Better Aerobatics: Modified RANS S-9 KITPLANES

OCTOBER

2017

® Murphy Radical • Drag Reduction Murphy • RANS Radical S-9 • Static Ports • Cosmic Fish • DAR Inspections • Leak-Down Tester • Robbie Extreme Grove • Blind Bush Plane Rivets • Spin

Class Static Port Accuracy

BELVOIR Location is Everything OCTOBER 2017

DAR Inspections In the Shop:

PUBLICATIONS • Make Your Own Spinner Paperwork Made Easy • Specialty Wrenches Drag Reduction • DIY Leak-Down Tester

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DynonAvionics.com [email protected] (425) 402-0433 October 2017 | Volume 34, Number 10 Flight Review 6 Get Radical! Murphy’s latest is all about fun. By Paul Dye. Builder Spotlight 16 changing a Perfectly Good Airplane: Building a modified RANS S-9, part 1. By Michael Ryer and John Wells. 20 l anding Gear Guru: Robbie Grove of Grove Aircraft Landing Gear Systems. By Eric Stewart. 26 Static Port Location and Altitude Calibration: Often a challenge, accuracy depends on three things: location, location, location. By Reinhard Metz. 34 So You’d Like to Go Faster: Secrets for reducing drag, 16 part 2. By Dave Anders. 42 Getting Your Plane Ready for the DAR: Common pitfalls and problems that builders face. By Dave Prizio. 48 eRRor Chain: The demise of theCosmic Fish. By Lewis Bjork. 52 build Your Own Leak-Down Tester: Converting a Harbor Freight compression tester for aircraft engine use. By Vince Homer. 64 c ompletions: Builders share their successes. 66 a sk the DAR: Phase I testing not completed, understanding operating limitations, non-TSO’d position lights. By Mel Asberry. Shop Talk 41 the Creative Homebuilder: Make your own specialty wrenches. By KITPLANES® Staff. 54 Plane and Simple: Removing blind rivets. By Jon Croke. 60 Home Shop Machinist: Spin class. By Bob Hadley. 75 Aero ’Lectrics: So-lar, it’s been good to know you. By Jim Weir. 77 Unairworthy: Pitted wheel bearing cup. By Vic Syracuse. Shop Tips 40 alodine Sluice: By Larry Larson. 59 Fuel Dipstick and Holder: By Noel Fallwell. 74 Clamp Stick: By David Paule. Designer’s Notebook 6 72 Wind Tunnel: Gyroplanes, part 5. By Barnaby Wainfan. Exploring 2 Editor’s Log: While I’m in here… By Paul Dye. 56 Checkpoints: Phase I maintenance. By Vic Syracuse. 78 Rear Cockpit: Fuel follies. By Tom Wilson. Kit Bits 4 Letters 67 list of Advertisers 68 builders’ Marketplace 80 kit StufF: Drawing on experience. By cartoonist Robrucha. 20 On the cover: Murphy Aircraft’s new Titan-370-powered Radical, photographed near Chilliwack, British Columbia, by Paul Dye. For subscription information, contact KITPLANES® at 800/622-1065 or visit www.kitplanes.com/cs. KITPLANES October 2017 1 Editor’s log While I’m in here... It all begins so innocently. We have the odd digital instrument velcroed to panel space since day one. Every time I the best intentions to make a small modi- the glareshield for years and small black thought it was a good time to take the fication or simply fix something that isn’t boxes (like GPS receivers) stuffed behind airplane down, pull the panel, and do quite right. We take the airplane out of the panel, filling all available volume. the installation (plus all that necessary service and open her up to do the job. In short, the RV-8’s panel wiring is a cleanup), something else has come up, We stare at it a little while and think, “You mess, an embarrassment to anyone (like some other airplane was broken, or the know, while I’m in here, I might as well…” myself) who values parallel wiring runs annual inspections had ticked around on The next thing you know, months have with tight little lacing-cord knots. So the calendar. gone by, the airplane is spread all over the cleaning that up has been on the list. The But finally it was the RV-8’s turn—so hangar floor, and you are further from fly- last of my airplanes to get some sort of out came the panel and all that wir- ing than you were before you started! ADS-B In and Out equipment, the RV-8 ing came spilling into my lap. Cleanup The past year saw my trusty RV-8 in has sat patiently for the past six months began. Actually removing the old tran- this situation. With other, newer air- with a brand new Garmin GTX 345 sitting sponder and physically installing the planes in our hangar, the RV-8 occasion- on the shelf, destined to replace the old new one took about an hour; that was ally gets stuffed in the back, unflown for Mode C GTX 327 that has occupied the the easy part. Going through all my a few weeks (or sometimes a month) at a time. Originally flown in 2005 after a 1½-year build, it is equipped to state-of- the-art standards—or at least the state of the art in 2004. Things have advanced since then! Fortunately, the panel has been constantly updated as we tried new EFIS and avionics equipment, both the blessing and the curse of being an aviation journalist. Yes, it is great to get a chance to fly with the latest and greatest—but that often means a hurried and tempo- rary installation, with proper bracketry and cabling ignored in the interest of expediency and not wanting to make anything so it can’t be changed again later. Extra circuit protection can often be velcroed in place, and a forest of zip ties used to keep wires from dangling out from under the panel instead of nice neat lacing. I’ve had antennas and When you go in to change a light bulb, sometimes it gets a little more complicated.

Paul Dye, KITPLANES® Editor in Chief, 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, an RV-3 that he built with his pilot wife, as well as a Dream Tundra they completed. Currently, they are building a Xenos motorglider. A commercially licensed Paul Dye pilot, he has logged over 5000 hours in many different types of aircraft and is an A&P, EAA Tech Counselor and Flight Advisor, as well as a member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.

2 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes notes to figure out what serial channels had to do a little rewiring of the lighting written checklist, as always, to make sure were talking to each other between the switches since the strobe circuitry was that I didn’t lose track of where I was in EFIS, IFR navigator, and transponder different. To no one’s surprise, the nylon the month-long downtime) along the took longer. Molex connectors I used more than a way, mostly when I was frustrated with But since I was in there…the annual dozen years ago were getting a little some portion of the upgrades. And was due. And that meant I had to check brittle, so I figured it was time to “modern when the airplane was all buttoned back out all of the lighting. Lo and behold, up” and put in some better, newer CPC- up, its new transponder transpondering, the landing lights were both dead—HID style connectors I had on hand. Since I and its new lights blinding all that looked units with noisy power supplies that I was in there… my way, I took a look in the logbook and had installed years back in a test pro- Oh, then of course, I had a new little realized it had been 2½ months since the gram. I rarely fly the airplane at night, so Garmin aera portable GPS—the first airplane had last flown. Our other air- I hadn’t noticed them going out (that’s new portable I had used since my 696 planes were smiling, however. They took what inspections are for, right?), but now showed up about eight or nine years up the load and got lots of airtime during was the time to address the problem. ago—and that needed a mounting loca- the same period. Time for LEDs, of course! But since I was tion so I could use it with the wireless link It turns out that “while I’m in there” is in the wingtip…wouldn’t it make sense to to display traffic and weather from the one of the most dangerous things you upgrade the nav and strobe lights to LEDs new transponder. I freehanded a bracket can say if you want to get an airplane at the same time? Since I was in there… to mount on the left side of the cockpit in and out of maintenance as quickly So yes, all the lighting got changed. and only bent one of them the wrong as possible. It’s not so bad when you’re A new set of Whelen landing, nav and direction before I got it right the second motivated by the fact that it’s the only strobe lights got added, which means time. Funny how things work out—but airplane you have to fly, but when it can the old Whelen strobes and nav lights at least I have a good-sized pile of scrap take a back seat, it does. This just goes had to come out. And the wiring had to aluminum from multiple projects to use back to the old rule of knowing and stick- change. Since I was in there…I redid the for things like that. ing to your requirements. Break that mis- taillight mount that had served well, but The annual condition inspection? sive, and you might well create a hangar was a little outdated. And, of course, I Well, that went great! I did that (using a queen—and that’s no fun for anyone. J

Photo: Paul Dye KITPLANES October 2017 3 EDITORIAL Editor in Chief paul Dye [email protected] Whole-Plane Parachutes of NdFeB magnets easily reach through Executive Editor mark Schrimmer I enjoy KITPLANES® very much and aluminum skins and align concentri- Art Direction Dan Maher look forward to every issue. But I’ve cally with each other. Simply slide the Editorial Director paul Bertorelli been surprised that in the eight years inboard magnet into alignment with Contributing Editors larry Anglisano, Marc Ausman, that I’ve been building my Avid Flyer, the existing hole and transfer punch leRoy Cook, Robert Hadley, Dan Horton, Louise Hose, you’ve never, to my knowledge, done an through the hole in the outside mag- amy Laboda, Dave Martin, article on whole-plane parachutes. How net. Works good! Magnets (part num- sid Mayeux, David Paule, Dave Prizio, Ken Scott, come? Got one in the works? ber 636) from K&J Magnets (www. elliot Seguin, Dick Starks, Mike Rancourt kjmagnetics.com) are $1.28 each. eric Stewart, Vic Syracuse, David Barker barnaby Wainfan, Jim Weir, tom Wilson. To be honest, I have looked before for Web Editor Omar Filipovic someone to do an article on ballistic recov- We’ve seen (and used) the magnet trick Cartoonist Robrucha ery ’chutes for homebuilts, but have never ourselves. There used to be a kit that ADVERTISING had any luck. I think part of the problem involved small magnets and a “magnetic Sr. Advertising Manager Chuck Preston is that for aircraft faster and larger than viewer” that worked well. A good builder 805/382-3363 [email protected] ultralights, a ’chute system needs significant can add all of these to their bag of tricks, design work and testing for each installa- and use whatever works best in a given BUSINESS OFFICE Belvoir Media Group, LLC tion, and few of the kit manufacturers have situation.—Ed 535 Connecticut Avenue done that. If you do see a rare installation in Norwalk, CT 06854-1713 a homebuilt, it generally has not been tested, Homebuilt Judging EDITORIAL OFFICE so you have no idea if it will work properly Because it included Judging Form A, 535 Connecticut Avenue if required. I have flown two E/A-B aircraft the judges’ bible, I give Ed Wischmey- Norwalk, CT 06854-1713 that were equipped (the SubSonex jet and er’s article [Perfectionist’s Playpen,” [email protected] Merlin PSA), so they are out there—but July 2017] a 10+! CIRCULATION have not been widely accepted yet. Many John Knapp Circulation Manager Laura McMann talk about them, but when they discover Chairman, seaplane judging SUBSCRIPTION DEPARTMENT the facts of price and design integration, 800/622-1065 they decide not to do it. Perhaps an article What’s ADS-B? www.kitplanes.com/cs In “What is Happening on the ADS-B P.O. Box 8535, Big Sandy, TX 75755-8535 would generate more discussion, and we’ll For Canada: PO Box 328, Norwich, Ontario N0J 1P0 keep looking for someone who wants to do Scene?” [August 2017], you did a great job such an article. Any volunteers?—Ed with almost all the acronyms throughout REPRINTS FOR PUBLICATION AND WEB POSTING AVAILABLE the six-page article. But what does ADS-B Minimum Order: 500 Locating Holes stand for? This should have been defined Contact Jennifer Jimolka, 203/857-3144 In Jon Croke’s article, “Locate That in the very first sentence. Hole—Precisely” [“Plane and Simple,” Michael Scheetz April 2017], he showed how to align a Change of address? hidden hole with a dual-strap alignment As we mentioned in the letters column Missing issue? tool. That is not always possible due to Subscription Question? in our June 2017 issue, most style guides tool reach or geometry problems. To used by the media allow the use of “stan- Visit www.kitplanes.com/cs. solve that issue, use two cylinder mag- dard acronyms” without a definition. Or call 800/622-1065 from the U.S. and Canada. nets and a non-magnetic stainless steel ADS-B has been a hot topic in aviation punch that slides through the hole in for almost 10 years, so we feel it qualifies Foreign 903/636-1112 or fax the magnet. The strong magnetic fields 203/857-3100. as a standard acronym.—Ed. J

Website 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 ©2017 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 October 2017 www.kitplanes.com & www.facebook.com/kitplanes

Get Radical!

6 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Murphy’s latest is all about fun. By Paul Dye

Photos: Paul Dye KITPLANES October 2017 7 You know you are in for a fun flight when you see the airplane hung with bicycles on the wings! The latest design from Murphy Aircraft, a 35-year-old kit company from Chilliwack, British Columbia, is a fresh look at what it takes to design a machine that begs to go into the backcountry and let’s you enjoy it once you get there. The new Murphy Radical builds on previous designs from the company that brought you the Rebel and the Moose, giving pilots what they want in a package bigger than the typical LSA, but smaller than the moose-lifting Carrying bikes outside is just a Canadian thing to do. They are smaller than the canoes Moose. The Radical was conceived to many in the north country strap to their floats. carry two people and their outdoor gear into places most light airplanes fear to in the forward part of the tail cone in 0.20-inch aluminum, and sides, tops, and tread, and it gives them the load-carry- flight—the rest of the space is to pro- bottoms of thinner 0.016-inch sheet. The ing capability to do it in style. vide a place to sleep when safely on the sides have a crease that adds a look of fab- We recently had a chance to fly the ground! The engine drives a Craig Catto ric from a distance but is actually there to prototype Radical at the company’s home prop that seems to give a good balance of add stiffness to the thin sheet. field, and with only 31 hours on the clock, climb and cruise. it appears to be living up to its promise. The airplane as we tested it carried 22 Construction While development is still in the works gallons on each side in wet wing tanks for The Radical is primarily an aluminum and the interior was unfinished, we found a total fuel capacity of 44 gallons—plenty airplane that sports fabric-covered con- the core competencies for the machine are for getting way out into the hinterlands trol surfaces and fairly typical fiberglass being fulfilled quite nicely. With pleasant and back. The current version of the wingtips and cowling. The tail surfaces and unsurprising handling qualities, the plane has a firewall brought over from a are finished off with fabric on the balance airframe is both stable and responsive, previous model and is about three inches arms, eliminating the need for fiberglass leaping off the ground with two aboard narrower than Murphy would like. It tips there. The small dorsal fin is also and two-thirds fuel. The cavernous tail will probably be widened in production composite and requires simple trimming cone provides ample opportunity to load models, giving a little wider cowl and and no additional messy resin work. The up gear, and the EFII (electronic fuel eliminating a funny little depression on landing gear is designed to absorb touch- injection and ignition)-equipped IO-370 each side of the forward fuselage. The tail down shock with tried and true bungees, provides the power to lift it. Note, of cone, from the aft doorposts back, is com- and we found it to be well tuned to pre- course, that baggage should be carried prised of corner wraps fabricated from vent bouncing rebounds on touchdown. The aluminum is joined primarily with pulled rivets, making construc- tion fast and easy. Parts are provided prepunched and preformed. Murphy has a very large and impressive hydrau- lic press that fills their two-story work- space and makes quick work of flat sheet metal that has to be formed into three-dimensional shapes. They do their own welding of steel structures and also produce their own wheels and brakes— a surprising result of a financial analysis that shows that in the quantities that they produce kits, they can save their customers money by building these parts rather than buying them. Overall, the airplane is tradition- The side panels of the tail cone have fore and aft creases to increase the stiffness of the ally constructed, using tried and true thin aluminum sheet. They only look like fabric. structural components and methods

8 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes (Left) The oval rear window will likely be changed; it was convenient during the design phase. The prototype has exposed controls and plumbing, but this will be refined as production ramps up. (Right) Large swing-up doors make it easy to enter and exit the cabin. that can be easily learned by those right-seat occupant has a G5 attitude/ We didn’t do a hot start, but claims are just getting into aircraft construc- airspeed/altitude indicator in front of that it should still start just like a car, tion. There is significant commonality their nose to monitor what is going on. with the electronics doing all the things between the various Murphy models, Over on the left is a circuit breaker panel a pilot’s busy hands used to manage. and this continues into the Radical. with just a few switches underneath. Taxiing is simple and straightfor- The advantage to the builder is that it Between the breakers and the G3X ward, with the Murphy-made tailwheel is easier for the factory to keep parts in screen is a round gauge for monitoring providing positive control until it breaks stock if replacements are needed. the Titan 370’s EFII system. out to a swivel at 45 degrees deflection. Starting things up is simple: Pull the The brakes (also custom made, along Flying the Radical circuit breaker for the fuel pump (so it with the wheels, by Murphy) are effec- Climbing into the Radical, the first thing doesn’t run continuously before the tive and smooth. As noted, visibility you notice is the comfortably upholstered EFIS boots up), and wait for the screen over the nose is good, and we didn’t bucket seats. With padding and covers to complete its start-up. Crack the throt- feel the need to S-turn to see what was done by Oregon Aero, the fiberglass tle (the only engine control, since the ahead. Upon reaching the runup pad, frames make for a nice cocoon in the cock- Radical has a fixed-pitch prop, and the we had to stretch to figure out what to pit. Mounted on standard sliding seat rails, EFII system handles the mixture), then do—there are no mags to check, the fuel they allow the pilot and passenger to fit push in the fuel pump breaker to watch was obviously already on, the mixture perfectly between the rudder pedals and fuel pressure come up. Once it is stabi- was automatic…so we checked the con- stick. Visibility over the nose was excellent lized, hit the start button and watch as trols, pulled on two notches of flaps, and (for a taildragger) with the standard tires, things crank up—just like a modern car. headed for the runway. and with larger backcountry tires, only a little stretching was required to see where you were going on the ground. The stick grip is at a comfortable height, and the flap handle is in easy reach on the overhead, just behind the windshield and right in the center, where either person can reach it. Fuel valves are located just over the pilot’s and passenger’s shoulders; you select the appropriate tank by turning it on or off. You could, of course, feed from both by leaving them both in the on position. The return fuel from the EFII system is plumbed to the right tank. The panel on the prototype is simple: A large Garmin G3X screen is in front of the pilot, a com radio (with built- Murphy Aircraft uses brakes manufactured in house—all components are machined in intercom) is in the center, and the and assembled at the factory.

KITPLANES October 2017 9 Inspection windows allow you to check The panel on the prototype Radical is simple: The Garmin G3X Touch provides all that critical control connections before flight. is needed for flight and standard engine monitoring, and the EFII display adds what is This one is for the top rudder attach bolt. necessary to watch over the fuel injection and ignition.

Straightening out on runway head- rain and ragged clouds at various levels. life. Visibility into the turns was about ing, I added full throttle, and by the Oh yes, there was a little sun over that what you’d expect for a high-wing air- time the knob bumped the panel, the way, and in the other direction, some plane: a bit blind, but no worse than any tail was coming up with just a little for- higher ceilings. plane without an overhead window. The ward pressure. By the time we reached With a river in spring flood below, good news is that adding such a window a level pitch, the airplane just levitated winding through the hills surround- doesn’t seem like it would be a hard thing and began going up—like an elevator! ing and cutting through the Chilliwack to do. On the plus side, the visibility out Progress over the ground was over- area, it was an engrossing sight—green the side windows to the ground below shadowed by progress in the climb, and beautiful, and viewed through the was excellent—and airplanes like this are and I noted about 1700 fpm up, even large side windows of the quickly climb- all about looking at what is below. after dumping the two notches of flaps. ing Radical. My first impression of the Once we gained some altitude, I did That’s what 180 hp does for a two-place airplane was that it was responsive. My a pitch pull to about ten knots below airplane! Roll and yaw control were second impression was the same. Maneu- trim speed, and it took only about one positive during the levitation climb, and vering in the confines formed by the hills full cycle for the airplane to settle back we were soon pointed out of the pattern and clouds was simple and natural; it close to trim speed—very stable. A yaw on a Chilliwack day with scattered light was if I had been flying a Radical all my doublet was similarly quickly damped; Murphy—the Next Generation Tyler Penner grew up with Murphy Aircraft—he should have, since he is the nephew of Daryl Murphy—and spent his early years helping out around the shop. He likes to say that he has done every job at Murphy, from sweeping the floors to operating the big machines that bend, cut, and press parts, to now overseeing the business side of the company. As the new general manager, he is responsible for the day-to-day operations of keeping airplanes flying, building parts, and getting kits and components out the door. Daryl Murphy, founder and chief designer, is still around but is happy to stick to creating new machines and letting Tyler run the business. One thing on Tyler’s list is to get his pilot’s license as soon as pos- sible. Growing up around Murphy, he has flown quite a bit, but never General Manager Tyler Penner is shown with one of Murphy’s had time to buckle down and get the ticket. In his new position, being production rivet squeezers (used to rivet spars). Many of the fac- tory’s tools date back many years, but are the best you can find able to fly customers and check out new design elements for himself for solid reliability. makes having the certificate more compelling, and we expect that he’ll get that taken care of in the near future. advise his employees how to make parts he has made himself. It’s In the meantime, he’s at the shop every day, selling kits, mak- good to know that the guy running the show was once sweeping the ing sure everyone is producing the parts and kits necessary to fulfill floors—understanding the business literally from the ground up. demand, and not afraid to get back out on the production floor to —P.D.

