World Experience team to track engine performance, these have been shipped to users here. Since the ULPower engine’s first intro- engines have now been flying for over One of the first companies in the U.S. duction in 2002, over 550 engines have 900 hours. According to a spokesman to embrace ULPower was Zenith Aircraft been shipped from the factory in Bel- from the factory, a ULPower engine in in Mexico, Missouri (www.zenithair. gium. In 2009 the Twister Aerobatics France has logged over 1,100 hours. com). Zenith offers full firewall-forward Team (www.twister-aerobatics.co.uk), As a result of its work with the Twister installation kits for ULPower engines for a two-airplane aerobatic team flying Duo and Just Aircraft, it is now possible the STOL CH750, the CH750 Cruzer Silence SA1100 Twister single-seat air- to order any ULPower engine in an aero- and the Zenith CH650. planes, selected ULPower engines when batic configuration. Helms also told me that ULPower it needed more power to expand its ULPower engines are just beginning North America has agreements to sup- aerobatic routine. Peter Wells of Twister to gain traction in the U.S. According ply ULPower engines to many airplane

Zenith Aircraft offers full firewall-forward installation kits for ULPower engines for the CH750 Cruzer (shown here), the STOL CH750, and the Zenith CH650. (Photo: Notley Hawkins)

18 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes much heavier, but extremely durable, Lycoming 4-cylinder engines. How- ever, “I’ve really been putting the motor through its paces, and it’s been a good experience so far,” he said. Smith has run a variety of fuels in the 520i. “It does best on high octane mogas,” he explained. He also reports that the crew at Just has been sending in oil samples, and to date “they’ve been clean.” So far, so good. North-American Parts and Support Helms recently announced that Wicks Robert Helms is general manager of Aircraft and Motorsports of Highland, ULPower North America. Illinois, (www.wicksaircraft.com) has original equipment manufacturers been named the exclusive parts supplier (OEMs) including Arion Aircraft, for ULPower North America. Keith Kitfox, Hatz Bantam, Bede Corp, Just Gibbs is the primary contact. Aircraft, RANS, Sport Performance Ray Lawrence at Kaolin Aviation in Aircraft (Panther), and others. These Sandersville, Georgia, has been named companies have developed, or are in the the first authorized ULPower service process of developing, firewall-forward center in the U.S. Kaolin is also develop- kits for ULPower engines. The kits vary ing firewall-forward kits for additional from very complete to those that supply aircraft, including the Van’s RV-4. only a mount and cowling. Additional The RV-4 was designed for Lycoming packages for other kit aircraft are also O-320 and O-360 engines from 150 to being developed. 180 hp. According to Lawrence, the 200- hp UL520iS weighs about 40 pounds Just Aircraft’s Installation less than a typical Lycoming installation. Just Aircraft recently introduced a More power from a smaller package that ULPower 180-hp UL520i engine in weighs less; what’s not to like? the Stretch XL version of its popu- Lawrence also says he will begin lar SuperSTOL (see page 6). After development of a 4-cylinder engine installing the engine, Just discovered firewall-forward package for the Sonex that, due to the extremely high deck family of airplanes in the near future. He angles achieved during maximum- can be reached at [email protected] performance takeoffs, the oil pickup or by calling (478) 232-9560. tube in the engine sump would unport So there it is. ULPower engines have momentarily. ULPower solved the been slow to cross the Atlantic—they’re problem by quickly delivering a flop manufactured in Belgium—but are rap- tube that automatically adjusts for idly gaining favor as satisfied users spread steep deck angle operations. the word through online chat rooms and “Since the oil pan is simple to remove owners groups. and replace, we had the new pickup The question that’s unanswered today installed in less than four hours,” said is will these engines achieve the “bul- Harrison Smith, Just Aircraft’s test and letproof” status of Lycoming’s 4-cyl- instructor pilot. “We’ve now flown the inder aero engines. Time will tell that ULPower 520i on the Stretch XL for story, but from what I know about these over 70 hours.” engines I’d love to see one installed on Like others, Smith would like to my airplane. J see the data from “50 of these engines with over 500 hours each” before he’s For more information on prices and deliv- convinced that ULPower is going to be ery, contact Robert Helms at rhelms@ as favored by remote operators as the ulpower.com or (573) 434-0075.

KITPLANES January 2016 19 On a Wing and a Whim Flying a scratch-built Sonex is good for the soul. By Kerry Fores

On the morning of July 4th, I slipped from between cotton my kids from my life more efficiently than a team of Navy bedsheets and decided in that moment to fly. Anywhere. SEALs could have. Simply put, I was deciding in one moment To give my impromptu flight a light-hearted spin, I joke what to do with the next. that I woke up in need of a shot glass with a ceramic jackalope Metal Illness, a Sonex I scratch-built in my garage, and I had glued to its bottom and flew 700 miles to Wall Drug, in South taken trips together, but never like this. This trip began in my Dakota, to buy one. But in truth I was taking flight from 20 mind as I rolled from bed and developed even as we flew home years of Fourth of July family tradition, an unwanted holiday the following day. To be honest, the seeds of this impromptu weekend, and too much time to think. I was running from a flight were planted days before with the observation that present that seemed meaningless since divorce had extracted fair weather had settled on the Upper Midwest, bathing it

20 KITPLANES Januaruy 2016 www.kitplanes.com & www.facebook.com/kitplanes Fort McCoy’s Volk Field, east of La Crosse, Wisconsin, confirmed Just west of the Mississippi River and La Crosse, Wisconsin, the land- my position on the sectional. scape flattens quickly and roads carve the land into uniform squares. in sunshine and humid warmth. I was Mississippi where my kids had fed chip- water’s edge. Farmsteads hid within pro- fortunate to have just performed rou- munks. I couldn’t allow my thoughts to tective clusters of trees. The flat horizon tine maintenance on my silver-winged linger there so, more from boredom than remained continuously distant. Sonex, not in anticipation of a trip, but hunger, I ate a banana and tossed the limp Keeping Metal Illness on task required to pass the hours of the previous week- peel on the passenger’s floor. It jumped little effort. Thumb and index fingers end. A dash of lucky timing that was, and crawled on the vibrating floor like a lightly on the stick, an occasional nose- but my attention to routine mainte- yellow octopus, amusing me enough to down trim correction to compensate nance is why it has never let me down in take its photo. It was a distraction. for the decreasing fuel load, a habitual 500 hours of flying. West of the Mississippi River the land scan of the gauges. It was too easy to I knew I’d be gone overnight—even flattened and the cumulus clouds, which get lost in thought in the near silence if I didn’t know where I’d be—and floated lazily above western Wisconsin, of active noise-reduction headsets and gathered the basics for a night away. disappeared behind me, revealing a land- the warmth of the sun; I welcomed the While carrying my small bag to the car, scape partitioned by roads into uniform need to attend to my decreasing fuel I noticed my tent and, after evicting the squares. The roads converged at the hori- supply. Of the few airports that lay near spiders, brought that as well. zon, if not first fading into the increasing my hastily drawn course line, Pipestone haze. Occasionally a road veered from its (just shy of South Dakota’s eastern bor- No Particular Place to Go arrow-straight path to dodge a stream, der) was positioned for an unhurried The drive through Oshkosh to the air- trace the edge of a lake, or accommodate cruise descent. port gave me time to think about a desti- a landowner’s protests. Once, even a lake nation. West. I’ll go west. But where was wasn’t enough to alter a road’s course, Pipestone, Minnesota west? South Dakota—specifically, the and the road appeared to have been built Pipestone’s airport was quiet. The hot, Badlands and Mount Rushmore. South upon the lake’s surface. holiday weekend had most people Dakota had been a favorite family vaca- Towns, scarce on the landscape of occupied with summer recreation, tion, and it seemed a worthy and scenic corn and wheat, crowded against the parades, and family gatherings. While destination by air. I stopped at the FBO to purchase a Cheyenne sectional, but none were available. I rolled Metal Illness into the mid- morning sun and programmed the GPS with some distant waypoints. By 11 a.m. I was 60 miles west of Oshkosh, in a clean, blue sky flying toward a soft horizon of low, scattered clouds. Beneath me passed Wisconsin’s green, summer pallet and abundance of lakes, still awaiting weekend boaters. With my heading and altitude stabi- lized, I looked for landmarks. Volk Field was framed between clouds, just where it belonged. La Crosse, Wisconsin, and the Mississippi River were quick to follow. My eyes fell on a wayside on the bank of the The swollen Fox River in East Central Wisconsin.

Photos: Kerry Fores and Mark Schaible KITPLANES January 2016 21 I quenched Metal Illness’ thirst, a middle-aged man approached from a distant hangar. After the usual questions about my Sonex, where I was coming from, and where I was going, he told me he was restoring a Cessna and, as restorations often go, it had become a larger project than anticipated. He added that, because he was divorced, he had nothing else to do. I could sympa- thize—the combination of divorce and aviation delivered me to Pipestone that day as well. I politely acknowledged The finite surface of South Dakota’s Lake Madison churned with holiday boaters as I his comments, lowered myself into the passed overhead, in a deep ocean of air. cockpit, and continued running. Lake Madison, 30 miles northwest nothing. The screen, normally populated could not penetrate. I climbed to find the of Sioux City, South Dakota, churned with towers, roads, towns, water fea- ceiling of the haze, but there was none, so with holiday boaters. From high above, tures, and airports was white sans two I descended to bring the earth into better the lake’s dark surface looked like a night thin, gray lines: Highway 34 parallel focus. At 6500 feet I scattered a flock of sky filled with comets. Boats were creat- to my course, and an unidentified road birds, their white wings tipped with black, ing crisp, white wakes that spiraled in all which teed in from the south. It seemed their bodies tumbling from my path. directions. Some boats were chased by that to get somewhere I must first pass We droned on together, Metal the smaller wake of water-skiers or inner through nowhere. A metaphor, maybe, Illness and I. We were not commit- tubes towed behind. The apparent chaos for post-divorce life? ted to continue west. We could turn on the lake’s finite surface made me The sky I now occupied was far differ- back at any moment. We could turn appreciate the vast, three-dimensional ent from the one I enjoyed in Wisconsin. left and go south, turn right and fly ocean through which I flew. The sun was passing on my left. The smart north, or land at the next airport and West of Lake Madison something blue sky and crisp cumulus clouds had declare, “We made it!” But the Bad- appeared on my GPS I had never seen: been replaced by a haze my pinched eyes lands and Mount Rushmore were my

The airport at Pipestone, Minnesota, was a necessary fuel stop. Despite the flatness of the landscape, the field elevation was already 1000 feet higher than Oshkosh, Wisconsin, as I traveled west, toward the Rockies.

22 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Metal Illness posed next to the “Welcome to Wall” sign. The Sonex was a perfect travel Dave Hahn, Wall’s mayor and airport companion. manager. self-invented purpose, so we continued Wall, South Dakota to the Welcome to Wall sign. Open- forward. Without purpose there is no Wall cannot be ignored. Driving within ing the canopy provided no relief from forward, just as without gravity there is 500 miles of Wall, you see a Wall Drug the shimmering heat. Wall Municipal no up nor down. I urged each landmark billboard every two miles. On our family had five buildings, if I count the phone to appear on the GPS and celebrated as vacation we had no intention of stopping booth. I shouted “Hello?” into an open each passed behind the wings. at Wall Drug; our trips favored natural hangar, and a friendly voice answered my South Dakota slowly rises toward the attractions over tourist attractions. call. The man asked how he could help, Rockies, but with the Rockies far beyond However, the barrage of billboards elim- and I prioritized my needs: bathroom, sight, and most of South Dakota flat, inated our ability to resist. The stop was fuel, Cheyenne sectional, food. While this is easily forgotten. My eyes—cali- thusly justified, “We’ve driven this far, pointing the way to the bathroom, he brated over Wisconsin and Minnesota we’re this close, why not?” assured me he could help with my other to accept 6500 feet above sea level and I could not ignore Wall on this day needs as well. 6500 feet above ground level as equals— either, even by air. I was nearing airspace Dave Hahn is one of the gems you needed a conscious assist to maintain that I wouldn’t fly without a sectional, often find hiding at airports. After I the proper altitude. Though still flying I needed fuel, I needed a comfort stop, emerged from the bathroom, he helped at 6500 feet above sea level, the ground and I needed food. My descent to Wall with fuel, offered me a Cheyenne sec- had crept 1700 feet closer to the resting allowed a brief glimpse of the Badlands, tional, and set about to know me. He wheels of my Sonex, and grew closer still but the hot, turbulent winds brought my was very interested in my name and took with each passing mile. attention back to piloting Metal Illness great care committing it to memory, Lake Sharpe, a lazy expansion of the through a successful landing. “Fores, F-O-R-E-S, Fores. Interesting.” Missouri River, drifted off the bottom Wall Municipal Airport appeared to As we spoke and unhurriedly fueled my of my GPS at 3:19 p.m. Soon I would offer less than I expected but delivered parched Sonex, I entertained the idea of fly off the edge of my Omaha sectional. far more. With no FBO or self-serve fuel spending the night in Wall, camped next I decided to continue to Wall using my island in sight, I taxied past a lone aircraft to my airplane. GPS. I never rely fully on a GPS as batteries can die, fuses can blow, and software can crash. But if it were to fail my plan was to turn south, intersect Interstate 90, and fly the interstate directly to Wall. I had a printed copy of Wall’s airport diagram, so I had the necessary airport information even if I arrived blind. The famous Wall Drug in Wall, South Dakota. Wall’s popularity began in the hot summer of 1936, when the owners struck on the idea of giving free ice water to parched travelers. It now attracts up to 20,000 visitors a day. It has somehow attracted me three times, though I’ve never struck out for Wall Drug on purpose.

KITPLANES January 2016 23 Wall Drug is unique—a sprawling complex of connected stores and each is a department: cowboy hats, western shirts, ice cream, jewelry (Black Hills gold and turquoise, of course), souvenirs, art. I had no specific reason to go there other than, “I’ve flown this far, I’m this close, why not?” I moved quickly from store to store, but felt the need to purchase something to commemorate the trip. After considering the purchase far too long, I settled on a shot glass with a jackalope glued to its bottom. I had lost interest in touring the Bad- Crossing the Missouri River, just south of Fort Thompson. lands and Mount Rushmore by air. I started this journey on a whim, so why up our conversation where we had left my desire, so I continued to fly in the couldn’t I change it on a whim? Return- off earlier. Dave, I learned as I sipped moment, studying the landscape below. ing to the airport on foot, I smiled upon my soda—discussing South Dakota’s The smooth, green hills below were seeing an official sign that identified a weather, AirVenture, the source of the carved with deep, dry gullies that radiated gravel-covered rectangular area near the haze (wildfires) and the history of Wall down the slopes like lightning bolts or airport’s simple fence as “Short-Term Drug—was not only the airport’s man- cracked glass. Steep dirt banks and grassy Parking,” and pointed to the Main Gate, ager, but also Wall’s mayor. stream bottoms waited to usher the excess a 4-foot-tall chain-link gate swung open. waters of the next summer storm to shal- Dave offered me a soda, and we settled Heading East low potholes, to the Missouri River, and into lawn chairs placed in the shade of Flying east that evening, the sun was to destinations beyond. The water-filled the open hangar door. Though I had again behind me, illuminating the way. potholes attracted black Angus to their decided I couldn’t stay, I was in no hurry My course could eventually deliver me edges like ants to a dropped Popsicle. to leave. The summer sunset comes late to Detroit Lakes, Minnesota, where East of Pierre and the Missouri River, in the northern plains. My undeclared friends were vacationing on one of Min- the landscape quickly flattened again. destination for the evening could be as nesota’s 10,000 lakes. They didn’t know It was 8 in the evening and the shadows close as 20 minutes, or as far as the sun’s I was coming, but neither did I. Maybe were growing long, racing me eastward. fading rays and Metal Illness’ navigation I’d make a beeline for home or maybe It was time to land and only two options lights could take me. Dave and I picked I’d…well, detailed planning was not existed: the towns of Highmore and

24 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes The deep gullies radiating throughout South Dakota’s western hills are proof that the Miller, South Dakota, volunteered itself as forces that eroded these mountains into smooth hills are still at work. my host for the night. Miller. Highmore required a deviation idle, Miller, bathed in the orange light of to the parking ramp, I found the airport to the north and a rapid descent, but a hazy July Fourth sunset, oozed Ameri- to be unpopulated and the visible air- Miller fell near my flight path, allowing cana. To my right the bright lights of a craft to be in disrepair. I pulledMetal Ill- another cruise descent, just as Pipestone grandstand illuminated a dirt racetrack, ness into the grass next to an alfalfa field had earlier in the day. and off my nose cars were already seated and set up my tent. for a double feature at the drive-in the- The small pilot lounge provided an Miller, South Dakota ater. Miller seemed the perfect place to opportunity to wash up, but with no To my knowledge Norman Rockwell mark America’s birthday. I tightened my vending machines, dinner would have never painted an airscape, but if he had, harness, tidied the cockpit, and finished to be found elsewhere. I began walking it would have looked like Miller that eve- my descent with a landing worthy of the toward town, but as I walked, the farther ning. As I glided overhead, throttle near fresh, black, asphalt runway. As I taxied away town seemed to be. I considered

KITPLANES January 2016 25 turning back to preserve my remaining energy, rather than use it up on a potentially fruitless search for food, but a family on their porch assured me I’d find food and gave these directions, “Go straight to Broadway Street and then turn left.” I thanked them, and as I continued walking they jokingly added, “It’s closer by car.” The Hi Lite Bar and Lounge was my second choice, having first discounted a bar that served hamburgers, but was hosting a class reunion. I didn’t care to pay the cover charge for the band, and I Metal Illness and I set up camp off the tarmac in Miller, South Dakota. doubted I would bump into any former classmates, so I continued to the Hi Lite. was poor. I treated myself to a steak and Detroit Lakes, Minnesota A waitress seated me in a far corner of cocktail, and trekked back to the airport The Detroit Lakes airport radio fre- the empty dining room, facing the wall. under a dark sky punctuated by the spo- quency was busy. I landed in front of a I slowly slid the placemat and silverware radic flash and pop of fireworks. Cirrus, and we met at the fuel pump. I to the other side of the booth and qui- As I lay in the tent, pitched in the grass had an audience as I fueled and secured etly told her I needed to see the door, next to Metal Illness, sleep came fitfully. my Sonex, as it was Saturday morning there were people looking for me. The The town’s fireworks began after I -com and Detroit Lakes Aviation’s Duane humor was lost, or perhaps my delivery mitted myself to bed, but they sounded Wething Coffee Club was in full session. spectacular. The airport’s rotating bea- Outside and in, aviators holding donuts Kerry Fores Fores Kerry Kerry Fores is a private con flashed on the tent walls: White. and coffee-filled foam cups milled about pilot. He scratch-built his Green. White. Green. White. Green. individually or conversed in huddled Sonex, Metal Illness, prior The wind remained calm long enough to groups. And, most unusual for an avia- to going to work for Sonex lull me to sleep, then stirred the tent to tion gathering, the hangar’s lobby was Aircraft in 2003. Kerry wake me up. In the morning I emerged filled with women quilting, knitting, provides tech support for to findMetal Illness covered in dew, and and crocheting. Typical of small air- owners and builders of the the sky promising another nice day of ports, I was offered a ride to get lunch. Sonex Aircraft product line, flying. After circling the town of Miller but his stated goal is to starve once while I climbed, I pointed the pol- to death as a ished spinner a little north of east, com- writer. His mitting to the possibility of stopping in blog is at Detroit Lakes. www.The LifeOf Danger.com.

26 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Saturday mornings at the Detroit Lakes, Minnesota, airport are like so many others: This shot glass is a souvenir of a flight I pilots, coffee, and donuts. took on a whim, on wings I built myself. I phoned my friend Cathy before tak- but she insisted I spend the afternoon Flying occupies my mind and body ing off and surprised her with the dec- with them. I didn’t refuse. while nourishing my soul and spirit. laration that I was nearby and wanted Late that afternoon Jim drove me That flight was exactly what I needed to to make a pass by their cottage before back to the airport. As I climbed east- restore focus. Metal Illness assumed the turning for home. She gave me a head- ward, to 9500 feet, I leaned the fuel role of mental therapist, and sport avia- ing to fly and said to look for Jim and mixture until Metal Illness was sip- tion became support aviation. Though the boys on the lake, circling their boat ping fuel and home was within reach. it happened a few years ago, I still look to mark their location. I felt like a fighter The air was flawlessly smooth and, back on the trip fondly. The jackelope pilot answering a request for air support. with Earth over a mile below, it didn’t shot glass is a souvenir not of Wall Drug, After a few passes I rocked my wings and seem like we were moving despite a but of a flight I took on a whim, on wings told Cathy I was departing for Oshkosh, 150 mph groundspeed. I built myself. J

KITPLANES January 2016 27 Light Aircraft Fuel System Design Part 2: Every component is there for a good reason! By Ken Krueger

Last month we discussed aspects of light aircraft design and Having a good grasp of the fuel system in whole, let’s narrow how the fuel system plays into the overall picture. The designer the focus and look at the fuel system part by part. determines how much fuel the aircraft needs to carry to meet customer needs and how best to locate the fuel considering Fuel System Detail Design the sometimes-conflicting requirements of handling quali- Following the path of the fuel from the point of entry into the ties. This includes minimizing cg travel as fuel is consumed; system past each of the various fuel system components until how the inertia of fuel affects the dynamics of the airplane in it finally enters the engine, each part of the fuel system will be pitch, roll, and yaw; how the mass of fuel and its location rela- discussed and the design requirements applicable to that com- tive to the axis of torsion of a wing or stabilizer can affect the ponent will be reviewed. A homebuilt aircraft is not strictly flutter speed of the aircraft; and finally, how to configure the required to meet any design standards or requirements, but the airplane so that fuel is safely contained, even in the event of a successful kit aircraft designs meet many of the same criteria crash. The introductory article also included diagrams of two that a certificated light aircraft must meet. typical light-aircraft fuel systems that show all of the separate There is a great deal of similarity in fuel systems between dif- components in the overall design. ferent aircraft, so the components that are common to every

28 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes fuel system will be reviewed before discussing components that are unique to certain systems. Fuel Fill Opening and Cap Even something as seemingly simple as the fuel fill opening and filler cap have a number of design requirements beyond simply being a sealable opening where fuel is introduced into the system. Some amount of fuel is spilled nearly every time an aircraft is refueled. Spilled fuel is not only a fire hazard, but the fumes are nauseating and unhealthy for humans Figure 1: The recess around the Cessna 172 filler has a drain line to carry away any to breathe. For this reason, the tank spilled fuel. and cap must be designed to prevent spilled fuel from entering the fuel tank with turbine engines, the inside diam- attention and prompt a precautionary compartment or any part of the airplane eter of the fuel filler opening must be no landing before much fuel is lost. other than the tank itself. This means, smaller than 2.95 inches. This is to pre- of course, that the fill opening cannot vent fueling of a gasoline engine aircraft Fuel Tank be located inside the passenger com- with jet fuel. The tank is the place where fuel is stored partment. Most aircraft have fill open- How many pilots have either failed to until it is consumed by the engine and is ings located such that spilled fuel runs properly secure a fuel cap (or even left the first place where particle contami- more or less harmlessly off the wing or a fuel cap behind!) after refueling? For nants and water are separated from the fuselage. Some aircraft, however, must this reason, another fuel system design fuel. Because water and particle contam- utilize a scupper constructed around requirement is that siphoning of fuel inants are heavier than fuel, they will the fuel fill opening to drain away any (other than minor spillage) may not settle to the bottom of the tank. Each spilled fuel (see Figure 1). result if the fuel filler cap is improperly fuel tank is required to have a drain- To minimize the likelihood of some- secured or left off altogether. Figure able sump with an effective capacity, in one putting the wrong fuel in the wrong 2 shows the Fairchild 24’s classic “art the normal ground and flight attitudes, airplane, fuel fill openings must be deco” style fuel cap, which is tethered of 8 fluid ounces or, if the tank is larger marked at or near the filler cap with the to the filler with a short chain. Teth- than 25 gallons, 0.25 percent of the tank required fuel type (avgas, mogas, jet) ered fuel caps are a mixed blessing capacity. The tank design must allow and the minimum fuel grade. The inside as the benefit of never leaving a cap any hazardous quantity of water to drain diameter of the filler opening for air- behind at the pump is largely offset by from any part of the tank to its sump planes with engines requiring gasoline the damage done to the finish when the with the airplane in the normal ground as the only permissible fuel must be no cap is left unsecured. At the very least, attitude. By draining a sample of fuel larger than 2.36 inches. For airplanes the thumping noise will get the pilot’s from each sump and visually inspecting it, the purity of the fuel in the tank can be assured before leaving the ground. Fuel tanks fall into three basic categories: integral fuel tanks, rigid removable tanks, and non-rigid removable or “bladder” tanks. A tank is called “integral” when it is simply part of the aircraft structure that has been sealed to contain fuel. This type of tank provides the highest volume of space available with the low- est weight. It is also considered the least crashworthy of the three types of tanks. Integral fuel tanks must be able to withstand the pressure developed during the maximum limit acceleration of Figure 2: Tethered “art deco” style filler cap of the Fairchild 24. the airplane when fully filled with fuel

Photos: Ken Krueger; Air-to-air photo: Richard VanderMeulen KITPLANES January 2016 29 Figure 3: The integral tanks of this Cirrus SR22 are accessed via Figure 4: The Rans S-20 uses a molded plastic wing tank. removable covers on the bottom of the wing. with the critical limit structural loads puncture resistant and can deform any new aircraft will be developed that simultaneously applied. Integral fuel without spilling fuel (see Figure 4). The use bladder tanks. tanks must also have means for inte- beauty of a rigid removable tank is the Regardless of the type of construc- rior inspection and repair. Often this convenience of being able to remove a tion and capacity, each fuel tank must be is accomplished by making the integral tank for repair or replacement. able to withstand the vibration, inertia, tank removable as is the case with the A non-rigid removable or “bladder” fluid, and structural loads that it may be Piper PA-28, PA-32, and the RV-4, -6, tank, as the name implies, is made out of a subjected to in operation. With some -7, -8, -9, -10, and -14. Otherwise, access flexible rubberized material and requires variation, each fuel tank must withstand openings in the skin are the means of continuous support from the airframe. a positive internal pressure of 3.5 lb/in2. gaining access for inspection and repair The bladder is installed in a special bay Fuel tanks must be designed, located, (see Figure 3). through a small access opening. Being and installed so as to retain fuel when A rigid removable tank is a separate flexible, the bladder must be attached to subjected to upward acceleration of 3.0 fuel container that is supported by the the structure with clips or other fasteners. G (4.5 G if acrobatic category), forward airframe but, because it does not carry It must lay smooth in the bay because any acceleration of 9.0 G, sideward accelera- any structural loads, is not considered wrinkles on the bottom surface will pre- tion of 1.5 G, and downward accelera- integral. Rigid removable tanks are vent water or particle contaminants from tion of 6.0 G. held in place by screws or some type of migrating into the sump. A bladder tank The total useable capacity of the fuel strap arrangement. Tanks of this type is considered to be the most crashworthy tanks must be enough for a “reasonable” are often made from sheet metal and of all tank types. The Beechcraft Bonanza amount of flight time. Different light are assembled by welding or riveting. and Cessna 180 are examples of light air- aircraft design standards call for differ- Rotationally molded plastic tanks have craft that use bladder tanks, but they are ent minimum fuel capacities ranging become common in later homebuilt rarely (if ever) used in homebuilt aircraft. from 30 minutes to 1 hour at the fuel designs and are considered good for Given the crashworthiness advantages of consumption of the engine at maxi- crashworthiness as the plastic is both molded plastic tanks, it is doubtful that mum continuous power. Most aircraft

Figure 5: Fuel capacity for certain versions of the Sukhoi 26 limits flight time to less than an hour.

30 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Figure 6: The Piper Comanche fuselage is lower than the bottom Figure 7: Bottom view of a PA-28 left wing showing the separation of the wing, which keeps the tank from becoming ruptured in the between the landing gear and the fuel tank. event of a gear-up landing. designers will provide fuel capacity suf- Fuel tanks may be located in the fuse- electrically bonding the airplane to the ficient for at least 2 hours of operation lage, wing, or even in the empennage, but ground fueling equipment. For a metal at maximum continuous power, but the with certain limitations. No fuel tank aircraft with metal tanks, this is accom- designer of a competition aerobatic air- may be on the engine side of the firewall. plished by grounding to practically any craft may want to minimize fuel capacity There must be at least one-half inch of part of the airframe or even the engine. for reasons of safety and performance. clearance between the fuel tank and the But for a non-metallic aircraft and/or For example, the fuel capacity of a stan- firewall. No part of the engine nacelle non-metallic fuel tanks, an important dard Su-26 (see Figure 5) is only 16.7 skin that lies behind a major air opening detail that the designer must provide is a gallons. The Sukhoi’s 360 hp engine will from the engine compartment may act as means to dissipate static electricity. easily drink that amount of fuel in less the wall of an integral tank. Fuel tanks than an hour. must be isolated from personnel com- Fuel Quantity Indicator For aircraft with retractable landing partments by a fume-proof, fuel-proof The pilot must have a means during gear, each tank must retain fuel in the enclosure that is vented and drained to flight to determine the quantity of use- event of a gear-up landing on a paved the exterior of the airplane. Air ventila- able fuel remaining in the tank. The runway (see Figure 6). The tank must tion and fluid drainage must be provided simplest and least failure prone quan- also retain fuel in the event that one in each fuel tank compartment and in tity indicator is a section of transparent landing gear leg is collapsed and the each compartment adjacent to an inte- tube or a small window that allows the other landing gear legs are extended. In gral fuel tank to prevent accumulation of pilot to directly see the level of useable such cases, the possibility that an engine flammable fluids and vapors. fuel in the tank (see Figure 8). The next mount could tear away and rupture a Much like rubbing a balloon against simplest direct quantity indicator is a fuel tank must also be considered. your cat, the movement of fuel against float connected to a rod that protrudes For fixed-landing-gear aircraft, each the interior of a tank creates an electri- from a hole in the filler cap (see Figure fuel tank must be designed to retain fuel cal charge. To avoid buildup of electrical 9). Other quantity indicators have a float in the event that a landing gear leg fails charge and possible sparking, each fuel attached to a mechanical indicator that or is torn away (see Figure 7). filling point must have a provision for is mounted directly to the tank. The use

Figure 8: The fuel level in this Just Aircraft SuperSTOL is shown Figure 9: Baby Ace filler cap. A float attached to a piece of piano directly via a transparent sight tube. wire passes through the cap to indicate fuel quantity. The tube that is bent to face forward is the vent.

KITPLANES January 2016 31 Figure 10: Electric “float type” fuel sending unit as installed in Figure 11: Placing the vent outlet behind the strut helps protect it an RV-7 fuel tank. Note the coarse mesh fuel outlet strainer in from obstruction or damage. the lower right corner of the tank. of these direct-reading indicators is pos- tank. A further advantage of a capacitive equal to at least 2% of the fuel volume sible only when the fuel tank is located sending unit is that the quantity indica- has been designed into the fuel tank, the immediately adjacent to the cabin. tion does not change as much with air- vent must discharge clear of the airplane, When use of mechanical indicators craft attitude as with other types. The but for the sake of practicality, all vents is either not possible or not desired, an major disadvantage of a capacitive send- should do so. electric quantity indicator is most coming unit in an aircraft that uses gasoline Each fuel tank must be vented from monly used. The most common fuel level is that avgas, mogas, and mogas with the top part of its volume so that even sending unit consists of a float attached ethanol each have different dielectric when the tank is full of fuel, air can to an arm that is in turn attached to the constants; this means that the system move freely in and out with changes in wiper on a variable resistor mounted can be calibrated for only one particular fuel level, air pressure, and temperature. inside the tank (see Figure 10). The send- gasoline type and will not be accurate if Each vent outlet must be located and ing unit is wired to an electronic gauge another type of gasoline is used. constructed such that the possibility of in the cabin calibrated to display the it becoming obstructed by ice or other amount of usable fuel in the tank corre- Vent foreign matter (dirt, insects, etc.) is min- sponding to a particular electrical resis- This allows air into the fuel tank to imal. This is accomplished in a variety tance. This type of quantity indicator is replace the volume of fuel consumed by of ways. Many strut-braced high-wing almost universally used on automobiles the engine and to allow for equaliza- aircraft meet this requirement by plac- and has proven to be both sufficiently tion of pressure as the aircraft climbs or ing the vent outlet directly behind the accurate and reliable. descends. For some fuel systems, venting strut where it is still easily inspected, but Another type of electric sending unit can be accomplished by simply putting is protected from becoming obstructed consists of one or more capacitors in a tube (see Figure 9) or relatively small by ice or insects or even a bird strike (see the tank. Because the capacitance var- hole in the filler cap. For most fuel sys- Figure 11). This location also protects ies according to how much fuel is in tems, a separate vent line leading from the vent from people who like to bump the tank, it is possible to sense fuel level the top of the tank to some discharge their heads on such things. Other air- without having any moving parts in the point is used. Unless an expansion space craft have unshielded vent outlets, but

Figure 12: The vent outlet on a PA-28 protrudes from the lower Figure 13: Light aircraft that may encounter icing conditions surface, but is quite far aft on the wing. protect the vent outlet by placing it in a recess on the bottom of the wing.

32 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes 172, which has two tanks, each with two outlets, must have four strainers (see Figure 15). For reciprocating engine powered airplanes, the strainer must have 8 to 16 meshes per inch so only relatively large particles will be captured by the strainer. Other strainer design requirements are that the clear area of each fuel tank outlet strainer must be at least five times the area of the outlet line, the diameter of each strainer must Figure 14: Fuel outlet strainers are typically threaded into a pipe thread fitting built into be at least that of the fuel-tank outlet, the tank. and each strainer must be accessible for inspection and cleaning. they are located on the airframe where the fuel line and impede or even totally Looking ahead, this article series ice is unlikely to accumulate such as on stop the flow of fuel to the engine, each will cover the functionality require- the bottom of the fuselage or some dis- tank outlet is required to be protected by ments for fuel lines, fuel pumps, shut- tance aft from the leading edge of the a course mesh strainer (sometimes called off and/or selector valves, and fuel wing (see Figure 12). The most effective a “rock filter”). See Figures 10 and 14. filters. Also covered will be the hows strategy for protecting the vent outlet Because each fuel outlet must be and whys of header tanks, fuel returns, from icing is to place it in a recess on the protected, an aircraft like a Cessna and negative-G flying.J bottom of the wing (see Figure 13). There may be no point in any vent line where moisture can accumulate with the airplane in either the ground or level flight attitudes unless drainage is provided. Any vent drain valve installed must be accessible for drainage. No vent may terminate at a point where the discharge of fuel from the vent outlet will constitute a fire hazard. For example, placing a fuel vent directly in the exhaust stream or in a location where lightning is likely to attach to the airframe would not be considered an optimum choice. Each vent must be constructed to prevent siphoning of fuel during normal operation. For acrobatic category airplanes, excessive loss of fuel during aerobatics, including short periods of inverted flight, must be prevented. It must also be impossible for fuel to siphon from the vent after returning to normal flight. Vents must be arranged to prevent the loss of fuel, except fuel discharged because of thermal expansion, when the airplane is parked in any direction on a ramp having a 1% slope. Fuel Outlet Strainer To reduce the risk that foreign objects Figure 15: Each Cessna 172 fuel tank has two outlets to ensure that fuel will flow in all or other fuel contamination can enter flight conditions.