10 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes

Murphy Radical

Kit Price ...... $37,900 Estimated completed price ...... $95,000 Estimated build time ...... 1200 hrs Number flying (at press time) ...... 1 Powerplant ...... Titan 370 Propeller ...... Catto, fixed pitch Powerplant options ...... Rotax 914, 915

AIRFRAME Wingspan ...... 36 ft Wing loading ...... 10.56 lb/sq ft Fuel capacity ...... 44 gal The “shark gills” are part of the development process as Murphy determines the Maximum gross weight ...... 1900 lb necessary cooling air inlet and outlet requirements. The final configuration is still Typical empty weight ...... 1050 lb being determined. Typical useful load ...... 850 lb Full-fuel payload ...... 586 lb the airplane wants to stay where you One of the things that Murphy is still Seating capacity ...... 2 put it. Very little opposite aileron was working on is engine cooling—a com- Cabin width ...... 44 in required to hold the airplane in the mon problem with a brand-new design, Baggage capacity ...... 206 lb turn, again speaking for the stability of especially with airplanes designed to fly the machine. Pitch and roll were well low and slow with a 180-hp Lycoming. PERFORMANCE harmonized. For a given pull or push There simply aren’t that many air Cruise speed ...... 112 mph @ 2360 rpm in either axis, you got about the same molecules flowing through the cowl- Maximum rate of climb (1900 lb) . . 1300 fpm @ 73 mph response rate—a nice thing that con- ing at typical slow speeds to keep the Stall speed (landing configuration) ...... 38 mph tributes to the natural feeling of flight. powerplant happy. On our flights, we Stall speed (clean) ...... 43 mph Next up: slow flight. We pulled back were able to keep the CHTs in the low Takeoff distance ...... 400 ft on the power to approach speed, then 400s or below, sometimes with a little Landing distance ...... 700 ft back a little more. The airplane mushed power reduction, other times simply a little at about 50 mph (indicated, not by lowering the nose a little. So far, the Specifications and pricing provided by the manufacturer. calibrated), and the break was more of a factory has been working with inlet and slight complaint than a true break. Pull- outlet areas for the cowl, and the vents Tyler Penner, general manager of Mur- ing on two notches of flaps while in slow on the sides of the lower cowl are a result phy, told us that they had tried adjust- flight allowed us to drop the speed about of experimenting with outlet options. ing the mixture knob that is part of the 5 mph. Another notch gained us another For our flights, we were able to keep EFII system and had seen no changes in 3, and with all the flaps in, it slowed to oil temperatures within normal limits fuel flow or temperatures, hinting that about 37 mph before it paid off with a lit- without a problem. there might be something they don’t yet tle more noticeable break. The airplane Another area they are exploring is to understand about the system. We are was very well behaved throughout. uncover the source of the CHT issues. confident that this is something they

KITPLANES October 2017 11 The current air inlet to the fuel injection servo is 3D printed. The tail cone has a reinforced floor for rolling out a sleeping bag This allows Murphy to make easy modifications during and using the airplane as a camper. CG considerations will rule development. out using it for much baggage in flight. will solve, as it has been solved by other about the same time, it is doubtful that the nose a bit and give a Cadillac ride on manufacturers with similar projects. is was stalled at the time. A third land- touchdown. We didn’t see much of a loss Returning to the airport, it was once ing was slightly tail first about the time of airspeed, which was the reason for the again obvious that the Radical sim- the wing paid off. With these results, smaller wheels. You could always go ply flies like an airplane—it was easy we expected that adding Tundra tires huge if your goal was touching down on to descend and hold pattern altitude, would effectively lengthen the main really rough terrain, but these were per- and easy to slow down to flap speed on gear and allow a higher nose attitude at fectly adequate for operating off reason- downwind. We dropped two notches touchdown, giving a nice three-point. ably suitable places to land—prepared abeam the numbers and another on (There was also some discussion of or unprepared. base, then simply pulled power back and lengthening the gear itself, a change that Overall, this is a backcountry airplane slipped a little to control glide path to a has not been ruled out by the company.) that will go where you want it to, when soft wheel landing on the first try—then We got our chance to find out the you want it to get there, in a predictable had to add power to get to the first turn- next day, as when we arrived for a morn- fashion, and without a lot of drama. off. Yup, this airplane wants to land as ing photo shoot, the airplane had been short as it takes off. The good visibility magically transformed onto tundra About Those Bike Racks over the nose is partly attributable to a tires! They weren’t the 31 inchers most When was the last time you landed at a fairly low deck angle on the ground with people think of when imagining bal- remote airport or strip and wanted to go the standard tires. This also means that loon wheels these days. These were someplace on the ground when you got it is hard to fully stall the airplane for a 22-inch Goodyears—not extreme, but there? There’s no courtesy car at most three-point landing. Although our sec- something that Murphy had on hand. of the mountain strips I have visited, so ond landing touched all three wheels at They were more than adequate to raise why not take along some bikes? Sounds like a plan—until you remember the hassle of taking them apart to get the What’s in the Box components to fit behind the seats in Murphy kits are traditionally packaged and sold the way many airframe kits are these most airplanes. And then there’s the days—with subkits for the tail section, fuselage, wings, and firewall forward. You can buy whole greasy chain thing that always all the kits at once and save some shipping costs. Electrical, interior, paint, and finishing ends up making a mess on your hands. are left up to the builder, although Murphy is always willing to provide examples and So how about taking them along on the probably even some help; they want to see their customers succeed. outside of the airplane? Parts in the kits are cut and formed so that the builder has little to do in the way of This was the challenge that Mur- fabricating from raw stock. We visited their quality control department and saw some phy GM Tyler Penner threw out to his rejected parts that might have easily slipped by a casual inspection…but the eagle eyes team—and it was not hard for them to of the Murphy folks tossed them into the scrap bin before they headed out the door. respond. Hard points were built into Expect a large crate to show up when you order your Radical kit. Inside you’ll find the main and rear spars for simple racks almost everything you need to get ready for an engine and finishing. Also, check the that allow the bikes to be slung under Murphy website at www.murphyair.com and look up the model you are planning to order the wing, inverted. Safety straps keep to see all of the options that are available. the bikes from becoming ordnance. But —P.D. how well do they ride along? Far better

12 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes (Left) The bungee landing gear did a good job of absorbing shock and, coupled with Tundra tires, makes landing a breeze. (Right) The tailwheel assembly is built by Murphy and provides good steering on the ground. than I would have imagined, given the rock solid and stable. Yup, this looks like simple two-place biplane to the monster potential drag from all those flying wires a great way to haul bikes to a backcountry Murphy Moose. They have sold several (otherwise known as wheel spokes). In strip or just an airport a little ways out- thousand kits in that time, and many of fact, on our second flight, we took the side of town. No, you wouldn’t do this on those kits have become flying aircraft. bikes along—and noticed no perceptible your speedy cross-country cruiser, but for But the past few years have been a bit increase in drag at the speeds the plane a plane in this speed range, it seems to do quiet, with the company actually being likes to fly. Turning base, with three just fine. And it looks so “Radical”! advertised for sale at one time. Daryl notches of flaps out, I pulled the power was looking to retire, but like most kit back as I did when the plane was “clean” Murphy is Waking Up company founders, was reluctant to let (sans bikes), and it came down about the Murphy Aircraft, founded in 1985, is the marque go. With good designs and same as before—not steeper, as I would now 32 years young and has the feeling a loyal customer base, Murphy (the com- have imagined with extra drag. of freshness that only comes with youth pany) was just waiting for fresh blood, I was also concerned about the bikes and new energy. Founded by Daryl and it came along in the form of Tyler flopping around in their mounts, espe- Murphy, the company has produced Penner, a longtime company employee cially with a little sideslip, but they were a number of popular designs, from a who is also Daryl’s nephew (see sidebar).

KITPLANES October 2017 13 The company’s new Radical is a prime example of youthful inspiration in today’s world. With plenty of power and lifting capability, it’s a machine that can get into tight places and carry enough gear to enjoy those places once you’ve landed. It’s the stuff of TV com- mercials aimed at the youth who enjoy extreme sports—but it’s also an out- standing flying machine for people of all ages who strongly desire to visit the most magnificent, out-of-the-way places on earth. The Radical’s signature bike racks are removable and hold the bike firmly by the frame. The wheels and tires are held by Velcro straps to keep them from turning. The bikes ride A Work in Progress very well, with no motion or vibration. We flew the new Radical with about 31 hours on the clock. It was well behaved, for the IO-370 Titan engine. We noted much decided that airflow was not the pleasant, and capable. But there are changes high cylinder head temperatures, and issue. They were busy looking at the in the works by the factory to make it even the factory has been busy opening up timing and fuel injection provided by better before the first kits reach customers the cooling to see if that will make a dif- the EFII system to see if something (and several are already on order). ference. The cooling “gills” on the lower requires tuning in that department. At the top of the list right now is to cowling are evidence of this effort, and We’re sure that by the time you read figure out the best cooling configuration as we flew the airplane, they had pretty this, they’ll have this nailed down. Murphy—Sampling the Fleet Canada, lakes, mountains—and airplanes—it doesn’t get much better in as he flew over from his farm strip a few miles away, and I climbed than this! Visiting Murphy Aircraft in Chilliwack, British Columbia, can in without the need for a shutdown. All those steps and handholds make for some interesting and beautiful flying. While the Murphy fac- associated with floats made that simple. The fact that the prop was tory is located in an industrial park a mile or so from the airport, there is producing no windblast also helped. With the same basic fuselage as the a tight little Murphy community in a double row of T-hangars located at Yukon we flew earlier (the Moose is rated to carry a lot more weight), the the field. The Radical is there, along with a Rebel and Yukon on floats, cockpit was quite roomy, and the tall stick provided plenty of leverage to and the airport is run by a fine gentleman with a turboprop-powered maneuver what can certainly be called an aerial truck. Acceleration on Moose. With a day of improving weather, we had a chance to sample the runway was impressive, as you’d expect with 500 horsepower. the line and go do a few interesting things. Hemmed in by mountains with an overcast limiting us to a few The morning started with a photo mission for the shots you see thousand feet, we explored the valleys around Chilliwack. We were able illustrating this article on the Radical, and what better photo ship to to look down on the Fraser River, swollen with the runoff from one of the use than a big Yukon on amphibious floats. The Yukon features a large snowiest winters in recent history. It was a pretty scene, uninterrupted removable baggage door, and with the back seats installed, the spa- by the vibrations of a piston engine. The normal power for a Moose is cious baggage area was perfect for an average-sized human to occupy and use as a shooting platform. The speeds were very compatible with the Radical, and there was very little buffeting from the slipstream and wind. We took off from Chilliwack, formed up, and made several circles just a little ways south of the field, in front of some beautiful moun- tains with morning clouds and splashes of sunlight against the forest. A great way to start the day! Landing back at Chilliwack, we took a break for morning coffee and hangar flying. The denizens of the airport started talking about their various Experimental aircraft: a few Murphys, a handful of RVs, a Seawind project, and a one-off single seater that looks like a miniature SU-29. Good aviation conversation is always enhanced by well-worn hangar chairs and coffee! See that little path on the left? That serves quite well as a Next up: a turboprop Moose! The operator of the Chilliwack airport had runway in the Canadian north country. Just watch out for the numerous contributors to this project, including a local engineering firm golfers on the fairway on the right. The Radical has plenty of that helped with the powerplant, and the Murphy folks. The planes taxied room to carry clubs.

14 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes heavy items all the way back there, so they will have a cargo net and tie downs to keep things closer to the back of the seats. However, that is all useable space when it comes to using the airplane as a camper at some remote strip, so feel free to stretch out in the aluminum cocoon if you don’t like waking up in a wet tent. Conclusion: Get Radical! The new offering from Murphy is hon- est, simple, and lots of fun—exactly what it was designed to be. We look for- The attachment points for the bike rack are designed into the forward and aft spars. ward to seeing the changes they have on There is plenty of experience with be helpful. The airplane was easy to their list before finalizing the design, these engines and systems, and the land, but three-point landings were not but we saw nothing that should prevent vendors are excellent at solving these full stall, so raising the main gear a little it from being a well-mannered airplane kinds of issues. bit will increase the ability to drop into with solid capabilities and trouble-free The airplane as we flew it probably short fields at even slower speeds. systems. It should make getting out had the shortest landing gear of any Don’t be confused about pictures of into the backcountry and off the beaten Murphy plane, and even with the small that huge tail cone; it’s not all usable path easy—and going where there are bush wheels, it felt like a little more cargo space for flight! The CG would no roads is one thing that airplanes are nose up attitude on the ground would get pretty radical if you tried to shove all about. J

provided by an M-14 radial engine, giving the pilot a “mini-Beaver,” as the Canadians like to describe it. But some have been built with turboprops, and there’s no doubt that it makes a capable and flexible bush plane. Returning to Chilliwack, we found that the day was not yet half over. Lunchtime was around the corner, and we needed some pretty backgrounds to shoot pictures of the Radical on the ground, so hangars opened up and a gaggle headed to Rowena’s, a resort/golf course on the river just a little ways north of the Chilliwack airport. To call the runway an airport is a stretch by anyone’s imagination. It’s more of a slightly curving dirt road alongside a fairway and skirted by the brush of the riverbank on the other side—but more than adequate for our purposes. There was even a windsock and a seaplane dock for the float-equipped Rebel that followed us along. The Radical handled the little bit of dirt work like it was built for it (and of course, it was), and we all enjoyed a lunch among the pines of the north before once again mounting up to pop back to town. The golfers let us “play through” as we roared down the road for takeoff, and the Radical did its levitation When a big radial isn’t enough, you go to a turboprop! This Moose, like several, has been fitted with a kerosene burner— thing with two notches of flaps and very little ground roll. with the added benefit that you can back into parking spots. The final event of the day was to climb back into the left seat of the big Yukon and go get wet. I had never flown on amphibious floats, but Murphy caring where we touched down. The gentle kiss of the water signaled test pilot, Dave VanEmber, talked me through taxiing the tall machine. the time to pull the power, and we settled quickly into boating mode. (“Don’t worry about that fence, it’s way below the wing!”) I found that Coming from the Land of 10,000 Lakes (Minnesota), I have spent as four wheels make for a very stable platform on takeoff. We climbed out much of my life in boats as in airplanes, and I love it when the two of Chilliwack and headed up the Fraser to Lake Harrison, ringed by steep passions come together, if even for a few minutes. mountains that plunge directly into the water. Cabins on the few flat spots We taxied a little, then rigged for takeoff, and were soon winging of lakeshore all had distinctively shaped seaplane docks—probably the our way back to Chilliwack to wrap up the day. A nice landing, more easiest way for owners to reach their weekend retreats. handshakes, and our day with Murphy was over—a day we’ll remem- Two notches of flaps and slowed to about 70 mph, we set power ber for fun flying in solid machines with good folks. for a 150-fpm descent and lined up on the huge waterway, not really —P.D.

KITPLANES October 2017 15 Changing a Perfectly Good Airplane

Designing and building a modified RANS S-9, part 1. By Michael Ryer and John Wells

Over the years, Michael Ryer has similar homebuilts, homebuilders seem He built other airplanes and drifted flown a bunch of airplanes in the 5000 more than willing to leave a “thumb- away from hard-core aerobatics. In hours his logbook reflects. Subjectively, print” on designs. Some changes, like a 2003, he sold the Pitts and became an he liked some and hated others. Posi- paint scheme or interior leather color, old-guy weekend flier, flying a Rans tive subjectivity, for Michael at least, is address personal taste and have little S-6S (his 10th homebuilt). He moved the good feeling he gets when he moves or no effect on performance or safety. to Kansas and kept his airplane at the stick aft and the G loads come on Other changes alter performance char- Stearman Field near Witchita, a place smoothly and in a linear fashion as acteristics or structural integrity, and infected with an active aerobatic club. opposed to stick movements where these must be made very carefully. Watching airplanes like Extras, Pitts, nothing happens and then, all of a sud- Nearly five decades ago, when and clipped Cubs rekindled the urge den, the airplane reacts. Objective data Michael was in his 20s, he built a Pitts to loop and roll. Like any serial builder, is hard measurements in pounds, inches, S-1S Special to meet his need to fly Michael needed to build another air- gallons per hour, and so on, provided upside down and stop wearing out his plane—another aerobatic airplane. when an airplane is flown and inputs/ old Citabria. He built the Pitts and flew Michael retired from the aerospace results are compared to a performance it for over 30 years, accumulating nearly industry as a manufacturing engineer. standard. This article is about how sub- 3000 hours in the little red biplane. Fly- He knew his way around flying struc- jective requirements were built into an ing contests and airshows, he got really tures from building launch vehicles and existing, objective airplane. good at tumbling through the sky, airplane components for various com- Change is hard for most people, unless making noise, smoke, and snap rolls in panies. His new toy needed to safely they are in charge. When we compare front of spectators. perform old-guy aerobatics, help him

16 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes (Left) The original S-9 airfoil was designed by RANS and is similar to a Clark Y. (Right) The new airfoil is the RAF 34, which is similar to the M6 airfoil used on the Pitts. relive his glory days, and have a great a glider guider and Fly-Baby pilot. John spent four wintery days retrieving the ramp presence, like a Staudacher or and Michael got to know one another fuselage, landing gear, and tail surfaces. One Design, whenever he returned to through flying around the area. Michael It was a good starting point for all the the surly bonds of earth. Michael knew discovered John was a retired design changes he wanted to make. the Rans S-9 Chaos and its designer, engineer with at least a passing knowl- Randy Schlitter, through building the edge of how to engineer the changes New Airfoil Structure and Wing S-6S. The S-9 is a strong airplane (+6, being contemplated. Over many gal- Michael wanted to address the existing -4 G) and performs well on a 65-horse- lons of coffee at the Stearman Field Bar design’s inverted challenges by look- power Rotax 582. and Grill, John agreed to be Michael’s ing for a different airfoil for negative-G In the early 1990s, Michael had seen principal design consultant and men- work. The original S-9 airfoil is flat bot- Schlitter fly the S-9 in an airshow. The tor. Michael also got to know the folks tomed, like a Piper Cub. The new airfoil airplane had remarkable performance at California Power Systems. Michael needed a more symmetrical shape to and did positive-G maneuvers nicely. needed their help for changes to the allow the airplane to more easily per- Having seen the airplane in action, engine cooling and exhaust systems. form inverted maneuvers. Next, Michael Michael still felt it was a good start- Now, with the “concurrent engineer- wanted to improve the roll rate. For sim- ing point for all the changes he wanted ing team” in place, Michael was off to plicity, the original wing had ailerons to make to the little beastie. He set the races figuring out how to design and attached with four simple centerline the following goals for the proposed build the modifications. hinges, like gate hinges, between the aft changes: better inverted performance, Scanning the Barnstormers web- tubular wing spar and the forward tubu- more roll rate, great aesthetic appeal, site (www.barnstormers.com), Michael lar spar of the aileron. The near-one-inch use the 65-horsepower Rotax 582, and tracked down an uncompleted S-9 project gap between the wing and aileron creates have minimal airframe weight gain. He in Pennsylvania. Using a borrowed pickup a considerable discontinuity for the air- settled on the S-9 and started work in truck, he and his amazingly tolerant wife flow to negotiate as it moves across the January 2012. With the change criteria set, it was time to get started on the project. But first Michael needed to establish rela- tionships with technical experts to assist him with the changes. He knew he could build the airplane from a man- ufacturing standpoint, but he was not a design engineer. He needed someone who could engineer the contemplated changes in a way that would meet the criteria, yet still be within his manu- facturing capabilities. The last thing he wanted to do was turn a safe airplane into an unsafe one. Remember Stearman Field, men- tioned earlier? Well, one of the airport The completed right wing. The leading edge was reshaped by adding balsa wood and bums Michael ran into was John Wells, fiberglass to the leading edge tubular spar.

Photos: Michael Ryer KITPLANES October 2017 17 The completed wing skeletons, ready for covering. The bottom of the covered wings with the ailerons attached. gap between the wing and the aileron. The existing top surface shape was very the M6. With the RAF 34, Michael The original aileron design provided similar to the shape of the M6 airfoil. got a nice smooth underside curve from a roll rate of 100 degrees per second. The bottom, however, presented a prob- leading edge to trailing edge for ease of Michael’s goal was to reach a roll rate of lem. The M6 bottom shape has a distinct manufacturing (no sharp bends). John 240 degrees per second. “knee” at about the 60% chord point pointed out the last 20% of the upper To maintain structural integrity of of the airfoil. This posed a problem for surface was “reflexed,” resulting in gentle the wings, no internal changes were to manufacturing. The round tubing could delayed stall characteristics. This was a be made. The airfoil shape, totally new not make such a tight bend without win/win for the design and manufac- ailerons, and redesigned wingtips were being mandrel formed. turing team. The only challenge would the only changes made to the wings. The Now it was back to the drawing board. be accommodating the sharper leading changes to the airfoil shape came from a John introduced Michael to a valuable edge radius of this airfoil. subjective analysis of the existing airfoil resource at the UIUC website. Michael The basic wing structure was changed against other airfoils. Michael’s experi- was able to pull up the M6 airfoil and all by adding a new shape to the leading edge ences flying aircraft with the airfoils its technical performance data (lift and and a new aileron attachment method to formed the basis of this comparison, drag curves, station notations, and so the trailing edge. The new leading edge along with the mission profile of flying on) along with a listing of other, recom- was made by shaping the leading edge old-guy aerobatics. mended airfoils. Within the list was the tubular spar with balsa wood and add- The original S-9 airfoil was designed RAF 34 airfoil. John took his apprentice ing a fiberglass overlay for impact resis- by RANS. It is closest in appearance to aside and helped him understand the tance. The original internal structure of a Clark Y. The S-9 airfoil has a flat bot- interesting subtleties of the airfoils being the wing (drag/anti-drag bracing, fuel tom. When inverted, a Clipped Cub considered. The performance curves tank, wingtip structure, lift strut attach (which has a similar USA-35B airfoil) of the RAF 34 were nearly identical to points, and so on) was unchanged. The requires nearly full-forward stick and full power to maintain level flight. So, the Clark Y had to go. It simply demanded too much from the aircraft when inverted. A clipped-wing T-Craft, with the 23012 airfoil shape, performs well inverted. The last airfoil in this subjective evaluation was the Munk M6. Michael decided to go with the M6 because it was a good inverted per- former and had been used on the Pitts. With the airfoil selected, Michael proceeded to determine how to adapt the M6 shape to the S-9 wing rib struc- ture. The ribs are built of half-inch alu- minum tubing, cold formed to shape. The covered right wing with the aileron installed.