KITPLANES January 2016 33 Gear Collapse

Not all mishaps happen in the air. By Russ Erb

It all started innocently enough… On June 7, 2015, the seventh anni- on its gear, and it would be happy while For the last several years, my Bearhawk versary of the Bearhawk’s first flight, I I serviced the shock strut. I lifted the had a slow leak in the damper system of set out to attempt a repair on the shock fuselage, removed the shock strut, and the right landing gear shock strut. Every strut. I needed to use the shop crane replaced it with the EMT stand-in. All time I would preflight, there would be to lift the fuselage so that there was no seemed to be going well. a drop of automatic transmission fluid load on the right landing gear. Now, (ATF) hanging from the strut. The we have been told for years not to leave Then I Got Greedy fluid was pressurized anytime the spring anything supported solely by a hydrau- I noticed my tires were sufficiently worn moved in the landing gear shock strut, so lic jack because the hydraulic cylinders on the inside corners and decided it was the leaks would appear after flying. There have a tendency to leak down with time. time to remove the wheels and flip the were no steady leaks if just left sitting. I have seen this happen, but it was over tires the other way on the wheels so that ATF is fairly lightweight, so there’s the course of days, not minutes. My they would rotate in the opposite direc- no telling how much of it was left on the solution was to replace the shock strut tion and wear on the other corner. This runway or just evaporated. I had started with a piece of electrical metallic tub- is a time-honored approach to maximiz- to notice some fluid in the fuselage above ing (EMT) conduit that had been used ing tire life with uneven tire wear. It was the shock strut attachment point, imply- during the building process to hold the hot in the hangar, so I thought I would ing that the fluid was getting pushed landing gear in place until the shock remove both wheels, leaving the axles on out of the top of the strut. For my 2015 struts were fabricated. blocks, and flip the tires in the comfort condition inspection, I decided to try to The use of EMT for this purpose was of my air-conditioned garage while I was address the shock strut leak. I thought officially endorsed by the designer (it repairing the shock strut. that the problem might be damaged said so right on the plans), but appar- Convinced that the EMT was suffi- O-rings in the shock strut, so I ordered ently only during the build process. cient to take all of the loads, I removed up a new set. This would let me set the aircraft down the right wheel (since it was still off the

34 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Right wing resting on rear seat. Sheared out electrical metallic tubing (EMT). ground) and lowered the axle onto a I went back to the crane to lift the air- lower surface (the strongest being under block that was 2-3 inches lower than the plane up off the floor, and then decided I the mainspar). normal axle height. This caused the air- should get my phone and take some pic- The amount of damage to the wing plane to lean to the right, such that the tures; I knew I’d be talking about this. underside was further reduced by energy wingtip was about 18 inches lower than Again, it wasn’t getting any worse. Sur- absorption from the bending of the rear normal. This right lean shifted more prisingly, the pictures weren’t blurred seat structure and collapsing of the seat than half the weight of the airplane onto even though my hands were shaking— leg. As the seat back bent, the wing came the right landing gear, further stressing worse than usual because of the shock. into contact with more cushion until the already overstressed EMT stand-in, I lowered the left landing gear down reaching the other corner of the seat which was never intended to hold the from the jack to get the tire back on the back, which made another small dent in weight of the full airplane with engine, ground. I lowered the crane and hooked the wingskin. This force also tilted the fuel, and everything else. it up like it was originally, and started seat back, such that another portion of To remove the left wheel, I started pumping the airplane back to a normal the wingskin contacted the thick seat jacking up the left landing gear. Instead position. When the airplane was level cushion at the front of the seat. This of using the shop crane, I used a floor again, I started assessing what had hap- stopped the wing from falling just as the jack under the gear leg, as is the stan- pened. The cause was when I started jack- wingtip touched the floor. dard method for removing the wheel. I ing up the left wheel, even more load was There was no visible damage to the was sitting under the airplane to operate shifted to the right landing gear where wingtip, at least no fractures requiring the jack. A couple of strokes on the jack the EMT conduit was already over- fiberglass work like after the ground- and…bam! loaded. This was more than the EMT loop. However, I suspect the wingtip could take, and the bolt sheared out of did touch the floor, as there was a small What Just Happened? the EMT hole. Gravity did the rest. buckling in the aluminum strip that I turned around to find the airplane attaches to the wingtip on the upper lying on its right wingtip. The shock A Miracle? surface. Strangely, this was in the same and surprise were immediate—sort of What happened next borders on the like being in a violent car accident that miraculous. You can decide where you never saw coming. I wasn’t touched to put it on the pure-luck-to-divine- physically, but emotionally, I had just intervention scale, but the results are taken a massive sucker punch. unmistakable. As part of the condition Multiple things rushed through my inspection, I had removed the rear seat head. Memories of bashing the right and just plopped it on the floor under wingtip in a groundloop came to mind. the right wing because there was room Should I work immediately on getting there. As it turns out, the rear seat took the airplane back up? I figured every- major damage to save the rest of the air- thing was static at this point, so it wasn’t plane. The positioning was absolutely getting worse just sitting there. Working perfect. As the wing fell, the first con- with about 2% of my brain capacity, I tact was on the corner of the seat back, determined that I wasn’t injured in any with cushion between the wing and the way, so I got up and walked around to seat back structure. The point of con- the right wingtip. Surprisingly, it wasn’t tact was directly under the rear spar, damaged like I expected. the second strongest place on the wing’s Uneven tire wear.

Photos: Russ Erb KITPLANES January 2016 35 Deformed rear seat. Broken rear seat leg. location where similar damage hap- just reinstalled the shock strut, I would worked to pull out the spring package. pened during the groundloop. have accomplished nothing but dam- I inspected the O-rings and found no There was no damage to the wingspars aging the airplane. I needed to rework damage on them whatsoever. Since I had or twisting of the wing as evidenced by the shock strut, but the O-rings were at it apart, I replaced the O-rings anyway. lack of waves in the wingskin. There the house, not the hangar, since I had I got to thinking about engineering were three small dents in the wingskin planned to do the rebuild there. Since service bulletins of the past. I had built where it contacted the corners of the rear I couldn’t be in both places at once, I my shock struts to the original plans, seat. These dents were small enough as called my wife Tuki and asked if she which called for fitting the shock strut to not warrant any sort of repair effort. and our daughter Emily would come to with the spring compressed 1 inch. Later, They will most likely stand as reminders the hangar and monitor the jack while as Bearhawks were being built heavier, of gross buffoonery. I went home to expeditiously rebuild the designer, Bob Barrows, changed the Because the gear leg was supported the shock strut. plans to fitting the shock strut with the on the block, the block slid out, keeping spring compressed 1 3/8 inch. Another the brake caliper mostly off of the floor. Rebuilding service bulletin called for shock struts There was a small abrasion on the rubber The first step was to remove the rod end built like mine to be shortened as much cap covering the bleed valve, but no dam- bearing, which spun out of its threads as possible. With the replacement rod age to the actual valve. The caliper was very easily (smoking gun!). Since I didn’t end bearings, the only practical way to jammed sideways in the torque plate, but have a ½-inch fine-thread bolt to use to shorten the shock strut was to eliminate was easily freed with a few hammer taps. compress the spring, and no time to go the jam nut on the rod end bearing and The fairing at the top of the gear leg get one (it was past closing time at the screw it in as far as possible. Unfortu- was significantly bent as it was jammed hardware store), I used the drill press nately, it was the jam nut that pulled into the fuselage by the splaying gear leg. like an arbor press as I did when I origi- the rod end bearing threads up tight to It looked like this part could be straight- nally assembled it. With pressure on form a seal to keep the hydraulic fluid ened to be used as a pattern to make a the spring, I removed the snap ring and inside the shock strut. The workaround replacement part. A slight bend in the steel at the top of the gear leg seemed to have loosened the fabric on the gear leg slightly. Amazingly, the fuselage fabric was not damaged. Almost a Prop Strike Of significant note was that the propeller was still about 8 inches or more above the ground. Thus we know there was no prop strike or engine damage. Whew! So now I was back to the original problem. My airplane was supported by a hydraulic jack that shouldn’t be left unmonitored. The only way to get the airplane safely standing up again was to reinstall the shock strut. If I Damaged gear leg fairing.

36 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Buckled wingtip attachment. was published in the service bulletin Second is that EMT conduit is a suit- stating “The lock nut is not neededif able stand-in for the shock strut while Loctite (blue) is used on the threads.” building the fuselage and landing gear. Remembering how easily the rod end However, it should not be considered bearing had unscrewed and how clean suitable to support the full weight of the the threads were, I concluded that I assembled airplane with stuff like wings had failed to apply Loctite on the origi- and engine installed. nal assembly. Hence the now suspected So after several days, with the ben- source of the fluid leak—it was coming efit of 20-20 hindsight, how would I out around the threads! approach the same task? I would jack A quick look around the shop found a up the airplane the same way, remove tube of blue Loctite that had about four or the shock strut, and replace it with the five drops left in it. I took it and the reas- EMT just like I did before. However, sembled shock strut back to the hangar I would not have lowered the shop where my wife and daughter were wait- crane. Thus, the shop crane would ing. I applied the Loctite and reinstalled still be supporting the airplane. If the the shock strut before the Loctite could hydraulic cylinder were to leak down, cure. I inserted the bolts at both ends, when the wheel touched the ground, placed the washers on, and screwed on the EMT would be able to support the nut far enough to make sure the bolt that small load and would lessen the wouldn’t fall out. I lowered the crane to load on the crane, slowing the leak- place the airplane back safely on its gear. down. Even if the EMT were to over- With the airplane securely on its gear, I load and shear out, the crane would closed the hangar and went home before still be holding up the airplane. After I inadvertently damaged something else. replacing the shock strut, I would then remove the wheels one at a time to flip What Can We Learn? the tires. Other than sharing a traumatic event, Remember, we all learn from mistakes. what can we learn from this? One thing The smart people have figured out how to is that airplanes are rather unstable learn from other people’s mistakes. when jacking. As you jack up one side, the loads shift around, which leads to This Just In: flexing of the landing gear and twisting Jared Yates tells me that Bob Barrows of the fuselage with attendant disturb- now recommends securing the landing ing sounds. Without a wheel on the gear gear for shock strut servicing by stretch- axle, the gear is much less stable. This ing a come-a-long straight across from risk is manageable, but the risk goes up one wheel to the other, and then servic- if you try to remove both mainwheels at ing one shock strut at a time. Jared did the same time. The Cessna 180 service the same thing, but he used a very large manual strongly discourages removing ratchet strap. That would have been more than one wheel at a time. good for me to know. J

KITPLANES January 2016 37 ENGINE THEORY

Last month we chronicled how air and fuel get into your engine’s combustion chamber. This month we’ll see how that air escapes back to the atmosphere Exhaust via the exhaust. Unlike the seemingly laid-back intake side of engine breathing, there’s impressive energy involved in the exhaust system. That’s both boon and bust when selecting an exhaust system. Like everything else, not only is exhaust system design fraught with compromises, but it’s also a gray area of responsibility. Engine companies may or may not offer an exhaust system—Rotax does, Lycoming does not—and airframe manufacturers consider exhaust more an engine consideration than something they’re equipped to handle. Even worse, many times no one is seriously thinking about the exhaust until well into the aircraft’s design or construction. This is especially true with homebuilders, where exhaust is often an afterthought to a builder eager to finish his project and go flying. Thankfully, exhaust system appre- ciation has risen in the last decade or so. More specialist exhaust manufacturers are available to service the homebuilt market so quality tubing, bends, flanges, tabs, spring mounts, and mufflers, not to mention entire systems, are waiting on the shelf. Big Energy, Big Waste Burn gasoline in a laboratory and it’s easy to determine how much energy is released—a lot! Unfortunately, in a piston engine, if you’re lucky, possibly a third of that energy is harvested for productive work, while a second third is radiated as waste heat by the cooling

Built by Vetterman and polished by owner William Shook, this individual pipe system is a fine ambassador for sport aviation. The gold tint comes with time—340 hours in this case—and will Expelling the remains. eventually darken significantly. The cuff By Tom Wilson around the two pipes is for cabin heat.

38 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes This frame is taken from a video simulation of a Ford 5.0 “Coyote” V-8 exhaust manifold Every Reno Formula One racer directs their generated in Ford’s supercomputer laboratory. Immensely complex, such simulations headers down, extending cooling air exit are leagues ahead of piston engine aviation’s trial-and-error reality, but are a revelation ducts for an extraction effect. This seems when viewed by any engine enthusiast. Each cylinder’s exhaust gas is color-coded; it’s a tactic to more fully explore on daily amazing how much backwards flow and cut-off gas residuals take place. There really is driver aircraft. Cooling, noise, and speed benefit in exhaust tuning! enhancements seem likely for the effort. system, and roughly another third (or Water-cooled engines handle back- backpressure. Perfectly practical avia- much more) is expelled as hot waste gas pressure heat less strenuously because tion exhaust systems are designed using through the exhaust. Clearly there’s water’s higher density doesn’t allow bal- nothing more than good old mass flow potential for turning something we’re looning of CHTs and can more easily, thinking. Keep the pipe sizes reasonable throwing overboard to good use. And and evenly, absorb heat from localized for the gas volume, make a minimum just as obviously turbosupercharging is hot spots, such as the cylinder head number of bends, make no sharp bends, aviation’s exhaust energy recovery sys- around the exhaust port. keep it simple, and you’re good to go. tem of choice, which we’ll discuss in a No less importantly, backpressure is Far less intuitively, pressure waves separate article. a hindrance to engine breathing. If the form inside the exhaust primary pipes. But exhaust gas is also hot, dirty, poi- exhaust doesn’t exit promptly and com- If the primaries are joined to form an sonous stuff. Sure, the main byproducts pletely, there is less room in the combus- exhaust manifold, the waves and gas flow of burning gasoline are CO2 and water tion chamber for the incoming fuel/air from one cylinder can influence other (as a vapor), but the reality is, piston charge. Power and efficiency suffer. cylinders positively or negatively. Wave engine exhaust reeks of trace elements, tuning is truly arcane stuff; engineers many of them harmful. As a conse- Exhaust System Tuning write thick books full of math on the quence it’s often far easier to simply get As with intake systems, exhaust system subject, and the physics of it responds to rid of the stuff as fast and inexpensively physics include the expected mass flow a bewildering array of engine parameters as possible and call it good. And that’s of exhaust gas, plus the more abstract and environmental conditions. That’s mainly what we’ve been doing in Exper- wave tuning. all fun for the propeller heads, but what imental aviation for decades. Mass flow is mainly intuitive—hot matters if you’re trying to put some nice Furthermore, we pilots have an extra gas at high velocity rushes past the pipes on an RV is primary pipe diameter incentive to be rid of the exhaust: back- exhaust valve into that cylinder’s pri- and length. Diameter is important for pressure, the Great Satan of air-cooled mary exhaust pipe where it cools (but mass flow, sure, but also to pressure wave engines. Cylinder head temperatures still stays burning hot as the EGT speed. Too large a primary pipe results in soar quickly when a restrictive exhaust instrument shows) and slows while too slow wave (and gas) speeds. system is asked to process large volumes rushing for the pipe’s exit to the atmo- Pipe length is the most important of hot gas (takeoff and climb), and those sphere. Pipe diameter and shape play factor in wave tuning. Curiously, pres- hot heads lead to hot oil and high heat the expected roles in either smoothly sure waves run down, then reverse and rejection under the cowling. The result? guiding the slug of exhaust gas down the run back up the primary pipes. Get the More draggy cooling airflow through pipe, or, if the system has crimps, sharp primary pipe length synched with the the engine compartment, aggressive bends, poorly formed intersections, or oscillating wave speed, and you’ll have a heat cycling of the cylinder heads, other airflow speed bumps, the system pressure wave just starting to race down and a reduced detonation margin. introduces flow-killing turbulence and the primary pipe when the exhaust valve

Photos: Tom Wilson KITPLANES January 2016 39 opens. That helps scavenge the exhaust from the cylinder and better engine breathing results. Get the pipe length wrong and a pressure wave is racing toward the cylinder when the exhaust valve opens; gas flow is stymied, breathing suffers, and cylinder-head temps rise due to backpressure. How do you determine the correct pipe length? Consult an exhaust specialist offering design software services. Burns Stainless, for example, offers X-Design, which is their proprietary software. For about $80 they’ll plug all your numbers (engine displacement, valve size, compression Well-developed radial installations use carefully shaped cowlings employing mainly ratio, port dimensions, detailed cam- individual pipe exhaust systems aimed out the cooling air exits for an extractor effect. shaft specifications—they’ll want a Beechcraft T-34 and Twin Bonanzas do the same with flat engines. This showy Howard bunch of numbers and the more you 500 demonstrates how such systems often don’t need cowl flaps, thanks to the exhaust can provide the better) into their com- energy; the exhaust/cooling exits are marked by the bright stainless steel panels in the aft cowling. puter and report back the workable pipe diameters and lengths. Bad pipe lengths peak halfway stub or short or open stack. From the Because wave tuning resonates in fre- between the good pipe lengths. For “get rid of it” school, stub stacks are quencies there are first, second, third, our 360/540 cylinder you’d definitely very lightweight, inexpensive, pose few fourth, and many more orders of waves want to avoid 51-inch and 25.5-inch packaging challenges, and essentially to work with. Typically a 360/540 primary pipe lengths. no backpressure. They’re also louder Lycoming cylinder first order pipe Naturally, all primary pipe lengths than an indoor firefight, popping and length is about 78 inches, so the second need to be the same length if you’re barking annoyingly. They also offer no order length of 34 inches is far more making a tuned system. This is your carburetor or cabin heat, nor tuning practical. Third order would be half of goal, as you want all the cylinders to run possibilities. Just the same, given the 34, or 17 inches, which might also work, as similarly as their neighbors, mainly torque-centric camshaft and ignition but will likely be tough to package. for aggressive lean-of-peak operation, tuning of traditional aviation engines, but also for peak power. Burns Stainless stub stacks will make all the horse- considers +/- ¼-inch as close for a racy power a typical Lycoming is going to Hidden but Vital exhaust (you’ll have fun developing that make, and not lose too much torque. It’s easy to obsess over exhaust system pipe layout), but you can likely be +/- 2 These days stub stacks are often run design and overlook a physically tiny, but inches and not be able to measure the in dyno cells because they’re easy to bolt critically important, area of exhaust per- difference on a daily-flier engine. on and cause no backpressure-induced formance: the exhaust valve face and seat. Mind you, all of this tuning is appro- CHT worries. They were popular on In fact, both intake and exhaust gas flow priate only if designing a tuned exhaust some antique radials and met glory on are incredibly dependent on the shape (the system as we’ll detail shortly. If you are the big V-12s of WW-II fame. There angles ground into them) of the valve and not using a tuned design, then practi- they sound great, thanks to the full cho- seat because this narrow passage must flow cally speaking, pipe length doesn’t mat- rus of cylinders. under difficult high pressure and turbulent ter. Also, all the usual gray and gold conditions, and with a constantly changing general aviation engines run camshafts Exhaust System Pecking Order aperture, as the valve opens and closes. and rpm designed for maximum torque 4-Cylinder 6-Cylinder In realistic terms this means you want and fuel efficiency—they never rev high Good Stub stacks Stub stacks a three-angle valve job (a single angle is enough to reach their horsepower peak. Manifold Manifold typically stock on new cylinders) for your So tune for torque; you’ll never see the Crossover Individual pipes valves and seats. Seek the best machinery power peak anyway. Individual pipes (valve and seat machine) and machinist you Best Headers Headers can find. Once this first critical step is taken, Popular Exhaust Designs There are many variables in selecting an then optimized exhaust systems make Stub Stack—Several aviation exhaust exhaust system, but to simplify the choices, more sense. designs have remained popular for here is how we’d generally rank exhaust —T.W. decades. Simplest is the abbreviated system designs for typical applications.