18 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Typical S-9 ailerons are attached to the wings with simple hinges, Piano hinge was used to connect the new ailerons to the trailing resulting in a gap between the two structures. edge spar box. wing ribs required rebending the lower aft wing spar is a 2-inch tube, and the series of aircraft with L-section stiffen- tube to the proper shape, and remaining leading edge spar of the aileron is a 1-inch ers running between the spar and the internal structure was built using the tube. The two structures are joined with trailing edge. These stiffeners are riveted assembly steps provided by the RANS simple hinges, resulting in a gap of nearly to the skin. The new aileron is the same builder’s manual. To eliminate the an inch between the two structures. Air- shape as the original S-9 and one inch round tube shape of the S-9 rear wing flow between the bottom of the wing and deeper in its chord. Piano hinge was used spar, and to serve as the attach point for the top of the aileron is stopped by a gap to connect the aileron to the trailing the ailerons, Michael developed a box seal. Also, the trailing edge of the aileron edge spar box. Michael, following John’s structure. It resulted in a design very is a half-inch tube. The aileron is essen- recommendation, also mass balanced similar to every 100-series Cessna ever tially rectangular in cross section. The the ailerons to reduce flutter probability. built. John reviewed the new structure. roll rate of the S-6S, which has the same The last wing item to address was He added some additional reinforce- aileron design as the S-9, is slower than a the wingtip and its shape. The original ment at the aileron hinge points and a Cessna 150. The two airplanes have simi- wingtip was a very rounded, tubular few more rivets to resist buckling of the lar wing and aileron areas. structure with the end of the aileron set box structure when it was G loaded. With the wing ready for a new aileron, back from the wingtip some 6 inches. Now that the airfoil shape was resolved, the aileron shape was redesigned as an Michael originally drew up a Mooney- the next change was to the ailerons. aluminum-skinned triangular structure. style wingtip with the aileron mass bal- The structure had a leading-edge spar, a ance as part of the wingtip. John helped New Ailerons and Wingtips torque box at the control horn station, Michael understand the need to hold the The existing S-9 ailerons use the trailing and full ribs at each end. The skins were end of the aileron back from the wingtip edge wing spar as the attach point. The stiffened in the same manner as the RV by a few inches, about the chord span of the aileron. If Michael really wanted to get efficient ailerons, he needed to add end plates to the ailerons so air could not flow through the gap created when the aileron is deflected up or down. He did this on his symmetrical-winged Pitts and it worked. He has not done this yet on the S-9, and it is on the winter down- time project list. John and Michael, having completed the wing work, were ready to move on to the next part of the project—but first, it was time to enjoy a good Cab- ernet. We’ll talk about the fuselage, tail The aileron shape was redesigned as an aluminum-skinned triangular structure. Note the group and flight testing the S-9 next balance weight to reduce the probability of flutter. time in Part 2. J

KITPLANES October 2017 19 Landing Gear GURU

A visit with Robbie Grove of Grove Aircraft Landing Gear Systems. By Eric Stewart

Like most of us, Robbie Grove started building “a bunch” (his words) of wings, Northrop Global Hawk. If you read the out in aviation building model airplanes. primarily for Formula 1 and racing KITPLANES® article on Craig Catto Unlike most of us, this progressed to biplanes as well as aerobatic monoplanes. [“The Spin Doctor,” August 2014], building a VariEze as a teenager, fol- Self-taught in engineering, his com- this all sounds like a vaguely familiar lowed by an original design two-seater, posites skills and ability to oversee an “foundation story”—and in fact, Craig the GR-2 Whisper (which was featured airplane project in its entirety landed and Robbie are good friends. on the covers of KITPLANES® and him a job at Teledyne Ryan in the early Grove Aircraft Landing Gear Sys- Homebuilt Airplanes magazines). He days of UAVs, from whence he ulti- tems, which began in 1983, is located later designed and built a Formula 1 race- mately ended up working on the design east of San Diego at Gillespie Field, right plane, the GR-7, as well as designing and and construction of the aft end of the where Grove started out building the

20 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes (Left) Robbie Grove’s first homebuilt, a VariEze. (Right) The GR-2 Whisper was Grove’s second homebuilt and his own design.

VariEze. As you may be aware, Grove master cylinders before they get shipped airfoil cross section), and gun drilled makes landing gear, wheels, and brakes out the door. “My goal is to never run for brake lines. It is then sent to a heat for a large number of Experimentals, but the CNC machines—that is not the treater to be annealed in the O condi- at least half their market is for certified best use of my time. I don’t machine, tion, so that when it returns to Grove’s aircraft, with UAV gear also being a sig- but I know all about machining. I am shop, it is soft enough to be bent to nificant part of the business. always thinking of how we are going to shape in their presses. The original impetus to make gear machine a piece, how we are going to After bending to the desired shape, came from his composites company hold it, how we can reduce steps in the the gear is sent back to the heat treater. in 1993. Working on gear with a local manufacturing process by designing They treat it again, quenching it in a gly- manufacturer had proven frustrating. them out. When I design something col solution, which takes it to W condi- “At lunch one day we asked ourselves that is really new, I’ll bring it out to the tion (a middle hard condition). Then they ‘Can’t be that hard, can it?’” The answer guys in the shop for feedback, before put it in a freezer and keep it there until turned out to be “very painful,” laughs we ever make anything. And we make Grove picks it up. The reason for only Robbie. “We talked to a bunch of people changes along the way if necessary. It’s taking it to W condition, rather than we knew and got the first gear built, but always a challenge; that is why I like the back to T6, is that the gear warps from it was just very difficult to get the land- engineering part of it. And I am the only the shock cooling of quenching. Grove ing gear the way it needed to be. Getting engineer,” he laughs, “so I don’t have to needs to straighten out the warpage, and it machined, bent, heat treated—we argue with anybody.” a T6 condition would prevent that. W is didn’t know any of that stuff.” Clearly, just soft enough to allow the necessary they have since figured it out, and that Gear Manufacturing tweaking, but Grove notes that as soon first landing gear is still flying today. Grove gear starts life as a thick (1.25- as they remove it from the freezer, the Grove decided he wanted to be a dis- inch) plate of 7075-T6 aluminum. The gear starts getting harder by the minute tributor for Parker (aka Cleveland) profile is cut with a CNC water jet, and the clock is ticking: they have eight wheels and brakes, but they were not and then decked (i.e., thinned) down hours to get the gear straightened before interested, so Grove decided to start man- to the desired thickness, for example 1 it becomes too hard for further tweaking. ufacturing those items as well. He started inch or 7/8 inch. It is machined to final Once any warpage is removed, the out with one CNC mill and one CNC shape, drilled, contoured (if it has an gear goes to the heat treater for the third lathe in 2000, and in 2005 he closed the composites shop to focus strictly on land- ing gear. Grove Aircraft now has nine Haas CNCs and manufactures about 1500 sets of landing gear a year (and more than 15,000 to date). This includes several hundred TSO’d wheel and brake assem- blies, which has been their main focus the last five years. There’s also occasionally strange or exotic work—master cylin- ders for the Focke-Wulf FW190, Vought F4U Corsair, Messerschmitt Bf 109, and “weird UAV gear.” Robbie Grove engineers all of the company’s products. In addition, he handles tech support and general prob- lem solving, gun drills the gear, and per- Gear is CNC waterjet cut from 1.25-inch thick sheets of 7075 aluminum and then machined sonally assembles all wheels, brakes, and and gun drilled before being sent for the first round of heat treating.

Photos: Eric Stewart KITPLANES October 2017 21 time, where they take it back to T6 con- dition. Going from W to T6 can induce a small amount of final warpage—a tenth of a degree or so, says Grove—but there’s no quenching so warpage is usu- ally minimal, and that small an amount is easily straightened. Wheel Manufacturing Wheel manufacturing is completely dif- ferent, and Grove offers wheels in cast magnesium, cast aluminum, and billet aluminum. So what’s the difference? The magnesium wheels are sand cast, which is cheaper than billet since there is both less machining (for example, the interior of the wheel is largely left in Landing gear is inspected for dimensional accuracy after undergoing bending. In this the raw cast condition) and less mate- state, the gear is in a soft condition (O). It is then sent back to the heat treater, where it will rial cost since very little of the casting be brought up to W condition. W allows any necessary final tweaks for a few hours after gets lost to machining. However, the being brought out of cold storage. The gear then goes back to the heat treater for the third time for a heat-treat/aging process to bring it to T6 condition. material properties are not as good as wrought bar stock. Because of that, cast I can make it out of billet for almost learned to make these complex parts. wheels are designed to a safety factor of the same weight as a magnesium part “You just do it. You just go in there and 2.0 vs. 1.5 for billet. [since the aluminum billet only needs figure something out, and you make In comparison, billet stock can be a safety factor of 1.5 as compared to some, and they don’t work. So you go 6–12 inches in diameter, much of which the safety factor of 2.0 for magnesium, work on it some more, and you finally must then be machined away. “The other which makes the metals more equal get it to work, and you sell a bunch. Then way to build them is a forging, which is on a strength-to-weight basis], but you after a while, you come up with a bet- better, but it is very, very costly,” says have the benefit of aluminum not being ter idea and work on it some more…and Grove. “Although that gives the proper so corrosive like the magnesium is,” says after 15 years, you’ve got it figured out. grain flow when you do that.” Grove. “For example, all of the wheels But if you never get started, you’ll never Material selection is largely a mat- that go on floats and amphibians have figure it out.” ter of sales volume, although environ- to be aluminum; you can’t use magne- mental factors can play a part as well. sium there.” For calipers, magnesium is Cool Tools For low-volume wheels, billet is usually also the preferred material where pos- You don’t go into the shop of a guy used, whereas for high volume wheels it sible, though again sales volume might like Robbie without seeing a couple makes sense to invest in a casting. “In dictate using aluminum. of pretty cool tools. Two that jumped some cases where weight is a big deal, Looking at an assembled master cyl- out at me were Robbie’s gun drill and but we want to stick with aluminum, inder assembly, I ask Robbie how he wheel dyno.

(Left) Wheel half being turned on CNC lathe. (Right) A worker checks wheel dimensions using a height gauge and granite surface plate.

22 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes YOU CAN’T OVERHAUL PEACE OF MIND

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CM_US_Magneto_200x265.indd 1 12/06/17 09:21 As with Grove’s initial foray into gear making, gun drilling also resulted from the frustration of being dependent on an outside shop that just couldn’t do the job right. “In the beginning we sent the gun drilling to a place in Los Angeles, which was a nightmare because it took them a month, it cost a lot of money, and they never put the hole in the right place. So we decided to do our own. “We found a gun drill machine, but what it actually turned out to be was a Pratt and Whitney WW-II-era machine-gun barrel-reaming machine. It took us about six months to turn it into a gun drill. The reason it took so long is that we thought it a gun drill Grove brakes undergoing brake test on the dynamometer. Note the disc is actually turning was cherry red! machine, but it wasn’t—it didn’t have the right kind of seals, rpm, or pressure.” should say, since Grove has two. But be overwhelming. But it would be very Unlike a normal bit, the gun drill the dyno built for certification pur- expensive to go out and have someone does not peck. Rather, oil is pushed at poses is an impressive assemblage of custom design and build this for us.” high pressure through the center of the steel: Large enough for a 31-inch tire, rotating custom-made bit, cooling the it sports nine 1-inch-thick metal plates Quality Control head and taking away fine chips as it 47 inches in diameter, in addition to Clearly Robbie is a pretty can-do guy, exits along a V-notch grooved along one the main flywheel. With a total mass so it seems natural that aside from raw side of the bit. of 5227 pounds, it is capable of spin- materials sourcing and heat treating, “There are a lot of things going on in ning up to 800 rpm and over 1 mil- Grove Aircraft manufactures almost this machine. The biggest thing you have lion foot-pounds of kinetic energy. In everything in-house. “With the excep- to figure out is how to get 1750-psi oil into addition to this are machines to cycle tion of forgings, castings, and hardware a drill bit that’s rotating at 7000 rpm. We test master cylinders and brake calipers like bearings, brake pads, etc., we make got a huge education on that and used it for PMA certification, which requires everything here. We do all the machin- until about 2000. The problem was, it 100,000 pressure on/pressure off cycles ing here. I like to have control over man- only drilled 37 inches, so I built this new and 5000 overload cycles. “We had to ufacturing,” he said. machine, which drills about 47 inches. build the test equipment to do all that,” I asked Robbie if he sourced anything And I’m getting ready to build another Grove explained. “It’s all simple equip- from out of the country; 100% made one that is basically CNC.” ment now that you stand back and look in the USA is pretty rare these days. The braking dyno is across the at it, but when you are trying to dream “The only product we source out of the taxiway in the testing area. Dynos, I up what device to build, at first it can country is our friction material. Every- thing else is made in the U.S. I’ve gone the other route—I’ve gotten stuff out of China, out of India, in terms of steel forgings and steel castings, but the qual- ity is all over the map. You don’t know when or even if you are going to get the stuff. It’s cheap, but it’s junk, and in the big picture, it costs more. “The other problem is that when you start certifying stuff, if those countries are not on our bilateral FAA agreement, you have to qualify every single item you bring in. If we were bringing in brake disks for instance, we’d have to pull sam- ples from every lot and get them tested Brake torque plate being machined in one of Grove Aircraft’s Haas CNC vertical mills. at an approved lab. Even if you get the C

24 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes of C (Certificate of Conformance) from the manufacturer, it doesn’t mean any- thing; you still have to test it and prove to the FAA that it is what they say it is. I’ve been through all that, and it is not worth the hassle.” Grove’s tight control of manufac- turing has eased the way for parts certification. All parts have a control number and associated paper trail for the FAA. This guarantees traceability all the way through the manufacturing process. “We do the same whether it’s a homebuilt part or an FAA part. We have one quality control system that is approved by the FAA, and everything is done under that one system,” says Grove. “The only difference between a homebuilt wheel and a certified wheel is the label we put on it—otherwise they are identical. We make a lot of stuff that is the same: For example, pretty much all our 5-inch wheels are TSO’d as well.” One of the nice things about the paper trail is that all gear has a serial number and associated computer file. So if someone bends a gear with a hard landing, they can send it to Robbie, who can then pull up that gear’s file and (hopefully!) put it back the way it was. Regrets, I’ve Had a Few… In the course of our tour, I kept find- ing myself asking Robbie how he knew how to do this or make that, consider- ing he really knew none of this in the beginning. “The key to knowledge is you don’t need to know it all, you just need to know where to get it. Whether it be people, or the internet, or what- ever. You can do anything; you may not know how, but you can figure out how to do it. You need to be willing to make a lot of mistakes because you’re going to wreck a lot of stuff on the way. Knowl- edge costs money. “It took a lot of years to get to where we are at. We started making landing gear in 1993, and we went from people who knew nothing about metal to where we are today. It was a lot of work, a lot of time, a lot of money. The only thing I regret about making wheels and brakes is that I should have started 10 years earlier!” J

KITPLANES October 2017 25 Static Port Location and Altitude Calibration

Often a challenge, accuracy depends on three things: location, location, location. By Reinhard Metz

When you build an RV, the instruc- and ensuring that there are no leaks in that ideally provides a stable rendi- tions include the location and specify either system. Several articles detail- tion of the (static) air pressure at that the material (simple POP rivets) for ing manometer methods for perform- altitude. Pressure on the outside of your static ports. From what I have ing these checks may be found online, the fuselage varies substantially with heard, in most cases the static system including a spreadsheet (https://tinyurl. position, and often unexpectedly. An works perfectly right away. That is to com/m4vsbeh) by KITPLANES® con- ideal location should therefore be in a say, the altitude and airspeed are cor- tributor Kevin Horton. neutral pressure area, relatively invari- rect within some acceptable bounds. As measurement and indication sys- ant with airspeed, angle of attack, and That’s a fortunate situation, one that tems migrate to electronic ADAHRS altitude. Practical static ports may be many builders of other craft, especially sensors, indication errors are dimin- included in the pitot mast itself, plac- one-of-a-kind designs, don’t find them- ishing. Also, the pitot-delivered ram ing them presumably in neutral air. selves in. Furthermore, I suspect that pressures are generally accurate and rel- More typically, they are a pair of ports many homebuilts fly without the own- atively independent of pitot alignment, on either side of the fuselage some- ers really knowing how accurate their though the pitot must still be located where between the trailing edge of the airspeed and altitude are. well out of the propwash and spaced wing and tail. A typical variation of Altitude indication depends only below the wing sufficiently to avoid any pressure along the side of a fuselage is on the static system. Airspeed indica- disturbance by airflow over the wing— shown in the figures. There’s a transi- tion, and thus accuracy, on the other which are both relatively easy to achieve. tion from high pressure (above ambi- hand, depends on both the pitot and Therefore, airspeed errors are likely ent pressure) to low pressure from wing static systems, since indicated airspeed dominated by static pressure errors, to tail, and the neutral pressure area is is derived from the difference between just like altitude errors. Optimal static most desirable for port placement. In the pitot ram and static port pressures. port location is clearly important, but in reality, the neutral pressure zone is a Airspeed and altitude accuracy correc- practice is not easy. Our goal here is to line, as we will explore later, and port tion and calibration both begin with hopefully simplify the process.1 placement on that line will be the goal basic system checks, such as airspeed The key to an accurate static system to achieve the best compromise for all indicator and altimeter error checks, is the location of the port(s) in a place important flight regimes.

26 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Regulations Subsonic Static Pressure Distribution While you would like to know your altitude and airspeed as accurately as possible, altitude is clearly the more important for separation safety reasons. The FAA requirements are scattered in a few places and a bit challenging to resolve as to the static port accuracy by itself, but here are the pieces: 14 CFR Part 23—“Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes,” 23.1325 Static Pressure System, states: “(e) Each static pressure system must be calibrated in flight to determine the sys- tem error. The system error, in indicated pressure altitude, at sea level, with a Figure 1: Surface pressure typical lateral distribution. The numbers in the circles (1–6) standard atmosphere, excluding instru- indicate places where neutral pressure exists, i.e., surface pressure is the same as static ment calibration error, (my emphasis) pressure at that altitude. may not exceed ±30 feet per 100 knot speed for the appropriate configuration is up to the aircraft “manufacturer”— altitude, and verifies that the system— in the speed range between 1.3 VSO with us—to decide how to add all these up altimeter and transponder—indicate flaps extended, and 1.8 S1V with flaps and what tolerance to attribute to the and report altitude accurately with retracted. However, the error need not port location. Having an ADAHRS- respect to the applied standard pres- be less than 30 feet.” based system and a correspondence sures only, independent of whether Furthermore, per 14 CFR Part 43, test error for the Garmin G3X Touch or not the static ports are accurate in Appendix E to Part 43—“Altimeter system near zero, I set a goal of being flight. The static ports must be located System Test and Inspection,” the altim- within +/- 50 feet at 3000 feet, and +/- optimally and supply neutral pressure eter error limits shall be according to 125 feet for the range of altitude from 0 (within tolerances). the provided table, ranging from 20 to to 10,000 feet and the airspeed range of 130 feet, corresponding to 0 to 20,000 1.2 VSO to cruise. How My Trouble Started feet of elevation. It may be a bit surprising that the Our Wheeler Express N49EX was Finally, the altimeter/transponder biennial altimeter/transponder corre- originally built with a combined pitot/ correspondence test requires the trans- spondence test does not verify overall static probe, which when calibrated mitted altitude to be within +/- 125 feet altitude reporting accuracy. The test was sufficiently accurate for both alti- of the altimeter indicated altitude. For applies pressures to the static port(s) tude and airspeed. All was fine until an ADAHRS-based system this error corresponding to the standardized my recent glass panel upgrade, includ- will be near zero. So, to some extent, it model of atmospheric pressure vs. ing a Garmin autopilot, which uses the static pressure data for altitude N49EX and Surface Pressure Model capture and hold. It turns out that the pressure supplied by the static port on the pitot is slightly sensitive to angle of attack, which while not noticeable in the altitude display, makes the auto- pilot hunt some +/- 30 feet, a nauseat- ing experience! So, a more stable static port location was needed. A quick trial with cabin static pressure stabilized the autopilot, but was substantially off in altitude, as is typical due to lower pres- sure in the cabin, not to mention varia- tions from the air vents. After several failed attempts to improve the pitot Figure 2: Yellow and green areas depict zero pressure. Magenta is low pressure, and probe static performance, I decided to blue is high pressure. move the ports to the fuselage.

Photos: Reinhard Metz KITPLANES October 2017 27 Static Port Locations First Fuselage Static Ports I hate to admit the naiveté with which ➊ STA 180.5, Location of installed ➋ STA 152, ~ 80 – 120 ft. high, static ports ~ 92 - 128 ft. low, i.e. low pressure I first installed static ports on the fuse- i.e. high pressure lage: I simply looked at a number of factory-built planes, such as the Cirrus and Bonanza, and measured the relative distance from tail and trailing edge of the wing, and chose a similar location on my plane. Completing the installation, which of course included making holes ➍ STA 163, Best/chosen trial location, +18/-3 ft. altitude error in the fiberglass, I was dismayed that, ➌ STA 157.5, ~ 50 ft. high, although the autopilot was now stable, low pressure the altitude and airspeed were sub- stantially off (by about 130 feet and 10 Figure 3: Tests were conducted with the moveable static port plates in several different locations on the aft fuselage. mph respectively, cruising at 3000 feet). That’s when it became clear that the challenge is to determine the error in KITPLANES® in October and Novem- location of the static ports requires more altitude for any particular port location ber 2009. Kevin also provides a spread- than guesswork, or even good intuition. and how to improve it. sheet at http://tinyurl.com/jwp9r5a to After extensive investigation and discus- analyze flight data. sions with several experts, I learned that Determining Altitude Error Another way to determine alti- finding the best location was not easy With an initial pair of static ports tude error is to derive it from WAAS and, even with commercially produced (which may be the “moveable trial static GPS altitude. The WAAS specification airplanes, involves a significant amount ports” described later) and then further requires a position accuracy of 25 feet of trial and error—hundreds of hours trial locations, the first thing is to deter- or better, for both lateral and vertical as Paul Dye has put it. The prospect of mine the altitude error (which cor- measurements, at least 95% of the time. turning my plane into Swiss cheese did relates with port position error). One Actual performance has been shown to not sit well; there had to be a better way! approach is by inference from airspeed be better than 5 feet vertical. That makes The process, in any case, assumes and error, since airspeed may be relatively it an acceptable source of true altitude requires a starting point set of static accurately determined with GPS, as for static port evaluation, assuming one ports, which as described below, may described by Kevin Horton in “Flight has a WAAS-enabled GPS. be done with something better than Testing: Static System Error, Theory That said, it is well known that the guesswork hole drilling. Then, the next and Practice,” which appeared in indicated altitude will generally not be GPS Altitude Error Calculations

Inputs 1 2 3 4 5 6 7 11 12

hT ind Ind. Temp. Field Elev. Ft. Field Press. Field OAT F Test Alt. Ft. Test Alt. GPSA TAS kts h Feet Ind. Alt. Date and Test In HG OAT F T Error, Ft. 758 30.15 42.8 3000 35 3000 161 3092.5 92.5 2/27/2017 STA 180.5 758 30.54 36 3000 19 2874 161 3018.5 18.5 3/3/2017 STA 163 758 30.38 24.6 4000 17 3768 161 4016.3 16.3 3/15/2017 STA 163 758 30.39 32 6000 8 5666 164 6000.0 0.0 3/12/2017 STA 163 758 30.38 24.6 8000 7 7526 162 7996.6 -3.4 3/15/2017 STA 163 758 29.67 66 3000 58 2995 161 2948.6 -51.4 2/22/2017 STA 157.5 758 30.17 40 3000 30 2828 161 2933.0 -67.0 3/9/2017 STA 152 758 30.17 40 6000 28 5760 161 5938.4 -61.6 3/9/2017 STA 152

Figure 4: Test flight ground and altitude temperatures and altimeter setting were used with atmospheric pressure and altitude equations to adjust the GPS (true altitude) to what the altimeter should indicate for the test flight atmospheric conditions. This made it possible to calculate indicated altitude error.