40 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Need to raise the dead? Try some stub stacks on a Simple as they come, this manifold system still exhibits smooth bends, healthy Lycoming; they’re loud enough. Certainly easy intelligent increasing pipe diameters and the compactness the archi- to fabricate, inexpensive, good for horsepower (meh tecture offers. Probably the most popular lightplane exhaust system, for torque) and backpressure free, stub stacks are typi- manifold systems offer no tuning and are prone to backpressure if not cally too obnoxious for public consumption. Great in correctly built and sized. the dyno cell, though. Rolls Royce recognized the tremen- first cylinder’s pipe into the second the cost, power, noise, cabin or carb heat, dous gas flow roaring from their Merlin’s cylinder’s pipe—and continuing into and packaging curves intersect. stub stacks added measureable thrust the third cylinder’s on a 6-cylinder Individual Pipe—Lengthen the stub if the pipes were aimed aft and given engine. Because gas volume rises as stack to about a yard and noise subsides somewhat restricted, high-velocity exits. more cylinders are added, pipe diam- and torque rises. The Swearingen SX-300 Called ejector exhausts, Rolls Royce cal- eter should be increased as each suc- is just one Experimental employing such a culated they were worth about 150 hp of cessive pipe joins in. system, that is four or six individual pipes propulsion. The physics remains valid, For daily fliers manifold exhaust sys- thirty-something inches long. Essentially but even with what we now consider a tems are the clear front runners. They this is a set of headers, but without the “big” 300-hp 6-cylinder, the exhaust aren’t the most efficient engineering solu- collector, and such systems respond to mass is puny compared to a 1700-cubic- tion, but for standard duty they’re where wave tuning, so you want to get the pipe inch supercharged V-12’s. A jet a LyCon- tinental really isn’t. Furthermore, the worthwhile efficacy of ejector exhausts at altitude are at cross-purposes to sea- level horsepower (they are an airflow restriction given thick intake air). A variable exhaust nozzle might help a cross- country cruiser up in Class A airspace, but seems more weight and complexity than it’s worth for lower altitudes. Manifold Design—Easily the most popular exhaust design in general aviation is the “manifold” type, sometimes called a single side stack. Simplicity is its virtue; by running all primary pipes on one side of the engine into a single exhaust pipe, things are kept lightweight, physically robust, easily and tightly packaged, even affordable, and definitely less raucous than stub stacks. No tuning is possible with manifold Quieter than stub stacks, collector exhausts were a popular pre-war radial development systems so primary pipe length is not before the efficiency of cowlings and extractor exhausts were known. They’re still a good a factor. It’s as simple as running the way to go on training and commercial aircraft where maintenance access trumps efficiency.

KITPLANES January 2016 41 You’ll probably have to fab them yourself, Crossover systems are the practical, Don’t forget exhaust gas is hot. Either but equal-length headers are tops in cost-conscious exhaust for the 4-cylinder plenty of ducted, well-directed air naturally aspirated exhaust. Laying out owner interested in better-than-stock around the exhaust stream, or heat these systems is a challenge both for pipe performance. Shown here on a Vetterman shielding, is needed to protect the length and secondary concerns such as mock-up engine, the design uses twin airframe. This is especially true of fabric heater cuffs, heat shields, and collector tailpipes and most closely resembles a tri-y coverings, all of which shrink if subjected mounting, but power and fuel economy header design, but with obvious differ- to high temperatures. (LOP) benefit. ences in pipe length. length correct. Without the collector the reduced, carb and cabin heat can be col- engine’s firing order in mind means a tuning effects are peakier (work in a nar- lected, cost is reasonable, and the pipes mass of exhaust gas racing out of one rower rpm range) and not quite as power- are easy enough to package and fabricate. primary pipe puts negative pressure in ful, so the theoretical power and torque Headers—Take the individual pipe the collector. The next cylinder’s slug curves won’t be quite as broad as they design, bring the exit end of the pipes of exhaust gas thus meets less resis- could be, and the peak numbers should together in a collector and you have a tance and therefore speeds up. The suffer slightly as well. Given the narrow set of headers, or 4-into-1s as the O-320 higher gas velocity in the primary pipe operating range of our engines these are and 360 crowd call them. This is the helps better evacuate the cylinder and, minor losses, and for the experimenter ultimate in exhaust plumbing on a similarly to wave tuning, better engine looking for superior exhaust efficiency naturally aspirated engine and the most breathing results. without the overreaching cost of head- tunable design. Just as primary pipe diameter and ers, individual pipes are a smart and often The big attraction is bundling the length are important in this tuning, overlooked choice. primary pipes in the collector. Again, the collector is also tunable, although All told, such a system is a major timing is the key concept; joining typically not quite as critically as the improvement over stub stacks. Noise is the primary pipes together with the primary pipes. Again, there are many Mufflers As society loses its tolerance for useless noise, mufflers are becoming a stronger reality for aircraft engines. The trouble is air-cooled engines absolutely hate backpressure, and mufflers that actually muffle (especially at wide-open throttle such as at takeoff) cause backpressure. Mufflers also add weight, cost, and a source of heat-soaked metal requiring careful packaging to avoid fire concerns. On top of all that, propellers probably make most of the annoying noise airport neighbors complain about, and mufflers don’t help there. As responsible homebuilders (and for our own comfort), it’s wise to at least consider noise attenuation in our builds. Roughly speaking, the longer the pipe in a system, the Here large and small Vetterman mufflers quieter it will be. Gathering the pipes together in a collector also helps. A straight-through flank their shared internal perforated muffler typically mellows an exhaust note without introducing much backpressure, but is cone and associated assembly bits. These units offer minimal backpressure and just as typically effective only at cruise-power settings, and not much quieter than open WOT muffling, but do dull the sharp sonic exhaust at WOT. edge for more comfortable cruising. The —T.W. all-stainless construction is durable, too.

42 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes OK, mild steel is an exhaust no-no because it rusts, pickles, cracks, and generally leads a short, unhappy life as aircraft exhaust tubing. But if your system is this simple and you don’t mind welding up new downspouts every few years, go ahead and save the money. variables, and an exhaust specialist and his design software are the answer. Headers are a fact of life in tuned-up car engines and, as a practical observation, once specific output approaches 1.2 hp per cubic inch in a naturally aspirated engine, some sort of header, even a com- Print and Digital promised production piece, is a necessity. So, if headers are so neat, why doesn’t every Piper Archer have them? There are many good reasons, but the engineering answer is stock airplane engines don’t get close to 1.2 hp per cubic inch, so the gain from headers is minimal. Headers gain importance as exhaust gas volume rises from rpm, supercharging, or hot camming and compression with their attendant greater fuel burn. And there are hassles with headers. Costs skyrocket if headers must be custom built (available off-the-shelf header systems such as for RV-10s are more cost effective). All those exact-length primaries are tough to package, leading to prolonged design time, and the many linear feet of primary pipes contribute to under-cowling heat and require plenty of fabrication time. They also take up space, compromising service access. Either Format – Great Savings! Benefits are extra torque at high man- Subscribe Now at www.kitplanes.com/subscribe ifold pressures, a practical elimination

KITPLANES January 2016 43 of hot CHTs because backpressure is nil or even negative, excellent parity among cylinder EGTs and CHTs everything else being equal, and done right, a far more melodious and partially lessened exhaust note. Headers are a folly for pragmatic run-of-the-mill aircraft and the racer’s, aerobat’s, cross-country speedster’s, and backcountry STOL artist’s must-have. They’re also an excellent special touch for the experimenter wanting the fabrication challenge or looking to optimize each cylinder for aggressive lean-of-peak fuel economy. Crossover Exhaust—Lycoming 4-cylinders employ an unusual firing order that sees both cylinders on one side of the engine firing closely together Exhaust systems absolutely flex and twist with heat and must have some sort of accom- followed by the two cylinders on the modation for movement. This branch uses both a ball joint at left and slip joints at right; both work well with the ball joint showing a very slight increase in backpressure in the opposing side doing the same. The result laboratory, but no change in the real world. is exhaust gas from one cylinder partially chokes gas flow from its adjacent cylinder to the other side of the engine steels available, such as 401, but 321 has cylinder. This is a meaningful effect on simply to even the timing of exhaust gas the mechanical strength and corrosion manifold systems and a prime generator pulses flowing through the pipes. This resistance to withstand aviation use of backpressure. is an oddly tuned system—pipe lengths where the engine runs at high output Obviously stub stacks or headers vary wildly among cylinders—and almost all the time. Don’t even think of would eliminate this firing order con- scavenging effects can be pronounced mild steel as it will wear quickly. At the cern, but not without introducing cost, or nulled depending on the combined other end of the spectrum, super nickel noise, and other issues we’ve already pipe length. (For tuning purposes the alloys such as Inconel are too expensive discussed. Therefore it’s a good step for- entire length of joined pipe, even those and more difficult to fabricate. Their ward to run an exhaust pipe from one running backwards of gas mass flow, superior heat resistance is not needed are in play). in a naturally aspirated system anyway. Crossover exhausts are a good choice As for stress relief, aviation exhausts on 4-cylinder Lycomings because cost, run at sustained high temperatures noise, packaging, carb and cabin heat and thus grow considerably due to considerations are all reasonably handled. heat expansion. Plus, air-cooled avia- And if you’re thinking of lengthening the tion engines expand like balloons to two short primary pipes in a crossover begin with, and shake like wet dogs system until they equal the long primary when starting and shutting down, so pipes, you’re thinking correctly—and the exhaust must be flexibly mounted leading yourself to a set of headers, which in addition to being free to slip between is what you just imagined. pipe sections. Ball joints are typically used to provide the needed suppleness, Getting Practical but slip joints work as well. Nut and bolt details of exhaust system Next time we’ll examine ignition and design are fodder for separate articles, engine management systems. J but a few points regarding materials and stress relief are important enough Further Reading to mention here. The takeaway on materials is 321 stainless steel is the An excellent summary of exhaust testing Slip joints are formed by expanding a few inches of the female pipe. They are light- aircraft standard because it is the least and tuning for 4-cylinder aircraft engines weight, smooth-flowing joints. Retention expensive material (and we’re definitely can be found on the Experimental Air- is needed via tabs such as this robust pair, speaking relatively here!) that works. craft Association’s Member Hangar web or springs, which allow a little more give. You’ll find plenty of lesser stainless site: http://tinyurl.com/op6dk5c.

44 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes

Aircr aft Wiring

Instrument Panel Switch Layout for Experimental Aircraft. By Marc Ausman

This month we’ll discuss instrument closed or open. A double-throw switch be capable of carrying the load that it panel switches for use in Experimental has a contact that can be connected to switches. If you’re wiring with Verti- aircraft. To get things started, let’s take a either of two other contacts. The chart cal Power, you can choose almost any look at switch nomenclature—the way a below shows the most common switch switch because there is negligible cur- switch is described. types. Parentheses around a switch rent going through the switch. position indicates it is a momentary, • Availability in the configurations Poles and Throws spring-loaded position. “Off” indi- you need (SPST, DPDT, momentary, A switch is described by specifying the cates a switch position where the con- center-off, etc.). number of “poles” and “throws.” Each tacts are not connected. • Lighting. Do you need lighted pole can be thought of as an electri- switches? How is the switch light cally independent switch or switching Choosing Switches controlled and wired? Normally, you circuit. A single pole is one electrically Avionics dealers that build instrument want a lighted switch that has termi- isolated circuit within the mechanical panels have a pretty good idea about nals for the backlight independent of switch housing. A double-pole switch what works and what doesn’t. Other the switched terminals so you can is two electrically isolated circuits sources for inspiration include looking wire it to a dimmer. Also you want within a single switch housing, con- at other airplanes, and burying your the light to function as a backlight for trolled by a single lever by the user. The head in a Digi-Key catalog for hours. the switch, not to indicate that the throw refers to how many electrical The following items should be consid- switch is on. That means a minimum connections can be made. The num- ered when choosing switches: of four terminals on the back of the ber of throws is the number of sepa- • Switch quality. Use only good quality switch. Lighted switches with three rate wiring path choices other than switches. terminals power the backlight from “open” that the switch can adopt for • Availability in the current ratings that the switched power (i.e., power for each pole. A single-throw switch has you need. If you’re wiring an airplane the landing lights, strobes, etc.) and one pair of contacts that can either be the traditional way, the switch must cannot be dimmed—the backlight Switch Types only comes on when the switch is on. • Have a suitable connector on the Switch Type Desig. Symbol Mechanism back (a spade or ring terminal con- OFF-ON nection is preferred; some switches Single-Pole, OFF-(ON) only come in printed circuit board SPST Single-Throw formats, for example). OFF-(ON)

ON-NONE-ON Switch Layout Single-Pole, ON-OFF-ON SPDT How you physically arrange your Double-Throw (ON)-OFF-(ON) switches and what functions you decide ON-OFF-(ON) to place on a single switch are important Double-Pole, OFF-ON considerations. Some builders like to DPST Single-Throw OFF-(ON) have switches in specific locations on the ON-NONE-ON instrument panel and the stick because Double-Pole, ON-OFF-ON they were there on a previous airplane. DPDT Double-Throw (ON)-OFF-(ON) Perhaps you like to arrange switches ON-OFF-(ON) that match the workflow of using the

46 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes switches. The starter switch, for exam- Now let’s add a backup alternator. ple, can go on the stick or the instru- You can have two switches, one for ment panel. Same with the flap switch. each alternator, but you don’t want There is no right or wrong answer, only both alternators on at the same time. what you prefer. I recommend arranging The best way to make this idiot-proof the switches on a mock-up, and then do is to put both on a single switch, mak- some hangar flying to see how it works ing it impossible to turn on both for you. The ideas presented below are alternators simultaneously. You’ll suggestions and should be modified to want to use an On-Off-On switch, fit your specific needs. where the middle position is the “off” Figure 1 shows a basic switch layout position. Figure 3 is an example of for a VFR day/night aircraft. how this might be accomplished. Split master/alternator switch. You can use spacing to group the But now we’ve created an interest- switches based on when they are used. ing situation. One of the purposes of some voltage regulators work only with The left group is used before engine the master switch is to cut power to the the battery present, while most others start (assume the engine monitor/EFIS aircraft in case of an emergency. In the do not) which means power is present is on the main bus, and comes on with above scenario, if you turn off the mas- until both the master and alternator the master switch), the middle group is ter switch in flight (engine running, switches are off. used after start, and the right group is alternator on) then all you’ve done is One solution is to use a split master/ used for takeoff and landing. You might disconnected the battery from the rest alternator switch. move the strobe switch to the left group of the primary power distribution sys- This switch mechanically turns off if you want them on during engine start tem. The alternator continues to provide the alternator when the master switch (Figure 2). power to the electrical loads (note that side is turned off. Electrically, it is like having the master and the alternator

MASTER ALT AVIONICS NAV STROBE BOOST LANDING switches on two different switches. LIGHTS LIGHTS PUMP LIGHTS However, there are some limitations to using this switch: • It does not match the other switches (that’s good or bad, depending on OFF OFF OFF OFF OFF OFF OFF your perspective). Figure 1: Switch layout for basic VFR aircraft. • It can only be used for a single alternator. In newer certified aircraft (or older twins) with two of these MASTER ALT AVIONICS NAV STROBE BOOST LANDING LIGHTS LIGHTS PUMP LIGHTS switches there are two independent buses, and each split switch assembly is used to control an independent

OFF OFF OFF OFF OFF OFF OFF battery contactor and alternator. The dual-bus configuration is not neces- Figure 2: Switches arranged by usage. sary for the vast majority of Experi- mental aircraft. • The second alternator on a single bus MASTER ALT AVIONICS NAV STROBE BOOST LANDING PRIMARY LIGHTS LIGHTS PUMP LIGHTS system would need to be controlled by a separate, non-mechanically OFF linked switch, and that defeats the intended purpose. Therefore, this OFF BACKUP OFF OFF OFF OFF OFF switch is best used for single-bus, single- Figure 3: Single switch for primary and backup alternator. alternator configurations. The simplest way to wire the switches is shown in Figure 4, and it applies to SPST SPST on-off on-off the split master switch, as well as wir- Fuse ing two independent switches. If you’re Bus To alt field To battery contactor wiring independent switches, then be Alternator Master sure to procedurally turn off both the Switch Switch alternator and master switches during Figure 4: Split master/alt or two SPST switches wired independently. an emergency.

Illustrations: Marc Ausman KITPLANES January 2016 47 DPDT To cut field power to a single alterna- on-on SPST To Battery on-off tor when the master is turned off, we can Contactor accomplish this with a little bit of extra Fuse wiring as shown in Figure 5. Bus To alt field It becomes a bit more complicated Alternator Master Switch with dual alternators (Figure 6) as Switch you’ll need a 3PDT (3-pole, double- throw) switch for the master. DPDT Figure 5: Master/alternator switch combination for single alternator. switches are easy to find, but 3PDT are 3PDT more difficult. Be sure the switch fam- on-on ily you choose has this type of switch To Battery DPDT Contactor available, and it can handle up to 5 on-off-on Fuse amps current. To primary alternator field In these examples the alternator To backup alternator field field power is routed through the mas- Bus ter switch. When the master is turned Alternator off, it also turns off power to the alter- Master Switch nator field. Therefore, the alternator is Switch on only when both the master and the Figure 6: Master/alternator switch combination for dual alternators. alternator switches are on. You can also accomplish this (more simply) SPST with the Vertical Power system—see on-off the Vertical Power installation man- Fuse To autopilot servos ual for details.

Bus and/or control head Let’s consider additional switches for Autopilot a more advanced aircraft. Consider add- Switch ing the following switches if your mission requires it: Figure 7: Autopilot power disconnect switch. SPST Autopilot Power Disconnect: This on-off switch cuts power to the autopilot in an Fuse SPST emergency in case the autopilot behaves on-off Method 1: Fuse in an erratic fashion. Autopilots also Bus Method 1: Trim Power Trim Trim have shear pins on the control servos Bus Switch Relay Deck Motor that the pilot can break in case the servo Trim Power Trim Trim Relay Deck Motor itself jams. Both of these mechanisms Switch together make for a good safety over- SPST ride. The switch is located between the on-off autopilot circuit breaker and the control SPST on-off servos (Figure 7). Trim Power Disconnect: If you’re Trim Power Method 2: White not using a solid-state trim controller, Bus Trim Switch Controller Trim Power and instead using a relay deck to control Method 2: White Bus Trim Switch White your pitch trim motor, consider adding Controller Trim a switch to disconnect power in case White Motor Trim the relay fails. Of course, for additional Figure 8: Simplified view showing ways to wire pitch trim disconnect.Motor safety, you can add a disconnect to any trim controller. Normally, a discon- make the situation worse. There are two footwell lights. Dimmer switches are nect is wired only on the pitch-trim axis ways to wire a pitch trim power discon- actually knobs that rotate to set the dim- because it is the most sensitive. nect, shown in Figure 8. ming level. Clockwise rotation increases Note that once trim power is Pitot Heat: While flying in icing the brightness. Full counterclockwise removed, the electric trim motor cannot conditions is not recommended, pilots turns the lights off, and a separate on-off be moved and may be stuck in a hazard- like to have a heated pitot tube “just in switch is not necessary (Figure 9). ous position. Do not turn power back case” for those marginal conditions. Cabin Lights: This switch can be on in the air if you believe the trim sys- Dimmer: One or more dimmers for on the panel, or more often near the tem is not operating correctly as it may various instruments on the panel or light itself.

48 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes MASTER ALT AVIONICS NAV STROBE BOOST LANDING PANEL LIGHTS LIGHTS PUMP LIGHTS the basic idea, and you can modify it as needed for your particular application. Figures 11 and 12 are additional OFF OFF OFF OFF OFF OFF OFF switch layouts to consider. Figure 11 Figure 9: Switches with panel dimmer. includes autopilot disconnect and pitot heat, while figure 12 puts seldom-used

Front View Back View switches right-center, and switches used together on the far right. J NAV STROBE To nav lights

OFF Strobe power, from bus Nav power, from bus Read the Book

NAV To strobe lights Hopefully this article has helped your DPDT understanding of switch layouts when ON-OFF-ON Figure 10: Multi-function switch. Switch planning your instrument panel. It is an excerpt from my new book entitled Aircraft Wiring Guide. For more MASTER ALT AVIONICS NAV STROBE AUTOPILOT PITOT BOOST LANDING information, or to order a copy, visit PRIMARY LIGHTS LIGHTS POWER HEAT PUMP LIGHTS www.aircraftwiringguide.com. OFF Marc A Marc OFF BACKUP OFF OFF OFF OFF OFF OFF OFF Marc currently flies an RV-7 that he finished building in Figure 11: Switches including autopilot disconnect and pitot heat. 2006. He was founder and president of Vertical Power and has served as an EAA MASTER ALT AVIONICS NAV AUTOPILOT PANEL BOOST LANDING Director since 2011. He flew PRIMARY STROBE POWER PUMP LIGHTS with the U.S. Navy as a OFF OFF us Naval Flight Officer on

OFF BACKUP OFF NAV OFF OFF OFF board the P3-C Orion. He lives in

Figure 12: Group right-center is seldom used items. Right group items are used together. m California with his wife

Flap Switch: If you’re installing elec- off, and the top position turns on two an and three tric flaps, you can install the flap switch devices. An example is a switch that turns children. on the panel or on the stick. If you install on the nav and strobe lights. The exam- it on the stick, you need to install a sepa- ple shown in Figure 10 demonstrates rate flap controller (from Vertical Power or TCW Technologies) because the stick switch is not rated to handle the flap motor current. Flap switches that look

Flap switch. like actual flaps can be purchased from shops that make instrument panels (like Aerotronics or SteinAir). Starter Switch: This is normally a pushbutton switch or part of the magneto/starter combination key switch. Multi-Function Switch: You may want to wire a switch where the bottom position turns on a device, the middle is

KITPLANES January 2016 49 Stressing Structure Buckling of Panels By David Paule

You might have noticed that most reasons why we often have stiffeners Figure 1: Mike Rettig’s RV-10 aft fuselage airplanes have some sort of exterior attached; they divide a single large panel section uses aluminum panels and stiffen- surface, perhaps fabric or something into smaller ones. If done right they also ers for primary structure. (Photo: Mike Rettig) more rigid like aluminum or composite. carry some load themselves and that Structurally, it can make sense to make further helps. We’ll look at stiffeners in the equation for this for panels loaded the outer surface rigid, since that can another article. Here, we’re looking at in compression: provide the maximum possible rigidity. the panels themselves. We’re assuming π 2 * Kc * E 2 Plus the surface generally has to be there that the panels are flat. Often there’s fc = * ( t / b) Equation 1 anyway, so it might as well be useful. If actually a slight curvature and we should 12 * (1 - ν2) it’s properly done and carries load, then ignore the minor additional buckling Where it can even save weight, compared to an resistance the curvature provides. If the fc is the compressive stress that internal skeleton. curve is significant, though, we ought will buckle the panel, psi Panels can buckle when loaded in to take advantage of the curve, because Kc a constant we’ll pull off Figure 2 compression or shear, and that’s a major it’ll stiffen the panel. If the curve is in E our old friend, the modulus of issue. The panels are generally thin, and the direction of the compression load, elasticity, psi thin panels can’t carry as much load, so that the panel is being loaded out of t the thickness of the panel, inches obviously, as thick panels. Less obvious plane, the techniques described here b the short dimension of the panel, is the fact that their overall dimensions aren’t applicable. inches affect the buckling load just as much Panels start to buckle at a stress that ν Poisson’s ratio, a material as the thickness does. That’s one of the we can calculate, fortunately. Here’s property

50 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes The equation for the buckling stress Stressing Structure of a panel in shear is almost exactly the same. The only differences are that it uses a constant from a different graph: π 2 * Ks * E 2 fs = * ( t / b) Equation 2 12 * (1 - ν2) Where fs is the shear stress that will buckle the panel, psi Ks is a shear constant we’ll find on Figure 3 There might even be some in-plane bending. If there is, that also uses a form of the same basic equation: π 2 * Kb * E 2 fb = * ( t / b) Equation 3 12 * (1 - ν2) Where fb is the bending stress that will buckle the panel, psi Kb a constant we’ll get from Figure 4 Figure 4 shows curves that are a bit more complicated than the other graphs. The first thing to note is that the curves are wavy. You can see a little bit of that in Figures 2 and 3, too. This is because the proportions of the panel matter a lot Figure 2: Parameters for buckling in compression. Generally speaking, curve C is in bending, and this gives you a way to usually applicable. Panel Buckling Stress Example The first panel is loaded in compression. Its edges are simply supported. the same panel. Using Figure 3 and the bottom curve for hinged edges, a = 18 in Length of the panel in the loaded direction which are the same as simply-supported edges, we find b = 9 in Width of the panel π2 * Ks * E t 2 Ks = 6.4 fs = * t = .032 in Thickness of the panel 12 * (1 - ν2) ( b ) fs = 739 psi a = 2 Look at Figure 2, curve C, for a/b = 2.0. Kc = 4 b The calculations are very similar, so I didn’t show the actual numbers. The panel is 6061-T6 aluminum Try it yourself and see if you can get the same result. Also, note the low E = 9.9 * 106 psi Modulus of elasticity for 6061-T6. See Table 1. allowable stress. Finally, find the allowable buckling stress for in-plane bending of the same panel: π2 * Kc * E t 2 fc = * ν = .33 Poisson’s ratio for 6061-T6 Looking at Figure 4, we see that there’s a new term, β, that we need 12 * (1 - ν2) b ( ) aluminum, see Table 1 to deal with. β is a way to include the effect of an overall compressive With this information, the allowable compression stress before the stress on the bending. There’s often some compression along with panel will buckle is: the bending, but right now let’s assume that there’s not. If there’s no compression, then β = 2. That gives: π2 * 4 * 9.9 * 106 * .0322 fc = fc = 462 psi π2 * Kb * E t 2 12 * (1 - .332) * 92 fb = * Kb = 23.9 12 * (1 - ν2) ( b ) This is low strength. Depending on the applied stress, the panel might fb = 2761 psi need some stiffeners. Next let’s see what its shear buckling stress is, for —D.P.

Illustrations: David Paule KITPLANES January 2016 51 2 fo focr π E t 2 k = b 2 32 η 12 ( 1 - νe ) ( b ) b y ß N.A. b TO

28 a y f = f (1 - ß ) b o b ASYMPTOTIC m = 1 m = 2 m = 3 m = 4 ß = 2 24 23.9

1.9 21.5

20 1.8 19.25 1.75 k 18.17 b 1.7 17.10 16 1.6 15.15

1.5 13.38 1.4 12 11.78 1.3 10.52 1.25 10.00 1.2 9.47 1.1 8.59 1.0 8 7.80 0.75 6.35 0.50 5.30 Figure 3 (Above): Shear buckling of panels. 0.25 4.55 4 0.0 4.0

Figure 4 (Right): Buckling of panels for in-plane bending. 0 0.5 1 1.5 2 2.5 3 a/b tweak the strength at relatively low cost. β = 2. If there were some compression, Simply supported means that the edge If you can get a length/width ratio that we’d have to draw it out, making a little can’t move out of plane, but it’s free to falls near a peak on the curve, the panel sketch to scale and assess β as necessary. rotate. It’s the panel version of the pin- will buckle at a higher stress than if it As you might have guessed by now, ended condition that struts have. For falls in a trough. it’s not quite as simple as it seemed. But example, a large panel with a stiffener Another aspect of the curves is that it almost is. down the middle is simply supported at there are a lot of them, and they seem First, we have the usual three types the stiffener. In Figure 1, all the skin pan- to depend on a mysterious factor called of edge fixity. Since the panels are rect- els are simply supported by the stiffeners β. β is a number that is used to assess the angular, they have four sides. Each side or bulkheads. amount of the panel that’s in compression. can either be fixed, simply-supported A fixed edge means that the edge not Normally, of course, symmetric panels or or free. It’s difficult to put loads or reac- only can’t move out of plane, it can’t beams in pure bending have a neutral axis tions into a free edge, so generally those rotate. These aren’t too common, but halfway across their height. If there’s a would be on the unloaded sides, if any they do exist. A good example is that compression stress applied to the panel in are free at all. Most aircraft panels aren’t. often if a wingskin is riveted firmly to a addition to the bending, then there’s more The panels are either simply supported or mainspar cap, the skin’s probably fixed at of the panel that’s in compression and β fixed. “Clamped” is another word used to the spar. But it might not be, since that allows for that. If there’s no compression, describe a fixed edge. takes considerable stiffness, so be sure.

Table 1. Material Properties Read the exponential notation like this: 29 * 106 means 29,000,000. Look at the exponent on the 10 and add that number of zeros to the number. Also, ksi is the same as 1,000 psi or 103 psi, so don’t get ksi mixed up with psi.

Poisson’s Ratio Max Allowable Compression Material What is it? Modulus of Elasticity Max Allowable Shear Stress ν or Bending Stress 2024-T3 Aluminum 0.33 10.5 * 106 psi Fcy * (1 + Fcy / 200000) .61 * Fcy 6061-T6 Aluminum 0.33 9.9 * 106 psi Fcy * (1 + Fcy / 200000) .61 * Fcy 4130 Condition N Steel 0.32 29 * 106 psi Fcy .61 * Fcy 300 Series Stainless 26 * 106 psi to Stainless Steel 0.27 .835 * Fcy .61 * Fcy Steel, 1/2 Hard 27* 106 psi Ti-4Al-6V Annealed Titanium 0.31 16 * 106 psi Fcy .61 * Fcy

52 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes However, I’d expect it to be simply sup- box or plate structure of it is often Table 1 also shows the maximum ported at a rib, though. highly loaded, and it’s worth checking strength values that go along with these Table 1 shows some of the material it for buckling. I’ve included titanium equations. For the rest of the material properties for some of the more com- because of its excellent strength. If properties, you’ll have to look up MMPDS mon metals. While not many homebuilt you’re designing an airplane, it might (www.kitplanes.com/includes/structure_ aircraft use panels of 4130, a welded be worth considering. stress.html) or a similar resource. Interaction Between Compression, Shear and Tension Usually in aircraft panels, if there’s compression there’s also shear, Rc = .36 Rs = .45 Rb = .445 and there might be some in-plane bending. With all that going on, 1. Find Rc / Rs = .36 / .45 = .8 Use curve .8 we’ll most likely need to work out how they interact. Please take a 2. Draw a line from Rs up to the .8 line. It’s the blue line that starts at look at Figure 5. Rs on the graph. We’ll have to find the stress ratios. Here’s what stress ratios are: 3. Draw a line from Rb to the .8 line. This one is the red line from Rb to Applied stress * factors of safety the curve. Rc, Rs or Rb = Allowable stress 4. Draw a line, this one is the dotted line, from the origin through the place where the first two lines crossed. where 5. Draw a line from the place where this new line hits the .8 curve Rc, Rs or Rb The compression, shear or bending stress ratio down to the horizontal axis. This finds Rsa and I’ve drawn it in blue. Applied stress Stress from your structural analysis, psi 6. Draw a line from the place where this new line hits the .8 curve across Factors of safety Usually the ultimate factor of safety to the vertical axis. This finds Rba and it’s also shown as red here. Rsa = .515 Rba = .51 Allowable stress Calculated as shown in the example below, psi 7. The margin of safety is either Use the same factor of safety, such as for ultimate, for each stress Rsa Rba MS = - 1 or MS = - 1 ratio unless there’s a darn good engineering reason not to. Rs Rb There are two sides to the interaction graph. The left side is for What if they’re different? Easy—use the smaller margin of safety. the case where the shear stress ratio is smaller than the compressive The curve isn’t that easy to read precisely, and as this example shows, stress ratio, and the right side is for when the compression stress ratio one or the other might give a lower margin of safety. That’s the one to is smaller than the shear. I’ve arbitrarily chosen that for the example. use to be conservative. J For this example, —D.P.

1.0

Rcx Rs 0 0.8 0.2 0.4 0.6 0.8 0.6 1.0 Rba

Rs bx R Rcx Rb 0 0.4 0.2 0.4 0.6 0.2 0.8 1.0

0 1.0 0.8 0.6 0.4 0.2 0 0 0.2 0.4 Rs Rsa 0.6 0.8 1.0 Rcx Rs

Figure 5: Interaction diagram for compression, shear and bending. Rcx is the stress ratio for compression, Rs is the stress ratio for shear, and Rbx is the stress ratio for bending. The bending is in the plane of the plate, that is, not trying to roll it up.

KITPLANES January 2016 53 Ten Universal Tips for Experimental

Aviation By David Boeshaar

Have you ever wondered why when laws, so must Experimental aviation. 5. The smallest unit of measure for working on a car and you drop a tool, it These universal laws of nature can be time is the ohnosecond. It is the hits the floor and then rolls to the exact confusing, frustrating and cruel to the amount of time between flipping the center of the car? Have you noticed that novice. As we grow older, however, we power switch and realizing you have it is always easier to get into something see with clarity and understanding why made a serious wiring mistake. than to get out of something? Why is it the universe is as it is. These laws of 6. If it doesn’t matter, it doesn’t matter. that no matter how many bugs you find nature also apply to Experimental avia- 7. Every budget will be over by 20%. If in your project, there is always one more tion, and the sooner we understand that, you plan to be over by 20%, you will bug? Why is the guy wearing both a belt the sooner we can move on. be over by 40%. and suspenders always the guy with a So as a public service announcement, 8. Nothing is foolproof. Fools are too broken fly? here are my 10 universal tips as they ingenious. Just as physics, chemistry, mathemat- apply to the universal laws of Experi- 9. If there is no chance of making a ics, and biology must follow universal mental aviation: mistake with an assembly, and you 1. If anything can go wrong, it will go wrong. (1) At the worst possible time and (2) in a manner to make you look the most foolish. This is called Murphy’s Law and the first two cor- ollaries. It is an interesting note that Murphy was Captain Edward Mur- phy, an engineer from the Wright Field Aircraft Laboratory. 2. No one knows how a fool and his money got together in the first place. 3. To make a small fortune in Experi- mental aviation, you must start with a large one. “Uncle David, what do the bubbles mean 4. Nature always sides with the hid- “Oops! That wasn’t supposed to pop off on the fuel tank?” den flaw. like that!”

54 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes “OK, I think it’s fixed—try it now!” know there is no chance of making a mistake with an assembly, you will make a mistake. 10. After hours of diagnosing an electrical problem and you ask for ...and leave your engine help, the solution will be blatantly monitoring to EIS. obvious to everyone else, even Trusted with everything from 2-strokes people who know nothing about to turbines for over two decades. electrical problems. So, relax, build on, and realize that the world is not out to get you. Do your best to plan for every possible FLY IT outcome, but realize that everything like you stole it... takes longer than you think. Left to themselves things tend to go from bad to worse. And if things are going along www.grtavionics.com • (616) 245-7700 pretty well, you have probably over- Proud sponsor of Tiger Airshows and airplane “thief” extraordinaire, Hotwire Harry! looked something. It is just the universe as we know it, and don’t be upset when you are over budget. J Davi David Boeshaar is a systems analyst for corporate Disney. A former mechanic, teacher, and computer d help desk guru at a major Boeshaar university, he is now building a Van’s RV-9A for fun with his brother-in-law. As the new guy in aviation, Dave has learned lots, both good and expensive, and hopes to pass along a little help to the builders coming up behind him.