28 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes (Left) The relocatable static port plate is made from 1/16-inch thick polycarbonate and is attached to the fuselage with aluminum foil tape. (Right) When the moveable plate is in the same location as the existing static ports, the altitude and airspeed errors are the same as the ports by themselves. the same as the GPS altitude unless you used with the atmospheric pressure and is included on the KITPLANES® web- have standard atmospheric conditions: altitude equations to adjust the GPS (true site at www.kitplanes.com/staticports and temperature, pressure, and lapse rate. altitude) to what the altimeter should is shown in Figure 4. Indicated altitude is the universal refer- indicate for the test flight atmospheric Now, the problem remains: How to ence used by all, whether or not it hap- conditions, which then allows one to cal- correct the port position error? The pens to be the same as true altitude—for culate the indicated altitude error. Cave- assumption by some is that may be separation it matters most that everyone ats are that the method will not work achieved by placing dams ahead of or is using the same relative altitudes. How- with a temperature inversion, and your behind existing ports, but I have found ever, test flight ground and altitude tem- OAT measurement capability must be that often does not work adequately, peratures and altimeter setting can be accurate. A spreadsheet for the approach especially if the port is too far from

KITPLANES October 2017 29 the actual neutral pressure zone. It also Altitude and Airspeed Errors does not make for a very aesthetically Indicated GPS Method Airspeed Method neat solution. Port Location Altitude Altitude Error Altitude Error TAS Error Moveable Trial Static Ports ➊ STA 180.5 3000 ft. + 93 ft. + 129 ft. - 9.8 mph What if one had a moveable static 3000 ft. + 18 ft. + 4 ft. + 0.3 mph port—one that could be placed in mul- 4000 ft. + 16 ft. + 6 ft. + 0.4 mph tiple locations, gathering data to con- ➍ STA 163 verge on the best location? There are two 6000 ft. 0 + 1 ft. 0 challenges in creating such a tool: First, 8000 ft. - 3 ft. + 9 ft. + 0.6 mph it needs to be thin and flexible enough to conform to the fuselage at the area ➌ STA 157.5 3000 ft. - 54 ft. —­ — of attachment and not materially affect ➋ STA 152 3000 ft. - 67 ft. - 98 ft. + 8.3 mph the local airflow as regards the pressure at its port. Second, a tube must be able STA 163 with 3000 ft. - 0.8 ft. - 13 ft. - 1 mph to be routed from it into the plane and installed port 6000 ft. + 26 ft. + 40 ft. + 0.2 mph connected to the rest of the static sys- tem. This was accomplished with an Figure 5: Through trial and error, STA 163 was determined to be the best location for the static approximately 4x4-inch, 1/16-inch thick ports. The bottom rows show the data for STA 163 with the actual ports installed there. polycarbonate plate with a 0.035-inch hole for the static port. The hole was in Plexiglass is glued to provide a place for fuselage with aluminum foil tape, with turn routed near to the edge of the plate a ¼-inch access hole that in turn con- the Plexiglass piece parallel to the air- with a 1/8-inch-wide milled channel on nects to the channel with a small per- flow. Connection from the port plate to the back side, with a depth about half pendicular hole. The channel is covered the static system is accomplished with the plate thickness. At the edge of the and sealed with a piece of Kapton tape. a length of ¼-inch nylon pitot/static plate, a ½-inch-wide piece of contoured The plate assembly is attached to the tubing, contoured along the side of Pressure, Altitude, Temperature, and Airspeed Math

Here is the atmospheric and airflow physics used in the spreadsheet to Where TAS is in mph and OATI is the indicated OAT at the test altitude. determine altitude error. The sensor recovery factor is assumed as 0.8, and the speed of sound at the altitudes we fly is assumed as an average of 750 mph. Pressure as a function of altitude can be calculated with the equation -0.03416 Ph = P0 × [1 + (L × h)/T0] /L where: Airspeed may be calculated as: 2/7 1/2 Ph is pressure at altitude h in Pascals (Pa) CAS = a0 × [5 × (qc/P0 + 1) – 1] where: P0 is the pressure at sea level in Pascals a0 is the speed of sound at 15°C h is altitude above sea level in meters qc is impact pressure T0 is the temperature at sea level in °K (= °C + 273.15) P0 is standard pressure at sea level. L is the temperature lapse rate per meter (negative number) Finally, pitot impact pressure may be calculated as: 2 7/2 If the conditions are standard, T0 is 288.15 °K = 15 °C, the lapse rate is qc = P × [(1 + 0.2M ) – 1] where: -0.0065 °K/meter, and P0 is 101325 Pascals (= 29.92 in. Hg). An error-free P is static pressure static system in standard atmospheric conditions would then indicate M is the Mach number, which in turn is CAS/Speed of Sound actual height above sea level. With typically non-standard conditions, (at altitude). the altimeter setting will offset the difference from standard pressure, The pressure and altitude equations are used in Figure 4, the error calcula- and the indicated altitude difference from actual altitude will be tion spreadsheet, to adjust GPS altitude to what the indicated altitude dominated by the difference of the temperature and lapse rate from should be for a given set of test-time atmospheric conditions. They may standard, for which altimeters are not compensated. The temperature also be applied to calculate the rate of change of pressure per change of component will typically dominate, as, except for days with inversions, altitude, and then predict the error in airspeed for a given error in altitude. the lapse rate does not vary so much.

For example, at 3000 feet the change in pressure is about 3.35 Pa per Complementary to the pressure equation, the height above sea level is foot, and change in airspeed for a given change in pressure is 0.022 given by: mph/Pascal, so the airspeed error for a given altitude error is 0.074 h = (T /L) × [(P/P )-0.19026×L – 1] 0 0 mph/foot. In other words, if the altitude is off by 100 feet, the airspeed OAT at altitude and airspeed may be calculated as: will be off by about 7.4 mph and vice versa. 2 OAT = OATI / [1 + 1.6 x (TAS/750) ] —R.M.

30 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes the fuselage, held in place with a cover in between, and in fact can be approxi- port positions as shown in the pictures, of foil tape, and entering the cabin mately predicted by interpolation of and at 3000, 4000, 6000, and 8000 feet through an available location. The lat- data points. for STA 163. From the data, it looks ter, in my case, was at the gear leg, fol- Of course, it’s never quite that sim- like a slightly better position might have lowing the route of the brake lines. ple. The pressure gradient is not lin- been about 1 or 2 inches forward, but Now, one obvious concern might be, ear, and in addition a vertical position that would have put the right port in the can this arrangement fly without fear of needs to be found that minimizes the baggage door, so I decided that within a it coming off at cruise speed? Well, the effects of angle of attack, altitude, and few feet and less than 1 mph error was answer to that came to me while walk- airspeed, while avoiding any signifi- good enough. The bottom rows show ing under the Airbus A330 at Oshkosh cant errors in landing configuration the data for STA 163 with the actual a few years ago where I saw a bunch of with flaps down. ports installed there. aluminum foil tape on the wings. Talk- Additional tests at lower and higher ing to the Airbus folks, I was told, “Oh Data/Analysis altitudes, lower speeds, and in landing yeah, we do that all the time in develop- After three new trial locations using configuration all confirmed errors within ment, no problem.” If it works for them, the moveable port plates, I found what the original goals. One insight is that the it will certainly work at 160 knots! looked like an acceptable final location. pressure gradient is not linear. With multi- Figure 5 shows the altitude and airspeed ple points, a curve fit could be created, but Pressure Profile Modeling errors at 3000 feet cruise for the four you may find an acceptable location with Relocatable static ports in hand, the first test was to place them directly over the existing installed ports and verify that they delivered the same incorrect altitudes and airspeeds, which they did. This looks like it might work! Just before proceeding with more guesswork placements of the newly crafted moveable static ports, I lucked into a bit of marvelous scientific method and rigorous engineering that anchored the process in some real data. In an email discussion of my problem and mission with Peter Garrison, who writes the “Technicalities” column for Flying magazine, Peter mentioned to me that he had the CAD model for the Express aircraft and would gladly run a surface pressure analysis for me. That predicted where the areas of zero error should be, providing a starting point for locating the ports. You can see in the pictures the line where this is expected to be, back of the wing. Superimposing the model on ...and leave your engine a picture of the plane provided guidance for new trial port locations. monitoring to EIS. Trusted with everything from 2-strokes Trial Results to turbines for over two decades. Starting with the predicted neutral pres- sure zone, the first test flight data made my day! Whereas the original ports were in a slightly high pressure area, resulting FLY IT in airspeed 9 knots low and altitude like you stole it... indication 129 feet low, the new loca- tion was now in a slightly low pressure area. The model was not perfect, but I www.grtavionics.com • (616) 245-7700 knew the best location was somewhere Proud sponsor of Tiger Airshows and airplane “thief” extraordinaire, Hotwire Harry!

KITPLANES October 2017 31 a few iterations. Note that whereas the 5. Preferably on smooth days, fly your better location. The pressure gradi- plates delivered nearly identical data when test combinations holding at each ent may not be linear, but within installed over my original ports, when the of the altitudes (easiest if you have just a few locations, the altitude STA 163 ports were installed, there was an autopilot), and record indicated and airspeed errors will likely be some difference, though probably accept- altitude, GPS altitude, indicated reduced into the range of +/- 30 feet able. One refinement may be to make the airspeed, true airspeed, OAT on the and +/- 1 mph. plates with ports that are more like the ground and at altitude (and some 9. Determine the trial location that contour of the port to be installed. intermediate altitudes to verify there provides the best compromise over- is no inversion). all results. Summarized Procedure 6. Determine the altitude errors for the Once you’ve found your best loca- To recap, here’s the process in review: various tests using either the infer- tions, it’s time to take the plunge and 1. Verify that your pitot/static system ence from airspeed error or adjusted put holes in the fuselage. One last does not have any leaks. GPS altitude method. If you use the thought: You may wish to start with 2. Determine any calibration errors in airspeed inference method, your test just the first port on one side and make the altitude and airspeed indicators. flights need to include a three course sure nothing has changed before pro- 3. Establish a set of test conditions, pattern, as described in Kevin Hor- ceeding with the second port on the including various combinations of ton’s spreadsheet. other side. J airspeed/power settings, altitudes, 7. If the altitude error is such that the and flaps extended/retracted for the actual altitude is higher than indi- 1NASA Technical Memorandum 104316, slow speeds. cated, then the static port pressure Airdata Measurement and Calibration, 4. If a surface pressure model is available is lower than standard for that alti- Edward A. Haering, Jr., 1995 for your plane, use it to determine the tude and likely the port is too far initial placement of the static trial forward, and vice versa. Relocate the 2NASA Reference Publication 1046, Measure- plate. If not, pick a location roughly trial port in the direction appropri- ment of Aircraft Speed and Altitude, 1980 1/3 of the distance from the trailing ate for a correction. 3Final Report, FAA Contract No. FA- edge of the wing root to the tail. For 8. Use the data from the second port 64WA-5025, Project No. 320-205-02N, vertical position, locate roughly at to determine a rate of correction per Flight Calibration of Aircraft Static Pressure the vertical tangent point. inch of port relocation to predict a Systems, 1966 Does This Really Work? OK, I know what some of you are thinking! Having read most of the pitot/ 3. When I have placed the moveable plate in the same location as static system threads on the Van’s Air Force forum (www.vansairforce.net), the existing static ports, the altitude and airspeed errors are the there are many tales of extraordinary sensitivity to minor variations of same as the ports by themselves. Further, when I finally deter- the static ports. Narratives abound of 10-knot airspeed errors or varia- mined the best port location and took drill to the fuselage, the tions associated with minor static port features/changes, even due to final ports again provided the same altitude and airspeed results N-number decals or paint interfaces in the vicinity of the ports. Given such as the plates. discussions, I can imagine you might have serious doubts about how well The nagging and remaining question then is how and why a moveable static port on a plate structure like I have described might have some RV owners had such radical differences in altitude and work. Can it really perform like a fuselage port at the same location? airspeed resulting from minor port changes, particularly at the To address that concern, I offer the following: same location? Perhaps it is that the rivet ports are not actually at 1. Bernoulli’s principle says that the static pressure at any location the best neutral pressure location, but their particular shape and along the fuselage is inversely proportional to the velocity of the air hole entry curvature have local flow altering effects that result in at that location. That is why, per the figure, the static pressure has good measurements? a low to high gradient as it moves from the fuselage area behind I am using Cleaveland Aircraft Tool (www.cleavelandtool.com) the wing to farther back; it was moving faster to get past the wider aluminum ports bonded into the fiberglass, which have a minor portion of the fuselage and slows down as the fuselage gets thinner. outward curvature, but otherwise are generally flush. Their holes are So, for the relative part of locating a static port, one that delivers a flush and sharp, similar to what NASA testing showed to be ideal hole lower altitude and airspeed than actual needs to be moved forward shaping.2,3 Perhaps the moveable plates would not perform the same and vice versa. as the Van’s rivets. 2. While I am not a fluid dynamics expert, it appears that pressure at The general method is still applicable even if the first static location any given location will be the same on the surface of the thin plate ends up not quite right on. The difference from the moveable plate and port described because it maintains essentially the same contour other plate positions can then be used to calculate a new, and hopefully of the underlying surface, and being thin enough, it maintains the final, location. It’s still better than the many trial and error holes! same flow velocity and thus the same static pressure. —R.M.

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Secrets for reducing drag, part 2. By Dave Anders

In Part 1 of this article, we covered Dynamics at the time regarding efficient Plenum Considerations basic principles for drag reduction, engine cooling. 1. Inlets should be positioned away from then looked at rigging, gear leg fairings, Mass flow = inlet area x a/c the spinner to prevent or decrease wheelpants, hinge fairings, and empen- velocity x plenum efficiency possible reverse flow out of the inlet nage gap seals. Taking a peek under the on the side nearest the spinner. This cowl, we saw small upper baffles on the The Lycoming installation manual is due to the pressure differential cylinders and discussed cooling air drag for a 360-cubic-inch engine indicates across the inlet and the root region and exhaust air convergence zones. 6½ inches of H2O delta p across their of the prop, which suffers a momen- That’s a good start, but there’s much cylinders will adequately cool. In a max tum deficit and thick boundary layer, more work to be done. Let’s begin with climb, below 4 inches may produce heat- especially with the cowl shapes neces- the upper plenum and inlets, followed ing. I did the mass flow calculations sary for compact hubs. by the augmenter outlet and cooling years ago and decided a pair of 45/8-inch 2. Using a diffuser to slow the incoming tunnel. I made these modifications in inner-diameter inlets should cool my air and increase pressure (Bernoulli’s 1995, and they reduced the drag another engine. In fact, they overcool except at principle) decreases cooling drag losses. 6.0%. Remember, it gets harder and wide-open-throttle (WOT) and in max- Up to 10 degrees appears to work, how- harder to find large areas for additional imum-rate climbs. I originally estimated ever, I use 8 degrees because if the flow drag reduction as you go faster because the inlet size to be 10% smaller in vol- separates, it’s equivalent to choking the all the low-hanging fruit is gone. ume, and knowing I’m not an engineer, inlet. A nicely sealed smooth transition I read Stan Miley’s data about plenum I increased the estimated size. So, they into the plenum results in lower losses. design and talked with aero engineer work in the most adverse conditions and 3. The plenum can be sealed directly to Dave Lednicer of Computational Fluid overcool in cruise. the engine with soft foam weather

34 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes stripping on the plenum edge and essentially eliminate all leaks. This achieves the maximum pressure recovery from free stream velocity, which will increase the delta p across the cylinders producing more poten- tial for cooling. 4. The inlet area in the throat of the inlet is called the A1 area. The diffuser starts here and proceeds toward the cylinders. At some point, you can no longer maintain the conical expansion, which is effectively the end of the diffuser. This is called the A2 area. The area The plenum seals to the engine and essentially eliminates all leaks. By achieving maximum over the cylinders and heads above pressure recovery from free stream velocity, it produces more potential for cooling. the fins is the A3 area. The general formula for a good plenum is that 2. Oval-shaped inlets will produce Just make the seal about ¼ inch tighter, the A1 area conically expands at lower losses, as the shape of the ple- so it will stretch over the diffuser with- 8–10 degrees to the A2 area, then num over the cylinders is more rect- out any leakage. The gap between the the A3 area above the heads and angular and requires less energy to plenum and inlet doesn’t need to be cylinders is equal to the area of the change flow shape. Look at the wing greater than ¼ inch. A2 location. The A3 area includes root inlets on the Grumman F8F only the area above the cylinders Bearcat and notice they are slightly Augmenter Outlet Considerations and heads—not the case. This is a below the leading edge of the wing. 1. Exhaust velocities are higher than very oversimplified explanation of Obviously, they had something in our IAS, so we should attempt to Stan Miley’s work. mind. Tight corners are bad. Oval recover as much as we can for thrust. 5. Of course, all the principles are inlets are just harder to build and 2. Some have advocated crushing the subject to best application for harder to seal than round ones. exhaust pipe to increase the veloci- your installation. 3. A rounder lipped inlet may also ties, and this may work. However, I reduce the possibility of inlet stall. decided to get the most I could with- Inlet Considerations 4. Oversized inlets do not produce out potentially causing some possible 1. Generally, the inlets or inlet cowl more cooling; they only increase drag adverse condition for the engine. I interface should have round-lipped around the inlets. selected a 4-into-1 exhaust system, shapes about the size of a nickel or 5. Inlets are easily sealed to the diffuser which produces the smallest cross a Kuchemann A30 shape. Both will area of the plenum using ¼-inch bi- sectional area for four exhausts. work well. directional stretchy wetsuit material. 3. Direct the exhaust flow as close to the free stream direction as possible to recover maximum thrust. Con- siderations for increased noise and heat can cause some to abandon this avenue. However, by proper cowl exit design, you can use the high exhaust velocities as a type of augmenter. 4. Augmentation can be accomplished with multiple exhaust pipes as well; it’s just a little tougher. Cooling Tunnel Considerations 1. NACA studies indicate cooling air should emerge with free stream air as close as possible to parallel at the Oval-shaped inlets like those on this Grumman F8F Bearcat produce lower losses but highest velocity achievable. are harder to build and seal than round inlets. (Photo: Spartan7W [CC BY-SA 3.0, http://creative- 2. A shallow-angled, straight-sided ramp commons.org/licenses/by-sa/3.0]) is very effective. For cooling air, a

Photos: Dave Anders KITPLANES October 2017 35 Inlets are easily sealed to the diffuser area of the plenum using Half-inch machine wiping felt is used to seal the area between quarter-inch bi-directional stretchy wetsuit material. the spinner and cowling. The felt rubs against the propeller hub.

width-to-depth ramp ratio of 7 to 1 Controlling Airflow against the propeller hub. It is beveled at is recommended. Air exiting or entering places it isn’t sup- the inside rubbing edge (it cuts well with 3. For augmenters the distance around posed to causes drag. The airlines recycle an angled dye grinder with a coarse abra- all sides is best at 1 to 1. air in the cabins for various reasons but sive wheel), so it’s a little tighter inside My first attempt at an improved one is to reduce drag, so only use what the cowl, and any pressure will help it outlet is still in use today. The ramp is you need. It takes energy to slow the air seal. The felt was saturated with silicone attached with POP rivets tangent to the down and then reaccelerate it as it enters and it has worked well for over 1500 cowl. The ratio of the ramp is about 7 to the free stream. hours. The felt is sandwiched between 1, shallow angled, and it diminishes to Seal all possible gaps. The area around two pieces of aluminum and screwed zero at the wing spar. The area around the propeller is often neglected. The flow and sealed to the cowl with a bead of the exhaust pipe is 1 to 1. The exhaust at the back of the spinner is poor, and the RTV. If your cowl doesn’t permit sealing collector is cut off inside the cowl to aid boundary layer is thick. If air were col- to the prop hub, you can easily seal to the the extraction of the cooling air. From ored, you’d see an arching spray coming angled front surface of the starter ring. examination of the exhaust flow on the from all around between the spinner and Be creative. bottom of the plane, you can see the front edge of the cowling. This is because Another area often overlooked is straight flow. the pressure in the lower plenum is exit- the fuselage air entering or exiting The area of inlet on my RV-4 is 34 ing into this area and causing drag. through the empennage. This can be square inches, and the exit area is about I sealed this area with a 1/2-inch sealed easily—it just requires taking 26 square inches, for a ratio of 1 to 0.76. machine wiping felt from McMaster- your plane apart, so maybe do it when With the combination of systems I have Carr (www.mcmaster.com) that rubs you’re already working in that area. on my RV, I have the following: Upper plenum pressure @ 200 knots: 24.5 inches of H2O (using a Magenhelic inches of H2O gauge). Plenum efficiency: 24.5/26.63 (standard day, H2O at 200 knots) = 92% recovery Delta p across the cylinders: 87 knots = 5.0 inches 104 knots = 6.8 inches 174 knots = 14.8 inches From 104 knots to 200+ knots, the delta p is almost a straight line, and the delta p is greater in the power-on condi- tion then the power-off condition at all speeds, indicating that exhaust augmen- tation is helping to extract the cooling air from the lower plenum. This aids in cooling the engine during sustained A shallow-angled, straight-sided ramp can be very effective. For cooling air, a width-to- full-power climbs at lower airspeeds. depth ramp ratio of 7 to 1 is recommended.

36 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes The canopy rails in my plane are sealed with “P” molding to pre- A small piece of self-adhesive soft weather stripping prevents flow vent leaks. The small hole to the right of the hinge is sealed with through the vertical stabilizer and the rudder counterweight. a small piece of foam rubber bonded to the canopy.

Simply get out a sewing machine and I sealed flow-through air on control the gap between the stabilizer and sew a cone. You do have to figure out surfaces by contouring a piece of Sun- counterweight arm and flows toward where the control tube goes through Mate pressure-sensitive foam. Simply the hinge line. It then turns 90 degrees the bulkhead because you want the cut it to fit the void it goes into, and around the corner and flows out of the panels on the cone to produce the least make the fit a little snug. It holds in gap between the stabilizer and con- amount of load as the control tube goes place by conforming around the rivet trol surface, which produces drag. The through its motion. heads. Do not use temperature-sensi- simple addition of the foam prevents You don’t have to secure the cone tive foam here. The high-pressure air this. Also, a small piece of self-adhesive to the tube; as a matter of fact, that from free stream flow normally enters soft weather stripping can prevent flow may be a bad idea in case it acts like a diaphragm with the changing air pres- sure. I used synthetic leather because it’s soft and air tight. The seal to the tube is just 1-inch-wide Velcro (the fuzzy side snug to the tube) sewn in snugly so it prevents air from flow- ing through too easily. The cone is bonded to two aluminum rings that are bonded in place to the bulkhead. The rings may need to fold to get them in place, so they might have to be split. The bulkhead is sealed with a bead of RTV to the skin, and SunMate pres- sure sensitive foam is used to seal the rudder cables. SunMate is not very thermally sensitive foam. You’ll never know the tube seal is there. If air exits anywhere it’s not supposed to, it produces drag. You can use a deci- bel meter to check for leaks around your canopy while you’re flying along, and any area producing drag will be quite noisy. The canopy rails in my plane are sealed with “P” molding to prevent leaks. Although it’s difficult to see in the photo, at the rear of the canopy hinge is a small hole that is easy to seal with a small piece of foam rubber bonded to the canopy.

KITPLANES October 2017 37 through the vertical stabilizer and the rudder counterweight. I’ve flown with these changes for thousands of hours with no problems. But like any modification, you need to evaluate its safe application before using it on your own plane. These mods are also small and might not seem to make much difference. However, if the changes are scientifi- cally sound, they all add up and will help reduce drag. If you’re flying an RV with Van’s These wingtips are common now, but when I added them in March 1997, they were older Hoerner wingtips, you might perhaps 2 mph faster than the original Hoerner wingtips. consider changing to the new wingtips with a higher aspect ratio that produces Fastback Modification not be polished due to risk of melting smaller wing vortices. These are com- By the year 2000 I did the last major drag your canopy. It took me a long time to mon now, but when I changed mine in change, a lower canopy and fastback learn that. The last Sun100 race was in March 1997, the new tips were margin- deck. It’s very important to make certain 2000, and the last modifications added ally faster, perhaps 2 mph. that the canopy totally seals. Remember, another 9% of drag reduction or 6 mph I also increased my ram air pres- air entering and exiting is bad, so it could at top speed. I believe that the fastback sure a little with my first attempt at a be that you go through the entire exer- added about 4–5 mph of that, which is Bernoulli-principle ram airbox with cise and not add anything. amazing since it was the last modifica- corresponding sigmoidal shapes that My canopy is completely sealed all tion. It was getting very hard to find were calculated to smoothly increase around. You can place a business card additional meaningful changes. volume. One was used as a diffuser anywhere on the back edge of the can- The rear canopy seal is part of Dave cone over the end of the air filter, and opy skirt, close it, and it will still be there Howe’s entire fantastic technique for by this method I was able to get a little after a high-speed run. Then I painted building the fastback. The seal is from ram boost through the filter. The other the plane. It started out polished and McMaster-Carr and is 1/32-inch-thick shape was the airbox having a 5-degree had remained that way for eight years, self-adhesive felt. It not only seals, but divergence until it got to the K&N fil- but there was strong evidence out there also prevents chaffing the paint. I’m still ter, but this was not optimal. that painted planes were faster, maybe 1 using the original felt, placed perhaps During this time period, I added mph or so. That was worth $5000.00— 1800 hours ago. Careful work can pro- 3.4% more drag reduction from all the not hardly. But I was tired of polishing, duce a no-leak seal. modifications. By March of 1997 the and I had melted three canopies dur- I also improved the elevator inboard total drag reduction was about 17%. ing that time. Low-wing planes should fairings to help decrease the turbulence off

The last major drag change was a lower canopy and fastback deck, which added an estimated 4–5 mph. At this point, it was getting very hard to find additional meaningful changes.

38 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes The rear canopy seal is 1/32-inch-thick The business card closed into the rear canopy overlap is still there after a wide-open- self-adhesive felt. It not only seals, but throttle test run. also prevents chaffing the paint. Current Efforts Caboon (http://tinyurl.com/nzdrhrn), the empennage (see “Putting the Experi- Since I first tried to increase ram pres- describes the elliptical profile velocity ment in Experimental,” KITPLANES®, sure, worthy scientific articles have stack. It even includes the formula for March 2017). become available, and more empirical the best bellmouth ELL-23-23-49-3 During all this time, I documented evidence from good experimenters like with a picture. So, in order to build the what I changed and what it produced, Tom McNerney has come to light. It’s best ram intake you can for your appli- and I use the same formulas and proce- worth trying to improve your induction cation, first design the optimum ellipti- dures today—but now with autopilots because on a 360-cubic-inch Lycoming, cal velocity stack, then see how much and downloadable data you can analyze every 1-inch increase in manifold pres- room you have. Next, design the largest on Savvy Analysis (www.savvyanalysis. sure (MAP) is good for about two hp per 8-degree divergence Bernoulli-principle com), it is much better and easier. cylinder (rule of thumb). This has been airbox that will fit. This will decelerate I am still working on the plane, but borne out by the performance formulas of my efforts have been redirected toward predicted speed increases from increased efficiency. It now has dual Light Speed hp. So when you can go up another 1000 Plasma III electronic ignitions by Klaus feet in altitude, run the same MAP and Savier (www.lightspeed-aero.com), driv- engine settings as you did at the lower alti- ing an electronic fuel injection SDS tude, you will be going about 2% faster. EFI by Ross Farnham (www.sdsefi.com) Remember, I’m not an engineer, so most with a much better induction system. things are rules of thumb and trial and This has worked really well (see “Put- error. Isn’t experimenting fun! ting the Experiment in Experimental,” A very easily read article, “Best KITPLANES®, March 2017). Bell” by Gordon P. Blair & W. Melvin

A simple way to attach the new airbox parts to the throttle body.

KITPLANES October 2017 39 the airflow and increase the pressure as much as possible in each case. I made molds with a cheap Harbor Freight woodworking lathe, using alumi- num templates to guide the final shapes for the molds. The result was a ram induction airbox that works much better than my earlier attempts. This airbox, coupled with the With its 8-degree divergence, the new Bernoulli-principle airbox works much better improved, very impressive induc- than earlier attempts. tion tubes and cold induction plenum from Kevin Murray, president of Sky also made the exhaust tubes that are 360-cubic-inch Lycoming when run- Dynamics (www.skydynamics.com), is 4 into 1 with cyclonic firing order and ning 2700 rpm. So what’s next? Only the induction system I am currently nearly equal lengths. your imagination can stop you. running. Sky Dynamics makes incred- With the modifications described, I remember when I was out there ible products that when you look at and having an engine that now produces trying things. I really appreciated all them you just say, “How did they do about 195 maximum hp at 2825 rpm, the help everyone gave me, and it really that?” Just look at the formed light- I can maintain 16.4 inches of MAP helped to see what they did or how they weight stainless steel intake plenum (it’s at 17,500 feet while getting 37.6 mpg did something. I hope this article can one piece) and tapered curved stainless at 209 mph TAS turning 2230 rpm. get your creative juices flowing. What’s steel induction tubes. Amazing! They Not too bad for a fat-winged RV that really going to be neat is to see what the is now producing about stock hp for a next generation of ideas will be. J Alodine Sluice By Larry Larson SHOP TIPS

Alodine is an excellent corrosion inhibitor plus it adds zero weight. I should have Alodined before assembly but didn’t care for the chemicals. AlumiPrep and Alodine are not environmentally friendly and handling the chemicals is always a concern. How- ever, they are the best choice for a vinyl-wrapped plane. So the question is, how do you capture the chemicals and rinse water? The answer is a sluice. You will need a shower curtain, four pieces of conduit, a large storage container, sev- Four pieces of conduit are attached to eral bungees, and a clip with a weight. Disable the garage door opener as a precaution, the door track supports with wire S-hook then hang the four sections of conduit from the garage door tracks. One each across planter hangers. The part being treated and one each from the inner tracks works pretty good. I used wire S-hook planter hang- with Alodine is attached to the chain. ers from the door track supports. Secure them so they can’t fall. As you can see in the photo, they are really handy for all sorts of work like holding lights and hoses. Steal the bathroom shower curtain, but you may want to buy a new one and replace it first. I keep old ones for just this sort of thing. They also make a great paint booth by hanging them from the conduit frame. Use various-length bungee cords to hang the curtain so one end is higher than the other. Place the container under the lower end and clip the weight on the edge of the sluice. Use chains slung over the conduit rails to support parts. You can slide the chains as needed to fit the parts. Now you’re set and all the nastiness will end up safely in the container. When the job is done, leave the container in a safe place with a piece of screen over The shower curtain is held at an angle by it so animals won’t fall in. When the water has evaporated, collect the remaining resi- bungee cords attached to the conduit due for disposal. Most cities have a hazmat disposal site. Remember to wear protective frame. The vertical stabilizer is suspended gear any time you handle these chemicals. J from two chains.

40 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes The Creative Homebuilder Make Your Own Specialty Wrenches By KITPLANES® Staff When conventional store-bought wrenches don’t seem to to grab while tightening the retaining screw. Our Creative do the job, most builders find themselves occasionally grinding Homebuilder, with a little welding and cutting, made a simple down or bending a cheap wrench from the local, discount Chi- tool to manage this problem. nese tool store. But for more challenging problems, our Creative The wrench that he created slips over the bug nut, allow- Homebuilder suggests you take the process a step further and ing the control wire to pass through the cut slots while allow- make your own (MYO). He has made a variety of simple wrenches ing access to the retaining screw head. As the retaining screw for specific purposes when no existing wrench was available. The twists and tightens, the wires in the slot provide resistance and grip ends of the tools typically start life as a steel flat washer that keep the bug nut from rotating. J is cut, filed, and welded onto a suitable steel flat stock handle. The aluminum hex wrenches seen in the photos were used to install specialized bulkhead couplings designed for hose and tube pass-throughs of the firewall, fuel tanks, or side skins. Sometimes the install locations restrict access for con- ventional wrenches, but these custom hex units, with a slight offset bend in the handles, make for an easy and consistent installation. The open-end steel wrenches are for more mun- dane jobs, such as loosening the hole cutter from the mandrel on Blair Rotabroach cutters. Tightening a “bug nut” on push-pull cables, such as mixture or other engine controls, provides another challenge in the pursuit of the perfect wrench. As one tightens the Allen-head or slot-head screw into the cylinder (bug nut) drilled to pass The aluminum hex wrench has a slight offset bend in the handle. the control cable through, the entire cylinder tends to twist The open-end wrench is made from a steel flat washer welded to and kink the cable. Bug nuts often provide no purchase points a steel flat stock handle.

(Above) This MYO bug nut wrench was made from scrap material, but did require some welding. (Right) The bug nut wrench slips over the nut, allowing the control wire to pass through the slots. The wires The aluminum hex wrenches are used to install specialized bulkhead held in the slot provide couplings. The steel open-end wrenches are for more mundane turning resistance when tasks where conventional wrenches aren’t quite right for the job. the screw is tightened.

Photos: KITPLANES® Staff KITPLANES October 2017 41 Getting Your Plane Ready for the DAR

Common pitfalls and problems that builders face. By Dave Prizio

42 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Building an airplane is a long and com- plicated task. Years of effort come down to the final step where you are anxiously awaiting the signoff from your local Des- ignated Airworthiness Representative (DAR). It doesn’t seem too hard to fill out a few forms, write a letter, and check your plane over one more time. What could possibly go wrong? Apparently a lot, based on my recent experience. To help you avoid the common problems I often see, let’s go over the process of pre- paring for the DAR visit. EAA Resource The EAA has a packet designed to help the builder through the registration and airworthiness process. I urge everyone to join EAA and then take advantage Whatever you list on your registration is what you will need to match everywhere else. Be of their extensive resources to aid you in sure to have this in front of you as you complete the other forms and your data plate. this process. I have one warning, how- ever. Lately, some of the forms in the form, which begins on page 2 after the The form begins by asking for the EAA packet have expired, so double- instructions, for the expiration date. As name and address of the registered check the form dates before you fill them we went to press, the expiration date owner. The name you put on this form out. Out-of-date forms will be rejected on the form was 9/30/2017, which is should match exactly what you have on by the FAA. I have already reported this around the same time that many of you your registration in the box titled Issued to EAA, so I am sure they will take care will be reading this, so check the date on To. This may be different than the name of this right away. When in doubt you your copy of the form carefully. in the box labeled Manufacturer and can always get the most current forms from the FAA website. Registration You must have your permanent registra- tion in hand before the DAR can begin the airworthiness certificate process. Be sure to apply for your registration at least two months before you think you will need it. The process usually goes faster than that, but it can drag on in some cases. Your DAR has no ability to assist with registration issues because that is handled by a completely separate division of the FAA. The old cartoon caption, “No job is finished until the paperwork is done,” is particularly apt when it comes to get- ting your plane released for flight by the FAA. There are several forms to consider, so we’ll go through them one-by-one. Eligibility Statement The first form you will need to deal with On Form 8130-12, as with the other forms, enter the owner’s name just as it appears on the registration. Model, serial number, and registration number should also match the registra- is the Eligibility Statement Amateur- tion exactly. List yourself under builders and include others who made major contributions. Built Aircraft Form 8130-12. Be sure Type N/A on the commercial assistance line if that is true. Otherwise, expect to complete a to look in the upper right corner of the detailed evaluation of the work you did with your DAR.

Photos: Dave Prizio and Louise Hose KITPLANES October 2017 43 Manufacturer’s Designation of Aircraft. Please use the Issued To name. In Section II fill in the model, serial number, and registration number exactly as it appears on your registration. If the model as it appears on your registration is “Van’s RV-8A,” then that exact thing must appear on this form. Do not abbre- Be sure to fill in Section I exactly as the information is shown on your registration form. Note viate it to RV-8A, for example. that the builder name is the name from the Manufacturer box on the registration. In Section III use the same name exactly as it appears in Section I. In Section IV if the notary acknowl- edgement is on a separate page, put “see attached” in this box. Program Letter The airworthiness certificate process begins with a program letter, which is simply a letter to the FAA asking them to issue you a special airworthiness cer- tificate. In this letter, you will describe your airplane and the location where it will be available for inspection. You will You have some boxes to check in Section II of Form 8130-6: Special Airworthiness Certificate, also “request” a flight test area, which is Experimental, and Amateur-Built. generally not subject to your wishes but is predetermined based on the airport or his or her supervisor at the FAA. In of the most current biweekly airworthi- you will be using for your Phase I flight Section I things seem pretty straight- ness directives notice. Go to the FAA testing. The EAA has a model program forward, but people do get the builder’s regulatory guidance library (https:// letter in its packet, but you will need to name and model number wrong from tinyurl.com/y9r5vo5q), and then click get the exact language and the flight test time to time. Be sure the aircraft build- on “Small Aircraft, Rotorcraft, Gliders, area from your DAR. Instead of spend- er’s name is the same as the name listed Balloons, and Airships.” This will give ing time with the EAA form, simply in the Manufacturer box on your regis- you any ADs that have appeared in the contact your DAR and ask for a sample tration. This is not necessarily the same last two weeks. The number you need letter. When completing your program as the owner’s name. The model and to enter on the form will look like this: letter, be sure to list the builder, reg- serial number must also match the regis- 2017-10, 5/1/2017-5/14/2017. That istration number, serial number, and tration. Do not guess or try to remember description goes in the text box under model exactly as they appear on your this. Get your registration in front of you Airworthiness Directives. Of course, the registration. Always remember that and copy the information exactly. assumption is that you have searched the builder name and the owner name In Section II you have two boxes to for ADs related to any certificated or may be different. Whenever it asks for check. Check Box 4 where it says “Experi- TSO’d parts you may have on your air- builder, use the name shown in the mental,” and then check Box 2 to the plane, and that you have checked the Manufacturer box on your registration. right where it says “Amateur Built.” biweekly report for anything new. In Section III, Box A asks for your But ADs don’t apply to Experimen- Application for name. This is the owner’s name as it tal/Amateur-Built aircraft, you say. Well Airworthiness Certificate appears in the Issued To box on your that may be true, more or less, but the The Application, Form 8130-6, seems registration. This is usually shown last FAA still wants to know if there are to be the most troublesome. This name first, but the most important any outstanding ADs on any parts of form is available online from the FAA thing is to have it exactly match what- your plane, and if there are, what you website as a PDF file that can be com- ever is on your registration. have done about them. Your condition pleted on your computer. This is much In B there are four boxes. Only check inspection says that the airplane is in a preferred to having you fill it out by the box marked Airworthiness Direc- condition for safe operation, so the logic hand. Just be sure to use the most cur- tives. Put N/A in the text windows of the is that a part with an uncorrected AD is rent form. other boxes and leave them unchecked. not safe for operation. You are not nec- This form must be exactly correct or In the text section of the A/W box, you essarily required to comply with the AD it will get rejected, either by the DAR will need to list the number and dates in the same way a certificated aircraft

44 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes DAR. Your calculations should show the forward-most CG loading, the maximum loading, and a typical load- ing for the flying you expect to do. You will also need to list your CG limits and gross weight, which should be the gross weight and limits recommended by the kit or plans manufacturer. To be sure, you are not bound by their recom- In Section III of Form 8130-6, be sure to use the Issued To name from your registration in Part A (Registered Owner Name). In Part B check the Airworthiness Directives box mendation, but you should only deviate and put the number and date of the most current Small Aircraft Biweekly Report in from it for a very good reason, none of the text section. Put N/A in the other boxes as shown. In Part C check the box and which comes to mind. Be sure to have a write 0 in the hours boxes. Date the application as shown, and again list the owner’s copy that the DAR can keep. name and title. 3-View Drawing You must include what is called a 3-view drawing or photos showing the same with your application. These are usually easily obtainable from the kit maker or plans designer. If not, the builder group for your particular type of airplane is usually a good resource. The drawing or photos must show a front, side, and top In Section VIII check boxes A, B, C, D, F, and J as shown, and type 21.191(g) in box J. view of the plane. The drawing does not need to have dimensions. If you can’t would, but you are required to ensure Experimental/Amateur-Built aircraft. find any drawings, photos will do. Just that your plane is in a safe condition by You are now finished with this form. be careful when trying to get a top-view some reasonable means. photo. We don’t want you to fall off the Part C of Section III should be Data Plate roof of your hangar. checked and the airframe hours entered A fire-resistant data plate must be in both boxes. Presumably this is zero installed on the airframe showing the Builder’s Log for a new plane. In other cases, such as builder, the model number, and the The builder’s log is your record of the applying for a renewal, the hours will serial number. Many data plates will list construction process. There is no set reflect the actual time. other information, but that information format for this, but all agree that a good Part D of this section contains the is not required. The important thing is selection of photos is the best evidence date of the application that should be to get the required information right. of your involvement in the building pro- entered in this format: day (two digits)/ The builder name must match theMan - cess. Be sure to have a few photos that month (three letters)/year (four digits). ufacturer box from your registration include you. Written records of what you For example, 17 May 2017. The name exactly as it is shown. The model number did and when you did it are also good following should be the name listed on and serial number must also match the evidence of your efforts, as are records the registration under Issued To, plus registration exactly. The data plate must of any EAA technical counselor visits. the title, owner, or other appropriate be permanently affixed to the airplane, Photos on your computer or tablet are title if the owner is not an individual. usually near the tail on either side with fine for this purpose, but do try to have Lastly, you will sign your name. metal rivets. The important thing is to them organized and edited for redun- There are no entries required in Sec- make sure the information on the data dant photos before the DAR shows up. tion IV, but in Section V you should list plate matches the registration exactly. If you have built from plans or an the date of the inspection in the same Many builders have had their airwor- approved kit and not used any commer- format as before. Your DAR will fill in thiness certificates delayed while they cial assistance except for instructional the rest of this section. waited to get their data plates remade. Be purposes, the builder’s log will be suffi- On the last page, you have some more precise. Check twice, then order once. cient evidence of your compliance with work to do. In Section VIII, check boxes the majority Amateur-Built require- A, B, C, D, F, and J. In the text win- Weight & Balance ment (51% rule). If your kit is not on dow for J enter “21.191(g).” This is the You must weigh your plane and com- the approved list or you did use com- section of the federal aviation regula- plete your weight and balance calcula- mercial assistance, your DAR will need tions that deals with airworthiness for tions for your own use and to show the to do a detailed evaluation of your work

KITPLANES October 2017 45 to determine its eligibility for Amateur- Built status. Logbooks You need an airframe (aircraft) logbook and an engine logbook to keep track of your maintenance. A propeller logbook is also nice to have, but some people simply make prop maintenance entries in the aircraft logbook. Many prop manufacturers will include a prop log- book with their new prop. All logbooks should be filled out with the relevant information about the aircraft and Secure all spark plug wires and sensor leads with cushioned Adel clamps. It is better if they are kept separate as shown here. engine or prop as applicable. You must have a condition inspec- If you will be conducting your Phase out of the building phase and into tion entry in your aircraft logbook I out of a Class D airport, you will need Phase I flight testing. before the DAR can sign you off. Here to have your transponder certified, proof is the required entry: “I certify that of which should also be in your logbook. Preparing Your Plane this aircraft has been inspected on If you do not have an electrical system, Your plane must be complete and ready [insert date] in accordance with the you are exempt from this requirement. A to fly before the DAR arrives. That scope and detail of 14 CFR part 43, pitot/static certification is not required means you would be willing to get in appendix D; and was found to be in unless you plan to fly IFR. In any case it and fly it after replacing the inspection a condition for safe operation.” After is not required for Phase I. However, it is covers. If your plane isn’t complete to this you need to list your name, cer- highly recommended for everyone, even that point, you are not ready for the tificate number, and type of certificate VFR pilots, at least this one time. DAR. That means the plane has been held, and then sign your name. Since Please note that you as the builder are weighed, the fuel system has been tested, you do not yet have your repairman’s responsible for conducting a thorough the avionics have been tested, the engine certificate, you will use your pilot’s condition inspection, not the DAR. monitoring system has been tested with license (certificate) number. Your When the DAR is finished with the operating limits set, and the engine type of pilot’s license will be the type everything, he or she will make an has been run at least for a few minutes. of certificate held. Once you get your entry in your logbook referencing the If any of these steps remain undone, repairman’s certificate you will use airworthiness certificate just issued to you need to take care to get them done that number and description. you. At that point, you will be officially before the DAR visit. As part of your inspection, you will need to present evidence of a fuel system test. This does not have to be anything elaborate. Simply a sheet of paper with the recorded fuel flow will do. If you have a photo of the test being performed, that would be nice, but it is not required. The EAA has a fuel system test form that you can use. If you are unsure about how to test your fuel system, there is an EAA webinar that goes into the process in depth. There is also an article that covers the topic in the December 2012 issue of KITPLANES®. Last but not least, the FAA covers fuel system testing in its advi- sory circular AC 90-89B, which is avail- able online. Your DAR is required to ask for evidence of this test, so be prepared. The DAR must see your engine run. Be sure to check your fuel flow and record the results so you can show it to your DAR. Be sure that you can start your engine This is now required, not to mention a good idea. easily and that there is enough fuel in

46 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Use Torque Seal to mark control rod jam nuts and hose fittings Check to be sure all cotter pins and safety wire are in place after you tighten them as a reminder of what has been completed before your DAR inspection. Some places such as this are easy and what has not. to miss. the tanks to do so. Also, be sure that things you should look at to be sure your well marked if their intended use is your battery is fully charged. Often plane is ready to fly. not obvious and conventional. Be builders will forget this as they have • Be sure all nuts and bolts are tight, sure that controls work smoothly been testing and programming their properly torqued, and have at least and move through their full range of EFIS and avionics. If your airplane one, but not more than four, threads travel with some cushion. In other won’t start, you will not get your signoff showing. Fasteners that need cotter words, the item being controlled and airworthiness certificate. pins or safety wire should have those should reach its limits of travel before Beyond these requirements there is installed; same for turnbuckles on the control does. no universal agreement within the FAA control cables. Jam nuts at control • In the engine compartment, watch as to how thorough a DAR inspection rods are a special area of concern. It out for wires and SCAT ducts that should be. Some do almost no physical is easy to forget to tighten these, so I are too close to exhaust pipes or are inspection, simply limiting themselves recommend that builders mark them not well-secured. Correct any places to a review of the paperwork. Others will with Torque Seal after they are tight- where wires could chafe against get more involved in the nuts and bolts of ened. That makes inspection very easy. other parts, especially the engine your airplane. In any case, do not count The same marking works well for fuel mount. Be sure that any open- on the DAR to find any problems that and oil line fittings. ings in the firewall are sealed with may exist with the construction of your • In the cockpit, switches, breakers, a 2000-degree-rated sealant. That airplane. That is your job. Here are some fuel valve, and controls should be does not include red RTV. • Make your plane look like it is ready to fly. Or maybe to put it another way, make your plane look like you are ready to sell it, and a buyer is on the way. Tidy up the area around the plane to present an appearance of order. This will give the DAR confidence that the things he or she will be looking at, and the things he or she can’t see, will be properly done. In short, make it easy for them to say yes. It is not the DAR’s job to enforce best practices on your project. But he or she should try to catch any problems that will make the plane unsafe to fly now or in the near future. Take advantage of the many resources available, such as back issues of this magazine and your EAA technical counselor, to get things When all is said and done (and inspected), the result of good preparation should be an right on your project. Good luck on airworthiness certificate! your big day. J

KITPLANES October 2017 47 The Demise of the Cosmic Fish

Some mods don’t work out as planned. By Lewis Bjork

Long projects, like long journeys, inches up and down as though on a When the right brake locked up, the eventually come to an end. After nine trampoline. The wing boasts a generous Cosmic Fish departed the runway and hit years in the shop, countless rebuilds, carbon spar, so the movement does not a runway light. unspeakable money, and an entire the- threaten the wing structure. Prop clear- saurus of creative expletives, the Cos- ance is another story altogether. The rotary, by comparison, is shaped mic Fish completed a fateful journey The Cosmic Fish is a mostly stock more like a big can, with the crank cen- to the airport. Tooelle Valley Airport Q200 with a rotary engine. The engine tered in the middle. If I mounted the (KTVY) is located well away from presented the lion’s share of problems engine high enough to match the Rev- population centers and is surrounded during construction and is, by far, the master thrust line, I’d have difficulty see- by many square miles of flat, mostly most satisfying part of the project. From ing over the engine from the cockpit. If I unobstructed land. With the approval the very beginning, the engine seemed centered the engine on the firewall, only and blessing of the FAA, it promised to too large. Not that a Mazda rotary is a very short propeller could work, unless bear witness to the first flight attempt of particularly large itself—it isn’t. In fact, I wanted to redesign the entire canard this unusual airplane. I hoped the flight from a power-to-weight and size per- and landing gear arrangement. I found test would go smoothly, despite numer- spective, it’s positively miniscule. Trou- a compromise, of course. Mounting the ous setbacks and minor frustrations. ble was, this rotary barely fit in the space engine as high as I could, while redesign- Indeed, the plane had made the airport designed for a much smaller Revmaster ing the cowl and forward fuselage, pre- journey a few times already: once to test engine. Although offering much greater sented an acceptable solution that could the trailer itself, the next for taxi tests. power and theoretically better reliabil- swing a 62-inch propeller, but suggested The trailer worked pretty well. Taxi tests ity, the rotary was dimensionally larger only three-point landings to maintain revealed several problems. and significantly heavier from the get-go. adequate ground clearance. This seemed The Quickie Q200 is a beautiful When first mounting the engine to like less of a solution when the airplane design. I’ve always admired the sim- the firewall, I could see prop ground began to bounce on the taxiway. plicity of its landing gear. Downturned clearance becoming a problem. The After several bounces, much sweating wingtips house a small tire and brake Volkswagen-based engines are compact and puckering, it appeared the prop had assembly, presenting a wide, very stable and relatively flat. The distance from adequate ground clearance after all. The stance on the ramp. The wing itself is the crankshaft to the top of the engine steering, on the other hand, felt squishy. fairly springy—almost alarmingly so, is fairly small, similar to the geometry This was my own doing. The Q200 as it allows the fuselage to bounce six of most flat, boxer-style aircraft engines. rudder and ground steering control

48 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes circuit was not intended for dual con- around a bit more. Initial taxi went as At that point, I realized that prop trols. I wanted dual rudder pedals and expected. The soft feel had gone away, clearance had become a problem. The extended the torque tubes accordingly. and overall control pressures felt lighter. engine continued to idle, but suffered a They seemed stiff enough during con- The brakes showed improvement, but mild prop strike, breaking the outer few struction, but taxiing around the airport still seemed weak. I headed for the run- inches of each wooden propeller blade. revealed a sort of play, felt as softness in way to try a little more speed. Although not hurt, my heart broke. I steering response, when making a right Accelerating through 32 knots, I cut felt a heaviness that has weighed on me turn. I reasoned the torque tubes were the power and applied brakes. Direc- for quite a while since. The little air- too small in diameter, and thus allowed tional control to that point was light, plane that showed such potential now for some play, when faced with the load but positive. Slowing down, however, sat, fairly ruined, in the dust of a distant of an active tailwheel. I wondered if the made my hair stand up. TheFish began airport. It’s an image I won’t forget. tailwheel could be improved with bear- to fight, darting left and right with small Authorities came soon after. The local ings to lighten its resistance to control oscillations that kept me busy tapping police wanted a report. The airport rep- inputs. Higher-speed taxiing on the on the new pedals. I felt surprise that resentatives documented the damage. runway showed directional problems the difficulty increased after making the The FAA spoke with me on the phone. when decelerating, which I attributed modifications to the steering system. We conference-called the NTSB. Dur- to the soft steering. The plane was easy The oscillations increased in ampli- ing their questioning they asked, “Was enough to control when gaining speed, tude until I made a scary transition this a flight?” but very difficult when slowing down. from pilot to passenger as the plane “No.” Lastly, the brakes didn’t work very well. swung aggressively to the right, with “Was it intended to be a flight?” They could bring the plane to a stop, but me standing hard on the left rudder and “No, just a taxi test.” barely. A slow and gentle stop required pulling the brake lever to its limit. Skid “Then we’re done. Have a nice day.” maximum braking effort on the han- marks on the runway told the story. The That ended it. It was nice for the dle. So we packed the plane back on its right brake had locked up. With the authorities to walk away, but “a nice trailer and made a return journey to the wheel located at the wingtip, it easily day?” Nope. shop with a small list of details to fix: overpowered steering commands from The Fish could be repaired. I began • Bleed the brakes. the tailwheel and sent the plane off the to compile the damage and consider • Install new rudder pedals. runway and through a runway light. the cost. New prop, engine teardown • Add ball bearings to the tailwheel. Interestingly, the wide stance did not (again), wing inspection/repair, landing allow the plane to flip, but the locked gear, brakes, etc. More Tests wheel assumed the role of an anchor For sure, single-lever brakes, as sug- Weeks later, we headed back to TVY and caused the plane to slide sideways gested in the plans, were a bad idea. with renewed enthusiasm. The tailwheel until the wheel on the left wingtip Individually controlled brakes might moved freely. Rudder pedal torque gave way to the heavy side loading and have prevented the mishap, in hindsight. tubes were doubled in diameter, and the ripped free of the wing. The whole she- Looking forward, however, I lost sight of brakes were bled thoroughly. I planned bang came to rest, just off the runway, the journey’s end, and I felt weary. The on attempting a flight after taxiing in a big cloud of dust. engine sold very quickly to a gentleman in

Damage included a prop strike and the left wingtip and wheel were ripped from the wing.

Photos: Lewis Bjork KITPLANES October 2017 49 (Left) The Mazda Rotary engine isn’t particularly large, but it barely fit in the Cosmic Fish. (Right) The engine sold very quickly and was shipped to a builder in New Zealand.

New Zealand. Another builder claimed Cosmic Fish was my seventh homebuilt is a fire-breathing thrill ride in the air and the airframe and panel, and trailered it airplane, and I took full creative license. easily my favorite airplane to fly, but it’s to New Mexico. Both have plans to fly Unfortunately, some of that assumed not terribly practical. I have flown it on a their own, similar projects. risk did not pay off. few cross-country trips, all less than 300 From a practical perspective, the miles, and found it noisy, a little uncom- Why Do It? Experimental airplane has mixed results. fortable, hard to see out of, and a bit With a little cash in hand—far less than If you enjoy the creative process, like I expensive. My plane has no tiedown rings I’d spent on the project—I considered do, the project offers years of fun in the (to save weight), so must be hangared the costs and benefits of building a shop from the very beginning, but not a when visiting other airports. Although homebuilt airplane. This is a moment single bit of transportation value during a wonderful airplane for a local aerobatic of cold, clear reality. Experimental air- that time. Once completed, the practi- flight, it was never intended for efficient plane projects can fail, and often do, cal value depends on what you built. cross-country travel. The Lancair IV, by sometimes with very serious results. It Many homebuilts are terrific traveling contrast, carries twice as many people begs the question, “Why mess around machines—often with great efficiencies in pressurized comfort almost 130 mph with Experimental airplanes, at all?” over certified designs—but most others faster on less power. For me, it’s a fascination with possi- fit a recreational niche. My Pitts Model The Cosmic Fish showed theoretical bilities. When considering a Q200 proj- 12 is a good illustration. I loved build- promise in the cross-country department. ect, I went right past the idea of building ing it, spending seven years’ worth of It was designed for efficiency at a single the plane strictly to plans. Most builders creative energy in the shop. The benefits point on its operating envelope—cross- of the type, in fact, recommend several of building that airplane go way beyond country cruise. Had it flown, I expected important modifications to enhance the benefits of owning it. I acquired 200-mph cruise speeds, burning car gas its safety and utility. This suggests that several tools, a myriad of skills, and at little more than 6 gph—then trailering many homebuilt designs are far from confidence that enabled me to build my it home for zero fixed ownership costs. perfect—they often lack the benefit of own house, including everything in it, Quite an accomplishment in itself, but it intense testing and proving that cer- where I now live. Scrounging ability and was hampered by a tiny cockpit, very lim- tified airplanes endure. If the words penny-pinching skills developed with ited runway capability—and bad brakes. “some assembly required” were printed airplane projects translated into a house Don’t forget the brakes. in block letters under the “Experimen- that was paid for soon after we moved in. tal” placard, it could qualify as the My family has lived debt free ever since, Do Sweat the Details understatement of the century. partly due to the skills attained by build- Perhaps the most annoying aspect of any That said, Experimental airplanes are ing an airplane. Now I build everything, project, but particularly Experimental also malleable—the builder is free to and count time in the shop the way some airplanes, are the devilish little details. modify and customize at his or her own folks assess fishing—it doesn’t subtract The Fish ended in a dust cloud prob- risk. This is not possible with a certified from your life. ably due to a bubble in a brake line—a design, and one of the primary attrac- The completed Pitts 12 is a different bubble I tried hard to round up and flush tions of the do-it-yourself airplane. The animal when no longer a shop project. It from the system. Other airplanes might

50 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes What’s Next? I’m not content to sit still. Although somewhat shell shocked by the demise of the Fish, I returned to the shop to build a lightweight canoe—very nice to start and end a project in the same season. Now I’m in the middle of a hov- ercraft project, probably for the better part of a year. There is another airplane stirring in me though. After years of building someone else’s designs, I intend to cre- ate one of my own. I bought several textbooks, a computer program, and a delightful little book by Daniel P. Raymer—Simplified Aircraft Design After the demise of the Cosmic Fish, my next project was a lightweight canoe. for Homebuilders. I’m at the conceptual stage right now—my absolute favorite fall out of the sky due to a missing cot- airplanes. I suppose it’s why some of my part—no real details, just broad ideas ter pin or a poor-quality glue joint. I had ancestors traveled west to build a life in and general considerations, fleshing out the misfortune of a seat belt letting go the mountains. They wanted self-suffi- an airplane that will be mine from start while flying upside down at low altitude ciency. They carved a life out of the des- to finish. Not much to describe yet as in a Cri-Cri several years ago. I fell about ert, found a way to thrive, and enjoyed I’m still getting an education, but it will three inches until the secondary lap belt the thrill of it, I suppose. Anyway, they be powered by rotary engines (got that caught me—a detail I installed only a did it themselves. This is the essence of education, already) and will be called few days before. It was still far enough an airplane project. The risks are real, but The Cosmic Ray. to pop the canopy open and send my the benefits are deep and long lasting. I’ll keep you posted. J heart to my throat. We’re on our own out there. Like a rock climber on the face of a cliff, our well-being is quite up to us alone and directly affected by our atten- tion to the smallest details. Print and Digital There is an implied responsibility here that feels deeply satisfying. I am responsible for me. I cannot sue some- body if the plane slides off the runway. I cannot blame anything but whatever the hell it was that caused the problem— ultimately my own inattention. This personal stance is why I enjoy building Lewis Bjork Bjork Lewis Lewis Bjork has constructed many airplanes, authored a few books and numerous articles. He enjoyed flying for SkyWest Airlines the last twenty years, and is married to Linda, a very patient wife. They are the parents of Either Format – Great Savings! five children. Subscribe Now at www.kitplanes.com/subscribe

KITPLANES October 2017 51 Build Your Own Leak-Down Tester

Converting a Harbor Freight compression tester for aircraft engine use. By Vince Homer I bought a Harbor Freight compres- sion tester, only to find out that it wasn’t designed to do the type of test required for aircraft engines. When I purchased it a few months ago, the U.S. General Cylinder Leakage Tester (Item #94190) was on sale for $21.95. However, that unit is no longer shown on the Harbor Freight website (www.harborfreight.com) and appears to have been replaced by the Pittsburgh Cylinder Leak-Down Tester (Item #62595). Except for a black-and- yellow sticker on the gauge base and a black carrying case instead of red, the Drill out the .080-inch orifice in the gauge Tap the #36 hole using a 6-32 tap. base using a #36 bit. two units appear to be identical. Not on sale, the current price is $39.95. When I tried to use the tester right out of the box, it didn’t work in the

Make a new orifice from a 6-32 socket-head The gauge base after drilling and tapping. Grind the cap screw to the correct diameter cap screw. for clearance.

52 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Drill a .040-inch hole in the cap screw. The cap screw after cutting and drilling.

New .040-inch orifice ready for insertion. Orifice screw with Teflon tape.

usual 80/xx mode required for aircraft careful, it can be done by hand with the engines. I disassembled the unit and screw held in a vise. The entrance and found that it had a .080-inch orifice exit of the .040-inch hole were tapered in it instead of the .040-inch orifice with a larger drill bit that was ground to specified for aircraft engines with a a 60-degree point angle. bore of less than 5.00 inches or a .060- The cap screw head was too large to inch orifice for engines with bores of fit into the orifice block, so the diameter over 5.00 inches. The photos show a was ground to fit. I did this on my 1-inch .040-inch orifice because I am flying belt sander, or if you have access to a behind a Jabiru with a bore of less than lathe, it can be turned to size. 5.00 inches. Thread sealer was applied to the cap The .080 orifice in the gauge base was screw threads and the screw was inserted drilled out with a #36 drill bit, then into the gauge base. Be careful to not get tapped with a 6-32 tap. Next, a 6-32 any thread paste or tape in the orifice. socket head cap screw was cut off so that The leak-down gauge supplied by the distance from the bottom of the Harbor Freight must be replaced with a socket in the head to the end of the screw 0–100 psi range gauge. As shown in the was .250 inches. photo, the supplied gauge has been moved A .040-inch hole was drilled length- to the cylinder-pressure side of the orifice. wise through the screw. This is done To make the tester easier to use, I added most easily in a lathe, but if you’re a shutoff valve on the air supply.J

Insert the new .040-inch orifice into the gauge base.

Photos: Vince Homer KITPLANES October 2017 53 PLANE and SIMPLE Removing Blind Rivets By Jon Croke

A drill is used to remove just the head of the rivet, using a circular motion to help pry the head off.

Blind rivets, pulled rivets, POP riv- rivet’s head. While the dimple in the The solution is to simply remove or ets—all are names for the same perma- head guides the drill bit perfectly down displace the stem prior to drilling. Two nent fastener used in many homebuilt the center, problems often occur when options are available: a pin punch or a and kit aircraft projects. “POP” is a the tip of the drill meets with the rivet spring-loaded automatic punch. Find- brand name, “blind” refers to the fact “stem” hiding just below the top of the ing a punch that fits inside the rivet that you do not need access to the back- head. This stem was used by the rivet head dimple is the key. Depending on side for installation (as a solid rivet gun when setting the rivet, and it breaks the rivet sizes you are working with, it is requires), and “pulled” refers to the off just below the head during installa- important to find one or more punches process used by a tool to set the rivet in tion. While designs of rivets vary, many that can reach into the dimple and con- place. This type of rivet is fast and easy rivets need this stem fragment to remain tact the top of the stem. to install, and comes in a variety of sizes in the rivet to add extra strength. When Using some good judgment with a and material composition (aluminum drilling to remove, the tip of the drill manual pin punch, the right amount of and various steel materials). contacts the top of the stem. What hap- tapping with a hammer (don’t damage Although these rivets are permanent, pens invariably is that the drill is pushed your airplane!) will move the stem down. it is very common to need to remove off center and the hole becomes dis- The stem does not have to be completely them due to mistakes while build- torted. This all happens in a split second removed—just enough to give the drill ing or for required repairs. Removing and is then too late to remedy. bit a little more room. these permanent fasteners is easy—but extreme care must be exercised if you do not want to damage the hole during the removal process. A not-so-obvious obstacle will challenge your ability to keep the original rivet hole from becom- ing enlarged while drilling the rivet out. At all costs we want to keep that rivet hole unchanged so that it can be used again with a new rivet and maintain maximum strength. To remove a blind rivet, a drill bit (the same size as the original hole or a little smaller) is used to remove the A spring-loaded punch is used to displace the hiding stem so that the drill bit stays centered.

54 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes PLANE and SIMPLE

A spring-loaded punch and a manual pin punch surround a The punch is used once again to push the rivet fragment from blind rivet. the hole. My favorite stem remover is the motion by pinning them down until the used to pull the remaining rivet frag- spring-loaded punch (from Amazon or head is removed. ment from the hole. Harbor Freight). No tapping is needed; Next, using the spring-loaded punch Using this process and always making you simply press until the internal again (or manual punch), the rest of the sure the stem does not disrupt your drill- spring unloads its stored energy and rivet body can usually be easily pushed ing precision, blind rivets can be removed creates a mild impact at its point. This out. If you have access to the other side very quickly and easily, leaving the origi- can be repeated rapidly several times of the rivet, side-cutter pliers can be nal hole practically untouched for reuse. J in a row if needed. We just need the stem to move a little bit! The problem with this spring punch is that the tip is too large for the popular ⅛-inch rivets found in many kits. A one-time effort of grinding the tip a little thinner on the bench grinder is all that is needed. It can also then be used for larger rivet sizes. Works like a charm! With the stem out of the way, the rivet head can be quickly drilled off using the dimple in the head as a guide. I like to use a slight circular motion with the drill to help pry and break the head off while drilling. Do not drill the rest of the rivet out! Sometimes stainless steel rivets can start to spin while drilling. If this occurs you need to prevent this Jon CRJon As the founder of Homebuilt HELP.com, Jon Croke has produced instructional videos for Experimental aircraft builders for over 10 years. He has built (and helped others build) over a dozen kit aircraft of all makes and O models. Jon is a private

KE pilot and currently owns and flies a Zenith Cruzer.

Photos: Jon Croke KITPLANES October 2017 55 CHECKPOINTS Phase I maintenance. Last month I ended the column with of the maintenance being done by the his/her aircraft enough to recognize a a foray into the challenges faced by local A&P. They rarely ever look past the change that may require attention. first-time builders/owners who are oil filler dipstick or dare take the wheel- I tell everyone that you should not now first-time mechanics. This month pants off to look at tires and brakes dur- trust the airplane until you have at least I am going to start a series on some of ing the course of the year. By the way, I 100 hours on it. After that, you can cer- the things to which new mechanics or am not being judgmental here. For most tainly begin to have some confidence in new owners of Amateur-Built aircraft of the certified fleet it’s an OK practice. the airplane. That same adage applies should pay attention. The aircraft have been flying a long to new Amateur-Built aircraft during As with being a pilot, attitude has a time, with the majority of them having the first 100 hours of operation, and for lot to do with being a good mechanic been built the exact same way (unless new owners of Amateur-Built aircraft, or owner. I have found that there are modified with STCs), the wear items no matter how many hours are on the separate factors that come into play are known, and (except in the case of airframe/engine. Why so on one that here between the first-time builder and rentals) the owner usually understands has been flying, you ask? Well, after the first-time owner. For the first-time builder, it’s usually been a long ardu- ous journey to get to the flying stage. Even for those who have lots of family support, the building of an airplane is work. It requires good project man- agement skills along the way, and lots of decisions that require large sums of money, especially when it comes to engines and avionics. It can be very stressful at times, but it can be one of the most rewarding things you will ever experience, especially when your air- plane takes to the air for the first time. Then the flying begins, and you realize that 40 flight hours can be a long time calendar-wise, given weather delays, time to and from the airport, and any potential new-airplane problems. Then friends and family start asking when they can get a ride. No pressure here. So you can see that the stage is already being set for maintenance to take a During the first few hours of flying, the alternator belt should again be checked for proper back seat. tension. You’ve probably heard a loose alternator belt squeal in a car, but it’s hard to hear First-time owners of Amateur-Built air- in an airplane. Sometimes a loose belt will be reflected by voltage fluctuations. Usually craft are used to the majority, if not all, after one adjustment, a properly sized belt will be fine for a long time.

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 39 years, he has built 10 award-winning aircraft and has logged over 8000 hours in 70 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.

56 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Here’s a common problem with the tightly cowled engines on Amateur-Built aircraft: The alternator pulley clearance looks fine on the ground, but when subjected to flight loads it can rub the cowling. The engine sagging from the rubber mounts can cause the same problem. Be sure to check it often during the first 100 hours or be prepared for some repair work. inspecting an RV-7 that had been flying completely rub a hole in the cowling. check for cotter keys and safety wire in for over seven years and still had five You may have thought you had enough the proper locations. At our local airpark loose jam nuts throughout the control clearance with it on the ground, but we had one RV crash on takeoff with two system that had never been tightened flight and torque loads do cause a lot aboard due to complete loss of power. and subsequently missed on all of the more movement of the engine then you The culprit? A missing cotter key on the condition inspections and preflights might realize. carburetor throttle bolt! by the owner/builder, you realize how By the way, the engine compartment As for new owners, it’s probably not easy it is for someone to constantly look is one area you will be glad that you necessary to take the cowling off after at something that is wrong and com- used Torque Seal or some other marking the flight home. However, I do recom- pletely miss it. It’s not malicious—it’s medium on all of the nuts and fittings, mend an oil change within 10 hours so human. That’s one of the reasons why I as it will only take a quick visual check to you can at least see the engine compart- don’t mind anyone looking over my air- verify nothing has moved. If you didn’t, ment and gain a little understanding of planes anytime the cowling is off. I’d like you really need to check the tightness the aircraft’s powerplant if so inclined. to think I’m human, too. of all of the fittings and nuts, and even Not everyone is, and quite a few new Let’s also not forget that even in the certified aircraft world, with a fleet that has accumulated millions of hours, we still see airworthiness directives (ADs).

Is it Leaking, Rubbing, or Loose? Now that I have set the stage on why maintenance needs to take a front seat after first flights or new sales, let me share with you some best practices that should help lower the risk. I’ve always made it a practice to completely remove the cowling after the first flight to make sure everything is tight and there are no leaks. Certainly you had no leaks on the initial ground runs, but temps and pressures are much higher on the initial flight, and for a longer length of time. It is also a good time to check and see if any parts of the engine are rubbing against the cowling, such as exhaust All too often the top cowling is removed and set aside without taking the time to inspect stacks, alternator pulleys, or airboxes. it for chafing. If left unchecked, the baffling can quickly put a hole in the cowling, ruining a It’s best to catch these now, before they nice paint job. A cowling touching the engine will also be felt as vibrations in the airframe.

Photos: Vic Syracuse KITPLANES October 2017 57 owners tend to treat an Experimental as they treated their certified aircraft— turning all maintenance over to an A&P. I think this is OK as long as you have someone perform the maintenance that is intimately familiar with the particular type of homebuilt. Past the first flight, I think it is a good idea to take the cowling off again and change the engine oil and filter. Most engine manufacturers recommend changing the oil at 10 hours and check- ing the filter for any signs of metal. It is also a good time to thoroughly go over the engine compartment. Sometimes a minor oil leak can become a major problem by this time, or at least have the potential to become a major problem if not corrected. I hear many times about the engine instruments going crazy when the radio is keyed. I once had a minor oil leak on my new Here is one culprit: a poorly crimped coax cable. There should be none of the braid showing, as it allows for spurious radiation. engine in the RV-7. It was just enough to throw light specks on the windshield It required removing the front baffling that during the engine manufacturing and leave a tiny film on the front of the so I could take a closer look at the front process this plug is removed to mea- engine. Initially I thought it could have seal. The front seal looked fine, but right sure the oil-pressure drop across the been the prop or the front seal. I kept above it, on the front of the engine, was crankshaft. It had never been tightened wiping it down but couldn’t locate the a 1/8-inch plug that had a telltale streak properly when it was reinstalled. It was problem. Finally, at the 10-hour mark, of oil emanating from it, and it turned pretty close to completely falling out, I got serious about finding the source. with just finger pressure. I found out which would have been a pretty serious problem if it had occurred during flight. Crisis averted! After the 10-hour inspection, there shouldn’t be much to do until the next oil change, which I usually do 25 hours later. Why? Well, it gives me a chance to thoroughly go over the airplane again and get the oil changed with only five hours until Phase I completion. That way, the aircraft and I are ready for trips with passengers after the Phase I signoff. Any needed maintenance or corrections performed at the 35-hour mark have had five hours to insure they are rectified. Notice I said go over the whole air- plane? Yes, I pretty much open up the panels and perform a condition inspec- tion toward the end of Phase I. Remem- ber the RV-7 I mentioned earlier? It had a loose jam nut on the main pushrod On non-metal aircraft it is really important to have a properly sized ground cable from to the elevator. I could completely turn the engine to the electrical bus, along with a good solid crimp on the connector. Things the pushrod in my hand! Whether it might work well on the ground, but in flight with all of the electrical equipment working, came loose or was never tightened along with high-demand items such as gear retraction systems and air conditioners, a poor ground will start to burn and corrode, making things worse over time. A quick we will never know. I do know that I in-flight check is to turn your alternator off and see if the oil temp changes radically. If it haven’t seen one come loose that had does, start checking the engine ground. been properly tightened. I also know I

58 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes haven’t seen everything yet. So I check just in case. Fuel Dipstick Phase II After Phase I is completed, the real fun begins and the reason we spent SHOP and Holder so much time building the airplane in TIPS By Noel Fallwell the first place—the ability to go places and enjoy the freedom of owning your own airplane. No more need to watch the Hobbs meter or press your luck to The first photo shows the fuel dipstick I made in its holder, and below that is the get back on time for the next sched- fuel sample tester for my Van’s Aircraft RV-6A. The dipstick is a wooden dowel rod uled renter. However, the reliability of 15 inches long x 7/16 inch in diameter. It fits into a pair of modified AA plastic battery the new toy now rests squarely on your holders that I purchased from Radio Shack. shoulders, and there is no worse feeling than coming out to the airplane for the return trip from vacation or a fly-in only to find a dead battery, leaking brake, or fouled plug during the runup. It can really put a damper on things! Especially if you happen to be a part of a group trip on a long fly-out and yours is the only airplane that won’t start. That’s where preventative maintenance can play a big role in assuring aircraft reliability. And the first year of ownership is a good The second photo shows how time to put some best practices in place. one end of the battery holder is For the recommendations I am pass- cut away, leaving the spring. The ing along here, I am assuming one other end of the dipstick is held in flies approximately 100 hours per year. place by removing the spring from That’s usually done quite easily with a another battery holder. kit that was properly assembled with The mounting points for the the recommended engine. I don’t fault modified battery holders allow the alternative engine guys, but the the dipstick to be positioned majority of the ones I have been around inside the holders, and the spring seem to spend more time tinkering provides enough pressure to keep the dipstick held securely. along with more unplanned downtime Once the dipstick was calibrated for the fuel levels in the tank, I notched during the first few years as opposed to a groove around the circumference of the dowel for each quantity I wanted, flying. Some of them knowingly went then used a black Sharpie marker to highlight the groove. I applied a label and that direction and don’t mind the tin- painted the entire dipstick with West Systems epoxy to provide protection so kering. They had different objectives in the stick would not absorb any fuel. For my plane, the markings are 4, 6, 10, mind. But I sympathize for those who 14, and 18 gallons. The 4-gallon mark shows when fuel just becomes visible in were lead to believe the alternative the bottom of the tank. The uppermost mark, labeled “Top of Tank,” is visible engine was the Holy Grail. I have seen above the top of the wing when the dipstick is held straight up when dipping lots of time and money lost, with an the fuel level. eventual refitting of a conventional air- The length for the dipstick was chosen to be just long enough so that if I were craft engine as the answer. to somehow drop the stick into the fuel tank, it could not be completely lost inside Next time I will start with some ideas the tank. A part of the stick would always be sticking out above the tank filler open- on first-year preventative maintenance ing. This length also was the maximum size that would span the area across my that will both help you better under- seat back without interfering with the seat back tilt-forward feature. stand your particular aircraft as well as The fuel sample tester and holder were purchased off the shelf. The short3 /8- ensure you have a reliable one. In the inch stubby wrench is the tool I use to open the fuel cap cam tabs when checking meantime, have fun, especially for those fuel levels. It is placed around the Phillips screw point of the fuel sample tester. So it of you either in Phase I or just completing won’t flop around, I installed a short length of plastic tubing over the Phillips shaft it. What an accomplishment! J to provide friction to the box (closed) end of the wrench. J

KITPLANES October 2017 59 Home Shop Machinist Spin class. Spinning is a low-tech method of forming axially symmetrical shapes from sheet metal. It’s popular because there’s minimal set-up: with a wood lathe, some basic tools, and practice, you can make your own spin-formed parts that look like, and are as good as, factory-made. I had never done any spinning, so I watched a good hour or so of videos on YouTube to get a sense of the tools and techniques involved before my first attempt. It took a couple of tries before initial success, and I revisited the videos frequently in order to solve issues with centering, trimming, and getting wavy Spun aluminum bowls with rolled edges. edges (caused from uneven stretching of the sheet around the perimeter). I was was too big, but salvageable for my Jabiru fiberglass (impossible to attain a consis- encouraged with good results on only if I could trim it from 11 inches diameter to tent thickness). Spinning seemed like the my third try, and subsequently, my suc- 9½ inches, and buy, or make, a new back- perfect option because that appears to be cess rate has been about 75%. plate. With no apparent source of buying how many factory backplates are formed. The goal of this spinning endeavor was a suitable backplate, I contemplated a Any malleable material, in sheet form, to make a custom backplate for a second- variety of options, from machining one can be used for spinning. I tested a sam- hand prop spinner I acquired. The spinner from billet (too heavy) to laying up one in pling of O-temper aluminum sheet avail- able from Aircraft Spruce: 2024 (0.040-inch thick), 3003 (0.050-inch thick) and 6061 (0.040-, 0.063-, and 0.080-inch thick). They all seemed to work about the same, the only difference being thicker material requires more leverage. The lathe used was my 2-hp Jet 1640 wood lathe, but almost any type of lathe will work, pro- vided you can mount a tool rest with a fulcrum. The tool rest fulcrum is a basic necessity for spinning. It provides the leverage to control the tools (a burnish- The basic spinning setup consists of the With a liberal coating of paste wax for lubri- ing bar or roller) that push the workpiece mandrel, the round blank of aluminum cation and a suitable burnishing tool (in this over the form. My tool rest was shop- sheet, a rotating tail center, and a tool rest. case a simple wood stick about 12 inches This setup is for making a shallow dish, long), the 0.040-inch-thick aluminum disk is made from a tool post welded to a short which is a good project for spin practice. stretched over the mandrel. length of steel bar, which I drilled with a

Bob Hadley is the R&D manager for a California-based consumer products company. He holds a Sport Pilot certificate and a Light-Sport Repairman certificate with inspection authorization Bob Hadley for his Jabiru J250-SP.

60 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes row of four ¼-inch holes to allow some adjustability (see photos on page 60). All spinning projects start with mak- ing a mandrel in the desired shape and diameter of the final part, minus the thickness of the sheet if it’s critical for mating with another part. One-off man- drels are usually made of wood because it’s easy to shape and low cost. Any hard- wood of reasonable density will work. Softwoods should be avoided because they dent too easily. Mandrels should be turned with the wood grain running end to end, or what turners call end-grain ori- The four-inch mandrel for these 3-inch firewall shields was made from sycamore. Note the entation. End-grain turnings are more center hole in the form for locating the stock. The parts are 0.040-inch 6061-O aluminum. stable than side-grain turnings. Depend- After trimming, they were polished to a mirror finish on the lathe. ing on the species, wood expands and contracts with changes in moisture 10 to 20 times more across the grain than lon- gitudinally with the grain. This makes a side-grain mandrel unsuitable for most spinning projects. Sanding, changes in humidity, or internal stress in the wood can noticeably warp a side-grain form, whereas the same factors barely affect an end-grain form. In a pinch, side-grain mandrels are fine for small-diameter (Left) Using a spindle gouge to shape the glue block into a mandrel. Wood turning skills objects with relatively shallow dish. The are a big plus for spinning projects. (Right) A short length of wood imparts the clamping 3-inch diameter firewall shields (shown pressure from the tailstock. A cup adapter on the rotating center provides the interface. in the top photo) are a good example. But for anything with a deep dish or large diameter, the mandrel needs to be as stable as possible. Gluing several blocks together is a good option for making larger, and even more stable, end-grain forms. I glued up several pieces of scrap to create the nine-inch diameter man- drel for the backplate project. Once the mandrel is turned, it should be sanded smooth with 180-grit or (Left) Sanding to eliminate any tool marks. Any rough edge or unwanted bumps in the higher, or at least until there are no vis- mandrel will be picked up by the workpiece. Note the 15-degree taper and smooth ible ridges or tool marks. After sanding, I radius between the face-to-flange transition. (Right) Applying HUT Crystal Coat to seal the mandrel. applied a coat of HUT Crystal Coat, a fast- drying shellac-based finish, to seal the wood. A finish helps keep fingerprints and other grime from contaminating the wood, but it’s not absolutely necessary. Spinning requires firmly clamping the workpiece between centers (the man- drel and the tailstock). Most projects will require some sort of custom pressure plate in between the workpiece and rotating center. What this is depends on (Left) Using a 3/8-inch spot drill to locate the center for aligning and indexing the blank. what you’re spinning. For the firewall (Right) After trimming the sheet to size on the table saw and making a center hole, the shields, which have a pre-drilled center rough blank is marked for final trimming.

Photos: Bob Hadley KITPLANES October 2017 61 hole, I used a length of wood with a pro- truding dowel and a cup center. For the bowls, I used the cup center directly on the workpiece. For the backplate, I used a ¾-inch plywood disk. Having a center hole to locate and index the workpiece to the mandrel prevents the workpiece from sliding off center, and allows you to relax a bit in the tailstock pressure. For parts with- out a center hole, you have to really crank (Left) Trimming the blank with a carbide-tipped Easy Rougher woodworking tool. For the tailstock to make sure it won’t slip. wood, this tool is designed to be held flat, but to trim aluminum it must be tilted, as shown, to present a positive rake angle. The lathe is set to 500 rpm for trimming this Finally, you need some basic tools to 11-inch diameter disk. (Right) With the lathe set to 200 rpm, a light touch with a file push, squeeze, and stretch the workpiece deburrs the sharp edges. Note the plywood pressure plate. over the mandrel. These can be as simple as a stick or metal bar with a rounded and polished end. Roller tools are often used for spinning, especially for forming beads. It’s worth noting that I had just as much luck beading edges with direct pressure from a blunt stick on the 0.040 material as I did with a concave roller tool. Except for my trimming tool, which is a carbide-tipped woodturning tool, all my spinning tools were homemade. (Left) Applying a liberal coat of paste wax is a critical step to prevent the burnishing tool The rest of the backplate project is from galling the work. Reapply frequently! (Right) Using the full leverage of the 30-inch best explained by the photos. To see burnishing tool to force the aluminum over the mandrel. The trick is to sweep across the entire face of the unsupported disk in order to even out the stretching. If you concentrate how I made a firewall shield, visit www. too much on the inside, without stretching the outside edges, the outside edge will curl kitplanes.com/spinning. J back toward the tool or could become wavy. When that happens, start over!

(Left) The flange is almost fully developed. A few passes with the burnishing tool make sure the part conforms snuggly to the mandrel. Unlike most forms of bending, there’s no apparent springback on spun parts. (Center) Trimming the excess using the Easy Rougher. (Right) The process of spinning 0.080 material on this form resulted in 0.050 thickness on the flange.

The factory backplate (left) shown with the home-shop replacement. Final mounting holes and modifications to the prop spinner TBD.

62 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes

Ed Lee’s Sonex I completed Sonex #1212 and made the first flight August 28, 2016. It now has 112 hours on it with its Corvair 3100cc engine, and it is run- ning perfectly. Thanks to William Wynne and Bill Clapp for their wis- dom on Corvair aircraft engine conversions. The plane is licensed at 1320 pounds and was fully test flown at that weight. It has 11 gallons of auxiliary fuel in the wings and flies at 145 mph on less than 6 gallons per hour at 6500 feet at gross weight. It’s the most fun I have ever had in over 4000 hours of flying. Lancaster, South Carolina [email protected]

David Otero’s RV-7 My RV-7 project started on January 5th, 2014 with the empennage kit. From the moment I opened the first crate, I knew this would be a plane that I would complete and fly. One week shy of two years later, it was time for the first flight. On Wednesday, December 30, 2015, Segundo Viento (Spanish for Second Wind) took off from Albuquerque’s Double Eagle II’s (KAEG) Runway 17. The plan I had coordinated with the tower was to orbit the airport above pattern altitude (6800 feet) at 8500 feet. At that altitude I contacted ABQ Approach; they gave me a squawk code and cautioned me to keep below 8500 feet. This happened just as I saw my altimeter blasting right through 8500 feet. The flight lasted about 25 minutes, but the RV grin lasted a couple of days. After eight months of flying, I decided to wrap my plane in vinyl rather than paint. I’m very happy with the results at one-tenth the cost. Primary thanks go to my wonderful and patient wife Margie. She helped me pick which model of RV to build, picked the interi- or colors and registration number, and even did a bit of drilling, Clecoing, and riveting, too. I’d also like to thank Rich Tichy and the other members of Illinois EAA Chapter 461, and the Albuquerque RV group. I was very fortunate to have your help. Albuquerque, New Mexico [email protected]

Bryan Cobb’s Mini-500 Bravo Plus It took me three years to assemble this helicopter while working a full- time job. It is equipped with all factory updates and the PEP tuned exhaust (78 hp). The Mini-500 started life as a new-in-the-crate kit, purchased on eBay in February 2013. Another old barn-find Mini- 500 was also purchased on eBay from which to cannibalize all of the mast support and other items. A second-hand Rotax 582 blue head was purchased off of a flying airplane (Rans S-14). I have been a Mini-500 enthusiast since the early 90s and flew one for 100 hours in the late 90s. Changes made during this build include four matched feathering bearings in each blade grip (cones), a two-piece tailrotor driveshaft with two Morflex elastomeric couplings, a Weldon main gearbox oil pump with large oil cooler, an Arrow brand ring and pin- ion in the main gearbox, and tapered roller bearings on the pinion (indirect mounting method) to carry thrust load. It also has an aluminum engine coolant radiator, a graphite impregnated Garolite slider for T/R pitch control, aerospace-grade Aurora SS teter bearings, and a centrifugal clutch balanced to 12,000 rpm. The airworthiness certificate was received on May 11, 2016. The helicopter weighs 524 pounds and has a maximum takeoff weight of 840 pounds. It holds 14.5 gallons of non-ethanol 90-octane fuel and burns about 6 gallons per hour with the current jets (158 main, 2.78 needle). Cartersville, Georgia [email protected]

64 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes Dan Palmer’s Wittman Buttercup This is my Steve Wittman-designed Buttercup, built and flown at Mori- arty, New Mexico. Earl Luce plans were used for the airframe. It is pow- ered by a Corvair 2700 engine with William Wynne components, Dan Weseman 5th bearing, and a Warp Drive prop. I used Stewart Systems, fabric through top coat. Moriarty, New Mexico [email protected]

Scott Alperin’s Sportsman I completed construction of my Glasair Sportsman on November 1, 2016 in the Two Weeks to Taxi program at Glasair Aviation and received the airworthiness certificate the next day. The plane remained at Glasair and had the required 40 hours of test flying completed and was then sent to the paint shop. The finishing touches and final preparation were done by the Glasair technicians, and the plane was once again test flown to be sure it was ready for me to take delivery. My good friend Robert Metelko and I departed Arlington, Wash- ington, on a late Friday afternoon en route to Cleveland, Ohio. We made stops in Missoula, Montana; Billings, Montana; and Fort Dodge, Iowa. Performance was excellent and all of the systems operated as expected during the 1900 n.m. journey. We flew as high as 14,000 feet to remain free of icing, and once we reached the flatlands stayed at about 5000 feet. I recently placed the plane on Clamar amphibious floats to complete the project. Cleveland, Ohio [email protected]

John R. Murphy’s SubSonex My JSX-2 SubSonex was completed in November 2015 after 22 months of building, and it is the third customer-built SubSonex to fly. Many thanks to the Sonex crew: John, Mark, Kerry, Jason, Levi, and Jake for all the support. I am sure Jeremy Monnett also would have been very proud to see this kit completed and flown. I couldn’t decide on the paint scheme, so putting a different scheme on each side seemed to be a good solution. A BRS emergency parachute is installed, along with an MGL Avionics 8.5-inch EFIS Explorer, V-6 com radio and Sandia STX-165c transponder. A belly-mounted video camera allows me to watch the landing gear go up and down. My flight training was accomplished at Desert Aerospace by Bob Carlton, Billy Hill, and designated pilot examiner Bob O’Haver. Special thanks to Tom Ward and many other homebuilders at Spirit of St. Louis Airport for their help. Chesterfield, Missouri [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-inch print size at 300 dpi). Other builders may want to contact you by email, but let us know if you prefer not to have your email address published. Email text and photos to [email protected] with a subject line of “Completions.” Additional information can be found at www.kitplanes.com/completions.

KITPLANES October 2017 65 Phase I testing not completed, understanding operating limitations, non-TSO’d position lights. By Mel Asberry Question: I’m considering buying find any evidence that Phase I test- This may require an amended air- a homebuilt aircraft from the estate ing has been completed. If I decide worthiness certificate to move the of a pilot who has passed away. to buy this aircraft, what should I do flight test area. According to the Hobbs meter and about this? Remember, Phase I testing is all tachometer, the aircraft has flown Answer: Unless you can get written about testing the parameters of the air- several hundred hours. I looked confirmation that Phase I testing has craft, not a specific number of hours. the airplane over carefully, and it been completed, someone will have Without that sign-off, all flights out- appears to be in good condition, but to perform Phase I testing in accor- side of the test area and/or with a pas- in reviewing the paperwork, I can’t dance with the operating limitations. senger have been made illegally.

Classic Mel Timeless Advice From the Kitplanes® Archives Question: I read your September 2013 column with The basic operating limitations are spelled out for us in the question about TSO’d position lights on E/A-B FAA Order 8130.6. While we cannot remove any require- aircraft. You mention “our operating limitations.” ments, we may add anything we deem necessary for safety. What is the definition of operating limitations? Is For example, we can add hours to Phase I testing, we can this something that is specified in the paperwork for issue only Phase I and require another inspection before our aircraft? Who writes the operating limitations? Phase II, etc. The issue of a TSO requirement for position lights Since 91.205, the FAR that lists requirements for air- for night operation of an E/A-B aircraft caught me craft, only applies to “standard” certificated aircraft, our by surprise. I would have thought that it was OK operating limitations include a paragraph that makes to use non-TSO’d lights. What concerns me is that 91.205 apply to our aircraft during night and/or instru- I didn’t catch this. How does a builder catch these ment flight rules. Section 91.205 does not differentiate types of things? between certified and Experimental aircraft. Therefore, to Answer: The operating limitations are issued by the meet 91.205, the lighting system must meet the same stan- inspector in conjunction with the airworthiness certifi- dards that they would on a certified aircraft. J cate. They are as important as the airworthiness certificate because the airworthiness certificate is not valid unless it Please send your questions for DAR Asberry to editorial@ is accompanied by the operating limitations. kitplanes.com with “Ask the DAR” in the subject line.

66 KITPLANES October 2017 Photo: Mel Asberry BACK ISSUES List of Advertisers O NEW eBOOK O Please tell them you saw their ad in KITPLANES® Magazine. eBook download is exactly the KITPLANES® interactive makes it quick and easy for you to receive instant same magazine as on the newsstand. information about products or services directly from our advertisers’ websites. The difference is: ➥ Go to: www.kitplanes.com/links for a virtual shopping tour via links to their websites. you get it now! ➥ Call the phone numbers listed below and be sure to tell them you saw their ad & in KITPLANES® Magazine. no shipping costs for e-books! Advertiser page # telephone Advertiser page # telephone Aircraft Spruce & Specialty CV4 877-4SPRUCE Better Half VW 68 281-383-0113 (a big savings for our international customers) Avemco Insurance Company 33 888-241-7890 Crow Enterprises 70 714-879-5970 eBooks download as a single, full size, full color .pdf document which you can view Better Aircraft Fabric 31 907-229-6792 Falconar Avia Inc 68 780-465-2024 on your desktop, laptop or tablet computer. California Power Systems 39 800-AIRWOLF Flight Data Systems 70 831-325-3131

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KITPLANES October 2017 71 Gyroplanes, part 5. For the past few months, we have If the thrust line acts through the CG, like amphibians with pylon-mounted been exploring the flying qualities of changing power settings will produce engines, also suffer from this effect. gyroplanes. This month we will conclude little or no change in pitching moment. our gyro series with a look at a subject Figure 1 shows the effect of moving Stability Effects that has risen to prominence in the world the thrust line either above or below The trim effect of an offset thrust line is of gyro design: thrust line. the CG. As we can see, if the thrust line is similar for airplanes and gyros. What is As with all of our previous discussions high, adding power causes a nose-down different about thrust line position on of gyros, a caution is needed here. Rotor- moment, and reducing power causes a gyroplanes is that the vertical position of craft stability and control theory is very pitch up. If the thrust line acts below the the thrust line affects the pitch stability complex and much of it is far beyond CG, the opposite is true. of the machine. the scope of what we can cover in these Neither of these characteristics is A gyroplane depends on inclining the pages. The analyses that follow are highly desirable because the pilot will have to rotor and aiming the rotor thrust vector simplified and intended to give a subjec- compensate for the thrust-induced trim (RTV) to trim in pitch. If the gyro has no tail tive understanding of some important change with the stick. This increases the to add stability and a constant trimming effects. They are by no means complete workload for a simple power change to moment increment, it is entirely depen- or comprehensive. climb or descend. dent on the rotor thrust orientation to trim. This is not unique to gyroplanes. Air- As we saw a few months ago, a tailless Thrust Line planes with highly offset thrust lines, gyro with the thrust line through the CG The traditional Bensen Gyro-Copter con- figuration has a thrust line that passes significantly above the center of grav- ity of the machine. In more recent years many gyro designers have reconfigured their designs to bring the thrust line down so it acts through the CG, or in some cases slightly below it. Much of this effort was in response to a published research paper that called out thrust line position as the major deter- minant of gyroplane pitch stability. This led to a frequently-asserted claim that all that was necessary for adequate pitch stability on a gyro was a low thrust line. While thrust line has a significant effect on gyroplane stability, the situation is not that simple as we will see.

Throttle Effects Figure 1: The effect of moving the thrust line either above or below the CG. If the thrust The first factor to consider is the effect of line is high, adding power causes a nose-down moment, and reducing power causes a throttle variations on pitching moment. pitch up. If the thrust line acts below the CG the opposite is true.

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

72 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes trims with the rotor thrust vector aimed through the CG. Since the RTV rotates in pitch with the rotor plane of rotation, this means that the gyro will be neutrally stable in pitch. If the propeller thrust line is moved off of the CG, the inclination of the rotor thrust to trim must also change. The effect of this is shown in Figure 2. The three lines on the figure show the change in pitching moment with angle of attack for three cases: high thrust line, thrust through the CG, and thrust below the CG. In all three cases, the rotor tilt angle has been set to trim the machine at 4 degrees angle of attack (AoA). As expected, the green line, which is for the thrust line through the CG, shows zero change of pitching moment with angle of attack, indicating neutral stability. The blue line represents what happens Figure 2: If the propeller thrust line is moved off of the CG, the inclination of the rotor when the thrust line is above the CG. thrust to trim must also change. The three lines show the change in pitching moment The high thrust produces a nose-down with angle of attack for three cases: high thrust line, thrust through the CG, and thrust below the CG. moment. To compensate for this and trim the vehicle, the rotor is tilted back. of the CG, increasing angle of attack statically unstable in pitch at the rotor This moves the line of action of the rotor increases the nose-up moment caused setting required to trim in level flight. thrust vector forward of the CG, produc- by rotor thrust, and decreasing AOA Moving the thrust line below the CG ing a nose-up moment that trims out the causes a reduction in the nose-up rotor reverses this situation and leads to a nose-down thrust-induced moment. moment. This is an unstable variation. stable, trimmed condition. As we saw There is a second effect of this From this we can see that if a gyroplane above, however, this might not be as change in rotor thrust vector orien- does not have a horizontal tail and the desirable as one would think because of tation: With the RTV acting ahead thrust line acts above the CG, it will be the way trim changes with throttle. Another significant point here is that the stability of the gyro changes with power setting. The higher the thrust, the more compensating moment we need from the rotor. For a high thrust line, this means that the rotor must be tilted back more, and the gyro will become even more unstable. It’s quite possible that this effect contributed to the fact that the early slow-flying Bensens were rea- sonably manageable, but serious acci- dents started to happen as people tried to increase gyroplane performance and fly faster.

Speed Stability The effect of thrust line on overall fly- ing qualities is complicated further by the way propellers behave. At con- stant power, the thrust of a propeller is Figure 3: At constant power, the thrust of a propeller is approximately inversely proportional to airspeed. As airspeed increases, propeller thrust drops and vice versa. If the thrust line approximately inversely proportional does not act through the CG, this causes the thrust-induced pitching moment to vary to airspeed. As airspeed increases, pro- with airspeed. peller thrust drops and vice versa. If the

Graphs: Barnaby Wainfan KITPLANES October 2017 73 thrust line does not act through the CG, A high thrust line is statically destabiliz- is left without effective pitch control. In this causes the thrust-induced pitching ing but produces positive speed stabil- this situation, a high trust line becomes moment to vary with airspeed. ity, while a thrust line below the CG does very dangerous because the thrust of This effect is illustrated in Figure 3. the opposite. the propeller, acting above the CG, will As before the gyros are trimmed at the Positive speed stability can mask or still cause a nose-down pitch accelera- same condition initially. compensate for low or slightly unstable tion. The combination of high power The blue curve shows the case for a static pitch stability and make a stati- and low rotor load will lead to a rapid high thrust line. As airspeed falls below cally unstable vehicle more flyable. Once nose-down pitch (often called bunt- the trimmed airspeed, the thrust of the again, this may be a contributor to why over) with disastrous results. propeller increases. Because the thrust is the classic gyro configuration was flyable acting above the CG, this causes the prop over a limited envelope. Final Thoughts to generate more nose-down moment. From the above we can see that thrust If airspeed increases above the trimmed Bunt-Over effects on gyro stability and control are airspeed, the propeller thrust drops, There is one other effect of a high thrust not simple. We can, however, draw a which produces a net nose-up change in line that can exacerbate a very dan- few conclusions: pitching moment. gerous situation. Many gyro accidents First is that a low thrust line near the This is a stable behavior. The thrust- involve a rapid pushover or nose-down CG is desirable, but it is not a guarantee of induced moment tends to drive the nose pitch that leads to the rotor flapping good flying qualities. Moving the thrust down if airspeed drops, and up if airspeed downwards and hitting the tail or other line down to the CG helps, but it is not increases, which causes the machine to fixed parts of the machine. It’s possible a substitute for having a large enough seek to remain at the trimmed airspeed. to get into this deadly situation through horizontal tail to augment stability. The opposite is true if the thrust line is a too-aggressive push on the stick, but a A thrust line that passes slightly below the CG, as shown by the orange high thrust line makes it worse. above the CG might actually be desir- curve in the figure. A gyroplane rotor produces pitching able on a tailed gyro to improve speed Notice that the effect of thrust line moment by aiming the rotor thrust vec- stability, but large vertical offsets of the vertical position on speed stability is tor. If the rotor is unloaded, there is little thrust line are undesirable and should opposite to its effect on static stability. or no rotor thrust to aim, and the pilot be avoided. J

Clamp Stick SHOP By David Paule TIPS

Every once in a while, there’s not really a good way to clamp a small fitting to the drill press. What I do is clamp a stick to it. That gives me sufficient leverage to hold the part steady while I drill it. The only important factor is to be sure that the clamp can’t mar the part. I find a small piece of model airplane plywood works well to prevent the clamp from damaging the part. J

74 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes So-lar, it’s been good to know you. Ah, the signature song of The Weav- ers. When shall we see a folk group like that again? Probably not in our lifetime. In 1921, a young feller got the Nobel Prize for showing how sunlight makes electricity. Feller’s name was Einstein, and the technical name for his discovery was the photoelectric effect. It has taken us nearly a hundred years to put this discovery into wide practice. Today that wide practice takes us to an invention in 1903 called the airplane. And the battery. And the starter motor. And how not fly- ing our machines every day leads to the battery not batting, and consequentially, the starter motor not starting. The test setup at 8 a.m. on the 7th of June. At this time, it looked like it was going to be a very pretty day. Note that the author spared no expense for test facilities. An old trash can The problem is that keeping a trickle and a piece-of-junk plywood sheet work just fine as a test bench. charger (even most of the smart ones) on our batteries leads to bad juju inside We need to rest and (you should pardon is available every day that we don’t need the battery, especially those with the the expression) recharge our batteries to plug in—the sun. The nice part about AGM (glass mat) method of construc- and then go back to work. using the sun and a solar charger on our tion. These little rascals like to go up to It is also true that even if you get a trickle batteries is that we have an automatic full charge, then periodically drop back charger that does the cycle-on, cycle-off charge timer on them. It is called the sun down to a lower level, then back up and routine, you need commercial AC power going down at night and coming back up so forth. Sort of like our bodies don’t like in the hangar or at the tiedown to plug in the morning. Charge during the day to work at full speed 100% of the time. into. We do have a free power source that and ever so slowly discharge at night… and then back up the next day and so on. Serendipity strikes again. The prime mover in this little scheme is an inexpensive solar charger from the aviation department of our favorite air- plane parts store: Harbor Freight. The HF 62449/68692 solar charger is rated at 12.5 volts at 1.5 watts…which is a rather strange way to rate a charger. Usually it is volts and amps, not volts and watts. The kicker is that the little beast puts (Left) The test was started at 9 a.m. Still looks like a nice day, and our 12.91-volt battery is out about 22 volts in full sunlight and getting 15.8 mA of current charge. (Right) The gel-cell battery getting the charge. expects the battery to drag it down so

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 website at www.rst-engr.com/kitplanes for previous articles and supplements.

Photos: Jim Weir KITPLANES October 2017 75 The little charge regulator circuit. Note that for breadboard circuits, Texas Instruments sells ($20) one of these little chargers all set up we use “dead-bug” construction where the parts are put on the and ready to go...with the exception that you have to remove two board upside down with their leads in the air. This gives the effect surface-mount resistors and install your own resistors to set the of a dead cockroach. output voltage to whatever your battery needs.

(Left) By 10 a.m. the clouds had started to roll in, but we were still generating 21 mA of charge. (Right) It’s now 11 a.m. Note that even with this small amount of current, the Solar charger aiming angle. battery is now up to 13.21 volts, but heavy cloud cover dropped the current to 20 mA. that it doesn’t overcharge. That problem charger, which is too high volts and too three resistors, three capacitors, and one goes away if you only charge a day or two low amps, to the correct voltage with an inductor are all we need to make the con- and then drive the car. With the airplane increase in amps. Let’s say that again. troller, including a nighttime charge leak in the hangar for a week or two, and Our little charge controller is going to drain the battery down just a little. with the small batteries in our aircraft, I to take power (the product of voltage The question then becomes, how do see the probability of overcharge and times current), decrease the voltage, we get maximum power out of the solar ruining a perfectly good (and perfectly and increase the current at about a 90% charger? The answer is easy to say, some- expensive) battery. efficiency. We will throw away a few mil- what difficult to implement. The easy There are going to be a couple of rela- liwatts in the process as heat, but we get answer is just keep the charger pointed tively simple problems to solve to make a pretty decent boost in charge current at the sun at all times. The difficult part this $12 charger do the job for us. First of for our trouble. comes when you have to climb up on the all, we are going to use a power charge The schematic shows the relative sim- hangar roof every day and every hour to converter to take the output of the solar plicity of the charge controller. One IC, repoint the charger. Not a good idea.

Solar battery charger regulator.

76 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes quite a bit. I’m still looking for something that will protect the plastic lens over the solar cells and haven’t found anything that doesn’t drastically decrease the charger’s output. Q. I see that HF has a $70 12-volt 35-amp-hour sealed glass mat battery for sale. Any comments? A. Yup, lucky you. Experimentals can use any battery the owner wants. My (Left) By 2 p.m. the clouds had slightly parted and we were getting 24 mA into a 13.22-volt 182 isn’t so fortunate. Caution—the case battery. Other tests I’ve done with this same device and charger are easily double this (+) and (-) terminals seem to be reversed current in bright sunlight. (Right) At 5 p.m. the sun was nearly down, we were down to 9 mA, and the battery had started to go down in voltage for the night. from the aircraft convention. Hey, that was kind of fun for me. Some pretty smart folks have done weatherproof to the point where you can I think we ought to branch out and some calculations that show the best con- leave it out in the elements. revisit some of the stuff I did 20 years stant angles to point the charger for maxi- Q. Will low temperatures affect the ago and see if we might want to mum insolation or capture of the sun’s rate of charge? update it with currently available parts. energy. All calculations are done with the A. Yes. The colder the temperature, I haven’t forgotten about the ADS-B charger face pointing due true south. Here the better a solar charger works. While article(s) in plain English, nor about are the calculations (“latitude” or “lat” is the sun is much lower in the sky and the shielded switching power supply the latitude of your homedrome). is visible for fewer hours in a day, the for the LED nav lights. All in good time. If you don’t want to repoint the charger colder temperatures will help increase Until then…stay tuned… J at all and are willing to take less charge in the current output. both winter and summer than is possible, Q. The case of the charger is plastic. Note: The images for this story were taken just do the following calculation: Will it deteriorate over time? on a cold, dark day. You should expect at A. Yes. I’ve painted one with silver “UV” Angle = (lat * 0.76) +3°. least double the performance on a typical dope, and it seemed to increase the life bright spring/summer/fall day. For example, the home airport latitude at KGOO (Nevada County Airport, Cali- fornia) is 39°, so the compromise angle is 33°. The efficiency at this point is 72% of what you could achieve with perfect charger tracking of the sun. Unairworthy If you don’t mind repointing for summer (on the 30th of March) do the following: Pitted Wheel Angle = (lat * 0.93) – 21° Bearing Cup And in winter (on the 29th of Septem- This was discovered ber) do the following: when the wheel bearings were prepared Angle = (lat * 0.87) +19° for repacking during a Your overall efficiency increases to 76%. condition inspection. Again, at KGOO, these angles are 15° and Notice the severe 53° for summer and winter respectively. pitting of the cup. The Here are a few questions that I think dark spots are not dirt, this project might pose: but places where the plating has worn off of Q. Harbor Freight has some 5 watt the metal. This is not an uncommon find on aircraft that have been tied down and 13 watt chargers. Will this controller outside for long periods of time or have had their wheels submerged in water. work with them? The constant rocking in the wind, especially if they are not kept packed with A. The 5-watt charger is a 5-volt charger the proper grease, will cause the pitting. In a car the noise created by a pitted for cell phones and tablets. No, it won’t bearing would be very audible. Not so in an airplane due to engine noise. That’s work. The 13-watt charger is a 12/24-volt why it’s important to thoroughly remove all of the old grease and inspect the charger. This controller will probably bearing cups as well as the bearings. J work in 12-volt mode. I don’t know if it is —Vic Syracuse

KITPLANES October 2017 77 REAR COCKPIT Fuel follies. For all its vaunted vitality, for the most part youth is an affliction on society. All that enthusiasm coupled with so little experience for what can go wrong means parents spend a decade playing something between provider and parole officer while the general public hides behind airbags and curfew laws. But somewhere along the way most of us used-to-be-youths successfully empty the bag of experience into a sack of knowledge, wherein lies many a good story. That each of these tales has a mes- sage, a little knick in our brains that says, “Don’t do that again,” or “Maybe a little less throttle next time,” is the blessing of it all. Or so we hope. As a social irritant I was to a great extent a dullard if only because I was sequestered out in the sticks. But I did prove something of an overachiever on a steering wheel. So, naturally, I became the sandy patch where the access road pavement shortly after learning how to the airport’s line boy and was handed curved around the end of the runway. shift out of first. the keys to the gas truck. But the gas truck did prove instru- Arriving at the local airport at 16 should Now, the gas truck was simply too mental in a youthful indiscretion so have had front-page results according to far left of the F=ma formula to pose egregious I never told anyone about those who knew me then, but there was any real danger as a dynamic object. it until now. It was nearing sunset, the something of importance about avia- An early ’50s Chevy, it matched what time for making the fueling rounds, tion—likely an advanced fear of falling felt like 80 pound-feet of torque to when I parked the ’ol fuel bowser in from great heights—that more nurtured what must have been 10,000 pounds front of a hangar. In those days there a love of learning rather than flying under of curb weight. The 3-speed transmis- were no worries about fueling aircraft bridges. In short, I was a nerd in the air, sion shifted with the alacrity of a bored inside hangars, so I opened the hangar and besides, that tempting span over the DMV clerk, and the manual steering no and began fueling the Cessna. interstate east of town was decades in the doubt served as the inspiration for info- Then the gas truck ran out of gas. That future in those days. mercial workout equipment. is, the truck’s mogas tank ran dry, not On the ground, however, there was No, the gas truck could not be tossed the big avgas tank. Bereft of combusti- no fear of falling and I was still as absent- around, unlike my dad’s pickup and bles the Chevy went silent, meaning the minded as a length of pressure-treated camper combo I often drove to work. I PTO quit turning, and the 100 octane 4x4. And for sure keen as a groom given never failed to pitch that rig sideways on stopped flowing out of the hose. So,

Pumping avgas and waxing flight school airplanes got Tom into general aviation in 1973, but the lure of racing cars and motorcycles sent him down a motor journalism career heavy on Tom Wilson engines and racing. Today he still writes for peanuts and flies for fun.

78 KITPLANES October 2017 www.kitplanes.com & www.facebook.com/kitplanes as we always did, I put the 100 octane neck, spreading at least 80 feet from apparently never swiveled her office hose in the truck’s gas tank, cranked the shore to shore, with the old Chevy like chair around. The evening breeze was starter motor until fuel made its way an island in the middle. Safety being blowing, and a half hour later the gas from the big tank to the Chevy’s carbu- paramount, the exhaust system on truck was on dry ground once again. retor, whereupon the engine restarted the fuel truck ran forward, the muffler The Cessna was fueled and no one ever and the truck began filling itself. ensconced behind the front bumper asked me where all the extra gas had Bored with waiting to fill the truck’s and the tailpipe pointing downward. It gone when the meters and fuel receipts gas tank and endeavoring for maximum was puffing ripples in the 100 octane, were read at the end of the month. efficiency lest I raise the considerable and I still recall imagining the scene I was luckier than a July snowflake on wrath of either the FBO owner or my should providence provide a spark suf- Mt. Kilimanjaro—and learned a big les- Calvinist cum Marine Corps upbringing, ficient to complete the fire triangle. son on paying attention around gasoline. I levered the nozzle open with a handy And at the same time I realized there Fright of burning to death was (finally) stick and went back in the hangar to was no way around it. I was going to enough to get my teenage attention; clean the Cessna’s windshield. have to walk into the middle of this that, and what the boss would have done A thorough nerd, I was long into potential hell and switch off the engine. should he known or I had somehow sur- debugging the windshield when some- Then get rid of the stick in the hose vived reducing our airport to cinders. thing—the smell of fuel perhaps?— nozzle and hide like a mole until all that Luckier yet, all this happened back reminded me the gas truck was running gasoline evaporated. when dumb kids had more of a chance out there on the ramp, and hadn’t it Maybe, if I were lucky, no one would to learn almost the hard way. Today been running a long time? Uh oh. notice. there are probably 15 new rules against I dashed to the hangar door and No one ever did. The boss was else- everything I was doing that day, and yet abruptly stopped, realizing I was quite where (probably out flying), even better, bad as it could have been, it wasn’t. I possibly moments away from being so was his wife who really ran the joint, learned and sinned no more, a fact I try dead in my tracks. For there was the gas and the office manager, who had an to remember when some “dumb kid” truck idling in a sea of avgas. Gasoline up-front view of my personal Vesuvius innocently goes about learning a new geysered from its long since full filler through her expansive office window, skill in front of me. It’s tough, but I try! 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 website: www.kitplanes.com/cs or call us toll free to speak to customer service.

Photo: Tom Wilson KITPLANES October 2017 79 By Robrucha

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