Photos: David Boeshaar KITPLANES January 2016 55 maintenance matters Maintenance for an extended journey. Good maintenance always makes or other damage. You can also do a quick some spares. Even if you don’t plan to good sense, but there is something about visual check of the brake pads. fly at night, you might end up having to a big trip that seems to call maintenance If it is at all close to the time to change look for something or, worse yet, repair to our attention. Maybe it’s a trip to your oil, go ahead and do it now. And something in the dark. While you are at Oshkosh or a backcountry adventure to be sure to cut open your filter and look it, check out any other critical electrical Johnson Creek, Idaho, or just a trip of sev- for metal. Now is the time to find out if items such as fuel pumps or fuel transfer eral hundred miles to visit friends or rela- there is a problem, not when you are pumps, alternator belts, and the battery. tives. In any case, who wants to have their halfway to Oshkosh. While you are at To really be sure of the condition of your vacation spoiled by a mechanical failure, it, take a good look at the engine bay battery you need a battery condition especially, as Murphy’s Law commands, and take care of any little thing that isn’t tester. You can get one at Harbor Freight at the worst possible place and time? To right. You don’t have to do a complete for less than $50, but be sure to open it hold Murphy at bay, we need to think of condition inspection if your plane has up and tighten the connections inside if maintenance in two parts—before the been running well—unless it will run you do. For some reason that one par- trip and during the trip. Each has its own out while you are gone—but a quick ticular item is famous for being almost special considerations. check of wires and hoses makes a lot of completely assembled. If your battery sense while the cowl is off. is getting old and tired go ahead and Before the Trip Especially if you plan to fly at night, replace it now. It just makes good sense to be sure check out landing lights, nav lights, Be sure to update the databases in your plane is in good shape before you strobes, and cabin lights. Now is also your navigation equipment. I know it can leave the comfort and security of your a good time to put new batteries in be expensive for some equipment, but local flying area. If something breaks your flashlight and make sure you have you certainly can afford to do it at least 500 miles from home, no one is going to hop in the car and come and get you. You will have to solve the problem yourself, so eliminating as many possible problems as you can before you leave is a really good idea. It makes a lot of sense to begin your pre-trip maintenance with a good cleaning of your plane. In the process you go over the entire surface of the fuselage and can get a good look at the condition of rivets, skins, exposed control cables, door hinges, and tires and wheels. By the way, while doing your cleaning, take off your wheelpants to inspect the entire It is a good idea to actually test the condition of your battery before a big trip if it is surface of your tires for flat spots, cracks, more than two or three years old. This condition tester came from Harbor Freight Tools.

Dave Prizio is a Southern California native who has been plying the skies of the L.A. basin and beyond since 1973. Born into a family of builders, it was only natural that he would make his living as a contractor and spend his leisure time building airplanes. He has so far completed three—a GlaStar, a Glasair Sportsman, and a Texas Sport Cub—and he is helping a friend Dave Prizio build a fourth, an RV-8. When he isn’t building something, he likes to share his love of aviation with others by flying Young Eagles or volunteering as an EAA Technical Counselor. He is also a licensed A&P mechanic and a member of the EAA Homebuilt Aircraft Council.

56 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes includes a number of landings at rough dirt strips, this can be a major driver of what needs to be included in your tools and parts kit.

Parts Parts can get heavy pretty quickly, so spare parts need to be focused and limited to what you are most likely to need. A small assortment of nuts, bolts, washers, and cotter pins can be put together in a small package that weighs little— not more than a pound—and takes up minimal room. This assortment should be targeted to what you have on your plane. For example, bring cotter pins that You will need to carry some extra weight if you want to be able to replace a punctured specifically fit your main axle nut, your tire tube. The jack weighs about five pounds, and the other items add another four tailwheel nut (if you have a tailwheel) pounds. However, there are times that it may be well worth it. and ones that fit essential control link- once a year. It is nice to have something two guys in a Glasair Sportsman may not ages. One or two of each should suf- like ForeFlight, with its reasonable yearly give a second thought to taking 15 or 20 fice. Nuts and bolts should be selected fee including monthly updates, but your pounds of tools and parts with them on the same way. One or two spark plugs onboard equipment needs a little atten- their big adventure. gapped and cleaned with new gaskets tion once in a while, too. While updat- For most people weight matters, so are good to have along and take up little ing things, be sure your registration is when you think about a list of tools and room. A coil of .032-inch safety wire and a current and your other paperwork is in parts to take, the goal is to leave nothing partial roll of duct tape round out a basic order. Ramp checks are rare, but they do home that you need, but bring nothing parts kit for most situations. Lastly you happen. You surely do not want to get that you don’t. To do that two things can include a length of #20 AWG insu- in trouble with the FAA a long way from factor into the decision process—where lated wire and a few connectors. home where retrieving missing paper- are you going and what is most likely to If your travel includes backcountry fly- work could be very difficult. cause trouble on your plane? In some ing in remote locations, a few more parts Last but certainly not least, do a ways these are related and in others not. are worth considering. A spare tube quick test flight after your maintenance If your plane has a tendency to foul spark for your main tire can save your bacon work is complete and before your big plugs, it really doesn’t matter where you if you get a flat far from home. A spare trip. The beginning of your trip is not are going. On the other hand, if your trip tailwheel tube (and even a spare tire) the time to find out your maintenance work actually caused a problem rather than prevented one.

What to Bring As your focus shifts from preventative, pre-trip maintenance to repairs you might have to do along the way, you need to think about what tools and parts to bring. This becomes a balancing act between keeping weight as low as possible and being prepared to deal with likely problems you might encounter. Where you end up in this will depend a lot on where you are going and what you are flying. A couple of good-sized guys in an RV-6 may feel that a Leatherman and A small parts kit can really come in handy and doesn’t weigh much. This one has a half roll of duct tape is all the weight assorted fasteners, spare spark plugs with gaskets, Camlocs, electrical connectors, they can afford to sacrifice for en route cotter pins, some 20-gauge wire, and some safety wire. That and a roll of duct tape will repairs. On the other hand, those same solve many minor problems along the way.

Photos: Dave Prizio KITPLANES January 2016 57 may also come in handy. It is surprising how hard it can be to find a tailwheel tire and/or tube at an FBO anywhere outside of Alaska. Along those lines, a spare tailwheel control cable spring and chain are small and could come in handy. You can add to or subtract from this list based on your own experience with your plane in these conditions. The point is to think about what could go wrong and build your parts list around those scenarios.

Tools Tools and parts selections are driven by the same considerations. Think likely repair tasks and the specific tools required This small tool kit will cover most maintenance and repair problems and weighs about five to complete them. Here is an example. pounds. You can add or subtract from this to suit the needs of your plane and your trip. Say you have decided that you want to be able to repair a flat tire by replacing Next, remove the wheelpant, which To reassemble the wheel and tire, you the tube. Let’s go through the steps and requires a #2 Phillips screwdriver and a should also have a valve stem tool and a see what tools we need. First you will small cup to keep the screws from get- tire pump. Lightweight and inexpensive need to jack the plane up, which obvi- ting lost. Then you will need to unbolt tire pumps are available, but be sure to ously requires a jack or a few friends who the brake caliper so you can remove the test yours before you go, since some can lift one wing long enough to get the wheel. That takes some side-cutting pli- of them are not very good, and even in wheel off and back on again. Obviously ers to cut the safety wire and a 7/16-inch good ones, seals can dry out and fail, lifting a wing is not the preferred way socket and ratchet to remove the bolts. leaving you with no way to pump up to change a tire, but if weight is a major You will need the side-cutters again to your tire. Some small containers of grease concern it may be something you are will- remove the cotter pin on the axle nut. and tire talc can be also useful. The tools ing to do in an emergency. A jack weighs Taking the wheel apart requires a 1/2-inch you already used will put things back about five pounds, so that is a big weight socket with an extension, and you will together with the help of that safety wire consideration. One thing about traveling need a second socket and an extension and cotter pin you put in your small parts in a group is that you can spread parts or a deep socket to get to the wheel bolts kit. A spare tube, a tiny compressor or and tools around so no one has to carry on the other side. If the tire bead is stuck foot pump, and the other tools needed all the weight. There is no need to dupli- on the outside rim, you will need to work to change a tire, not counting the jack, cate heavy items in a group that plans to it off with your feet. Do not use tire irons will weigh about four pounds. stay together and help each other. or screwdrivers on airplane wheels. Other repair tasks get thought through the same way. What tools do you need to do the job? Bring those and not others. To be fair, it may not be all that easy to decide what tasks you may need to perform in the field, especially if you haven’t taken such a trip before. Here is a list I would include for a trip where access to airports with FBOs is good and wear and tear from rough-field operations is unlikely. Parts: small parts kit (see photo), spark plug and gasket, five feet of safety wire, partial roll of high-quality duct tape, two quarts of oil, and some paper funnels. Tools for this same type of trip: ¼-inch- drive socket set; 3/8-inch-drive spark plug socket, extension, and breaker bar; If you are the group mechanic and can spare the space and weight, a magneto timer, a spare 1/2-inch-deep socket; two 3/8-inch multimeter, and a wire stripper/crimper tool can come in handy. I would only take these combination wrenches; one each 7/16- on a trip to a remote place where help will be hard to find. inch, ½-inch, and 9/16-inch combination

58 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes wrenches; an 8-inch adjustable wrench; electrical connection, removed broken more than one job if possible. Good pre- safety wire pliers; side-cutting pliers; spinner backing plate, rigged up tempo- trip maintenance can prevent many en combination screwdriver; small electrical rary oil pressure gauge after sender failed, route problems before they occur, so screwdriver; half-round file and sandpa- replaced broken starter, removed engine do a good job of preparing your plane per for prop nicks; X-Acto knife; a hack- and prop for teardown and inspection before you leave home. Tailor your parts saw blade; a 3/32-inch Allen wrench for after a groundloop accident. The satel- and tools list to your plane and the trip removing radios; a tire gauge; and small lite phone came in very handy that time. you plan to take. Different circumstances Vise-Grips. All of those tools weigh about Good preparation (or good luck) provided will dictate different types and levels of five pounds. me with all the tools I needed to address preparedness. If you will be traveling in a For a backcountry trip add: tire pump, each of these challenges. Fortunately, group, urge your companions to get their jack (if travelling alone), and maybe a most of my trips involved substantially planes in shape, too. It is no fun waiting for multimeter for tracking down electri- less drama, but from time to time things someone who broke down because they cal problems. You should also include do go wrong. didn’t have their plane in good condition basic survival equipment, but that is for at the beginning of the trip. And if worse another article. Lastly, if you are really Conclusion comes to worst, be sure to have some way going to be off the beaten path, consider Think tasks that might need to be per- to let people know you need help. renting a satellite phone for your trip. If formed when selecting parts and tools, As the Boy Scouts say, “Be prepared.” A you can’t fix your plane, at least you don’t and always try to pick tools that can do safe and happy trip comes from just that. J want to be stuck there forever. Some optional tools, if you can afford the weight or spread them out among a group of planes, might include: a 5/8- inch combination wrench for engine bolts (I actually used that once), a ¾-inch combination wrench for removing the prop and the spark plug wire caps, some water pump pliers, and a magneto timing light. The important thing is to think through each task you may need to perform and have the tools and parts you need to do that work. Here are a few things I have dealt with during my travels, many of which involved someone else’s plane: replaced fouled spark plugs, replaced blown-out tire, replaced lost tailwheel steering cable spring, repaired loose

A broken spinner backing plate forced us into a quick repair on the ramp at Abbotsford, British Columbia, on our way to Alaska. Luckily we had the tools we needed with us, including a hacksaw that saved us from removing the prop.

KITPLANES January 2016 59 The Dawn Patrol The dropped tool disastrophe. This latest little bump in the convo- have the stick forward keeping the tail Now, to the south of the turf and sand luted road making up my life started off off the ground…you suddenly become toads part of the runway is the world in the simplest way…as do most disas- just a passenger in one of the most famous Liberty Landing International ters in my life. exciting rides in the world. Third, 1800 Airport plane-eating ditch. It was a common touch-and-go land- feet of runway is a very long runway for So, you’re faced with a quandary. Do ing. I’d been out flying in my beloved us…but it’s insanely short to pilots used you want to land on the gravel and risk a 28-year-old Graham Lee Nieuport 11, to wide four- and five-thousand-foot nick in your prop and a trip in the beans? strafing the German trenches just south runways. Liberty Landing International Or…do you choose the turf and run the of Liberty Landing International Airport. Airport’s runway is narrow. Maybe 15 risk of cleaning out the plane-eating After running out of ammo in my 303 feet wide of smooth gravel with about ditch? (And your shorts!) Lewis machine gun mounted on the 30 feet of rough turf and sand toads just On a gusty 90º crosswind day, it’s a top wing, I decided to head back to the south of the gravel strip. heck of a decision to have to make while field (at least a two-minute flight) and To the north of the gravel part is always on a short quarter-mile final. Personally, enjoy some quality time hangar talking a grain crop. Soybeans are the most I’ll take the ditch over a crop anytime… with the rest of the airport bums that desirable. Corn on the other hand… particularly corn. Been there, done that, hang out there. I’m not saying we’re old, whooeee! Losing control on landing or don’t ever want to do it again. but…most of us are retired and banging takeoff and making a groundloop into But the rewards are great. If you really around the 60 to 80 year old age ranges. a field of eight-foot tall corn is a surefire nail a perfect landing in a gusty cross- OK…we’re old. recipe for a big repair job. wind in a WW-I replica you’ll get, in my

Touch and Go Anyway, I decided to finish off the flight with some touch and goes down the 1800-foot, gravel, grass, and sand-toad surfaced runway 3/21. I don’t think there’s anything more enjoyable or as challenging as spending time doing touch and goes in a WW-I replica aircraft. Add a crosswind and you’ve got a real educational opportunity. First, it’s a taildragger aircraft with all the challenges associated with that. Second, most WW-I aircraft had no vertical fin to add some directional stability as you come bounding down the runway. If you make a wheel landing and hold the tail up too long, you risk A groundloop or forced landing in a field of eight-foot-tall corn is always going to do losing rudder control right at the end some significant damage to the plane (and sometimes the pilot). This is my Taube replica of the roll. If that happens and you still after the engine sagged just after takeoff.

has written two books about the joy of flying; “You Want To Build And Fly A What?” and “Fokkers At Six O’clock!!” He was the recipient of Flying’s 2001 Bax Seat Award “for perpetu- ating the Gordon Baxter tradition of communicating the excitement and romance of flight.” Dick Starks Dick and his wife, Sharon, both fly WW-I replica aircraft.

60 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Going into a field of soybeans is rarely as damaging as a trip into The plane-eating ditch, especially after a heavy rain, is a surefire the corn. Sharon’s damage was fixed in less than a week. (See plane magnet. Harvey Cleveland and one of his students had the Kitplanes® October 2012.) right brake hang up on landing. The sound of that prop splashing the water was actually kinda soothing. opinion, the same feeling of accomplish- we have to add power taxiing to make wanted to show them that, for once, I ment a USN F-18E/F Super Hornet carrier the mid-field turnoff about 900 feet from could fix a problem on my engine all by pilot gets when he catches the third wire the threshold. Add a 10- or 15-mph direct my lonesome. It hadn’t happened yet, landing on a rolling, pitching deck at crosswind and you’ve got high drama. but I was hopeful. night…in the fog…short of fuel…with Uhhhh…I kinda got off topic there for snow and ice on the deck and your back- a while…Back to my touch and go. Back at the Hangar seater busy blowing beets behind you I made an acceptable touchdown and I taxied back, shut down, and pulled the in the cockpit. Landing a short-coupled, once everything was settled down, I plane into the hangar. Taking off the cowl, twitchy WW-I plane in a gusty 90º cross- shoved the throttle in for the takeoff and I looked first at the throttle linkage to see wind on a narrow strip with obstacles on go-around. The engine sagged for about if the little thingy that operates the accel- both sides of the strip is that kinda pres- two seconds and then picked up and erator jet was attached. It looked OK. sure…at least it is to me! away we went. So, the next thing on the list was to Hmm…What could have caused that? I remove the carburetor and just check it You’re Going Down did three more touch and goes and it did out. I wanted to see if there was some When you come across the fence at 45 the same thing each time. crud in the float chamber, clogged jets, mph in a WW-I replica and pull the throt- We can’t have that. I decided to look or maybe some inner springy thingy in tle all the way back, you’re going to stop into this myself with no help from the the accelerator pump had gone bad. I flying right now. About 99% of the time, rest of the herd there in the hangar. I rolled my tool chest over to the plane

There are two schools of thought on how to land a WW-I taildragger. Sharon favors wheel landings because she wants to be able to see I favor full-stall three-point landings and like to get the tailwheel where she’s going at all times. The disadvantages are you’ve gotta on the ground as quickly as possible so I have directional control. carry more speed on the round-out and, at some time, as your With this type of landing you’re going as slow as possible when you speed drops, the tail has to come down. When that happens, there’s contact the ground—but you can’t see squat when you’re in the a period of time when your rudder may—or may not—provide any middle of flaring out. authority to keep directional control.

Photos: Dick Starks KITPLANES January 2016 61 and opened it up. That’s when the slow- motion ballet started. First I heard someone mutter, “Uh- oh…Starks is getting out his tools.” Plas- tic chairs could be heard being moved around in the hangar. Someone else opened the first-aid cabinet. All this was going on while I was loos- ening the throttle cable, unhooking the gas line, and cutting lots of zip ties that were used to hold everything in place in the engine compartment. It got real quiet, so I turned around and there they were. The audience was This is a reenactment of the disaster with me looking like I’m sure I looked when that Allen arranged around me in a semicircle of wrench went down between the cylinders to the top of the cooling tin. interested eyes. This was usual when anyone was working on his or her plane. used to direct air through the cooling clearances. I was looking at more than a There is always an audience. fins on the cylinders. full day’s work. I ignored them. It was while I was tak- My blood ran cold. This was a very All in all, my day had suddenly turned ing the bug nut off the throttle arm with bad thing! dark brown with the “tinkle…tinkle… a little Allen wrench that disaster struck. To get to the cooling tin and hence ping” and all that it entailed. The wrench popped out of the Allen to the Allen wrench, I’d have to do a lot Stunned at this shocking turn of events, screw and fell down into the engine. of tedious, time consuming stuff: First, I staggered back from the engine and sat Tinkle…tinkle…ping. That was it. There take off the baffling around the engine. down in one of the available chairs. was no sound of the Allen wrench hit- Second, take off the rocker arm cover. The audience quit chattering when ting the floor. In my hurry, I’d forgotten Third, take off the rocker arms. Fourth, they noticed me sitting there with a to put a towel over the engine to catch take out the pushrods. Fifth take out the shocked look on my pale face. things like that, and now I was paying pushrod tubes. Tom Glaeser finally broke the silence. the price. Then I’d finally be able to take out “What’d you do dummy?” (“Dummy” Looking down between the cylin- the cooling tin and get to the #?&*@%!! is one of the more printable names I’m ders, I could barely make out the end of Allen wrench. called at the field.) the Allen wrench where it was resting After that, I’d get to reverse the whole “I dropped the Allen wrench in the on top of the cooling tin. The cooling tin procedure. After everything was all back engine.” is a metal insert that sits under the cyl- together, then I’d have to go through “I’m guessing you didn’t have a rag inders between the pushrod tubes. It’s the ordeal of readjusting the rocker arm over the engine.” “Nope.” There was a long silence. Jerry (The Rotaxman) Sharp broke the silence. “Can you see the Allen wrench?” he asked. “Sorta,” I replied. “Lemme in there,” Jerry said. “I bet I can get it out.”

Rotaxman to the Rescue Now, I’ve gotta tell you, Jerry Sharp is one heck of a mechanic on anything that moves. He’s really talented on Rotax engines, which is where his nickname, the Rotaxman, comes from. He’s flown with them for over 25 years. Now, even though he’s moved up to an Avid Jay Williams gets his score after he “lost it” on landing and drove Dick Lemons’ Quicksilver MX into the beans.

62 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes The audience is in place, ready to jeer and offer contradicting I stand there while Jerry (The Rotaxman) works his magic with advice just to muddy the waters. two lengths of safety wire.

Magnum with a big ol’ snarly 150-hp equipment. They are also totally confus- That was two months ago and nothing’s Lycoming in front, he’s still the num- ing. As far as I’m concerned, they use changed. She still sags, but only on touch ber-one man people in the Kansas City black magic to work. and goes. Heads are being scratched and area go to with Rotax engine issues… It was squeaky clean inside. No online engine blogs read and discussed. or for that matter, anything else engine clogged jets. The accelerator pump was What’s a pilot to do? related. If Jerry can’t fix it, you might as working fine. The final consensus was This Adventure ain’t over yet. J well throw it in the river (which he’s done that there was no reason for the engine too, by the way). to be doing that. Airdrome Aeroplanes With me holding a flashlight and tell- That was not particularly what I www.airdromeaeroplanes.com/ ing him what the wires were doing, Jerry wanted to hear, but it was also good to Graham Lee Nieuport plans did some magic with several bent pieces know that there was nothing wrong with http://nieuports.com/ of safety wire and got that Allen wrench the carburetor. out of the cooling tin in about 15 min- The carburetor was reassembled with The Kansas City Dawn Patrol utes. I did learn some new words while new gaskets. Then it was put back on the www.kcdawnpatrol.org/index.php he was working, too. Guys like the Rotax- now rag-covered engine. Everything was If you want to know what man are good to have around! hooked back up, and we gave it a “smoke it‘s like to land on a carrier in With that problem solved and a rag test” to see if the engine still ran. extreme situations, go to the placed over the engine, the carbure- With everything checked out, I took links below. www.youtube.com/ tor was removed and taken to a work- her back up for a touch and go. watch?v=4gGMI8d3vLs and bench. Now I did have a circle of heads She still sagged when I pushed the www.youtube.com/ grouped over the carb as we opened it throttle back in, but came back strong watch?v=S0yj70QbBzg up. A carburetor is a fascinating piece of after one or two seconds.

Dick Lemons has to make wheel landings in his Airdrome Airplanes Fokker DR-1 triplane. It is the worst plane at the field in terms of visibility in the three-point configuration. But on the plus side of the column, it’s the easiest to control in the tail-high configuration.

KITPLANES January 2016 63 Editor’s logTemporarycontinued Downdraft

SHOP Paint Booth TIPS By Larry Larson

It gets cold in the mountains of Colo- Materials rado. Often the temperature is too cold to spray paint or primer outside. I didn’t 1. 3 foam project boards, 32x40 inches, 7. 1-inch x 6-inch x10-foot board of any kind 3/16-inch thick (longer for double-wide garage doors) want to build a dedicated paint booth for the few times when priming and temper- 2. Rule 240 Marine Bilge Blower 8. Baby gate ature didn’t coexist, so here’s my tempo- 3. 110v to 1st 12v, 6A power supply 9. Velcro straps rary downdraft paint table. Approximate 4. 4-inch dryer vent coupler 10. 2 old plastic shower curtains cost was about $50. 5. 4-inch dryer vent, adjustable 90 degrees 11. Various curtain hangers 6. 4-inch x 20-foot dryer vent hose 12. Drop cloth or paper Instructions 1. Cut a 4-inch hole in a long board. Cut the board to length to fit under the garage door between the frame joists. 2. Cut one of the foam boards in half to 20x32 inches for the two sides. Cut slots for the boards halfway down (16 inches), 1 inch from the edge. Do this the opposite of the photo. I learned later it’s easier to slide the sides down than the back and front. The business end of the paint booth showing the blower connected to the side of 3. Cut a 4-inch hole in a side or back the booth. for the dryer vent coupler. Lay down some paper or a drop cloth and assemble the box. 4 Cut a short section of dryer hose to The complete assembled paint booth. The 90-degree dryer vent connects to the connect the bilge blower to the vent board that goes under the garage door. coupler. Attach it to the bilge blower and secure with Velcro or tie straps. 10. Hang the shower curtains to contain This part stays together for future use. overspray. Insert the other end of the vent cou- 11. Hook up the power and paint! pler into the hole cut in the board. Parts for the blower and hose. Note how 5. Connect the remaining vent hose to Optional the blower is mounted to a piece of scrap the output of the blower and secure I mounted the bilge blower on a board board. with Velcro. You want this side to with a coaxial power jack matching the come apart for storage, so Velcro plug on the power supply. I also made works best. a filter for the inside, but it works fine 6. Release the garage door lock and open without it. For a larger paint booth, the door enough to insert the board. you could make a similar version from 7. Close the door on top of the board 1/4-inch plywood. and insert the 90-degree dryer vent. This keeps heat inside and fumes from Disclaimer coming in. Make sure it’s not pointed This is not a replacement for a real paint Slots cut into the foam boards. The slots at the wife’s new car! booth, but it works great for small parts. should be cut so the ends are the last part 8. Connect the dryer hose. Wear protective gear per the manufac- to slide down into the upward oriented 9. Lay the baby gate on top of the box. turer’s recommendations. J slots in the wide boards.

64 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes CHECKPOINTS Oshkosh 2015 musings. Having just returned from AirVenture great VFR, I will reserve an IFR reservation on arriving within a minute or 2 of my 2015, I thought I would share some slot. I did so this year again, and it was a scheduled time, but this year Chicago thoughts while they are fresh in my mind. good thing. While weather was marginal Approach threw a wrench into the game. The trip up in the RV-10 was very pleasant VFR due to ceilings with broken to scat- We were held on the ground at Gary for as we did our usual flight at 10,000 feet to tered clouds, below the clouds it was almost 20 minutes, and once airborne Gary, Indiana, for the first leg. We always typical July haze, and a flight across Lake and in cruise on our assigned routing, I use oxygen at or above 10,000 feet during Michigan without reference to instru- could see that we were going to miss our the day and 5000 feet at night. It’s amaz- ments would have been very dicey. Fel- slot by at least 10 minutes. I pushed the ing how much more rested we feel when low Kitplanes® writer Dan Horton saw power up a little more than usual and we land, and I am sure we are much more it firsthand and, discretion being the bet- started asking for routing changes and alert in the airplane. And even though the ter part of valor, he turned around. The “direct to” intersections in order to shave RV-10 could make it non-stop to OSH, it’s accompanying picture doesn’t really do some time off. Eventually Milwaukee nice to take a break in order to be rested justice to the actual view out the window, Approach came on and said to not worry for the final leg. Also, there’s a really nice and I suspect it is due to some filtering about my Oshkosh window. Great— FBO, B. Coleman Aviation, at Gary/Chi- by the camera. Suffice it to say there was pressure off! We now enjoyed the rest of cago International Airport (KGYY) with no visible horizon while over the water. the flight, culminating in an uneventful really cheap prices and super friendly In Dan’s own words: “I swear, the Mark 1 landing on the orange dot on Runway 27. staff. The fun part of the next leg, if the eyeball saw none of that; it looked like the weather cooperates, includes taking the inside of a featureless green-blue ball.” Welcome to OSH scenic shoreline tour up past Chicago. I For those of you who have used the So here we were again, at the one event usually watch the weather forecasts and IFR reservation system, you know that that has created so many fond memories actual weather for about a week prior to you are assigned a 15-minute window in since our first trip in 1981. Of course there the trip, and if there is any doubt about which to arrive. I’ve always prided myself is always the weather factor at Oshkosh.

Here is the view captured by Dan Horton while attempting to IFR approach to Runway 27. Cleared to land on the orange dot, and cross Lake Michigan on the way to OSH. The view is actually better we know a whole new set of great memories will begin to unfold through the camera lens. Dan turned around! at AirVenture.

Vic is a Commercial Pilot and CFII with ASMEL/ASES ratings, an A&P, DAR, and EAA Technical Advisor and Flight Counselor. Passionately involved in aviation for over 36 years, he has built 10 award-winning aircraft and has logged over 7800 hours in 69 different kinds of aircraft. Vic Vic Syracuse had a career in technology as a senior-level executive and volunteers as a Young Eagle pilot and Angel Flight pilot. He also has his own sport aviation business called Base Leg Aviation.

Photos: Vic Syracuse and Dan Horton KITPLANES January 2016 65 passing the torch as we get older. I still remember my first Oshkosh and how overwhelmed I was, and realizing how much I had to learn. And now, too fast, it seems like it is time to help others learn.

Still Overwhelmed Speaking of Oshkosh and overwhelming, I had a little of that same feeling this time as well. No doubt the leadership team at EAA has done a wonderful job of growing AirVenture into an immensely successful convention that covers just about every facet of aviation. It truly is amazing, This was the view of the unforecast storm just before it hit with a vengeance. It was like an and one only has to go out to the flight old friend just reminding us of Oshkosh’s potential for varying weather. line and climb up one of the photo plat- Those of you who have been there know of the storm that morning. From what forms and slowly do a 360° turn. It has a what I mean. We’ve come to learn that we heard only a few airplanes were dam- wow factor beyond belief. there is going to be a surprise sometime. aged. I think we all got away pretty easy The focus on the youth aviation We just don’t know how much or when. with that one, although I am sure the programs is also wonderful, espe- This year was no different. We landed owners of the damaged airplanes may cially seeing such great people as Dick Friday afternoon, and the Welcome feel differently. The rest of the week was VanGrunsven and other aviation icons Wagons were Johnny-on-the-spot to absolutely wonderful weather wise! being so actively involved. get us over to Camp Scholler. Aren’t This Oshkosh was a little different for However, looking past that, I also those Welcome Wagons a great service? me. In past years it was my getaway, a think it can be confusing for new peo- It’s also amazing how much gear the time to really enjoy aviation and friends. ple just getting into aviation. Believe RV-10 will carry, as Carol and I barely had This time I had some responsibilities, me, I love this place, and having been enough room to sit in the back of the which included presenting a forum, so many times, I kind of know where to Welcome Wagon once we loaded all of speaking at the Van’s Aircraft banquet look for things. But I can’t help but won- our stuff in it! Friday’s weather was very (what an honor!), spending time in the der if there is an opportunity to arrange pleasant, and we retired to bed around KITPLANES® booth, and having our air- the flight line in a way that would show- 11 p.m. with a really great weather fore- plane on display for the Avidyne team. case all of the aviation opportunities cast and nothing showing on the radar I was also invited to interview for the available to everyone, much like a walk in ForeFlight. EAA Homebuilt Aircraft Council, a nice through a museum or nature center. Around 5 a.m. I was reminded of a line surprise and honor. By the time you As an example, starting at show center, from one of Bob Seger’s songs: “I woke read this, you may have already seen the aviation could be split left and right into last night to the sound of thunder. How announcement of the new members, two categories: “you build them and far off, I sat and wondered.” Only I didn’t of which I am one. How cool is that? I you fly them,” and “we build them and have to wonder how far off it was, as it am starting to understand the axiom of you fly them.” was clearly pretty close. Huh? No mention of this in the forecast a few short hours ago. A quick peek outside to the west showed a pretty ugly, yet beauti- fully colored sky. In a few short minutes we had some pretty terrific winds that I thought were going to capsize the camper, and that was followed by almost 2–3 hours of rain. Here we were in muddy Camp Scholler again! The difference this year was seeing the quick reaction of all the volunteers with huge water-vacuum trucks taking away most of the large puddles that in the past had made a huge mess. By the time we came back All good things come to end. A new stuffed-aviator toy headed home to our new that evening, there was hardly any sign grandson, Connor.

66 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Each side could start from simplest to the most complex, such as Light Sport to Epics on the custom-built side, and Give Us Your Light Sport to jets on the certified side. And just like at museums, there could be signage, or even apps for the iPhone, that give you more information about the air- Best Shot! craft, as well as pointing you to the loca- ® tion of the vendor on the field.N o sales Enter the KITPLANES “Best Of…” pressure should be allowed on the flight line. I know it would take some work contest for a chance to win a and organization, but I think it would be really cool for an aspiring aviator to see $25 gift card from Aircraft Spruce. and understand all of the opportunities available to them. There is nothing like a little contest to help folks share more and better The Next Generation ideas about Experimental aviation. Speaking of young, aspiring aviators, Each month, we’re asking for pictures the funniest thing happened at lunch on a specific topic like: right after we returned from Oshkosh. • Best example of aircraft wiring We flew the Stearman to Peach State • Best VFR panel Airport (GA2), which has a wonderful • Best tool storage idea restaurant right on the field, a grass • Best homebuilt on a beach strip. When the weather cooperates we really enjoy eating outside and watch- • Best small workshop ing the other airplanes, as well as seeing • Best “workshop extraction” (getting and meeting folks interested in aviation. an airplane out of a basement or loft) It’s also one of those places where you There’s a new topic every month, still see parents bringing their kids to so enter the contest often. the airport to see airplanes. While waiting for our food I noticed a young mother with two small children, a You Be The Judge boy and a girl. The young boy was clearly Each month, our editors will pick excited about airplanes. As I often do three finalists from all photos when I see such enthusiasm, I asked the mom if she would like to get a picture submitted. Then it’s your turn of her children on the wing of the Stear- to vote for the best of the best. man. This time the kids answered before The winner will receive a $25 gift she did, so I put them up on the wing. I card from Aircraft Spruce, and the couldn’t help but notice the young boy’s winning photo will appear on the fixation with the cockpit, so I asked if he KITPLANES® web site. wanted to get in. Silly question, huh? Once seated he did the usual playing with the controls, but what he said next We All Win completely blew me away. He looked at Only one Aircraft Spruce gift card will his mom and said, “Mom, I am going to be awarded each month. But when work real hard when I get older so I can we share ideas, everybody comes out buy you an airplane like this.” Did I tell you ahead by learning how to do a better he was 5 years old? Wow, wouldn’t you job of constructing, maintaining, love to watch this kid chase his dreams? I and flying homebuilt aircraft. bet he is going to have lots of fun. I hope he makes it to AirVenture someday and Visit www.kitplanes.com for more information. sees all of the choices available to him. We had a great week at AirVenture By entering the contest, you grant KITPLANES® magazine the right to use your image in print, 2015 and hope you did, too! J online, and for promotional purposes.

KITPLANES January 2016 67 Combining parts from multiple kits, N-numbers, using an amphibian for land-only training. By Mel Asberry Question: A friend and I are put- indeed amateur-built. By the way, this painted. The aircraft owner may place ting together an Experimental particular aircraft had already been the numbers inappropriately during aircraft from many aircraft parts denied by another FAA inspector. painting. Although this does not make we have collected over the years. It would be good, and possibly save the numbers legal, the inspector has no The fuselage and control surfaces you a lot of heartache, if you contacted control after certification. come from three partially com- your inspector now and discussed the Question: My dad and I built a pleted Seawind kits. I believe the situation. Be careful. Searey amphibian taildragger, and Lycoming engine and Aero Com- Question: I’ve seen quite a num- my dad is the registered owner. posite prop are certified. What ber of Experimental aircraft with Can a taildragger-endorsed pilot or forms or paperwork must I file with the N-number under the horizontal instructor fly/teach in this plane for the FAA to let them know that this stabilizer. Don’t the FARs prohibit land-only operations without hav- project is underway? this? If so, how do these planes pass ing the amphibian endorsement? Answer: You will need to be able to the airworthiness inspection? Also, is there a legal way for me to prove that the items from the partially Answer: You are correct that FAR pay an instructor for training while completed kits were indeed amateur- part 45.25(b)(2) covers this placement. flying in my dad’s plane? Would that built. Engine and prop do not count It states that markings must be dis- violate the for-hire regulations? against the 51% rule. played horizontally on both sides of the Answer: Unfortunately if the aircraft You will need to complete and sub- fuselage between the trailing edge of the is capable of landing on water, the pilot mit the checklist found in AC 20-27G, wing and the leading edge of the hori- must have a seaplane rating to fly it. Appendix 8 to help show amateur-built zontal stabilizer. Otherwise it would be similar to a sin- compliance. No other paperwork is Notice that this is the placement gle-engine pilot getting into a twin and required unless your inspector requests requirement if marks are on the fuse- promising to use only one engine. further 51% proof. lage. An alternate placement may be on You may pay an instructor for instruc- I just went through this for a Pitts S1S. the vertical tail surfaces. So, if you place tion in your dad’s airplane as long as The builder was claiming amateur-built the marks on the rudder, there is noth- there are no charges for the aircraft percentages in the 90s. It took several ing that says that they cannot be under itself. But be aware, the instructor must days of research to prove amateur-built the elevator. be Single-Engine Sea (SES) rated. J status. The final tally ended up in the As far as the airworthiness inspector lower 60s. Yes the aircraft qualified, but missing this, the most common reason Please send your questions for DAR he had to do a lot of research to prove is that many times the airworthiness Asberry to [email protected] with that the parts from other aircraft were inspection occurs before the aircraft is “Ask the DAR” in the subject line.

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KITPLANES January 2016 73 Bob Alexander’s RV-7 On May 10, 2013 I made my first flight in my completed RV-7. After a decade of building, it was finally time to experience the joy of flying this marvelous kit from Van’s Aircraft, and it did not disappoint! The plane flew perfectly, and I have now completed the testing phase, flying out of the Tacoma Narrows airport in Gig Harbor, Washington. My RV-7 includes an IO-360 engine from AeroSport, Hartzell blended airfoil prop, interior by Classic Aero, Lightspeed electronic ignition, TruTrak autopilot, Advanced Flight System Sport AOA, and a beauti- ful paint job by Dan and Linda Mauer of Red Bluff, California. Thanks to EAA tech/flight advisors Marv Scott and Terry Burch. Fox Island, WASHINGTON [email protected]

Al Leppanen's Dakota Hawk I built my Dakota Hawk from plans over a period of about three and a half years; the first flight was in October 2011. I've built many R/C models over the years and my wife said, "The Hawk under construction looked just like a big model." I must agree. The plane is a simple, classic design, all wood, fabric covering, steam gauges, and powered by a Continental A75 with no electrics. I finished it with latex paint, and I carry a handheld radio and a simple GPS. Many parts that I didn't think were worth trying to build, such as the windshield, fuel tanks, and engine mount, were supplied by Fisher Flying Prod- ucts. The total cost was about $19,000. Cambridge, Ontario, Canada [email protected]

Jimmy Young's Zenith CH 750 On August 10, 2012, I made my first flight in N75ZX, a Zenith CH 750 I had started construction two years and nine months before. She has flown flawlessly straight and true from day one, requiring absolutely no changes in rigging. This was by far the most fulfilling personal sense of accomplishment I have ever had, and it made all of the 1008 hours I had spent over the previous two years and nine months building it well worth it. It was built from the kit Zenith sells, which utilizes CNC match-hole technology. Though there is still a lot of work to do, this makes the process easy compared to laying out every hole yourself, and it really speeds up the construction time. It is powered by a Continental C-90 engine, which I had completely rebuilt locally by Dan Martinez, a great guy I met via referral from other builders. Six months later I have over 150 hours on it, including a three-day cross-country trip from Hous- ton, Texas, to Fayetteville, Arkansas, I took back in November. Many thanks go out to Curtiss Shuetzberg who helped me install my engine and instruments, Danny Still who helped me with paint, James Cameron who designed the paint scheme, and the fine staff at Zenith Aircraft. Houston, Texas [email protected] J

Submissions to “Completions” should include a description (250 words maximum) of the project and the finished aircraft. Also include a digital image of the aircraft. Minimum digital image size is 1500 pixels wide x 900 pixels high (5 x 3 print size at 300 dpi). Please include a daytime phone number where we can contact you if necessary. Also indicate whether we may publish your address in case other builders would like to contact you. Email text and photos to [email protected] with a subject line of “Completions.” You may also submit electronically at www.kitplanes.com, just click on “Completions: Add Yours” in the upper right corner of the home page.

74 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes Horns and spades. Last month we took a look at using fixed surface ahead of the moveable the control surface leading edge from hinge-line offset to aerodynamically bal- balance surface. Shielded horn balances the free stream at low control deflec- ance control surfaces. Offset hinge bal- are common on the tail surfaces of mod- tions, reducing the balance’s effect on ances are effective, but they were not ern light airplanes. floating tendency. the first type of aerodynamic balance to Aerodynamically, horn balances Like offset-hinge balances, horn bal- appear, nor are they the only effective behave very much like offset-hinge-line ances will stall if the control surface is way to use aerodynamic balances to tai- balances with the exception that they deflected too far. Unlike offset-hinge bal- lor control surface hinge moments. have a much larger effect on the floating ances, the stall is not total. Only the sur- tendency of the surface. The exposed face near the balance horn stalls. The rest Horn Balances horn balance has a greater effect on of the surface is likely to remain effec- A second type of aerodynamic balance floating tendency than the shielded bal- tive. Although the pilot will feel sudden is the overhanging or horn type balance because the leading edge of the changes in control forces and buffeting, ance. The horn balance is a section of the exposed balance is directly exposed to he will probably retain control over the control surface at the tip that extends the airstream, and can develop signifi- airplane. The effect of stall of horn bal- forward of the hinge line. It extends out- cant aerodynamic force in response to ances is further reduced by the fact that board of the tip of the fixed surface the changes in the airplane’s angle of attack. the exposed balance tends to be a rela- control surface rides on, hence the term The fixed surface ahead of the balance tively low aspect ratio, so it can get to a “overhanging or overhung balance.” area on the shielded balance protects higher angle of attack before stalling. There are two types of horn balances. The first type shown is the exposed horn balance. In this type of balance, the leading edge of the balance area is exposed directly to the airstream and has no fixed surface ahead of it. This type of balance was popular for ailerons during WW-I and for about 15 years thereafter. Simple horn-balanced ailerons, sometimes called “elephant-ear” ailerons were a feature of the Fokker Dr.I triplane and the Fokker D-VII, as well as the post-WW- I Travel Air airplanes. The horn-balanced ailerons on the Travel Air gave it a super- ficial resemblance to the Fokker D-VII. Since Travel Airs were easier to get than war-surplus Fokkers, they appeared as “German fighters” in several movies, leading to a nickname of “Wichita Fok- With an exposed horn balance, the Shielded horn balances have a fixed surface ker” for the Travel Air. leading edge is exposed directly to the ahead of the movable balance surface. They The second type of horn balance is airstream and has no fixed surface ahead are common on the tail surfaces of modern the shielded horn balance. This has a of it. light airplanes.

is a principal aerodynamics engineer for Northrop Grumman’s Advanced Design organization. A private pilot with single engine and glider ratings, Barnaby has been involved in the design of Barnaby Wainfan unconventional airplanes including canards, joined wings, flying wings, and some too strange to fall into any known category.

Photos: Kathryn Wainfain KITPLANES January 2016 75 Horn balances are most commonly used on tail surfaces (horizontal and vertical) where the reduction of the floating tendency is highly desirable because of the detrimental effect elevator and rudder float have on the stability of the airplane. Horn-balanced ailerons are rarer since the floating tendency of ailerons is of less concern than the floating tendency of elevators or rudders. Since ailerons move antisymmetrically, that is one up and one down, the floating tendency of the ailerons puts symmetric loads into the control linkage to the stick, and the two ailerons balance each other out. Horn-balanced ailerons have been Horn-balanced control surfaces are less likely to destabilize an airplane than surfaces with no balance or an offset hinge line. This is particularly important for elevator design. used in the past, particularly on early airplanes, but are no longer common. surface can be hung on simple hinges, hit. The exposed nature of horn balances while a surface with an offset hinge line also increases the possibility that the Horn Balance Advantages must have more complicated hinges that surface can be jammed by debris lodg- and Disadvantages are cantilevered a significant distance ing in the fore-and aft slot between the The horn balance has two primary away from their mounting point. balance and the tip of the fixed surface. advantages over the offset-hinge-line A third advantage of horn balances is The fixed surface ahead of the balance balance. The first is that the horn balance that the balance area can also house the on the shielded balance greatly reduces reduces the floating tendency more than mass-balance weights used to prevent the chances of this happening. the offset-hinge balance while having the control surface from fluttering. This A second disadvantage of horn bal- about the same effect on the restoring is very common practice in the design of ances, particularly if they are large, is that tendency. This means that a horn-bal- light airplane elevators and rudders. since they are cantilevered off of the end anced surface will float less and there- The primary disadvantage of the horn of the control surface they can produce fore destabilize the airplane less than a balance is that it is vulnerable to damage. relatively large structural loads on the surface which has no balance or an offset The horn is exposed at the tip of the con- rest of the surface. The designer who hinge line. This is particularly important trol surface and is therefore the first thing uses horn-balanced controls must take for elevator design. to be hit during the seemingly inevitable this into account when designing the The second advantage of the horn bal- ground handling mishaps that cause movable surfaces. ance is that it is easier to build and hinge hangar rash. This is a problem particu- a horn-balanced surface than to provide larly if horn-balanced ailerons are used External-Airfoil Balances an offset hinge line. A horn-balanced since wingtips are the first areas to get An external-airfoil balance is a small surface mounted to the main control surface on struts so that the aerodynamic center of the smaller surface is ahead of the hinge line of the control. This type of balance has recently become very common on aerobatic airplane ailerons as designers attempt to reduce the aileron forces to improve roll performance. The most common design is a flat metal plate suspended ahead of the aileron on a single supporting tube or strut. This type of balance is sometimes called a paddle balance, but are usually referred to as “spades” because of their resemblance to small shovels. The spade balance affects the control Paddle balances are the most common type of external-airfoil balance. They are flat metal surface hinge moments very much like plates suspended ahead of the aileron on a single support tube or strut. the simple, unshielded horn balance.

76 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes While spade stall will cause an increase cross-country performance. They are, Another danger that must not be in hinge moment, it will not significantly however, quite common on aerobatic overlooked is control-surface instabil- affect the control power of the main con- airplanes where proper tailoring of the ity, sometimes known as overbalance. If trol surface it is attached to. aileron forces is much more important to the aerodynamic balance is too large, or The primary advantage of the spade good performance of the airplane mis- behaves nonlinearly, the control surface balance is that it is easy to modify to tai- sion than a small reduction of drag. may have an unstable restoring ten- lor the control surface’s hinge moment A secondary advantage of spade bal- dency. This means it will tend to go hard to the desired level. Both the size and ances is that the struts supporting the over when deflected. If this happens, planform of the spade affect how it spade can be used to hold mass-balanc- the pilot must fight the control to keep changes hinge moment over the full ing weights to prevent aileron flutter. it in the neutral position. When this hap- range of control surface deflection. Mod- pens on ailerons it is known as “aileron ifying spades is one of the primary tools Warnings snatch”. Control-surface overbalance used to fine-tune competition aerobatic When designing an airplane with bal- is extremely dangerous and has been airplane roll performance. anced controls, proceed with caution. responsible for several fatal first-flight The primary disadvantages of spade In general it is more dangerous to have accidents. An airplane with overbal- balances are their vulnerability and the control forces which are too light than anced controls is, at best, difficult to fly drag that they produce. Because spades too heavy. An airplane with heavy and may prove to be uncontrollable. are exposed, they are relatively easy controls may not be particularly pleas- Before deciding to balance the controls to damage in ground handling. This is ant to fly, but unless the forces are so aerodynamically, the designer should have offset by the fact that they are easy to heavy that the pilot cannot move the some idea of what the control forces on replace or repair. controls, it will be safe. An airplane with an unbalanced control surface would be. Spades add wetted area to the air- excessively light controls will be prone In many cases, aerodynamic balance is plane, and the struts supporting the to pilot-induced oscillations, and it will unnecessary. In situations where control spade can produce significant drag. be easy for the pilot to exceed the air- forces will be too high, or floating tendency Because of this, spades are rarely seen plane’s structural limits by an abrupt excessive, aerodynamic balancing offers a on airplanes which are designed for fast control input. way to get satisfactory characteristics. J Kitplanes subscriber alert! several of our Kitplanes subscribers have received what appear to be “renewal notices” or “automatic renewal notices” from a company known as preMier subscriptiOn serVice, 5star subscriptiOns, rapiD MaGaZine cOllectiOn, MaGaZine billinG serVices, publisHer’s billinG serVices, circulatiOn billinG center or other similar names. Addresses for these firms include Dallas, tX; lincoln, ne; Omaha, ne; san luis Obispo, ca; salt lake city, ut; White city, Or and prescott, Fl. These firms have nOt been authorized by us to sell subscriptions or renewals for Kitplanes and we cannOt Guarantee that any order or payment sent to them will be forwarded to us. Kitplanes does nOt offer a subscription term of more than 2 years, nor do we retain your bank account information. if you see an offer for 3 or more years or if you receive a notice that references your subscription anD your banking information, it is nOt an authorized offer. We urge you to report these notices to us, as well as to your state’s attorney General and better business bureau. any offer you receive that does not bear our company logo or corporate/customer service address or 800 numbers should not be considered approved by us. the only autHOriZeD inFOrMatiOn for Kitplanes is: toll free via telephone 1-800-622-1065, Dial america renewal telemarketing, or www.kitplanes.com/cs Our texas customer service center: 1-800-622-1065, pO box 8535, big sandy tX 75755 Or our corporate offices at: belvoir Media Group, llc. aviation publishing Group 535 connecticut ave norwalk ct 06854 should you have any questions at all about mail that you receive, please contact us at our web site: www.kitplanes.com/cs or call us toll free to speak to customer service.

KITPLANES January 2016 77 Winging it with LEDs. As I said last month, Oshkosh ’15 has a receiver detector crystal caused it to want, be it red, green, or white. Nothing come and gone. However, some of the glow. It took until 1962 for that glow to is lost to color filtering. things we learned there are still quite become useful with the first red LED— Now that we think we might want LED vivid in my mind. One of them is how cost $2,000 each. By 1968 LEDs cost a lighting, let’s see what the feds have to say far we’ve come with modern electronic nickel each, and we started getting about lighting on the aircraft. Instrument devices in our homebuilt aircraft. While other colors…first green, then yellow, lights (which we covered in Kitplanes® I don’t think now is the time for me to then orange. In 1992 along came the August 2015 issue) are covered in FAR write about making your own ADSB-Out blue LED followed in 1993 by the white 23.1381 in four simple lines that say that circuit for two Cracker Jack boxtops and LED. This sets the stage for our article the lights must make the instruments vis- a first class stamp, we might want to look this month. ible and not shine in the pilot’s eyes. at some of the easy stuff. Like using LEDs For some years the incandescent bulb Taxi and landing lights are covered in for both navigation (wingtip and tail has held sway for aircraft lighting. How- 23.1383 which say that the lights must feathers) lights and landing lights. ever, incandescent bulbs are roughly give “enough light” for the pilot to see at About seven years ago (KITPLANES® 2% efficient at converting electrical night and can’t shine in the pilot’s eyes. August 2008) we discussed what might power to light. Even worse, when you Nothing more. be possible in the years to come with put them on the wingtips as nav lights, Navigation lights are covered in LED navigation lights. We neatly side- you filter out all the light you don’t want 23.1387 which goes on for four pages stepped the landing light and rotating in favor of the color you want. The effi- of really small type and uses words like beacon; but the technology has matured ciency goes down to below a tenth of “dihedral angles,” “steradians,” “Interna- to the point where we ought to be talk- one percent for both red and green. tional Commission on Illumination Chro- ing about all of them. While white is still up there at 2%, LED maticity co-ordinates” (i.e. color), and, in Just a little tiny bit of history. In 1907 lamps start at 15% efficiency and are the only instance I’ve ever seen in any (no, that’s not a typo) radio engineers knocking at the door of 20%. To boot, FAR, integral calculus equations to define noticed that passing current through this is the efficiency at the color you brightness. Whuf.

A 30:1 aircraft model with 1:1 LED nav lights (real size). Note: The Tail feathers white lights showing a 140° light angle to provide model is aluminum so it must be an RV of some sort. 180° rear coverage.

is the chief avioniker at RST Engineering. He answers avionics questions in the Internet news- group www.pilotsofamerica.com–Maintenance. His technical advisor, Cyndi Weir, got her Masters degree in English and Journalism and keeps Jim on the straight and narrow. Check Jim Weir out their web site at www.rst-engr.com/kitplanes for previous articles and supplements.

78 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes With a single LED instead of the FAA-specified incandescent With two LEDs the coverage is 10–20 times the FAA require- lights, the coverage is at least 5 times more than required. ment, and the rear angle blind spot problem is solved.

With either a single or double LED, the vertical illumination is at least triple the FAA requirements.

Hmm. Going over that nav light approaching from the rear of the aircraft model I made was constructed, and let requirement with several sheets of equa- from the 4 and 8 o’clock directions. you figure it out for yourself. tions and a fair amount of pencil lead Be that as it may, we can really improve What I can also give you are the part gives me graphs that let me prove to the FAA minimums using two relatively numbers and a source for them so that myself that this design I’m about to show inexpensive LEDs at each nav light loca- you can start to assemble the parts for you will let you put LED nav lights onto tion and eliminate that dead spot when this project. You don’t have to use my your Experimental aircraft in accordance approaching from an aft angle. sources, but you do have to use my man- with the regs. Note that now there are two major ufacturer part numbers if you want my Here, in a nutshell, is what the feds lobes of light coming from each wing calculations to be valid. Prices are current say you have to do with nav lights. You and about 20 times as much light to as of fall 2015 and do not reflect any ship- have to be able to see them directly off the aft and sides of the tail as the regu- ping charges or tax. the wing when approaching, full bright lation requires. Shucks, all those words and we still dead ahead, and just a little bit on the “But Jim, how do I install that on my haven’t seen a schematic as to how to other side of dead ahead. Similarly on airplane?” Since there are approximately hook them up or how the landing light the other wing, you need the same thing. 1000 kit and plansbuilt designs out there, works. Patience, patience—next month Thus, dead ahead, you get full brightness I’d have to do 1000 separate designs and we’ll tackle the landing light, how LEDs from both red and green wingtip lights, that just isn’t possible. What I can do is are powered, and a couple of ideas on but as you move to one side or the other, give you the general requirements, a how to (in)efficiently power them. all you get is the color of that wing light. few good photographs of how the little Until then…stay tuned… J They also say you have to have about half brightness when you are 45° above or Mouser Electronics Led Engin Lights below each wingtip. Part Part # Mouser Order # Price On the tail feathers, the white light has to be full bright from dead astern to Red LED for left wingtip LZ1-10R100 897-LZ110R100 $13 roughly 90° to the left or the right when Green LED for right wingtip LZ1-10G100 897-LZ110G100 $13 approaching from the rear. Now look at the graphs for single White LED for tail LZ1-10CW00 897-LZ110CW00 $13 lights and note that there is a complete White LED for landing light LZ9-M0CW00-0065 897- M0CW000065 $38 dead spot in the lighting if you are

Photos: Jim Weir KITPLANES January 2016 79 By Robrucha

80 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes