Unsung Heroes: Oshkosh Parking Crew KITPLANES
AUGUST
2018
® BD-4C • OSH Parking Crew • Retractable BD-4C Gear • Paul Poberezny’s Home • Engine Failures • Windshield Replacement • Electrical Wires
• What ’s Old Fabric Covering Is New Again • GlaStar
Project Paul Poberezny’s Home AUGUST 2018
BELVOIR A Very Special Tour
In the Shop: PUBLICATIONS Retractable Gear • Windshield Replacement Pros and Cons • Electrical Wires • Fabric Covering Homebuilt Accidents When the Prop Stops www.kitplanes.com FROM DYNON AND ADVANCED FLIGHT SYSTEMS
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You’re a homebuilder, not an electrician. You love crafting your airplane, and can’t wait to fly now that it has wings. A Quick Panel cuts hundreds of hours off your avionics system installation with a complete, professionally engineered panel, delivered ready-to-install in your homebuilt aircraft. To customize your Quick Panel, call us today at (503) 263-0037 dynon.aero/quickpanels CONTENTSAugust 2018 | Volume 35, Number 8 Flight Review 6 Ahe ad of its Time and Keeping Pace: The BD-4 flies into its sixth decade. By Scott M. Spangler. Builder Spotlight 18 pAul’s House : A very special part of EAA history…and an unforgettable tour. By David Gustafson. 22 getting Started on the GlaStar Project: Starting on the wings and ordering more parts. By Dave Prizio. 28 homebuilt Accidents—When the Prop Stops: 34 Too many accidents start with a stoppage. By Ron Wanttaja. 34 oshkosh’s Homebuilt Parking Crew: Bringing you safely to final stop…and off again. By Louise Hose. 40 going Retractable: The ups and downs of retractable gear. By LeRoy Cook. 44 rA pid Prototyping and Experimental Design: Learning from the pros. By Eric Stewart. 66 As k the DAR: SLSA max empty weight, sailplane condition inspections, licensing a RANS S-7LS as an ELSA. By Mel Asberry. Shop Talk 49 Unairworthy: Unlabeled lights. By Vic Syracuse. 50 Best Practices: Fabric covering. By Dave Prizio. 62 Plane and Simple: Riveting soft materials. 64 Home Shop Machinist: Interference. By Bob Hadley. 72 The Creative Homebuilder: Hardened steel mandrels for close-quarters dimple dies. By KITPLANES® Staff. 73 Aero ’Lectrics: Weir’s wires. By Jim Weir. Designer’s Notebook 76 Wind Tunnel: Initial weights. By Barnaby Wainfan. Exploring 6 2 Editor’s Log: Blurring the line…By Paul Dye. 58 Checkpoints: A new rating and a new windshield. By Vic Syracuse. 78 rear Cockpit: An inside look. By Tom Wilson. Kit Bits 4 Letters 67 list of Advertisers 68 builders’ Marketplace 80 Kit StufF: Drawing on experience. By cartoonist Robrucha.
On the Cover: Jim Bede Jr. and Paul Dye enjoy a flight in the BD-4C over Florida’s 40 Treasure Coast near Fort Pierce. Photographed by Richard VanderMeulen. For subscription information, contact KITPLANES® at 800/622-1065 or visit www.kitplanes.com/cs. KITPLANES August 2018 1 EDITOR’s LOG Blurring the Line... Auto or manual? That has always been is automated is a futile exercise. If we age of 8 (I was probably 9), I was sure I the question when discussing who should broadly define automation as using already had a handle on how my father’s be flying the airplane. Man or machine— machines to do something instead of car worked. But gee—this fire truck had which is better adapted to fly a chosen using purely human intervention, then all sorts of stalks and things that were course, follow a radio beam down to the the airplane itself is an automation, for unidentifiable. Fortunately, my father ground, or make a good touchdown? it allows a human being to fly through was of an age that he knew about man- Pilots have either been accepting or the air without having to madly flap their ual spark advance, chokes, PTO levers, decrying automation since someone arms to get off the ground. That’s an and compression releases. I learned that hooked a bungee cord to a stick in order extreme interpretation, of course—but the driver of one of those machines really to reach down and find the map that had where exactly do we draw the line? had to know the intimate details of how blown out of their lap and was hiding I remember enjoying going to a local an internal combustion engine worked in down in the floorboards of their wooden park when I was a young lad because order to make it go! crate—and the debate continues to this they had an old fire truck that kids could Today, of course, I don’t even need to day as advanced cockpits abound. Auto- climb all over. You could sit in the driver’s turn a key to start my car. So long as I mation is seen as a benefit or a curse, and seat and play with all the many and var- have the fob in my pocket, I touch a but- sometimes both at the same time. ied controls—levers, large and small, ton, and the computer(s) gladly feed The truth is that trying to draw a line that did mysterious things. Like all good fuel, air, spark, and other magic to the between what is truly manual and what mechanically inclined boys over the engine in the proper proportions and
There’s no question that automation reduces workload for aircrews. Compare the engineer’s panel from the famous B-29 bomber, Enola Gay, with the full FADEC engine controls of this Cessna Citation CJ3+.
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. Paul Dye A commercially licensed 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 August 2018 www.kitplanes.com & www.facebook.com/kitplanes timing to make it instantly purr like a superior beings, capable of fine con- with all the levers to see if I can coax it kitten. And it does that all without my trol of our machines if all we do is push to life. But that’s just to prove that I can knowing what the engine even looks buttons? Well, sure—I like to go up and still do it. A modern farmer is happy to let like under the hood because it is cov- challenge myself to fly a perfect loop or automation do the drudge work while ered with a big piece of plastic with not nail that steep turn down to a deviation they keep their eye on the rows. And the much more than a protruding dipstick of plus or minus ten feet. I love the fact fireman is just as happy to let the truck to give the curious something to look that I can plant a bush plane down on a take care of things, so they can manage at. Yes, cars have become so automated gravel bar or primitive runway and make getting water on a fire. that it is hard to know what they are it stop exactly where I want. Those skills In the end, the important part of auto- doing for you—and, amazingly, they are necessary if we are going to play on mation is not to reduce workload just so pretty much keep on working…almost the edges of the flight envelope. But if we that we don’t have to do a menial task— all of the time. are trying to get from A to B safely and it is to reduce the workload so that we Sophisticated automation, in the efficiently, automation is a friendly force can do something more important with guise of fly-by-wire, has been around that can help us to be better pilots. the time it gives us. Humans are great at in aerospace and large aircraft applica- The pilot as “systems monitor” may thinking and analyzing the unusual, the tions now for quite a few decades, but horrify many, and if that were all I was unexpected, and the unforeseen. We do it is late in coming to the light aircraft allowed to do in a cockpit, it would hor- an adequate job of following a guidance arena. The surprising thing, however, rify me as well. But having the automa- needle—but since the computer is gen- is just how fast it is taking hold in the tion there when I want to use it is a nice erating that needle, it doesn’t take much experimental world. No, I am not talk- option to have. It doesn’t make me less technical effort to close the loop and let ing about fly-by-wire—although there of a pilot to let the airplane fly itself while the machine fly the needle for us. are people working on that for some I check weather, troubleshoot a niggling But if you really feel the need to applications as I write this—but the problem, or get my lunch out of the bag. demonstrate your ability to follow that level of automation to be found in our Keeping my head up on the big pic- needle, you still have the option—and aircraft right now is astounding. It was ture and letting the machinery do what I will defend your right to have that not that long ago that an airplane flying machinery does is similar to me touch- option as long as we have human seats a coupled approach to minimums was ing that start button in the car and let- in the aircraft. Just don’t be surprised if turbine powered and carrying passen- ting the engine systems play games with you see me hitting that autopilot button gers for hire. Now I can do that in most mixture and timing to make things run after takeoff, so I can start evaluating the any of the EFIS-equipped IFR experi- smoothly. Yeah, there are times when it weather up ahead without the distrac- mentals out there today. The creation of is fun to jump on an old tractor and play tion of having to stay upright. J digital autopilots, coupled to GPS and equipped with navigational databases, allow aircraft to fly themselves from fix It’s OSH to fix and right down to the runway. A typical cross-country for me these NOTAM Time! days requires a tug on the stick to get air- borne, a few tweaks on the power levers, Whether it’s your first time then a push of a few buttons to engage flying into AirVenture or your the autopilot to take me to my destina- 40th, you need to read the tion at an altitude I have dialed in before 2018 NOTAM. Although the departure. This is followed by a descent basic procedures are similar and approach similarly programmed to those used in the past, along the way. Deviations are handled numerous updates have been without pulling out paper charts, just made to increase safety and pushing more buttons. It is an efficient efficiency. To download the way to fly—far more efficient, in fact, NOTAM as a free PDF, visit than I can fly it by hand. The truth is, no www.eaa.org/notam. If matter how good I can do at straight- you’re reading this before and-level flight, my mind and hands get June 30, you still have time bored. Computers don’t do that. to order a free printed copy There are, of course, many pilots who of the NOTAM at the same decry all this automation. Where is the web address, or call EAA at romance of flight? Where is the chal- 1-800-564-6322. See you at lenge? How can we prove that we are the show!
Photos: Paul Dye KITPLANES August 2018 3 LETTERS
EDITORIAL Editor in Chief paul Dye Through New Eyes • The hole is square to a large enough [email protected] Just read Tom Wilson’s “Through New flat side of the hardwood block. Executive Editor mark Schrimmer Eyes” [April 2018] and had to smile. It’s • The hole fits tightly with the tubing. Art Direction Dan Maher a great piece regarding the pleasures of • The hole is not too short. Contributing Editors larry Anglisano, Marc Ausman, aviating—not just flying! Then: leRoy Cook, Jon Croke, I have 30-plus years in many cock- • I cut the tubing a little too long, as robert Hadley, Dan Horton, louise Hose, Amy Laboda, pits, along with the usual ratings and straight as possible, with a saw. Dave Martin, Sid Mayeux, endorsements. That being said, I’ve had • I push the cut end through the hard- David Paule, Dave Prizio, the pleasure of flying many nice aircraft wood block so that it hardly sticks out Ken Scott, Elliot Seguin, Dick Starks, Eric Stewart, of different intended purposes. All were the flat side. Vic Syracuse, Barnaby Wainfan, fun and some interesting in different • I sand the hardwood block flat side Jim Weir, Tom Wilson. respects, including bells and whistles, with a sanding block in one hand Web Editor Omar Filipovic which brings me to my point here. while keeping the tubing fed into Cartoonist Robrucha the hardwood block with finger and ADVERTISING thumb of the other hand. I do this Sr. Advertising Manager Chuck Preston until the tubing is the right length and 805/382-3363 the cut is straight. [email protected] In practice, very little of the hard- BUSINESS OFFICE wood block needs to be sacrificed, and Belvoir Media Group, LLC it can be reused many times. 535 Connecticut Avenue Norwalk, CT 06854-1713 I recently stepped back to the reason Jan de Jong I started flying in the first place and EDITORIAL OFFICE acquired a Cygnet for the same reasons No Discount on Charger 535 Connecticut Avenue Norwalk, CT 06854-1713 the author spoke of—getting back to my Well, Jim Weir goofed up big-time on this [email protected] roots with a basic stick-and-rudder air- one. His article [“Harbor Freight Leads plane that can handle moderately short the Charge,” May 2018] specifically CIRCULATION Circulation Manager Laura McMann and rough strips. It’s not fast, but it is expressed the ability to purchase the char- exponentially fun! The passengers I’ve ger with the ubiquitous 20%-off coupon SUBSCRIPTION DEPARTMENT taken agree, and seeing it from their side that Harbor Freight sticks in virtually 800/622-1065 www.kitplanes.com/cs (no rear cockpit) is another very special every publication. Wrong! The charger P.O. Box 8535, Big Sandy, TX 75755-8535 reminder of how fun it is to fly in an is one of the “name brands” excluded in inexpensive stick-and-rudder airplane the really fine print at the bottom of all REPRINTS FOR PUBLICATION AND WEB POSTING AVAILABLE with kind-of-sort-of cabin heat. the coupons. As the song says, “Big print Minimum Order: 500 Thank you for affirming my middle- giveth, and the small print taketh away.” Contact Jennifer Jimolka, 203/857-3144 age desire for back-to-basics fun! Mike Dunlap Doran Jaffas You’re not the only one who found that Change of address? Missing issue? Square Ends, Round Tubes out—but we’ve also heard from other Subscription Question? The shop tip, “Square Ends on Round readers who were able to get the low price.
Visit www.kitplanes.com/cs. Tubes” by David Paule in the April 2018 There seems to be some variation in rules Or call 800/622-1065 issue reminded me of how I do it, not interpretation among the various Har- from the U.S. and Canada. having a lathe. Using my pillar drill, I bor Freight outlets (sort of like the FAA, Foreign 903/636-1112 or fax make a through hole in a block of hard- FSDOs, and the FARs), so it works for 203/857-3100. wood that meets the following criteria: some but not for others.—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 ©2018 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 August 2018 www.kitplanes.com & www.facebook.com/kitplanes GTX 345. Finding an all-in-one ADS-B solution just got easier. The Garmin GTX 345 series of transponders. ADS-B Out and optional WAAS position source and ADS-B In. Displays ADS-B weather and traffi c on select Garmin avionics, portables and tablets using Garmin Pilot and ForeFlight Mobile. And the same footprint as most existing transponders. Learn more at Garmin.com/ADSB or call 844-GET-ADSB
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35685 GTX 345 iPad Direct Ad-7.875x10.5-Kitplanes.indd 1 5/15/18 10:43 AM 6 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes Ahead of its Time and Keeping Pace The BD-4 flies into its sixth decade. By Scott M. Spangler
With all the kits available, why did Art Zemon choose a 50-year-old design? It’s a question he gets often, usually followed by “Are you nuts?” The BD-4 “is not pretty,” said the 59-year-old computer engineer based at the St. Charles County Airport west of St. Louis, Missouri. “It looks like the box the airplane came in— but it is nutty efficient!” A pilot since 1987, Zemon’s desire for a new airplane to replace his 1968 Piper Arrow began in 2006. “Stuff was wearing out [and] I wanted to replace all the mechanical stuff with modern electronic doodads.” Arrow-compatible glass “cost well into five figures, and I was simply unwilling to put that kind of money in a 40-year-old airplane. That started me noodling on the problem of what I would rather have and how I could get it.” New store-bought airplanes were too expensive. “That left homebuilts.” To nar- row the field, Zemon made a list of requirements based on his primary mission, cross-country travel: 1. “Four seats; I like to give airplane rides to more than one passenger at a time,” and back seats allow for easier baggage access when traveling with his wife, Candy. 2. “At least as fast as the Arrow, 150 mph, preferably faster.” 3. “Roomier than the Arrow, which is 42 inches wide and has only 5 inches of back seat foot room.” 4. “Fully electronic instrumentation, with no vacuum pump.”
Photos: Richard VanderMeulen and Art Zemon KITPLANES August 2018 7 Finally, it had to be a kit. As his first project, scratch building from plans was too daunting and time consum- ing. Shopping at AirVenture, Zemon found few that met his requirements. He looked at the Glasair Sportsman, but “technically, it’s a 2+2.” Van’s RV-10 “was a no-brainer,” but its six-cylinder, 235-hp engine used too much “expensive aviation gas” to cruise at 190 mph. Surprised, Zemon said, “I kept coming back to the BD-4C. It’s stodgy, boxy, but I appreciate fine engineering more than I like looks. It cruises at 191 mph on 200 hp [soon to be 200 mph on 200 hp due to recent improvements by the factory]. Its cabin is wider and longer than the Art and Candy Zemon with their roost-ruling red-lored parrot, Robin Hood. (Photo: Art Zemon) Arrow’s. And there’s no climbing onto a wing and down into the plane, something Designed for builders with little or fuselage angles.” The surprise was that Candy and I will certainly appreciate as no experience, the fuselage safety-cage builders wanted everything, “so in 1969 we approach our golden years.” frame is bolted together like an Erector he started selling kits.” Set, said Zemon. “While there’s no weld- The BD-4 ad in the November 1969 Ahead of Its Time ing involved, you have to remove and Sport Aviation lists seven kit packages Jim Bede designed the BD-4 to exceed replace 58 AN3 bolts to fit the stainless that ranged from $178 for the fuse- the Part 23 structural standards for steel firewall.” lage controls to $626 for the wings. Normal and Utility category aircraft, Discussing the BD-4 at a 1969 Rock- The complete kit, including electrical and at 1400 pounds gross weight, Acro- ford forum (transcribed in Sport Avia- systems and instruments ($514), was batic (with acro not recommended). tion), Bede said his goal was to make $2,940, not including engine. Then He introduced it at EAA Rockford in things “less complicated.” This leads to based at Cuyahoga Airport, in three 1968, and it was ahead of its time. Not economies without “going to cheaper months, said Bede, the company went only was it an all-metal four-seater, it materials.” For example, the fuselage from a T-hangar to the biggest one was bonded, not riveted. angles are press formed because “extruded available on the Cleveland, Ohio, air- Essentially, the BD-4 is an upside- angles are never exactly 90 degrees.” port. Interest in the BD-4 has waxed down BD-1, a low-wing two-seater that When his father introduced the and waned over the past half century, first flew in 1963 and became the [Grum- BD-4, said Jim Bede Jr., who bought as has its marketing, said Bede, “but it’s man] American AA-1. Both designs the company before his father passed always been available.” embraced building efficiencies like in 2015, “Dad figured that builders Just before Zemon started airplane square corners and slab-sided fuselages, could get wheels and brakes and hard- shopping, Bedecorp resized the four- and the BD-4 offered optional folding ware everywhere, so he’d just sell stuff seat BD-4C for 21st century occupants. wings and landing gear configurations. that was hard to get, like the aluminum “Nobody in the United States is getting
8 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Doors on both sides of the the BD-4C provide easy access to the roomy cabin. (Right) Trim is controlled by a lever on the floor, instead of a common trim wheel. Bedecorp smaller, so we made the fuselage 4 inches that create “artificial low spots in each Beginning in the early 1960s, Jim Bede wider [to 46 inches] and 14 inches lon- wing, so the fuel, short of being inverted, formed a series of companies to market ger. I fly it to Oshkosh,” said Tim Becker, will be there.” A flat wing with no dihe- his designs, with Bedecorp, LLC (www. the 6-foot-5, aeronautical engineer who dral, Becker explained, when departing bedecorp.com) established about 15 worked with Bede Sr. with just a few gallons in the panel-rib years ago. Jim Bede Jr., owner of a large The biggest change was an all-metal wing tanks at high angles of attack, could Ohio construction company, bought replacement for the BD-4B’s panel-rib unport the fuel pickups. Bedecorp shortly before his father wing. “The hollow fiberglass wing sec- Owners of the nearly 300 BD-4s passed in 2015. Shortly thereafter, he tions slipped onto the tubular spar, and in the FAA registry can easily replace opened the builder assistance center at tabs aligned the sections perfectly, so their panel-rib wings. So can builders Florida’s St. Lucie County International it was easy to build,” said Becker. “But with unfinished kits, and in increas- Airport, the operational hub for the the sections used as fuel tanks some- ing numbers they’ve been calling, said company’s three designs: the BD-4C; times leaked.” Bede. “They want to know if they can the BD-6 (a single-seat BD-4); and the Bede introduced the bonded-metal buy the new metal wings” and finish low-wing, single-seat BD-17L. wing with CNC-cut ribs of aluminum their airplanes at the assistance center. “Right now we’re selling BD-4s and honeycomb on the single-seat BD-17, The short answer: “Yes!” BD-6s like crazy,” said Bede, noting said Becker, and “it was just a natural The folding wing option is available that there are 15 under construction progression for the BD-4.” Solid ribs on the new wing, “but we haven’t sold worldwide, with three builders at work determine the wet wing’s fuel capacity, one in years,” said Bede. The update also at the assistance center, which Tim which ranges from 51 to 80 gallons. The replaced the sensitive trim wheel with Becker manages. Even more tantalizing, wing incorporates new fuel pickups, fins an anti-servo tab controlled by a lever before he passed, “my dad had six or seven designs that are all done in CAD. He would just go to town. You name it, from jets to whatever, he got one of them done.” To inspire aviation’s next generation, Bede established the 501(c)(3) Bede Family Foundation in 2015. It introduces youngsters to aviation by supporting homebuilt projects organized by schools and local organizations. One high school is about 30% done with its BD-6, and Bedecorp is in the process of shipping two more, to school and EAA chapter consor- Just a few of the 58 bolts that hold the stainless steel firewall in place, with the cutout for tiums in Virginia and Georgia. the nosewheel shock donut. (Photo: Art Zemon) —S.M.S.
KITPLANES August 2018 9
Bedecorp BD-4C
Kit price ...... $29,845.00 Estimated completed price ...... ~$100,000.00* Estimated build time ...... 700 hours Number flying (at press time) ...... 5 Powerplant . . . Lycoming IO-360, 200 hp @ 2700 rpm Propeller ...... Hartzell 72-inch constant speed Powerplant options ...... 180–260 hp
AIRFRAME Wingspan ...... 26.2 ft Wing loading ...... 23.2 lb/sq ft Fuel capacity ...... 51–80 gal Maximum gross weight ...... 2400 lb Typical empty weight ...... 1250 lb Typical useful load ...... 1150 lb Full-fuel payload ...... 844 lb Zemon attaches the vertical stabilizer to the bolted-together fuselage frame. (Photo: Art Zemon) Seating capacity ...... 4 Cabin width ...... 46 in between the seats. The new composite “We build this business one cus- Landing gear ...... Tricycle or tailwheel S-ply main landing gear struts eliminate tomer at a time,” said Bede. Giving Baggage capacity ...... 30 pounds with 4 pax rubber donuts, and where builders locate an example, they couldn’t figure out a the redesigned landing gear box deter- problem with Zemon’s stabilator over PERFORMANCE mines the gear configuration. the phone, so “I sent [a technician] to Cruise speed ...... 191 mph Art’s shop in St. Louis to help him with Maximum rate of climb ...... 1700 fpm Beta Testing it, at no charge.” Stall speed (landing configuration) ...... 62 mph Given his absence of building experience, Zemon spent three days prototyp- Stall speed (clean) ...... 70 mph Zemon was concerned about being the ing builder’s assist. Beyond the hands- Takeoff distance ...... 600 ft beta tester for the BD-4C kit and builder on guidance, its key advantages are the Landing distance ...... 600 ft assistance center, now located at Florida’s fixtures and tools that build and bond Specifications and pricing provided by the manufacturer St. Lucie County International Airport. a perfectly aligned wing. But first, and are based on the current configuration of the demonstrator aircraft. The Bedes “impressed me by being com- they bolted the aluminum angles into pletely up-front about the newness of the the fuselage safety frame with roughly *Completed price includes new engine and avionics. For full builder assist, add $30,000–$50,000 depending on builder’s assist program; they said they’d 1200 AN bolts. equipment. With good used engine and equipment, make any problems good for me, and Initially, Zemon thought deburring completed price can be as low as $70,000. they absolutely have,” said Zemon. aluminum was homebuilding’s least glamorous job, but then he mixed, in nine carefully labeled cups, 4.5 pounds of Pro-Seal needed to bond the skins to the honeycomb ribs. He mixed two types, regular Pro-Seal, and the ethanol-proof mixture used in the fuel bays. “It’s more expensive, but it allows builders to use mogas,” said Becker. Setting to work in his two-car garage, Zemon followed a mix of origi- nal hand-drawn plans and the CAD drawings that sequentially replaced them. As the beta-test builder, Zemon’s calls and emails refined the completely CAD drawn plans and building guid- ance, as well as the kit components. Zemon applies ethanol-proof Pro-Seal to the aluminum honeycomb rib at the Bedecorp builder assistance center. (Photo: Art Zemon)
10 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes rods, and trim system. The landing gear package includes the S-ply main struts, formed nose strut, wheels, brakes, mas- ter cylinder, brake lines, and hardware. The finish kit contains the wing tips, windows, and necessary hardware. The BD-4’s tubular spars of extruded 6061-T6 aluminum are not a new idea, said the elder Bede at a 1969 forum. Germany and others used it before WW-II. With an excellent strength-to- weight ratio, it’s difficult to bend in any direction. The design is simpler than a strut-based wing, with its high-stress joints at the wing and fuselage. The wing and center-section spars Zemon paints the fuselage frame with Scotch-Weld. It is also applied to the fuselage have different inside and outside diam- skins where the two meet. You have to get it right the first time because once the Scotch-Weld sticks, you cannot move the skin. (Photo: Art Zemon) eters, so the wings form a tight sleeve with 12-inch overlap, held in place with The fuselage package includes formed and torque tubes. Pro-Seal and the new several bolts. When his helpful mentors angles, precut gussets, aluminum skins, fuel pickup system, with electric fuel from EAA Chapter 32 lifted the wing center section, and hardware. The wing senders, complete the kit. panels into place, Zemon discovered kit includes CNC-cut aluminum hon- Starting with factory-bonded vertical that “nothing in life is perfect.” eycomb ribs, spars, formed rear spars and horizontal tail surfaces, the control The spars were not perfectly round. and formed wing, aileron and flap package includes all bearings, hard- Off by thousandths, the spars would skins, and their precut mahogany ribs ware, welded components, push-pull not sleeve. “It was a royal PITA,” said
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-VS-
(2) 250W Landing Lights (GE4596) and (2) 100W LED Light (SunSpot36-4696) and (1) 250W Taxi Light (GE4587) (1) 100W LED Light (SunSpot36-4587)
KITPLANES August 2018 11 BD-4 empennage before left skin is bonded to the frame. Also visible is the stabilator push-pull tube, trim cable, and rudder cables. Zemon. He solved the problem with Using Scotch-Weld, said Zemon, wrinkles in the 0.016 aluminum,” and his drill and a Flex-Hone tool. Learn- is simple, in concept. Paint it on the pressed all the surfaces together with a ing from this experience, builders fuselage frame and on the fuselage solid rubber roller. should fit the spars together before skin where the two meet. “Then stick bonding the wing ribs and skins. the skin onto the airplane. Get it right 90% Done, 90% to Go 3M Neoprene Contact Adhesive 10 the first time because once it sticks, you Wanting front seats adjustable in flight, (aka Scotch-Weld) bonds the fuselage cannot move the skin.” Zemon replaced the BD-4’s ground- skins. This high-performance contact Truthfully, it’s a little more involved. adjustable seats with those from a adhesive laminates sheets of stainless To align the skins Zemon drilled Piper. “I wouldn’t do that again.” Cut- steel, aluminum, cold rolled steel, and small holes in one end of the skin and ting down their mounting frames was many plastics, to various substrates. matching holes in the frame. While involved and didn’t leave a lot of head- With excellent heat and moisture resis- his wife and “several artfully placed room. “It’s the one thing on the plane tance, it holds tight up to 300° F. But scraps of wood” held the skin away I’m not happy with at all.” it’s expensive, said Zemon, and build- from the fuselage, he aligned the skin His instrument panel is a different ers should plan accordingly because it and inserted Clecos. Then they applied story. Zemon installed the MGL iEFIS, has a short shelf life once opened. the skin like a decal, “careful to avoid an integrated touchscreen system, with
Helping hands take shelter under the BD-4C’s wings after hefting them into place. (Photo: Art Zemon)
12 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes two 10.4-inch Challenger displays. a Trig TT22 transponder and TN72 Ultimately, he mounted the pitch servo “Being a computer engineer, I like how WAAS/GPS combination that meets the behind the baggage area and the roll open MGL is on its software and data ADS-B Out requirements. A portable servo beneath the right rear seat. formats. I don’t intend to hack their soft- receiver and his iPad will display ADS-B Zemon is powering his airplane with ware, but I do like that I can get the data In traffic and weather information. “This a 200-hp Lycoming IO-360 with a con- out of it, and I found the company very winter, I’ll install a Garmin GTN 650.” stant-speed prop. “It’s a certified combi- easy to deal with.” The installation’s biggest challenge nation that came out of a Skybolt, so I’ll Supporting this system are a PS Engi- was locating the iEFIS autopilot servos, only need a 25-hour Phase I test program, neering PDA360EX audio panel, VAL the subject of four posts on his building which will help me get the airplane to Avionics com 2000 and nav 2000, and blog (https://cheerfulcurmudgeon.com). Oshkosh for the 50th anniversary.”
The panel is large enough to accept just about any modern EFIS and avionics stack. Back seat in the BD-4C has room for two.
14 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes The prototype is powered by a 200-hp Lycoming IO-360 turning a constant-speed The square lines of the BD-4C fuselage prop. Engine options range from 180 to 260 hp. extend all the way back to the tail cone. As it has from the start, the airplane is tickertape parade, to bring out the angu- When he started, Zemon anticipated the beta test for the firewall forward kits lar shape of the airplane,” Zemon said. a chore “so I could fly a nice new air- Bedecorp is developing at the builder Looking back, he said there were “lots plane.” Instead, building the BD-4 has assist center, said Becker. It already gets and lots of small challenges because been supremely enjoyable and rewarding. OEM pricing for Continental, Superior, there was so much I didn’t know.” Per- “Working on computers, it’s a hoot for me and UL engines. haps the “biggest challenge was time. I to accomplish something and be able to The project’s final challenge is the paint tried to work on it every evening, but I hold it in my hands, something that exists scheme. “Right now we’re planning on had some lifecycle events, like eldercare. in the real world. I can move the stick and painting it white and using vinyl appli- It really hasn’t been a six-year project; it’s see the ailerons move. I wish I would have qués to02-28-18 make BRSit look Kit Planes like Version it flew 6.ai 1through 3/6/2018 1:39:34a probably PM a three-year project.” tried this way earlier in my life.”
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KITPLANES August 2018 15 BD-4C: What’s Old is New Again The BD-4C, the current model of the BD-4 being sold by Bedecorp, not innovating with everything he did, and if you look closer, you’ll see only has a clean wing, it is larger in a number of key dimensions. The things like the closeable covers on the wheel pants (not currently original cabin of the BD-4 was 42 inches wide, about what you find in a installed on the airplane) that fully enclose the wheels in flight. While Mooney. Yet the BD-4 feels roomier than the Mooney because the sides they add complexity, they also allow pilots to use the airplane to are flat. The 42-inch width is good from the lower to upper corners—it satisfy requirements for complex aircraft training because the FAA isn’t wide only at the hips or shoulders. The BD-4C has been widened concurred that enclosing the wheels was equivalent to retracting by 4 inches, making it as wide as a Bonanza, and that is some serious them—and that makes the BD-4 a retractable aircraft, even with the room! Not only is it wider, it is 14 inches longer, providing plenty of gear hanging out in the breeze! cabin space for back seats or, more likely, lots of baggage. One way Bede made the -4’s cabin roomier was to install a bench Approaching a BD-4, one’s first impression is often that it is a small seat in the front. Bucket seats restrict each person to a specific spot and compact airplane. This is probably because it doesn’t sit particu- and create sides that make the overall effect narrower. A bench seat larly tall on its gear. But once you get up close and slide into the cabin, allows each person to expand to fill the available space. you realize just how much room there is for people. The same is true Then there’s the full-swiveling nosewheel and differential braking. when you take off the cowl and discover just how much firewall width While this is pretty much the standard for tricycle gear airplanes is available. The factory demonstrator is flying with an angle-valve in this day and age, it was quite unique in the 1960s when Bede IO-360 and, as they say, “There’s no substitute for horsepower!” With introduced the concept on the BD-1. It has followed him on almost 200 horses fitting neatly under the hood, the BD-4 is ready to go fast all of his trike designs since, including the BD-4. The factory recently and far, given the amount of fuel you can store in a full wet wing. redesigned the nose gear and is making a fairing for the C model to go The basic structure of the BD-4 includes aluminum framing and around the block and sides of the nosewheel. It won’t be a full wheel skins for the fuselage, with honeycomb floors in the cabin area. The pant, but it will definitely improve the performance. There will also main spar carry-through takes up a little room in the cabin overhead, be a fairing around the nose strut. but it is generally forward of a normal person’s head, so it doesn’t cut into headroom. It does limit forward and up visibility for those Flying the BD-4 who are extra tall—but eliminating extra seat cushions will help The fact that the BD-4 is compact makes it lower in height than the you to see past that. The wings are fully cantilevered, so there are no average four-seat high-wing airplane, so you crouch a little when struts to add drag or get in the way during ingress or egress. There is, getting in. It also means that the wing is a little lower, making for however, a small faired sump (see sidebar) on the lower surface of each a steeper rake to the windshield. The view from inside is a little like wing, just outside the swing of the door. This is to make sure that fuel one of those cars that has been chopped to create the gangster look will feed no matter the pitch attitude. But it also serves to collect from the 1930s. In the factory demonstrator, the glareshield was the noggins of those not paying attention walking underneath the high, and the low ceiling and high glareshield work to limit visibility wing—so be careful and keep your eyes open! out of the cockpit. All airplanes are different and require a little accommodation, but this was the first impression we got when Bede Signatures setting up for flight. Interestingly, Jim Bede Jr. climbed in for one Jim Bede’s signature is evident throughout the BD-4, from the tubular of our photo missions, and without the extra cushion he usually uses, spar to the bonded construction. But Bede was always tinkering and he noticed the same thing—but he also said that current production
16 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes airplanes have the glareshield two inches lower, just about the Traffic was heavy as we returned to Fort Pierce, it being a major amount that would open things up nicely. training airport in Florida in the spring, so our attention was mostly The engine was typical fuel-injected Lycoming. Use whatever start- outside as we looked for traffic to follow. This is a good test for any ing technique works for you and your particular engine, and once it is airplane—can you fly it without having to concentrate just on flying it, running, we’ll all be in the same place. The panel on the factory -4 is or do you have to compensate for quirks to the point where it requires well laid out and roomy—there’s plenty of space for a full EFIS and IFR your full attention. The BD-4 came through just fine for us, with good capability, probably with space left over. The systems are normal for speed stability, even with flap changes on downwind, base, and a long this type of aircraft, and there was little to learn for someone raised final. Keeping the speed up on final seems to be the right thing to do for on the Grumman American tradition of a full-swiveling nosewheel and most Bede designs, and this one is no exception. You can develop quite differential braking. Steering is easy, and it is always a delight to be a sink rate when you get on the backside of the power curve, so 90 mph able to almost swivel on one wheel. The airplane tends to bob a little down final worked well to get good glide path response to power. in pitch when taxiing over lateral bumps in the pavement, but this There was plenty of energy to give a nice controlled flare, and a might just have been the spring in the nose gear at light weights. soft touchdown on the mains was simple, followed by the nose gear. There were no surprises in the takeoff prep, and I chose to depart Directional control on rollout was pure Bede—a little differential with no flaps on the long runway at Fort Pierce, Florida. Acceleration braking keeps things straight down the centerline. was quite good—as you’d expect from a 200-hp engine and constant- Overall, the BD-4 is a clean design that requires good coordination speed prop mounted to a relatively light airplane. Rotation speed and slightly higher speeds than those who have only flown Cessnas came quickly, and the airplane flew off with little effort. Initial climb and Pipers are used to. But with proper training and care, the airplane rate was good as we turned outbound and headed for some clear should serve well as a personal traveling machine. space between the building cumulus, looking to get above the —Paul Dye convection layer to find smooth air. I felt the need to S-turn frequently to clear the airspace ahead, mostly because of the high glareshield blocking much of the sky in that forward direction. Fortunately, the The BD-4 Head Knocker side windows are large, and it doesn’t take much of a turn to the right So what’s with that little inverted shark fin that hangs below the to give the pilot a clear view. BD-4 wing, just outside the swing of the door? Is it just there to The first thing we noticed about handling was that the rudder is catch the unexpected in the noggin as they climb out of the plane very effective and sensitive. Using no rudder produced a lot of adverse and swing around to get out from beneath the wing? Well, no— yaw, and using very much produced a lot of slip. To keep the ball cen- Jim Bede was not the tallest guy in the world, but he didn’t design tered, you needed to just touch the rudder at the initiation of the turn, it just to annoy those who are. then get your feet off the pedals as the airplane coordinates itself once That is the fuel tank sump, and it is designed to catch water established. Outside aileron was required when the bank angle was and also provide a reliable continuous fuel feed from the very flat greater than that needed for a standard rate turn, probably due to the tank, regardless of pitch attitude. With the fuel exiting the tank lack of dihedral in the wing. near the aft edge of the tank, a nose-down attitude could cause Once we had found smooth air, we settled down to do a few the fuel to uncover the feed line if the fuel quantity is low, caus- turns—first at standard rate, then at a 45° bank, and finally winding ing the engine to swallow air and quit—not a good thing. Rather things up to 60°. All were normal, except for the aforementioned need than create a fuselage header tank, Bede designed the sump to for out-of-turn aileron to keep the bank from steepening up. Most air- collect enough fuel for the engine to continue to run for a reason- planes are like this at a certain point; the BD-4 just gets there earlier. able length of time under low-fuel/nose-down attitudes. It’s a Nice again, a little rudder to start the turn, then get your feet out of clever solution to one of those edge-of-the-envelope problems. the game, and let the airplane coordinate itself, or you’ll be skidding Just watch your head as you exit the airplane…please! J around the sky. —Paul Dye After a few turns, we got a little more aggressive, flying a couple of step lazy eights and chandelles. This is where coordination is really required, and the airplane was easy to fly with the ball centered. What this really means is that it doesn’t take very long to get used to the sensitive rudder, and after an hour or two in the airplane, you’d prob- ably never notice it again. Stalls followed, and slowing the airplane down showed it to have good manners at the low end of the speed range. We flew to the buffet, which although not overly pronounced, is definitely there to notice. A couple of turns right near the buffet were easy, and roll control remained good. We didn’t fly all the way through the break, but our Below each fuel tank in the flat wing is a fin that creates a factory pilot said that roll and yaw control is good all the way through. gravity-fed sump for the fuel pickup inside the fin.(Photo: Paul Dye)
KITPLANES August 2018 17 Paul’s House A very special part of EAA history… and an unforgettable tour. By David Gustafson
Paul Poberezny bought this farmhouse and nine acres of land in 1991.
In January 2017, Jim Irwin, president vandalized, and needing serious repair, of Aircraft Spruce & Specialty, pur- Paul soon had the edifice in Bristol fash- chased the Paul Poberezny estate in ion after purchasing it. However, it was Oshkosh with the goal of preserving a too small for Paul’s needs, so a three- vital part of EAA history. Situated on a car garage with an upstairs office/bar/ little over nine acres of land, with a Paul- lounging area dubbed “Poopdeck” (he made pond (Lake Audrey) and dozens had an airplane with that name) and an of Paul-planted trees (the land was flat addition to the main house were soon and barren when he bought it in 1991), in the works. He then added an Annex the central structure is a century-old (read workshop), a “West Wing,” and a Paul Poberezny, founder of EAA. brick farmhouse. Abandoned for years, couple of storage sheds.
18 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes From left to right: Rob Irwin, Jim Irwin, Tom Poberezny, Mike Irwin, Lake Audrey, a man-made pond on the meticulously sculpted and Jeff Irwin. grounds of the Poberezny estate, is named for Paul’s wife.
Originally, the nine acres had a bum- collection of bound issues of The Exper- to form a corporation they named the per crop of weeds, tall grass, and brush. imenter and its successor, Sport Avia- Experimental Aircraft Association, but Color those gone. Paul planted one tion magazine. It’s the complete story he grew into the role of Convention of the largest lawns this side of a golf of EAA. But it’s the hundreds and hun- Chairman in 1977 and succeeded his course. Any golf course would envy dreds of photographs that really have a father as President of EAA in 1989. He that lawn. Paul and his wife Audrey message. Certainly there are plenty of retired from both positions in 2011, but kept it manicured with a pair of John airplane pictures, but it’s the people of has remained active in aviation, serving Deere tractors that the two of them EAA who occupy the greatest number on a number of boards of directors and would ride for nine hours on “cutting” of photos and carry forward the legacy doing consulting work. days. The embellishment of the willows, of the organization. Paul loved people. This past summer, at AirVenture evergreens, and hardwood trees artfully He often said, “I’m not a millionaire, 2017, Tom agreed to meet Jim Irwin at placed, has created a park setting that but I feel like one because I have a mil- the farmhouse on Tuesday evening to echoes Paul’s standards for beauty and lion friends. I’ve learned far more about provide Jim with a guided tour of his perfection…in the summer. people in my life than airplanes.” father’s home, the buildings, and the In January 2017, when Jim and his No one, probably including Paul, grounds around it. I got to tag along. For wife Nanci flew out to Wisconsin to could have identified all of the faces in about two hours, Jim and his sons, Mike, inspect the house during a howling bliz- the photos, but he’s certainly known a Jeff, and Rob, followed Tom around as zard, he was hard pressed to appreci- lot of those people. Paul died in 2013, Tom brought bits and pieces of history ate the natural setting, but he realized at the age of 91, taking a lot of history into the present. Jim later described it instantly that the house and the out- with him. Fortunately, there’s another as an event that wove humor, reflection, buildings constituted a museum. Here Poberezny who also knows a lot of the insight, nostalgia, explanations, and was collection of thousands of photo- history behind the pictures, and he’s still intriguing discussion into the kind of graphs, paintings, artifacts, trophies, with us: Tom Poberezny lived with the engaging historical texture that could plaques, and aircraft parts that docu- EAA from early childhood. He was only only evolve through an active life with mented a major portion of EAA history. 6 years old in 1953 when Paul recruited a grassroots/sport aviation. There was one Here resides the world’s only complete bunch of his friends in the family garage wall totally devoted to Paul’s career as a
The Annex contains a workshop, an office, and a bar. The Annex workspace, where Paul worked on many projects.
Photos: David Gustafson KITPLANES August 2018 19 One of Paul’s four desks. This one is in the Annex. Paul’s drafting table is also in the Annex. military aviator. Pictures showed Paul of EAA and spoke softly, noting with Tom doubled its size and expanded on with Tom as a young child, Tom as a a sweeping gesture that “Most of the its mission in ways that has made EAA a member of The Red Devils, then later, people in these photos are gone now, and formidable force at all levels in the avia- as part of the Eagles Aerobatic Team. most people at the fly-in this year never tion community. There were photos of Paul Harvey, John knew any of them. It’s difficult to realize The tour was an experience in enlight- Denver, Cliff Robertson, politicians, that so many people, who contributed so enment and discovery. Jim said: “Tom astronauts, FAA administrators, and the much to the movement, who were such expanded the meaning of this place. He earliest Young Eagles. a big part of it at one time, are gone and brought out the importance of Paul’s Paul loved offices…and bars. There forgotten.” It was obvious that Tom feels vision and determination. For any was an office and a bar in the basement indebted to the many people who shared EAAer, these grounds are hallowed. of his farm house, in the Poopdeck his father’s passion for building and fly- It’s a historical, national treasure, and it over the garage, in the Annex, and the ing, for neat and clean, straight and level, really seems fitting that Aircraft Spruce West Wing. He used all of the spaces and for innovation. At the same time, & Specialty, which owes its very exis- to write articles, letters, and to sketch Tom revealed a high level of respect tence to EAA and has grown along with ideas for aircraft. Paul designed, built, and admiration for his famous dad. He it, should be entrusted with the mission and flew 13 aircraft. He sold plans for admitted that it was a challenge growing to preserve these grounds for all who most of them. He built copies of each up in Paul’s shadow, but that all changed would dream of building their own air- one of them, and his passion for creat- when Tom won the title of National plane or who fly because it’s fun and a ing homebuilts was a big part of what Champion at the National Aerobatic truly spiritual experience.” inspired the homebuilt aircraft move- Championships and then went off to fly Jim and his sons stay at the house dur- ment worldwide and has resulted in in the World Aerobatic Championships. ing AirVenture. EAA maintains it for about 35,000 amateur-built aircraft The father/son relationship had its rough the rest of the year and provides tours of being added to the FAA Registry. spots, but in so many ways they comple- the estate during AirVenture. Put a tour At one point, Tom stared wistfully at mented each other. Paul will always be on your list of things to do when you a photo of the original board of directors remembered as the Founder of EAA; visit Oshkosh. J
Jim Irwin in the West Wing, surrounded by aviation memorabilia. The prop garden is next to Lake Audrey on the beautiful grounds.
20 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes
Getting Started on the GlaStar Project
A simple jig made up of aluminum angle attached to the flap worktable allows us to get the spars perfectly straight as the flap is drilled and assembled. A twisted flap will require disassembly Starting on the wings and and replacement of many parts. It is worth taking the time to get it right ordering more parts. the first time. By Dave Prizio
Just to recap, I bought a partly com- age, I felt that the fuel cells needed to be opened up to gain access for the new pleted GlaStar project [See “Taking checked out, so they had to be extracted flap tracks. Over Someone Else’s Project,” Decem- from the wings and sent back to the ber 2017] and got it shipped to me manufacturer. I also wanted to install Fuel Cells from Florida. The previous builder Sportsman flaps in lieu of the original The fuel cells had to come out to either be had installed fuel cells (bladders) to flaps in order to gain the performance replaced or rebuilt. That meant remov- increase fuel capacity and had already advantages of the newer design. This ing the main ribs from each end of each closed up the wings. Considering their also required that the wings be partly wing. The center ribs at the root of each
22 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Removing the root rib to gain access to the fuel cell is a major pain. Here the author is bending a long drill bit to align it with the rib to be removed. There are no straight shots into any of these rivets. It was similarly difficult to install new rivets later after the fuel cells had been overhauled. (Right) Co-builder Ed Zaleski works to remove varmint debris from the wings with a shop vacuum. It is amazing what tight spaces these little guys can get into and how hard it is to extract what they have left behind.
wing are particularly difficult to install When the fuel cells came back, we still kinds of things you find in a project that because there are no straight shots with had some work to do before they went has been sitting for a while. either a drill or a rivet set into any of the back in. The fuel lines and vent lines rivets that hold it in place. Memories needed some work, as did the transfer Flap Tracks of struggling with and cussing at these pumps that moved fuel from the aux- One of our early decisions was to rivets on previous projects came back to iliary tanks to the mains. One of the replace the standard GlaStar flaps with us as we started on this task. With some pumps was badly corroded, so it had to the later and much improved Sports- patience and concerted effort, the ribs go, and the fuel lines from the pumps to man flaps. Dimensionally the wings are yielded, giving us access to the fuel cells the main tanks were improperly sized. the same, so there is no reason why the at either end of the wings—mains near A few new fittings and some aluminum Sportsman flaps won’t work, but to use the root and auxiliaries at the tips. fuel line material solved that problem. them, the GlaStar flap tracks had to be The fuel cells looked good, but it was Another issue was an accumulation replaced. If the wings were still open, way too hard to extract and reinstall of junk inside the wings, no doubt put this would be a very easy task, but in them to leave anything to chance, so off there by some enterprising rodents this case, the wings were complete and they went to be overhauled. We could somewhere along the line. After their closed up, casting doubt on whether have elected to replace the bladders with nesting material was fished out and or not we could change the flap tracks aluminum tanks from Glasair, but the vacuumed up, and a few corroded spots without removing the top wing skins, a cost of doing so would exceed the cost cleaned and primed, we were in good job we were in no hurry to tackle. With of overhauling the fuel cells by a factor shape to proceed with the rest of the some patience and ingenuity, we were of four. That was $1500 we could spend wing work. Some chewed-up electrical able to extract the old flap tracks with- on something else. conduit also got replaced. These are the out dismantling the wings, but there
The author (left) uses a hemostat to fish a rivet into place while The auxiliary fuel cell goes back into the wing after being over- Zaleski reaches into the empty fuel cell cavity to position the hauled. It is a little tricky to get all the wrinkles out of the bottom bucking bar. Note the extended rivet set in the rivet gun that was side and secure the top to the Velcro strips on the top skin that made especially for this task. keep it from collapsing when fuel is removed.
Photos: Dave Prizio KITPLANES August 2018 23 A big part of making the Sportsman flaps work on the GlaStar is changing the flap tracks. The new Sportsman flap track is above in gray, and the old GlaStar flap track that we removed is below in green. The Sportsman flap track makes a major change in how the flap extends. Zaleski marks the centerline of the main couldn’t buck them or use CherryMAX the GlaStar, and we wanted to capitalize spar with a scribe tool and Sharpie. The pre-punched rivet holes in the flap skin rivets without a great deal of extra trou- on that or even improve upon it. must line up with this mark to be properly ble. With reluctance we substituted While working on a friend’s Sports- positioned for drilling and riveting. Cleave- stainless steel screws for three rivets in man, I found out about some extended land Aircraft Tool calls this an edge marker each wing. They are loaded in tension gear legs available from Langair Machin- block (Item #6352) on their website. It is in this application and their strength ing. They make gear legs for most RVs well worth the $19 cost if you need to do this kind of layout work. easily exceeds the aluminum rivets and standard gear legs for the GlaStar they replace, so there shouldn’t be any and Glasair Sportsman. These special were times that we weren’t so sure it problems with their use. We also used gear legs have a larger diameter for rough would work out. It helped to have the some CherryMAX rivets in some other fields and are three inches longer than fuel cells out of the way, especially when places where access was not available. I standard. They also utilize the bolt-on it came time to buck the rivets for the do not endorse the wholesale substitu- Grove stub axles. This will give better new flap tracks. tion of solid aircraft rivets with Cherry- prop clearance on rough fields and allow Glasair Aviation sent us some new MAX rivets, but they can be a lifesaver a higher angle of attack on takeoff and flap track parts, which went together in places where access for bucking is not landing. They add cost (ugh!) and weight quite quickly. It is so much easier to available. If you use these rivets, be sure (double ugh!), but the benefits seem work with new parts out in the open. to also use the Cherry G-27 riveter for worth the cost. After giving them a coat of self-etching best results. Note that these rivets are Gear leg installation is just the same primer, we got down to the task of riv- very strong in shear but not nearly as as it is with the standard gear legs. They eting them into place. The rivets that strong in tension. Any rivet substitution must be aligned and set to let the plane sit held the tracks to the aft spars were deep needs to take this into consideration. level and not have any toe-in or toe-out. inside the cove skins, which forced us With generous amounts of improvis- The tough part of the gear leg installation to create an extra-long rivet set. Our ing, adapting, and overcoming, we man- is drilling the holes for the retainer bolts. airport buddy and Harmon Rocket aged to get four Sportsman flap tracks The trick to making this process easier is builder, Jerry Scott, came to the rescue installed on our GlaStar wings. And we to start the bolt holes in the plane, but with just the right pieces for this task. It didn’t have to take the wings apart to do then remove the gear legs and drill the is very nice to have other airplane build- it. With all of this done, we could install holes in a drill press or milling machine. ers nearby. I can’t even count how many the fuel cells in the wings and reinstall This makes it much easier to keep the times we have either borrowed or lent the center ribs that had to come out to holes straight and to control the speed parts or tools to fellow builders, speed- give us access. and pressure on the drill bit. ing the day’s progress along, instead of At the other end, the project came stopping to track down a special wrench Landing Gear with a leaf spring and Scott 3200 tail- or the one last screw needed to complete A conventional gear arrangement wheel already in place. The tailwheel will a task. This helps offset the travel time (taildragger) was a given in this project. work well after we replace the steering disadvantage of building at the airport The idea is to create a plane with some arms with ones that have bent-up tabs, versus at home. decent short field and off-airport capa- but we are thinking about the Airframes On each wing we did finally get bilities that also performs well in cruise. Alaska T3 suspension. No final decision stuck on one row of rivets where we just This utility performance is the forte of has been made on that yet.
24 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes We used a piece of aluminum angle to get the gear legs level and straight. Here Zaleski checks the gap between the stub axle and the angle to be sure it is the same as the other side. Once the gear is positioned properly, the retaining bolts can be installed.
Aileron Servo Tab was about 2 inches wide and 23 inches Originally the GlaStar suffered from long. An abrasive cutoff wheel works best heavy aileron forces. After a number of for this, since it would have been very complaints, Stoddard-Hamilton came difficult to make the required cuts with out with an aileron servo tab retrofit shears. A quarter-inch pilot hole drilled kit that solved that problem and cre- into the corner before the cut helped to ated very nice harmony between aileron reduce stress cracking from that point. and elevator stick forces. The servo tab Once the notch was cut into the aileron, worked so well that it was carried for- a piano hinge was riveted into place for ward into the Glasair Sportsman when the servo tab. Assembling the tab was very it came out years later. Since this was a straightforward, with standard AD rivets very old kit, it had not been retrofitted used where there was access, and pull riv- with the servo tab, so this was definitely ets used where it was not possible to buck on the to-do list for this plane. standard rivets. The actuating rod and To install the tab, we cut a piece out of pivot placement will be completed when the trailing edge of the left aileron that the aileron gets installed on the plane later.
A 3x23-inch section is cut out of the left aileron and turned into a servo tab. The tab lightens roll forces by acting in the opposite direction of the movement of the aileron to which it is attached. Thus, when the aileron deflects up, the tab deflects down. This downward deflection of the tab pushes the aileron up.
KITPLANES August 2018 25 New Flaps Our experience with the Sportsman flaps made the decision to install them on the GlaStar a fairly easy one. They work much better aerodynami- cally and are much easier to deploy. The original GlaStar flaps take some real muscle power to extend them, especially if you are a little fast. The Sportsman flaps also have a 10-knot higher extension speed. The only prob- lem was, it had only been done once before that we know of, and that case A good way to tell if your drill is straight when drilling into new sheet metal is to look involved wings that were not yet closed at the reflection of the drill bit. If the drill bit and its mirror image form a straight line, up. This would be the first attempt to your drill is going in straight. If it bends where the bit meets its reflection, you need to reposition the drill. install the Sportsman flap tracks and flaps on essentially finished wings. We and drilled for rivet holes. These were in the skin determine the rivet locations were pretty sure it would work, but we then deburred, primed, and riveted after the holes are aligned with lines would have been very disappointed if together. Next, these and the other ribs that must be marked on the underlying our substantial investment in parts and were Clecoed to the main spar, with parts. This isn’t quite as easy as work- time did not pay off. As it turned out, the main ribs also attached to the aft ing with the match-hole drilled parts of the installation went fairly well. spar. All of the holes then got drilled to an RV-12, but it isn’t too difficult. It is Once the wings were completed, we size. After that, everything came apart just important to get started correctly. A were anxious to get to the task of build- for deburring before getting riveted piece of aluminum angle attached to the ing new flaps. It was nice to work with together. We decided not to prime the worktable served as a jig. Once the spar new material after reworking previously internal parts that would not be exposed was checked for straightness, the skin assembled parts. It just goes faster with to any weather to save weight and time. was placed into position, and the first fewer problems. The assembly process With all of that done, it was time hole was drilled at one end and then the is simple enough. First, we attached the to mark the rib center lines and begin other. Next, a hole was drilled near the nose ribs to the flap hinge points and attaching the skins. The spars and ribs middle, and then at the quarter points actuating points. All of these ribs got are not predrilled in either the GlaStar or along the spar line. This prevents the doublers that had to be trimmed to fit the Sportsman. So, the prepunched holes skin from warping or sliding out of posi- tion. Once it is well-secured, the rest of the holes can be drilled. The same pro- cess is used with the ribs and the aft spar. With all of the holes drilled, it is time to take everything apart and deburr everything in preparation for final rivet- ing. This is not the most fun part, but it is very important. Any burs left in place can keep the parts from coming together completely as they are riveted. Once the bottom of the skin is riveted into place, it will be time to flip everything over and work on the top part. Lessons Learned So Far We are relearning the need to go slowly, read the book, and be patient. It has been too easy to just jump in and start working. No major mistakes have come from this, but at least a handful of With both wings completed they get hung out of the way to make room for other work. poorly done rivets have been replaced. The new flaps are next, so we needed room for the 10-foot-long worktable that was This is a lesson that we should have required for that task. remembered from before.
26 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes We installed one of the fuel cells parts you are getting if you are buying a at planning for this, but we still get sur- without the vent tube in place. Too partly completed kit. I did my own pre- prised now and then. many distractions on “social” Satur- purchase inspection, being quite famil- One more surprise was how much days led to missing this important part. iar with the GlaStar and the seller. I gave effort it took to get the debris left inside Unfortunately, the fuel cell will prob- things a pretty good once-over, but not the wings by various varmint guests over ably have to come out to fix this, which good enough. I missed that the brake the years. Their junk is very difficult to means taking out some rivets again. It calipers were not there. This didn’t really get out of the nose section where there is wonderful to have friends come by matter too much because I planned to are a lot of ribs and very limited access. and help or just socialize, but extra care change the wheels and brakes anyway, There were also a few minor corrosion must be taken to prevent distractions but it was annoying to have missed spots in the main part of the wing, but from turning into mistakes. When we something so obvious. The mistake that these were easily corrected with some built the first GlaStar, we worked at really cost money was missing three of elbow grease and a shot of self-etching home until the very end. This meant the four required seat tracks. These items primer. There seems to be no corrosion in that few people came by to chat. With cost $120 each. I also missed the door the nose area, which is really good news. each new project, now all built at the latches, but those will be easy to make. The best surprise has been seeing how airport, more and more friends seem Lastly, we ended up with a lot of miscel- much fun it is to build again when there to come by. It is common for several of laneous hardware that we can’t use and is no pressure to get things done on a us to go to lunch together on Saturday, are missing a lot of miscellaneous hard- schedule. That doesn’t mean we don’t sometimes driving if we are in a hurry or ware that should have been there. This want to finish in a reasonable amount of are short of planes, at other times flying doesn’t cost much in terms of money, but time, but we are not committing to any somewhere nearby. I wouldn’t give this it makes for a lot of extra trips to Aircraft fixed end date. We build when we can for up, but it does present some challenges Spruce to get little things that I thought whatever time we have available. It will that seem to be greater than what we we had. Luckily, Spruce is only a 20-min- get finished when it gets finished. Things had experienced in the past. ute drive from the hangar, but each trip are not going as quickly as I thought they Perhaps the biggest lesson learned is costs at least an hour of build time every would, but they are moving forward at a to really take your time evaluating the time it happens. We are getting better pace that is satisfying. J
KITPLANES August 2018 27 Homebuilt Accidents: When the Prop Stops
For the first flight, the outside of the airplane doesn’t have to be in show-plane form, but the fuel system better be. (Photo: Mark Owens)
Too many accidents start with a stoppage. By Ron Wanttaja
There’s an old joke in the flying problems with the fuel system and prob- built a nest in the tank during construc- community: “The prop is a fan to keep lems with the pilot mismanaging his or tion, which eventually broke free when the pilot cool. Turn it off and watch her fuel supply. immersed in gasoline with the engine’s him sweat.” The biggest culprit for fuel systems? vibrations. Builders should thoroughly As one who has been there, I can Contamination. Primarily, this results in clean the fuel system before the first relate. There’s nothing like stumbling blockage. Fuel lines, fuel up front to get the heart racing. screens, fuel pumps, fuel It’s an all-too-common situation. As sensors, and practically Figure 1 shows, almost a third of all anything else in the fuel Experimental/Amateur-Built (E/A-B) system can get plugged aircraft accidents start with the engine with a foreign substance. stopping. That’s twice as often as the Even fiberglass tanks can Cessna 172. start to delaminate. In this part of our series, let’s take a Often, the blockage is look at why the fans stop turning. related to the construc- tion of the aircraft. Fuel Fuel Issues tank sealants come loose, Figure 2 illustrates why the engines or debris from the fabri- quit for fixed-wing homebuilt accidents cation of the fuel tanks from 1998 through 2016. Fuel issues remains in the system. predominate. They’re split between In one case, insects had Figure 1: Accident-precipitating events.
28 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes Figure 2: Engine-failure causes. flight, and perform a fuel-flow test to tems are probably planned out better. ensure the system can supply sufficient The homebuilt in one accident didn’t fuel in climb attitude. even have drains to allow inspection Even if the first flight is successful, and removal of water from the fuel you’re not out of the woods. Long-term system. In other E/A-B accidents, issues with sealants could occur, depend- the NTSB investigator noted that ing on compatibility with the fuel the installed drains were inadequate, you’re using. If you’re using auto gas, it’s poorly placed, or just not working. important to check for ethanol on every The second-most-common cause of fill. Not all sealants are compatible, nor fuel system issues? Poor workmanship. are some types of fiberglass tanks. Most of these cases appear to be rou- The other aspect of contamination tine oversights: loose fittings, failure centers on the introduction of liquid to safety-wire, and so forth. Others that isn’t fuel. Water, via condensation were due to assembly errors of the gas- or leaking fuel caps, is the most com- colator, fuel pump, fuel valves, or other mon. Nominally, homebuilts should system components. be no worse than production aircraft. The best fuel system in the world won’t However, production-aircraft fuel sys- help if the pilot doesn’t manage it right.
Figure 3: The biggest danger for homebuilt aircraft fuel systems is contamination, either by construction debris or non-fuel liquids.
Illustrations: Ron Wanttaja KITPLANES August 2018 29 Pilot fuel mismanagement kills engines two basic ways: exhaustion (using up all the fuel) and starvation (failing to ensure existing fuel is provided to the engine). One nice aspect is that the accident rates for both of these causes is about the same for homebuilts as for overall GA. The “Experimental” in E/A-B isn’t affecting this category. We’re in the middle of the general aviation pack. However, one interesting result: Homebuilts flown by the original builder have a reduced occurrence of mismanagement. When the plane is still with its builder, about 2.8% of Figure 4: It’s vital to ensure the aircraft fuel system provides a high enough flow rate to total E/A-B accidents are due to fuel satisfy the engine at climb attitudes. exhaustion. This jumps to 4.4% for subsequent owners. Fuel starvation Engine Mechanical Issues safety wire, and so forth—as well as shows the same effect, though the over- When it comes down to actual break- errors in assembly or adjustment. all magnitude is less (1% vs. 1.6%). downs of the engine itself, the category What’s happening? Best guess: The I call “Engine Internal” predominates. Undetermined Engine Failures original builders are more aware of both This covers any engine-related compo- For almost a third of homebuilt loss- the actual fuel capacity and how the air- nent that is not easily unbolted for sepa- of-power accidents, the NTSB does not craft’s fuel system operates. Thorough rate servicing or repair. specify a cause. I refer to this as “unde- builders will have gained insight from About a third of the total mechani- termined engine failure.” the fuel consumption testing recom- cal issues accidents qualify—but this At first, this seems logical—most of mended per the FAA’s Advisory Circu- definition of “Internal” covers a lot the time, isn’t the engine damaged to the lar, AC 90-89. of ground. About 40% of them were extent that any evidence is destroyed? Later owners may not have this top-section (cylinders, pistons, and Actually, no. As Figure 5 shows, familiarity. For instance, the plans for valves) issues. Among the bottom sec- NTSB reports note being unable to the Bowers Fly Baby include a design tion, crankshafts, bearings, and con- inspect the engine due to crash damage for a 16-gallon fuel tank. But many necting rods are mentioned just about in only 11% of the undetermined engine builders merely purchase a 12-gallon equally often. failure instances. In about 25% of the Piper J-3 unit. Obviously, a new owner Builder/maintainer errors factor into cases, the investigator was able to per- of a Fly Baby may get surprised if he about a quarter of the engine mechani- form shop tests of engine health (com- plans a flight without knowing which cal error cases. One sees typical oversight pression, magnetos, fuel pressure, etc.). tank the airplane has. issues—improper torque, improper They’re even able to restart the engine
In the event of an accident involving a homebuilt with a non-standard engine, the NTSB Figure 5: Breakdown of undetermined may not have an appropriate engine specialist available for a detailed investigation. engine failures. (Photo: Ron Wanttaja)
30 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) The condition of both propeller blades is a major clue as to whether the engine was turning at impact. One blade was apparently mangled during the turnover, but the other is intact. (Right) Accidents that result in engine damage so severe a failure cause cannot be determined are actually fairly rare. (Photos: National Transportation Safety Board) after the accident 10% of the time! These made by the Safety Board itself. The A suspected cause is provided—but probably indicate transient phenomena, investigators may include information not acted upon by the Board—in about like carburetor icing or vapor lock—or related to the cause of the engine fail- 9% of the accidents. Again, fuel-related even a pilot who changed the fuel valve ure, but the Board may not consider it issues predominate (almost half). after the accident, due to embarrass- strong enough to attribute the accident One other factor affects the assign- ment or concerns over liability. to that cause. In addition, some infor- ment of probable cause: the availability Investigators don’t make the official mation may come from the accident of NTSB resources. The NTSB’s goal probable cause determination for the pilot, whose suspicions may not be is to detect trends, which if corrected, accidents they handle; this is a decision accepted by the Board. may prevent similar failures of the same
NEW
&
2,000 lb Gross Weight New CubCrafters CC363i Engine Constant-Speed Propeller Greater Range, Higher Speeds
KITPLANES August 2018 31 Broken crankshaft found during NTSB investigation of a Long-EZ accident. (Photo: Figure 6: Undetermined engine failures among common GA types. National Transportation Safety Board) aircraft type in the future. But every and religiously guard the quality of the fuel consumption, its true usable fuel homebuilt is legally unique—insight stuff you put in your gas tanks. capacity, and how to manage it. Docu- from the investigation benefits only This shouldn’t be a surprise. The ment this information. You can find one airplane. Engine installations, even NTSB published an in-depth look at a number of homebuilt aircraft pilot among similar types, are not standard. homebuilt aircraft accident causes back handbooks online to act as a template Non-certified engines are installed in in 2012. A key finding was the recom- for your own. almost half of the aircraft involved in mendation for improvements in build- While engine mechanical issues cer- homebuilt accidents. Finding an issue ing and testing fuel systems. tainly factor into the problem, the basic in one airplane doesn’t mean it exists in A perfect fuel system doesn’t help if, as truth is that they’re “peanut buttered” any other planes built to the same plans. an ex-Air Force maintainer friend called across the entire engine system. Noth- So there’s less reason for the NTSB it, “There’s a short circuit between the ing really stands out. to spend a lot of resources on a typical headphones.” It’s an age-old problem, Actually, one thing does stand out, for homebuilt accident. but mismanaging aircraft fuel is one fine both engines and fuel systems: mistakes Figure 6 shows the results. The old tradition we could do without. made by people turning wrenches. Forty NTSB is unable to come to a conclu- Along those lines is another sugges- percent of fuel issues and about a quarter sion almost three times more often with tion from the NTSB’s 2012 report: the of the engine breakdowns involved faulty homebuilts than for Cessna 172s. The generation of accurate, in-depth pilot construction or bad maintenance. effect of having a traditional engine in handbooks for each homebuilt air- Be smarter building, be smarter main- the homebuilt is obvious. craft. The flight test period ensures the taining, and be smarter flying. Keep that The NTSB is also unable to deter- builder is aware of the aircraft’s actual fan turning, and stay cool. J mine engine failure cause more often for high performance aircraft such as the Bonanza 36 and Cessna 210. This is probably due to more cases of the engine being damaged beyond the abil- ity to inspect it because of the higher speeds of the aircraft. However, the rate of undetermined engine failures for Cirrus aircraft is sig- nificantly lower. My guess is that the ballistic parachutes are saving evidence, as well as lives. Wrap-Up Do you want to keep the fan turning? Maintain the fuel supply to the engine. Clean out construction debris, install recommended filters/screens/sumps, Figure 7: Engine mechanical failures.
32 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes Avemco Insurance Company is a member of the Tokio Marine HCC group of companies. ADS0165 (01/18)
KITPLANES August 2018 33 Oshkosh’s Homebuilt Parking Crew Bringing you safely to final stop…and off again. By Louise Hose
Sunday, July 24, 2016, will remain pilgrims found cozy hotels as close as the but it wasn’t until about noon that true a day not to be forgotten by hundreds, weather allowed and sat out the night, VFR conditions returned to our Mecca. perhaps thousands, of AirVenture par- waiting for better skies in the morn- The clouds parted and airplanes flooded ticipants. The day before, when the ing. When the field opened on Sunday, in from all directions! Oshkosh airport typically ramps up to a a thunderstorm pounded Oshkosh and Many a grizzled aviator arrived on the busy but not crazy flow of aircraft arriv- hundreds of little planes sat on ramps field that afternoon with horror stories als in anticipation of AirVenture’s Mon- and in hangars throughout the upper and frayed nerves. “I’ve been flying into day start, the skies were a dreary overcast. Midwest, awaiting the opportunity to here for over 40 years, and I’ve never The only VFR arrivals came from the take wing toward their destination. seen anything close to the number of north, tipping the percentage of Cana- About 10 a.m., MVFR was creeping airplanes and craziness I saw this after- dians on the field toward an all-time into the Oshkosh area, and a few planes noon,” one factory pilot told me. “When record high. Most of the traveling U.S. trickled into KOSH in the storm’s wake; we were circling Green Lake and saw two
34 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Aircraft greeters ready to welcome arriving pilots and ensure they register their aircraft. (Right) Wim van Malcot (right) of Belgium has been volunteering at AirVenture for four years, the last two with the Homebuilt Parking team. He joined the team by walking into the HBP prep area and volunteering.
planes circling in the opposite direction, to their final destination, maybe a cold and Virginie Jorion have returned for I knew it was time to get out of there.” bottle of water, and a sympathetic ear. several years to direct traffic at North Every person who flew in that day had According to the HBP staff, about 400 Point and various other jobs. In 2017, their own story, and just about every- homebuilts arrived on Sunday in 2016. several Germans volunteered to help. one felt worn and tattered. First-timers Given the short time that the field was Many of the American volunteers speak were at their breaking point. All anyone VFR, that would translate to about one of working with HBP for decades. Jeff wanted was to find a parking or camp- every minute in addition to the warbirds Point, Homebuilt Parking jefe, has been ing site, turn off the engine, and settle. competing for access to the same taxi- working the lines for 19 years. Some of With sheets of white paper declaring way. That day was likely the Homebuilt the regular volunteers started as Ven- their intent (e.g., HBC for Homebuilt Parking team’s most challenging ever, turer volunteers. The Venturer Scouts Camping, HBP for Homebuilt Parking, but it was also probably their finest. are teenagers involved in aviation- etc.), the flow of little airplanes taxiing focused groups affiliated with the Boy up to North Point didn’t stop until the Unsung Heroes Scouts. Some of the Venturers come field closed that night. Despite the long hours, heat, rain, irri- from local chapters, and some travel North Point is the entrance to the tated and tired pilots, mud, and even from distant states to volunteer. They homebuilt and warbird areas. It is a four- cold, volunteers for the Homebuilt are mostly involved with preventing way-stop intersection where homebuilts Parking team return year after year, and pedestrian-aircraft conflicts and helping and warbirds landing on both runways many think they have the best jobs at to flag aircraft to their next intersection. converge. Spam cans landing on Runway AirVenture. Belgians Wim van Malcot Galeb Gish joined five other Topeka, 36L also pass through on their way to the North 40 camping area. To add to the complexity, local homebuilt pilots who arrived on Friday, just to spend the week- North 40 end and help set up, were now looking to taxi out for a departure home to get back to their day jobs. Often, the conflict of traffic was handled by putting arriv- More HBC ing pilots in the “penalty box” (through Warbirds ➜ Penalty no fault of their own), making already ✦ Box North Point exhausted pilots and passengers wait sev- HBP Homebuilt eral minutes with their campsite in sight. Camping Despite all these challenges, the day went off without a significant hitch, thanks to the dedicated and professional volunteers of the Homebuilt Parking More HBC (HBP) team. Every frazzled pilot found a parking and/or camping spot, infor- mation on camping or obtaining a ride Airport diagram showing Homebuilt Parking and Homebuilt Camping areas.
Photos: Louise Hose KITPLANES August 2018 35 Each plane is escorted to parking by a scooter-mounted rider. Kansas, Venturers in 2017 to work his years as a volunteer, taking vacation second year at AirVenture. The kids time from her manufacturing engineer camp out next to the warbird area job with Pratt and Whitney. and swap stories and experiences with other aviation-minded teenagers. Ali- Arrivals cia Walby volunteered at AirVenture When a homebuilt arrives with their for five years while a Venturer with sign requesting either HBP or HBC, the Post 9924 in Appleton, Wisconsin. entire field seems to mobilize to direct She also had a part-time job load- the pilot to North Point, where they are ing FedEx trucks at the airport urged to take the taxiway west. A scooter while in high school. She went to or UTV (utility task vehicle) will take the college at Michigan Technological lead on the left side, escorting the aircraft University and earned a bachelor’s to the appropriate row, then turn into the degree in mechanical engineer- grass and guide it to a parking spot. The ing while continuing to volunteer scooter driver will hop off the scooter and with HBP as an adult volunteer. signal the pilot when they reach the exact A masters degree from Rensse- spot. If the airplane shuts down in HBP, a Each pilot is given a laer Polytechnic Institute followed. She golf cart generally follows, part of the air- helpful checklist upon arriving. continues to return to AirVenture most craft greeters contingent, and the scooter Ten Things to Know About Homebuilt Parking 1. Read the NOTAM! Everybody flying into Oshkosh for AirVenture must 4. Homebuilt Headquarters Usually Has a Few Hammers. read the NOTAM before arriving and have it handy. No excuses! Havoc Homebuilt HQ is where you will register. But the hammers can invariably reigns around those who just won’t heed this advice. be hard to track down. It’s better to bring one with you if your 2. Have Your Signs Ready. The easy way to prepare your signs is to tie-down system needs one. The same is true with a long lever for go to https://tinyurl.com/osh-signs and print out the appropriate screwing in tie-down anchors. signs. Then, carry them in a handy place so you can grab them as 5. You Can Order 100LL and Avgas Fueling at Your Parking Spot. soon as you leave the runway at KOSH. Similarly, have your VFR or It’s a great convenience to be able to fuel your plane at your parking IFR sign ready when you pull your plane out into the grassy lane spot or campsite. Your greeter has the cards to fill out and rubber in preparation for departure. If you are like me, you might lose bands to put it on your prop. It is especially helpful if you fly in the the carefully prepared departure sign during the hectic week. No Homebuilders’ Review or photo missions burning fuel during the problem, pull out your barf bag and write big, dark block letters on week. However, I always prefer to stop for fuel about a half hour it with your pen or marker before moving the plane. It works! But to an hour before arrival at KOSH for fuel and a bathroom stop. don’t ask me how I know. The price is usually cheaper, but more importantly, I have a huge 3. Bring Hefty Tie-Down Anchors and Ropes/Chains. No margin if I’m forced into a holding pattern due to heavy traffic wimpy dog pins will do. Even if you don’t particularly care about or field closure (due to an incident or accident). This practice also the durability of your own plane, your neighbor will undoubt- means I arrive without the need to rush off to empty my bladder, edly feel differently. so the tie-down and registration process goes much smoother.
36 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Safely taxiing while holding up your destination sign can be a challenge if no passenger is along, but it is essential to smooth parking operations. (Right) Most pilots are offered a bottle of cold water when they leave the cockpit, an especially welcomed treat on a hot day. driver heads out for his or her next escort. now not only has to manage arriving of planes around the field, but the HBP The greeters provide cold water, a handy and departing homebuilts and warbirds, staff can still be busy ensuring planes are shut-down list, the phone number for the but the kit manufacturer factory pilots securely tied down and folks remain safe. Welcome Wagon, a fuel tag (if needed), give hourly demonstration rides dur- and answer any questions. They also want ing the show, the two Ford Tri-Motors Departures to ensure that the plane gets securely each taxi in and out for passenger rides About Tuesday, the focus shifts from staked and tied down to protect the sur- about twice an hour, and the warbirds arrivals to departures. Scooters troll the rounding planes if a wind shear comes frequently go in and out to strut their taxiway, looking for planes pulled out through the area. In Homebuilt Camp- stuff in the air. All of them pass through from their parking spaces and pointed ing, the greeters from the Homebuilt North Point each way. The HBP team’s toward the way out. No engine starts Camping crew similarly greet arrivals and only reprieves during the entire nine until the escort arrives. Then the process help provide an orientation to camping days are between 8 p.m. and 7 a.m., reverses as the scooter driver escorts the next to the plane. Once the pilot seems prescheduled mass arrivals of Mooneys, plane to North Point, and flaggers point settled and comfortable, everyone is off to Bonanzas, Cubs, and others headed for the way to the departure end of one of greet and help the next arrival. different parts of the field, and afternoon the runways. While arrivals are strongly Arrivals slow on Monday, but North airshows. Airport closures following concentrated on the weekend before Point becomes a more complicated oper- incidents and accidents, as well as bad AirVenture opens, departures tend to ation during “the show.” The HBP crew weather, might also slow the movement be scattered throughout the week. A
6. The Welcome Wagon Will Take You Where You Want to Go on their wings. The latter group commonly have strong opinions Site. The greeter will have their phone number, and EAA Chapter 91’s about where they want to be in this large field…near the show- Welcome Wagon will take you to pick up your rental car at the FBO, ers, near the pavilion, as close as possible to the flightline…and grab lunch at restaurants adjacent to the field, or haul your camping the parking staff has recently attempted to accommodate those gear over to Camp Scholler. They are also available during the week requests through hand signals. The system is informal, but look to help folks who arrived in homebuilts get around to these places or for information in homebuilder’s online forums in the weeks carry their gear back to their planes. It’s a great service. Be sure to fill leading up to AirVenture. (We are reliably told that a single middle their tip jar as that’s how they maintain the vehicles. finger does not help ensure parking of your choice!) 7. Write Down Your Parking Row Number. Registration will 9. Do Not Start Your Engine Until an Escort Arrives. Also, no want to know it, and should you want to meet someone at your operating engines are allowed during the airshows or between plane or get some on-site assistance from a vendor, you’ll want to 8 p.m. and 7 a.m. know it, too. 10. None of the HBP Staff is Paid. These volunteers give scores of 8. There Are Two Formally Divided Homebuilt Areas. The hours, take vacation time from work, and spend a lot of their own eastern part of the area is reserved for Homebuilt Parking (HBP). money to provide this great service. No matter how cranky you feel These folks stay in hotels, dorms, private homes, or camp in Camp after a stressful flight or a tiring week, please be kind and thank them Scholler and such. The western, larger area is Homebuilt Camping for what they do for all of us. Volunteers are only paid in gratitude. (HBC), where pilots and passengers camp in tents under or behind —L.H.
KITPLANES August 2018 37 (Above) EAA added the much-welcomed Homebuilders’ Pavilion at the west end of Homebuilt Camping in 2017, complete with tables, benches, barbecues, and charging stations. (Right) Homebuilt Parking staff’s fun meter. few years ago, there tended to be a mass been consistent with a 22% increase in stronger. We all owe a debt to the fine exodus of homebuilts about Wednes- Homebuilt Camping between 2006 folks who welcome us at the end of day, but the HBP staff says more folks and 2016. These figures do not include our pilgrimage to Oshkosh and then are staying longer, and the flow out of Homebuilt Parking and the many send us safely on our way. Sometimes the area is generally less frenetic. None- homebuilts scattered on display across we forget to thank them in the tension theless, by the final weekend, homebuilt the entire AirVenture grounds. There of the moment before they rush off to camping and homebuilt parking resem- also are always a few “slumming it” in escort the next plane, and of course we ble ghost towns…mere shadows of the the North 40, in order to camp with can’t stop at North Point to do so. But glory days earlier in the week. less-fortunate friends. the next time you see someone with the Homebuilt aircraft are the fastest Many, including myself, argue that fun meter on their shirt, you are prob- growing segment of general aviation, the homebuilt community’s participa- ably talking to an HBP staffer. Please and the demand for Homebuilt Park- tion is the heart of EAA, and if that’s thank them for what they do to make ing and Camping continues to grow, true, the heart is healthy and growing AirVenture a great experience. J while some other areas are shrinking. EAA has said that no homebuilt air- craft will be turned away from land- ing at AirVenture, even when parking on the field is at capacity. They make room for all of our “show planes,” even when certified aircraft are told to land at other fields. Thus, our geographic domain has expanded, along with the HBP crew’s workload. The peak so far was 2016, in large part because Van’s Aircraft celebrated the 30th anniversary of the RV-6, the world’s most popular (Above) Friday before. Line markers are ready for the next day’s rush. (Below) The field is kit, and hundreds of -6 and -6A own- close to capacity by the end of most Sundays, but AirVenture says they never turn away ers made sure they brought their planes a homebuilt. (Be sure to let the controllers know you are in a homebuilt if they ever tell to the party. But the upward trend has you otherwise.)
38 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes CHOOSE
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CM_US_TITAN_GREY_200x265.indd 1 02/05/2018 16:16 Going Retractable
The SubSonex steerable nose gear is custom built by Sonex.
40 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes The ups and downs of retractable gear. By LeRoy Cook There may not be a really strong ben- drag-reduction advantage, in order to An electrically driven gear system efit to be gained from putting retractable maximize speed and range, we opt to fly uses a set of straight-run torque tubes landing gear on an airplane, but most with our wheels up. But in the final anal- to swing the gear, driven by a centrally builders and pilots have nevertheless felt ysis, we do it because we want to. Even mounted motor and transmission (or the heat of desire when a sleek retract- though a well-designed set of skinny chain drive), typically bringing the able-gear aircraft cruises past. That fixed landing gear can approach the drag main gear inboard and the nose gear cleaned-up airframe just looks right. reduction of simple open-well retractable aft during retraction. There must be a Flipping the gear switch or handle to wheels, it’s just not aesthetically the same. provision to disconnect the motor from “up” delivers a satisfying severance from Every Piper Cherokee owner wants an the system to allow for a manual backup the ordinary mortals who are stuck with Arrow, even if he won’t admit it publicly. extension, in case the drive mechanism dragging their wheels out in the breeze. locks up. Seldom do such backup sys- In truth, economics and common Putting It Together tems provide for retraction. sense support fixed gear. When Cessna It makes sense, however, to carefully Designers of hydraulic gear systems put retractable landing gear under the weigh the pros and cons of retractable have the advantage of being able to 182 Skylane, it picked up a mere 12 gear. From a design standpoint, we have run the lines carrying pressurized fluid knots of top speed (as measured by the to provide for a means to actuate the through Byzantine twists and turns, brochure), but the mod added nearly gear’s retraction and extension, which around corners, and through bulk- $20,000 to the base price, in 1978 inevitably adds complexity and extra heads, terminating with an actuator at dollars. A Glasair Super II FT (fixed weight. There are three common meth- each gear leg to motivate the gear in and tricycle) homebuilt can cruise at 210 ods of moving the gear up and down: out of its wheel well. The engineer is mph, barely 11 mph slower than the RG manual, electric, and hydraulic, the lat- thereby freed from having to find a way version of the same design. There will ter sometimes involving an electrically to route a stiff actuating tube through be weight and maintenance penalties to driven pump. A simple manual system, a wing or fuselage. A source of pressure be considered when installing retract- using a lever or crank to move the gear, for the hydraulic fluid can be an engine- able gear, and rough field operation requires smoothly operating linkages driven pump, an electrically driven should be avoided to a greater degree, and strong mechanical advantage to power pack, or even a hand pump. The given all the added stress on wear points avoid overtaxing the pilot’s strength. In weakness of hydraulics is loss of the sys- like joints and linkages. most cases, no backup extension method tem’s fluid. Proper design makes provi- And so, why do we do it? In the spirit is provided, the manual system suppos- sion for a standpipe, separate from the of innovation, seeking to maximize every edly being failure proof. main reservoir, that will retain enough
(Left) The landing gear indicators on the SubSonex jet are LEDs located above a guarded toggle switch. (Right) The SubSonex main gear features two tires per side—just like the Space Shuttle and many large aircraft.
Photos: Richard VanderMeulen and Doug Henson KITPLANES August 2018 41 fluid for an extension cycle if a rupture not locking into position, but when a occurs elsewhere. Most often, hydraulic landing occurs with all the wheels up, pressure holds the wheels up, so emer- it’s more than likely an “oops.” Later on, gency extension can be done by releas- I’ll be telling you about how I made my ing the trapped pressure and letting first gear-up landing. gravity do its work, but springs may be It is not true that every pilot flying needed to move forward-rotating gear a retractable will eventually slide to a legs over center to securely lock down. stop on the airplane’s belly. We can, A standby “blowdown” bottle of com- and we must, take measures to make pressed gas is used in some systems to sure it never happens to us. A properly force the gear into place. designed retractable gear system will However the gear system works, it include mechanical or illuminated posi- needs regular attention, including plac- tion indicators, actuated to show a gear- ing the plane on jacks and observing its down indication only when the cycle is cycle, in order to keep it rigged properly fully complete. To make sure the pilot is and check for wear in bushings, joints, aware that the wheels are still up during When retracted, the main landing gear on and attachments. Gear doors, switches, a landing approach, a throttle-actuated this Velocity is almost entirely concealed and motors are subject to periodic switch should sound a warning tone if by simple gear doors. adjustment and maintenance. Fixed power is reduced below a throttle posi- gear, on the other hand, is largely forgot- tion corresponding to 12 to 15 inches break in the normal routine, a distrac- ten about between tire changes. of manifold pressure with the gear up. tion, or a hurried approach, the warn- Recently certificated airplanes will also ings and indications may be overlooked. There’s Those Who Have… have a flaps-extension warning that actu- Headsets can do a fine job of masking a And Those Who Won’t ates when flaps are extended beyond the weak warning horn. Misoperation of retractable gear, approach setting with wheels retracted. You might habitually do the GUMP resulting in a gear-up landing, adds to These are all excellent safeguards, thing abeam the airport, but what insurance costs and affects resale value but the ultimate safeguard has to be a about those times when you don’t fly of the aircraft. While mechanical fail- participating pilot. It is not enough to a downwind? An unexpected traffic ures do account for some of the gear-up say “I always do a GUMP (gas, under- conflict might require a reapplication landing incidents, most of the time it’s a carriage, mixture, prop) check on the of power during a spacing turn, silenc- simple lapse of pilot attention that con- downwind leg” or “I never fail to use ing the gear-up throttle switch. Doing a tributes to an ignominious termina- the checklist.” Gear-up landings occur go-around heightens the risk of landing tion of the flight. System failures might because we didn’t pay attention, despite gear-up on the next attempt; because manifest themselves as having one gear the checklist. When we encounter a you were distracted by the sudden
(Left) Velocity nose gear viewed through an access panel. In flight, the gear is completely covered by tight-fitting doors that match the contours of the forward fuselage. (Right) A large toggle switch on the panel raises and lowers the gear on this Velocity.
42 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes The transition from draggy gear-down configuration to sleek, fully enclosed gear-up turns the Lancair into an entirely different airplane. (Photos: Doug Henson) reversal of fortunes, you may think you descending to pattern altitude, passing double-checking. An abnormal reduc- left the gear down, but you didn’t. the final approach fix, or lining up on tion of power to stay on the glideslope A friend of mine had to reposition a base leg or a long straight-in final. Any- probably means the gear isn’t down. few miles from one airport to another time landing is on the agenda, putting No matter what I’m flying, I always sit after a long day of flying. In his tiredness, the wheels down is a priority, earlier up straight and do a short-final check of he intended to leave the gear down as being better than later. landing readiness. Is the gear down? Is he essentially flew a parabolic arc across Moving the gear control is not equiva- the prop pitch set for go-around power? town. Instead, his right hand followed his lent to extending the gear; check that Did the tower give me a “cleared to land”? regular habit: gear-up, power to cruise- the wheels actually made the trip, noting You may not always fly a downwind leg climb, prop pitch tweaked, trim rolled the “gear down” indication and passive or base leg, but you always have to fly in. He didn’t verify gear-down because backups like mechanical indicators and down final. Make that short-final check he knew it was already down—until the gear-position mirrors. Any pilot familiar as the end of the runway approaches. prop blades bit into the concrete. with his or her aircraft should be able to In any checkout involving retractable Extension of the landing gear should tell by the added drag, noise, and trim gear operation, I invariably obscure a be done anytime the destination air- change that the gear has extended. In the gear-down indication while the student port is neared: entering the pattern, absence of such normal changes, start is distracted. I can turn down a dim- mable green light, flip the instrument lights to low-intensity night mode, or just hold my hand over the indicator. If the student fails to look for a gear-down indication on short final, the landing is deemed unsatisfactory. He or she should have gone around to trouble- shoot the problem. Having said all this, I will now tell you about my first gear-up landing. I flew a perfect approach to the touchdown zone, I leveled off normally, I eased the yoke back to reach the right attitude, and then let the aircraft settle onto the surface. The touchdown was as smooth as glass, and as I came to a swift, sliding stop, I opened the Lake Amphibian’s windshield to dabble in the water lapping at my elbow. Then I grinned and asked my instruc- tor, “Can I do that again?” No, I haven’t Small gear doors and fairings help clean up this Falco’s belly and wings. made a gear-up landing on a runway. J
KITPLANES August 2018 43 Learning from the Pros By Eric Stewart
Prepreg Kevlar sandwich core practice layup used in an Abaris training course.
This is the final article on composites experience) would consider the impor- My own learning in the area of com- and experimental design for the time tant things to know (a lemma of Rums- posites has been largely apprentice-based, being. I hope you’ve enjoyed the series. feldian epistemology). That is one of the with several months spent in others’ I’ll continue to have articles on various advantages of formal education: there is shops, supplanted by textbooks, trade projects in the future on a less regu- a generally agreed body of knowledge in journals, and my own in-shop experi- lar basis. To finish up, I’ve reviewed a which a student is expected to exhibit mentation. I felt like I had a good grasp couple of training classes I was able to some degree of competency. While I of the techniques and technology, but attend, and I’ve compiled a final “tool think self-guided learners can certainly had a nagging feeling of doubt: What if list” for prototyping with composites. achieve such competency on their own, the pros at, say, Boeing had a totally dif- the risk that there will be some areas in ferent approach? Doubts in mind, when Abaris Composite Training their competency that remain patchy is I ran into the Abaris Training booth at One of the problems with self-guided arguably higher than in a formal pro- CAMX (Composites and Advanced learning (of the kind I’ve espoused in gram with an accredited curriculum. Materials Expo) last year, I thought this these articles) is that you don’t always At least that’s been my experience with would be the perfect opportunity to get have enough experience to know if what too many years in both the formal and some industry training and see if I was you know is what others (with more informal education arenas. on the right track—or seriously derailed.
44 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Students work in pairs on their layups. One of the great aspects of the Abaris’ group approach is that every fabrication lab is an experiment: each group is instructed to do a slightly different layup, with the results inspected the following day. (Right) These unidirectional prepreg layups were an introductory fab lab and show how the symmetry of a layup can affect part warpage. (Full disclosure: Abaris waived their Although Abaris obviously real- layup schedules (symmetry, balance usual class fee so that I could attend, izes that composites are used in many and nesting), and nomenclature. In the with the understanding that I would industries, the company itself is rooted afternoon, the class divided into teams write a review for KITPLANES read- in the aerospace industry (they are an of two, with each team fabricating a ers. Like most journalists offered free- offshoot of the Lear Fan project), so that 4-ply 5x7-inch coupon of unidirectional bies to review, I always hope that what is the reference point for most discus- prepreg carbon fiber to illustrate the I’m getting is good stuff so I don’t have sions and fabrication/repair techniques. importance of symmetric ply stacks. to pan something. No problem with that That makes for a good foundation, since This gave everyone an introduction here—Abaris training was fantastic.) aerospace probably sets the highest bar to using prepregs, the importance of Abaris offers about 10 classes each for fabrication processes. There is an maintaining cleanliness, and accounting in three categories: engineering, manu- assumption of a base level of familiar- for materials (to avoid inclusions). Each facturing, and repair. Their most popu- ity with composites terminology, which team used a different layering method lar course is the M1/R1 course, which might be confusing to complete begin- in order to experiment with how that focuses on the fundamentals of com- ners, but the instructor checks in with can effect part warpage. The coupons posites manufacturing, but also includes the students frequently to assess under- were prepped for cure in the oven, with an introduction to repairs as well. Our standing—classes are less a lecture and Bill explaining the various components class, held in Reno, Nevada, had approx- more a guided discussion. of the bagging system (peel ply, perf, imately 16 students, evenly divided Classes are about 60% theory and breather, etc.). The day finished with all between industry (SpaceX, Stratasys, 40% hands-on fabrication. On Day 1 eight teams’ coupons being loaded onto Virgin Galactic, Euro-Composites) and our instructor, Bill Kinard, covered a caul plate for cooking that evening, in government (USAF, New Zealand AF, the basics of composites including fab- order to be examined the following day. Turkish Ministry of Science), with a ric types and weaves, matrices (i.e., the Day 2 opened with a discussion of couple of independents thrown in for “glue” that holds composite fabrics like health and safety, followed by an explana- good measure (myself and a paddleboard carbon fiber and fiberglass together, tion of vacuum bagging. Once we finished maker from Hawaii). such as polyester and epoxy resins), with classwork, we headed into the lab
(Left) Students performing a vacuum bag operation. Techniques being demonstrated include proper bag pleating, use of a vacuum gauge to determine quality of bag seal, and inclusion of thermocouple to monitor curing temps. (Right) Students load vacuum bagged sandwich panels into an oven for curing.
Photos: Eric Stewart KITPLANES August 2018 45 Monkey see, monkey do. (Left) Instructor Bill Kinard shows students the proper method of scarfing a sandwich panel for repair. (Right) Students have a go at it themselves. and discussed the results of the previous morning, followed by Bill’s discussion get hands-on experience with all the dif- day’s experiment. After lunch, teams did a of sandwich cores. This was followed in ferent types of composites. wet fiberglass layup, with each team using the afternoon by each team fabricating Day 4 started with an inspection of a different bleeder schedule (quite similar two sandwich core panels, one foam the sandwich panels made the previous in fact to the experiments I described in with prepreg fiberglass and the other day, looking for delamination, ply ori- my May 2017 article, “Coupon Testing, honeycomb with prepreg Kevlar. As you entation, and skin quality (i.e., bridging Part 2”) to illustrate approaches to vac- can see, each fabrication day involved a issues, etc.). Then it was back to the class- uum bagging and fiber/resin ratios. completely different material and fab- room to discuss methods of diagnosing On Day 3 we discussed the results of rication process, which I think is an and repairing damage. Each team’s fiber- the previous day’s experiments in the excellent opportunity for students to glass coupon from the previous day was Tools for Composites Back in the August 2016 issue of KITPLANES®, in “Best Practices—Hand 3. Layup table (for small projects or flat panels)—tempered glass is Tools,” Dave Prizio covered the basic tools necessary to set up shop for easy to clean. building an airplane. The tools he mentions are for any type of aircraft, 4. Vacuum system: pumps, tubing, connectors, valves, through-bag regardless of construction. Below are some additional tools that are connectors, vacuum gauges. particularly useful for composites work. 5. Safety equipment: respirator, nitrile gloves, safety glasses, and 1. Cutting table with self-healing plastic mat (Rhino 5x8 feet or dust masks. longer). Be aware that most rolls of fabric come in 50- or 60-inch 6. Tool cleanup tub: white vinegar denatures uncured epoxy. Acetone widths. Plan your table size accordingly. is the go-to cleaner before curing. To clean off cured epoxy, use paint + OLFA cutter and 6-foot straightedge. stripper (methylene chloride). + Scissors: Kai 7300 for fabrics, Clauss 18425 Kevlar shears, cheapo 7. Releases: scissors for everything else. (Even if you don’t use Kevlar, Clauss a. Mold release wax (Meguiar’s #8). shears are nice since many fabrics use a Kevlar selvage thread that b. Packaging tape. can be a real pain to cut with regular scissors.) c. PVA—shoot with Harbor Freight detail gun (6.75-ounce touch- 2. Sanding blocks: up air spray gun). a. Straight aluminum channel from metal supply store. 8. Dremel 4000—for trimming, grinding. Extra sanding drums can be b. Dura-Block 7-piece sanding kit (AF44L). purchased on Amazon. c. Adhesive sandpaper: RhynoDry White Line rolls, 40/80/ 9. Silver Sharpies for writing on carbon. 120/220 grit. —E.S.
(Left) Dremel with accessories. Sanding drums are great; buy the variety pack of replacement drums with various diameters. (Middle) Cutting tools. (Right) Sanding equipment. RhynoDry adhesive-backed sandpaper on rolls works great (get the white paper, not the red). You can make long, flat sanders from aluminum angle, cheap from the local metal store.
46 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) Finished scarf repair of sandwich panel. (Right) The class briefly looked at portable heaters used for onsite composites repair. These are used in the repair-focused classes. “damaged” with a hole drilled in it, fol- engaging. In addition, I have had rela- than taking Abaris’ M1/R1. In all hon- lowed by a repair, which allowed teams tively little experience with prepregs, so esty, I can’t imagine how Abaris could to decide their own bagging methodol- it was great to get a chance to use those improve on the program or the amount ogy to test knowledge gained from the materials. I also enjoyed chatting with of training they deliver over five days. I previous three days’ experiments. The my classmates about their own experi- wholeheartedly recommend the class. day ended with a discussion of mechani- ences using composites, which I think is For more information and pricing, cal fasteners (like Clickbond) and envi- one of the big plusses in these kinds of visit www.abaris.com. KITPLANES® ronmental considerations. continuing education experiences. readers can get a $200 discount on Day 5 began with each team explain- I mentioned earlier that the theory/ Abaris’ Phase 1 class by mentioning ing the repair methodology they had hands-on ratio was about 60/40. While this article. You’ll need to enroll by used the previous day, followed by band I can’t speak for other industries, to phone to do that; call 775-827-6568. sawing the coupons in half to inspect me this is the perfect ratio for a home- a cross section of our plug-and-scarf builder looking to do a crash course Micro-Measurements repairs. This was followed by a short preparing to build, say, a Lancair or Strain Gauge Training discussion of tooling, non-destructive other composite ship. While some Several months before taking the Abaris testing and, finally, an ungraded, open- builders might think the theory is less class, I was able to take a similar con- book “test.” Missed questions were a important, the fact is that you will get tinuing-education type engineering final opportunity for students to have plenty of hands-on experience as you class offered by Micro-Measurements, Bill re-explain whatever concept the build. On the other hand, theory is a subsidiary of Vishay Precision Group question was testing. what many builders lack (and manuals that specializes in strain gauges. For me, although only about 10% often don’t cover) and is, in my opinion, Those of you who attended the Reno of the material in class was completely quite important for understanding why Air Races may have seen the TECAT new, the class was a validation that my we do things the way we do them. The Performance Systems table set up in one self-guided learning was essentially Abaris class starts you off with industry of the sport class hangars. TECAT is a identical to what I saw in class. And best-practices habits. For someone who wireless torque measuring system that it speaks to the quality of the instruc- wants to jump into composites head is moving from automotive applications tion that, although the class was mostly first and get going as quickly as possible, (namely manufacturer testing and auto review, I still found it extremely fun and it’s hard for me to imagine a better way racing) into aviation by offering a system
Strain gauge bonded to Lycoming crank- shaft for TECAT installation.
KITPLANES August 2018 47 (Left) The M-M student kit includes a large 3-ring binder with copies of all PowerPoint slides used in the class, a strain gauge calculator and quick lookup guide, tech notes, and tips. In addition, all the equipment for in-class gauge bonding is included—gauges, adhesive, soldering iron, etc. (Right) Bonding a gauge onto a composite surface (fiberglass PCB). that provides in-flight crankshaft torque is even more theory intense, although end of the coupon and measuring strain (and thus, with rpm input, horsepower this stands to reason since there are with a data-acquisition unit). to a cockpit interface). This to me looks numerous factors that can throw off Because the aluminum coupons used like the way of things to come, and I the gauge readings if not installed/ have a known modulus of elasticity, com- introduced a few people to TECAT just compensated correctly, so a good basic paring the readings given by our gauge because I thought it was super interest- understanding of how strain gauges installations revealed errors that could ing. Well, next thing I knew, TECAT work is essential for good installation affect the installation (i.e., too much had sold a couple of units and needed and troubleshooting. glue under a gauge, failure to properly someone to do on-site aviation installs, On the morning of our first day, remove soldering flux residue from the and asked if I’d like to help them out. we went over the theory and history solder tabs, etc.). Before stopping for the This required that I take the Micro- of strain gauges and discussed how to day, we bonded a second gauge to a com- Measurements class to become familiar select the appropriate strain gauge for posite coupon of G10, otherwise known with strain gauges and their installation a particular task, which adhesive to as breadboard or PCB (printed circuit (the TECAT system uses M-M strain choose, and how to prepare the test sur- board). The adhesive used for this proj- gauges). As with Abaris, I was able to face to which the gauge will be bonded. ect was a room-temperature-cure epoxy get the class fee waived in exchange for We then started a lab project, bonding that needed an overnight cure. offering to write a review of the class. our first gauge to an aluminum coupon On the morning of Day 2, we contin- And again, I feel no conflict of interest using a high-performance cyanoacry- ued with the second project. We again here because the M-M course was, like late (similar to Super Glue) before stop- hung a weight from the cantilevered the Abaris course, absolutely fantastic. ping for lunch. After lunch we discussed coupon, checking the quality of our They pack a lot into a two-day course, instrumentation, followed by finishing installation against a known value, and and I could feel my brain stretching the lab project (soldering on the wiring comparing/troubleshooting problems by the hour. Compared to the Abaris and checking/comparing our installa- that appeared in anyone’s coupon. This class, the Micro-Measurements class tions by cantilevering a weight from the was followed by continued discussion of
(Left) Students have the opportunity to install gauges to both metal and composites. (Right) Gauges are connected to a data acquisition unit to allow students to test the quality of their install and also illustrate factors that can lead to measurement error.
48 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes instrumentation and how to correct for errors induced by temperature, etc. Although there is somewhat more theory in the M-M class, this made sense Unairworthy since most of it was related to how vari- ous environmental factors could cause reading errors, and was thus connected to the actual performance of instal- lations. Due to the high sensitivity of these instruments, good installation procedures are a must. Like the Abaris class, the M-M class was attended by a mix of industry and government, including SpaceX, the U.S. Navy and Air Force, Stanford University, Google, Specialized Bicy- cles, and other Silicon Valley folks (the class was held in San Jose, California). Class size was about a dozen, and was Unlabeled Lights held in a hotel conference room over All lights and controls in the cockpit are required to be labeled. Imag- the two days. The pace was fast, but we ine a pilot’s surprise when either the red light or white light on this panel had plenty of breaks, and lunch was pro- illuminates in flight! Is it time to switch tanks, or did the oil pressure just vided in the hotel, so we could quickly go out of limits? Is a door open, or is the alternator dead? Without know- get back to work afterward. It was like ing the answer, the potential situation could pose a serious problem. J drinking from a water hose, but if you —Vic Syracuse like to learn, and work in a busy indus- try, that’s not such a bad thing. Although I think strain gauges are super cool, and there is no doubt that instrumenting your airplane could pro- vide you with some interesting insights, I’ve featured the M-M class not because I think the average KITPLANES® reader is particularly interested in strain gauges, but because I think this type of class can really add another dimen- sion to your homebuilding experience. Even if you only go to an EAA course at Oshkosh, do go. You can check out M-M’s great blog, www.strainblog.com, which talks about all the cool projects that have used strain gauges. Who knows, you might be inspired! Pricing can be found at https:// tinyurl.com/ho9k9eo. Well, that’s it for this series! I hope you enjoyed following the various pro- totyping and testing methods we’ve discussed and how experimenting can help you build a better plane. The test- ing continues in my shop for sure—by the time you read this, I’ll be hosting my fourth summer of interns, and hope- fully we’ll have some interesting data again to report in the future. J
KITPLANES August 2018 49 BEST PRACTICES Fabric Covering Even though aluminum is by far the most popular material used as the skin of an airplane, there has been a resurgence in the popularity of fabric covering that parallels the growing interest in Cub-like kit airplanes. The experimental builder will find a number of fabric covering sys- tems to choose from, but most of them use very similar procedures. The two big- gest departures from standard practice come from Stewart Systems and Oratex, but even they incorporate many of the same basic practices as the more tradi- tional systems. For those who are doing historically accurate restorations or rec- reations, systems using Grade A cotton or linen may be required, but we will not deal with those here because they are The author’s Texas Sport (Legend) Cub. A combination of Poly-Fiber fabric and Air-Tech not popular with experimental builders. paint and primer produced a great looking fabric job. Note: Do not assume mixing When considering best practices, products from different manufacturers will produce good results. Do your research first. (Photo: Marc Cook) the system manufacturer’s installation instructions should be your primary up slightly to encourage good adhesion 100% of all the old fabric and adhesive. source of information. Applying things of the primer coat. After that, the tubes MEK solvent usually does a good job of learned from previous experience with a or wood structure must be coated with removing fabric and glue, but if there is a different system may get you into trouble, something that is compatible with the lot of flaking paint or rust present, proper if you ignore the unique requirements of fabric system being used. This is typi- cleanup may require extensive sand- the system you are currently using. You cally an epoxy primer of some sort. If ing or media blasting. Old paint does simply can’t know what best practices are tubes are going to be exposed to view not need to be removed if it is in good if you don’t read the instructions. after covering, now is the time to apply condition, but all fabric and rust must be a compatible color coat over the primer. removed and bare metal primed before Preparation In all cases the tubes or wood being proceeding with a covering job. Good preparation of the surface to covered need to be protected from rust If you have any dents in leading edge which the fabric will be attached serves or rot. They then must also be coated surfaces or other areas that you do not as the basis of any good fabric job, with a product that is compatible with want to see when the plane is covered, regardless of the system used. Good the adhesives in the covering system. now is the time to take care of them. preparation means that all dirt, grease, Consult the manufacturer’s literature for Use an aviation-type filler as per the and any other deleterious material must specific recommendations. fabric system’s recommendations for be removed. Even brand-new tubing If you are recovering a previously this (usually an epoxy filler). Do not use will need to be cleaned and roughed covered structure, be sure to remove automotive Bondo.
Dave Prizio has been plying the skies of the L.A. basin and beyond since 1973. Born into a family of builders, it was only natural that he would make his living as a contractor and spend his leisure time building airplanes. He has so far completed three—a GlaStar, a Glasair Sportsman, and a Texas Sport Cub—and is helping a friend build an RV-8. When he isn’t building something, Dave Prizio he shares his love of aviation with others by flying Young Eagles or volunteering as an EAA Technical Counselor. He is also an A&P mechanic, Designated Airworthiness Representative (DAR), and a member of the EAA Homebuilt Aircraft Council.
50 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes Anti-chafe tape gets applied to sharp corners and small protrusions such as rivet or screw heads before any fabric gets installed. The last preparation step is the appli- Superflite as the solvent-based systems, cation of anti-chafe tape. This goes at the water-based Stewart system, and sharp corners and over screw or rivet Oratex, which is a unique system that we heads or other small projections. There is will address later. The main difference no set rule for the use of anti-chafe tape, between these systems is that the Stew- but it is important to protect the fabric art system uses water-based adhesives from anything that could cut it or easily and paints that are more environmentally wear through. Never use masking tape, friendly and less toxic. I don’t know that duct tape, or aluminum tape as a replace- any of these systems can claim to repre- ment for anti-chafe tape. sent best practices over the others. They are all good products that can achieve Select a System good results if used properly. If we eliminate nitrate and butyrate dope- They all use the same basic polyester based systems as an option, something I fabric, but with subtle differences in the would strongly recommend unless there case of Superflite. The Stewart system is a very good reason not to, we have uses Superflite fabric and tapes. Air-Tech these options: Air-Tech, Poly-Fiber, and and Poly-Fiber use fabrics and tapes that
Here is a complete, covered wing. The round spots are reinforcing rings for future inspection holes. These are made by covering plastic rings with fabric in strategic locations.
Photos: Dave Prizio KITPLANES August 2018 51 appear to be identical, but the Air-Tech fabric has a Ceconite stamp on it, and the Poly-Fiber fabric says Poly-Fiber on it. The medium and lightweight Superflite fabrics are slightly lighter than those by Poly-Fiber or Air-Tech. The important consideration when it comes to fabrics is the weight to be used. Poly-Fiber and Air-Tech have three weights available. The heavy fabric weighs 3.5 ounces per square yard. It is best suited for aerobatic planes and oth- ers that have high wing loadings or will be subject to rough use. The more popu- lar medium fabric weighs 3.16 ounces per square yard. This is the weight of fabric that most builders will use. Superflite A household iron works well to shrink fabric. Just be sure to check the temperature of the has a lighter medium-weight fabric that iron in several spots on the heat plate, especially when working at 350° F. Aircraft Spruce sells these irons for as little as $35. comes in at 2.7 ounces per square yard. This will make a difference of something Oratex. This unique system, first made and Poly-Fiber products and is limited to less than two pounds on a typical Cub- popular in Europe, has made its pres- Light Sport planes (gross weight no more sized plane. There is also a very light fab- ence felt in the U.S., too. The Oratex than 1320 pounds). The standard-weight ric that weighs 1.87 ounces per square system comes with the color and UV Oratex 6000 is rated for planes up to yard (1.80 for Superflite) that is only protection impregnated into the fabric, 13,228 pounds. Its strength exceeds the suitable for planes with a wing loading so that painting is unnecessary. It uses strength of the heavyweight Poly-Fiber of less than 9 pounds per square foot, glue that is activated by heat and pres- or Superflite, so it could easily be used which would typically be ultralights or sure to bond the fabric together and to on aerobatic airplanes. Light Sport airplanes. the aircraft structure. There is a light- Oratex 600 weighs about 3 ounces If we are going to talk about select- weight version, called Oratex 600, that is per yard, and the 6000 system comes in ing a system, we can hardly ignore equivalent to the lightweight Superflite at about 4.5 ounces per yard. Although these weights are heavier than the equiv- alent strength Poly-Fiber or Superflite products, it is important to remember that Oratex includes integral color, so the weight of primer and paint needed with the other products is, in effect, included. In fact, the weight savings that comes from using Oratex to cover a typical Super Cub airplane is about 30 pounds. The downside to Oratex appears to be price, but if the required paint for the other systems is included, the extra cost quickly disappears, as does a great deal of labor, and the labor factor is big. Over half the time to cover an airplane is needed to prime, sand, and paint the fabric after it has been installed. Oratex eliminates all of that. The real downside is that Oratex cannot achieve the same level of overall appearance without it being painted, too. This is not to say that an Oratex-covered plane is unattractive, but it is arguably less attractive than the results that are On large areas, a Crain Model 920 S carpet seaming iron did a better job of holding a possible with, say, Poly-Fiber and a high- consistent temperature over the entire heat surface. gloss urethane paint. The final argument
52 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes against Oratex is that it has only been around for about 10 years, so its track record, while good, is limited. In short, if you are very focused on saving weight and/or wish to avoid the considerable hassle of priming and painting fabric, Oratex is worth a hard look. If, on the other hand, you are try- ing to build a grand champion show plane, it is really not going to give you the look you need to dazzle the judges. As for what is the best covering prod- uct, that will depend on what you wish to achieve. They are all good products that can provide you with many years of good service if properly installed. THE BEST PERFORMANCE The Fabric Covering Process PER DOLLAR! As is always the case, if anything here is contrary to the recommendations of the Sonex Aircraft B-Models manufacturer of the system you choose, Build & Fly starting at: $36,506 then you should follow their instructions and ignore what is here. That said, there are many workmanship points that are common among all of the various sys- tems. When attaching fabric to fabric, or fabric to structure, the best practice is to have a continuous bond that is at least one inch wide. On the leading edge of the wings, that should be increased to two inches. These bonds then get covered with two-inch-wide tape with pinked edges, except at the leading edge of the wings where four-inch tape is used. Protrusions need to get extra reinforc- ing around them, as do any hard edges, More of What You Want! such as the stringers that form the shape of a Cub fuselage. Rib stitching or other forms of fabric-to-wing attachment also get taped. As a general rule, any place See us at Oshkosh 2018! Booth 622 where a structural element makes con- www.SonexAircraft.com 920.231.8297 tact with the fabric covering, the builder should reinforce the fabric with two-inch tape or a patch cut to fit an irregular shape if such is the case. Reinforcing rings around possible openings should get covered with a patch of extra fabric. These are most commonly seen in wings where inspection holes will be required, but such openings could also be present in the fuselage covering. Grommets for drain holes are treated in a similar manner and should be provided anywhere that may trap moisture inside wings or control surfaces.
KITPLANES August 2018 53 After the fabric has been sealed it is time to apply the primer. The Ed Zaleski (left) watches Dave Prizio stitch the fabric on the Air-Tech primer has the advantage of being almost white in color, horizontal stabilizer. Special rib stitching needles, available from so a separate white coat under the yellow finish coat was not nec- fabric suppliers, work best, as does the flat (as opposed to round) essary. Note the personal protection being used by the painter. rib stitching cord. Once the fabric is glued in place, thermometer for this. Another really attached to them. Otherwise they may it is time to tighten it with heat. With important thing to remember is that bend badly out of shape during the Ceconite and other polyester products, polyester fabrics melt at 425° F, so a too- tightening process. this is done in three steps at increasing hot iron can ruin your work in a second. The fabric on wings and control sur- temperatures—250, 300, and 350° F. This During the initial covering process, faces will need to be stitched (or clipped can be done with a common household it is important to not try to tighten the or riveted) to the structure. Before stitch- iron, but a small hobby iron can be very fabric as you are attaching it. The heat- ing, reinforcing tape is attached to the handy for certain operations in tight shrinking process will take up a lot of fabric along the lines of the structure places. Usually the cheapest, simplest slack in the fabric. If all of that slack where stitching will be required. Holes irons work best. I have also had good has already been taken away, the fab- are then punched in the fabric, top and luck with a carpet seaming iron. The key ric could end up being too tight and bottom, where the stitching will go. Rib is to get an iron that has a fairly consis- possibly even bending the structure stitching spacing will vary depending on tent temperature across its plate and to to which it is attached. This brings up the speed of the airplane and whether or check it regularly with an accurate ther- a good point, that frail members will not the stitching will be in the slipstream mometer. I prefer a non-contact infrared need extra reinforcing if fabric is to be of the propeller. The basic guidelines are in AC 43.13-1B. For planes that have a VNE of less than 170 mph, rib stitching in the prop wash area should not exceed 2½ inches on center and in other areas 3½ inches on center. In all cases compare the kit manufacturer’s recommenda- tions and the fabric system guidelines to confirm this spacing. Once stitching is complete, cover all of those areas with two-inch pinked tape. A last step to the fabric covering pro- cess is to go over every joint and taped seam to be sure everything lies flat and has no raveled edges. It is just like prepar- ing to paint anything else. If the underly- ing work is rough, the final product will look rough, too. This is your last chance to get it right before paint. Note that while heat guns are strongly discouraged by the manufacturers of polyester covering systems, Oratex actu- ally recommends using a calibrated heat The fabric around protrusions such as this step on the gear leg should get extra reinforcing. There is no fixed standard for the size or location of these reinforcing patches. It is probably gun. To be sure, this is not the $10 heat best to be generous with these. gun you can get at Harbor Freight, so
54 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes expect to spend some money on a good heat gun if you go with Oratex. Its higher melting point of 485° F makes it more forgiving of less accurate temperature control and poor technique.
Priming and Painting All fabric, except Oratex, needs to be primed to protect the fabric from ultra- violet light. But before we apply primer, you will need to apply two coats of what Poly-Fiber calls Poly-Brush, which is the same chemical mixture you used to attach the tapes and reinforcing patches to the main body of the fab- ric. Other manufacturers will have their own similar products. With the fabric now fully sealed with a consistent surface, it is time to apply the primer. Each system will have its own priming requirements, but this important step should not be skipped or shortchanged. The sun is the enemy of fabric covering, so UV protection is vital. Primer should be sanded between each coat, but be sure not to sand over rib stitches or rivet heads. It is very easy to cut through the primer and fabric with overly aggressive sanding. Sanding with 320 or 400 grit seems to work well, with wet sanding generally giving better results. After the first coat of primer, you will Print and Digital have an opportunity to do some minor repair work such as flattening curled edges of tapes or filling pinholes. Fol- low the recommendations of your sys- tem maker for this. Apply more coats of primer after you have made these minor repairs. Apply primer in a pattern that is perpendicular (cross coat) to the first to ensure good coverage. If you can see a 60-watt light bulb through the primer coat anywhere, you need to apply more primer. Once you have achieved that level of coverage, it is time to stop apply- ing primer. More primer does not make it better. It just makes the plane heavier. Making the edges of the tapes disappear with layer after layer of primer is not a best practice. Poly-Fiber recommends against sanding the third coat. Selecting the finish paint is your Either Format – Great Savings! next task. Use a paint that is specifi- Subscribe Now at www.kitplanes.com/subscribe cally designed to go on fabric covering.
KITPLANES August 2018 55 Automotive paints do not have the flex- ing agents necessary to stand up to the kind of use an airplane will get. Be sure to use a paint that will work well on fab- ric and metal or fiberglass. Don’t forget that even though most of the plane is covered with fabric, the engine cowl, boot cowl, gear legs, and struts are metal or fiberglass. A careful cleaning with an approved paint prep and a pass with a tack cloth should precede the painting process. And don’t forget personal protection. Some paints, especially urethanes, are Fabric is applied to the bottom of the wing first and then the top with a minimum very toxic. A bunny suit and a fresh air two-inch lap at the leading edge. The sequence is more of a convention than a necessity, respirator may be required. Read the but the lap is important. A four-inch tape with pinked edges is applied over the lapped manufacturer’s literature and MSDS to fabric on the leading edge of each wing to give it extra protection. This tape should be applied after (and over) the tapes covering the rib stitching. determine what personal protection you will need. Fabric covering may look intimidating References with those specifically made for your system. to the first-time builder, but it can be fun No matter which system you choose, I rec- Poly-Fiber also has a video that is very help- and is not especially difficult if you take ommend reading Poly-Fiber’s How to Cover ful when it comes to mastering rib stitching. a little time to practice first and carefully an Aircraft Using the Poly-Fiber System. Of AC 43.13-1B is another good source of general read the system manufacturer’s literature. course, where their recommendations dif- information on fabric covering. See chapter Remember, best practices begin with a fer from the ones provided by your selected two in that book, something that should be in review of the manufacturer’s directions. J system manufacturer, you should always go every airplane builder’s library. 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.
56 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes KITPLANES January 2018 57 CHECKPOINTS A New Rating and a New Windshield At the beginning of 2018 I set a cou- ple of goals for myself, and I am happy to say that I have accomplished both of them during the first quarter. One was to get my Inspection Authorization for my A&P certificate, and I completed that one by attending the IA initial course at the Baker School of Aeronautics in Lebanon, Tennessee. The other was to replace the windshield in the RV-10, due to crazing that only seemed to be getting worse. It was definitely affecting the fun factor when looking out the front on sunny days. Let’s start with the IA accomplishment.
Back to School I’ve always had a hard time sitting through all-day classes. It’s not in my Making the first cut with the router is the hardest, and it’s not like I had lots of DNA to sit still for very long, but it’s also experience with routers. Following the intended line took lots of concentration, with debris flying everywhere. why I needed to attend the class. Since I primarily work on experimental aircraft, large breadth, and I understand why. for me. While I don’t intend to review the I really only need the A&P Certificate. There is a great deal of responsibility course here, suffice it to say that I had But I also own a Stearman, and the local to be shouldered for signing off some- no problem staying focused during the designated mechanic examiner has been one’s airplane. It’s not a whole lot differ- four-day program. The lectures were well pushing me for the last five years to get ent than signing off an aircraft in the A-B done and extremely fast paced, which my IA, so I can perform the annual inspec- world that I work in, but the difference is made the days go by quite enjoyably. tion myself. Actually, I really like having that I am focused solely on A-B aircraft. I Every night there were lots of studying someone else look over my airplanes understand them and know where to go and written exercises, but by the end of every once in a while, but it started to for service bulletins and manufacturer’s the week, I felt very prepared, perhaps sound like an excuse every year to him. updates. The knowledge required for the even over-prepared for the test. So, I purchased the study guides and IA covers pretty much everything in the In my whole history of taking all of the made multiple valiant efforts over the last certified aircraft world, including helicop- written FAA tests for every certificate few years to sit down and prepare for the ters and Part 121, areas that I will prob- and rating I hold, I had usually achieved test. Unfortunately, studying for some- ably never cross. So, after several failed a score of 88 or better. In the five practice thing as complicated as the IA test takes attempts at IA prep on my own, I realized tests during the day before the actual some concentrated time. Since I wasn’t I was not making good forward progress. IA written test, I had accomplished the doing anything with my hands while I After reviewing all of the online and same. Lo and behold, I achieved an 88 on was studying, it felt like I wasn’t doing available schools, as well as listening the IA test as well! In reviewing the ones anything, and I’m not good at that. to others who had attended the Baker I missed, I realized that if I had slowed Plus, the subject matter for the IA test School and given it high marks, I decided down and taken the time to thoroughly is very intense and detailed, covers a very that would be the best course of action read the question, I would have chosen
Vic is a Commercial Pilot, CFII with ASMEL/ASES ratings, an A&P/IA, DAR, and EAA Technical Advisor and Flight Counselor. Passionately involved in aviation for over 40 years, he has built 11 aircraft and logged over 8700 hours in 72 different kinds of aircraft. Vic volunteers as a Young Vic Syracuse Eagle pilot and Angel Flight pilot. He chairs the EAA Homebuilt Council and is a member of EAA’s Board of Directors. He also has his own sport aviation business called Base Leg Aviation.
58 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes (Left) I used a cutoff wheel on the front part of the windshield to cut through the fiberglass layers. Eye protection is a must when using the router and the cutoff wheel! (Right) Once the cut was made on the forward part of the fuselage, I was able to break the bond between it and the fuselage. a different answer, as I knew the right me it came in two stages. The first was place. I scoured the internet for other answer. I must admit that by the end working up the courage to make the people’s experiences, which basically of the week, I was ready to finish. One first cut on the aircraft that we had built told me what I already knew: Be care- accomplishment done! and painted. The second was actually ful tearing it out, and then just reinstall I had flown the RV-10 to the Baker making the cut, as I knew that once I another one. School as it was an hour-and-20-minute started, there would be no going back. I’ve included some pictures, so you flight versus a 5-hour drive, and the It would ground the airplane for at least can see the process. Basically, I marked weather cooperated on both ends. On a week, and that was without repaint- some lines with black electrical tape the way home, I was reminded by Carol ing it. I confirmed that I had a date with and then proceeded to make a cut with that the windshield was now at the top of a paint shop, and now that I had that a router I picked up at a Home Depot. I the list. So, the very next week, I decided date, I knew I had to get going. After always wanted a router, and this was an to get started on it, as my schedule all, I didn’t want to be flying around in excuse to get one, even though I’ve only appeared to have some open time. a “beater.” needed one about twice in the last 10 I knew I wasn’t the first person to years. What a mess a router makes! One Windshield Replacement have to replace the windshield, and has to go slow to follow a straight line Want to know what the hardest part I don’t know why it bothered me so across a curved surface such as at the top of replacing the windshield was? For much since I had to install it in the first of the windshield. Otherwise, it seems
(Left) The windshield proceeded to come out in pieces. I worked very slowly so as to not damage the underlying fiberglass support structure. (Right) Once all of the glass was out, I carefully sanded a nice flat bonding surface all the way around the perimeter, cleaned it very well, and primed it and the Plexiglas with Sikaflex primer and activator.
Photos: Vic Syracuse KITPLANES August 2018 59 (Left) The new windshield from Cee Bailey was almost a perfect fit, just requiring some minor trimming. It was much easier than the initial installation. (Right) Here it is, all bonded in and blended over the course of multiple days. I thought it looked pretty good, but I think the paint team may have improved upon it, as the final painted product looked fantastic! to have a mind of its own and runs afoul Weld-On were very strong. I needed to next step was to blend the forward fuse- of the intended cut faster than you can be careful to not damage the underlying lage into the windshield, which was done blink. Speaking of which, safety glasses fiberglass support. by sequentially laying up many layers of are a must, as dust and debris are fly- Once all of the glass was out, it took varying widths of fiberglass. I really hate ing everywhere. Frequent stops to dust quite a while to prep the new surface, that part, but the directions from Van’s off the surface and make the line visible removing all of the old Weld-On and Plexi- give very detailed directions on the vari- again are also par for the course. glas in order to have a smooth surface on ous widths and lengths needed, and it all The router only worked across the which to bond the new windshield. I had worked out fine again. I did remember to top of the windshield. For the lower cut ordered the replacement windshield from add the black dye to the fiberglass resin I used a combination of cutoff disks and Cee Bailey’s (www.ceebaileys.com), as they so it looks good from inside the cabin. sanding drums to remove the layers of advertised it as already cut to shape and fiberglass that blended the windshield ready to install. It wasn’t quite perfect, but Repainting into the fuselage. It was a very slow and it did save me a bundle of time compared After the fiberglass had dried overnight, tedious process of chipping the pieces to the initial installation. I spent the next three days sanding out a little bit at a time once the circum- I used Sikaflex this time. I had used it and filling, trying to make a nice aero- ferential cuts were made. I had installed on a couple of other canopies, and I really dynamic blend into the windshield. It’s it originally with the recommended liked the extra working time and less more of an art than a science, and frus- Weld-On glue, and the bonds from the mess as compared to the Weld-On. The trating at times for me, but it turned out
Here is Don Smith and his paint team. It’s the first time I haven’t painted one of my airplanes myself, and it turned out really great. From left to right: Chevy Smith, Jamie Yates, Christian Murray, and Don Smith.
60 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes very nice, although I think the paint shop may have finessed it a little, too. Speaking of the paint, Carol wouldn’t let me repaint it this time. After two bouts of cancer, we decided that my body has probably had enough of the chemicals from polyurethanes. So, I asked Don Smith Refinishing in Cartersville, Geor- gia, to do it, and he and his team did a wonderful job. They even added a new stripe to the airplane, so it has a differ- ent look to it now. Carol is really happy with the new windshield (I have to admit it was she who gave me the ultimatum to replace it), and the view out the front is admittedly much better. Looking back, it wasn’t much more difficult than installing it the first time, except this time I was working on a com- pletely finished and painted airplane, so I needed to be careful to not damage other areas. Canopies seem to be the most intense part of an aircraft-building project, as you are working with big unwieldy pieces, and a few missteps like scratches or smeared glue can make a dif- ference in the finished piece. I was lucky this time, with no missteps, and I am very pleased with the final outcome, espe- cially since it is the first time I let anyone else apply paint to one of my airplanes. Since I don’t relish replacing another windshield, we are very curious as to what caused the crazing in the first place. It’s not like there was an immedi- ate smoking gun. The crazing started out small in just one area, and over the course of a year or more, it propagated throughout the whole windshield. The manufacturer believes it was caused by using the foil-type silver sunscreens inside the cockpit. It’s interesting that another RV-10 close to us has the same crazing occurring, yet he has never used the interior sunscreens. Others think it could be a manufacturing defect in the windshield from cooling too rapidly dur- ing shaping, or even caused by the glue. It seems there are lots of opinions, but no real answers. Hopefully, we will just have better luck with this one. While the overall project wasn’t nec- essarily fun, it is a lot more fun now looking out a super-clear windshield while flying.J
KITPLANES August 2018 61 PLANE and SIMPLE
When it comes time to attach a plastic or fiberglass wing tip to the end of a metal wing, we sometimes grab a blind rivet to do Riveting Soft the job. This same fastener that is used to rivet our metal skins together might not be the best for this purpose. Close examination of using these rivets to bond soft and hard Materials materials together reveals some problems. By Jon Croke When a blind rivet is pulled during installation, the blind end expands into a small ball that prevents it from pulling through the material. For strong materi- als like metal, this system works great. For softer materials like plastic and fiberglass, the expanding ball can pull through the hole, defeating the grip of the rivet. The Backside of bulb-type rivets force of the expanding ball can also crack showing the “petals” expanded for grip. some materials. One method to prevent this problem is to use metal backing washers for reinforce- ment. This works fine as long as you have access to the backside of the material. Oth- erwise, you may need to glue these washers in place prior to rivet installation. Every builder should know there is a unique style of rivet that can alleviate the need to install washers when working with soft materials. These rivets are made entirely from aluminum, which makes them softer. But more importantly, the expanding ball is replaced with large protruding “petals” that provide a greater surface area for hold- Look carefully at a bulb-type rivet, and you can see the “petals” that will expand from ing. The petals extend automatically dur- the side as the rivet is pulled. ing the regular riveting process.
Jon CRJon These rivets can be found at McMaster- As the founder of Homebuilt Carr (www.mcmaster.com) with the name HELP.com, Jon Croke has “Wide-Grip Blind Rivets for Soft Materi- produced instructional videos for experimental aircraft als.” However, they are also known as bulb- builders for over 10 years. He style rivets, and this term works much has built (and helped others better when searching the McMaster-Carr build) over a dozen kit website. They are available in 1/8-, 5/32-, and aircraft of all makes and 3/16-inch diameter sizes. You need to deter- models. Jon is a private mine the grip length you want (the thick- O pilot and ness of all materials to be held together) to currently arrive at the exact part number. KE owns and Keep a box of these handy, and next time flies a Zenith you need to attach plastic, fiberglass, or Cruzer. Bulb-type rivets appear like normal rubber (engine baffling), you will be using blind rivets prior to installation. a great fastener for the job! J
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For fastest service, visit us at www.kitplanes.com/subscribe or call us toll free at 800/622-1065 HOME SHOP MACHINIST Interference A press fit, also known as an interfer- ence fit, is the preferred ways to assem- ble hubs to shafts when concentricity, balance, and security are critical, or when other means, such as bolting or welding, are less than practical. Depending on the class of fit, from a “light drive fit” to a “heavy” or “force fit,” the interference (the difference in diameter of the shaft, or the larger diameter, being pressed into a hole or bore, the smaller diameter) is typically between 0.0005 inch of interfer- ence per inch diameter, to about 0.0020 inch of interference per inch diameter. When delving into machining opera- tions like press fits, or any work that requires accuracy better than 0.001 inch, everyday calipers and micrometers (Left) This exaggerated view shows the difference between a light press fit (1.0005), a are often not accurate enough. A way to medium press fit (1.0012), and a heavy press fit (1.0020). (Right) The task: Press this shaft overcome this, at least with interference onto this hub, which is a section of 3/4-inch-diameter aluminum with a 3/8-inch hole drilled fits, is to machine a go/no-go gauge in the center. Since a 3/8-inch drill doesn’t exactly drill a 0.375-inch-diameter hole, a way is needed to accurately gauge the true diameter. right into the workpiece. The trick is to lathe turn the shaft 1½ the hub bore. Then turn the next step reach the point where the hub no longer to 2 times longer than necessary, then 0.001-inch diameter larger and check the fits. You should measure the steps in the machine a short step (the first of what will fit. If the hub still slips over the step, turn shaft with a good micrometer to confirm be a series of steps) until it just slips over yet another step, and so on, until you that each step is, more or less, larger by
The shaft was turned to have a series of The second step measured 0.00075 inch Since the hub partially fit the middle ever-increasing diameters, or steps. The larger than the first. A test with the hub step, a third step works for the press fit. first step should be a close sliding fit. revealed that one end would slip over the It measured +0.0008 inch from the Note: if using a three-jaw chuck, all fitting shoulder of the shaft, but the other end previous step. must be done with the part in the lathe to would not, an indication the drilled hole maintain concentricity. in the hub was slightly tapered.
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 for Bob Hadley his Jabiru J250-SP.
64 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes 0.001-inch diameter. By machining the steps accurately, the step where the hub no longer fits should result in an interfer- ence of between 0.0003 to 0.0008 inch. With a little practice, you can adjust the dimensions as needed to yield interfer- ence fits within reasonable tolerance for everything from the lightest to heaviest force-drive fits. While the method described is for fit- ting a shaft to an existing hole or hub, it can work the other way around, too, by step boring a hub to custom fit an exist- ing shaft. The basic ways to join an interference fit are by force, such as with an arbor or hydraulic press, a vise, or a hammer; or by A final check confirms an interference An arbor press is preferred for main- using thermal expansion (heat) or con- and that the parts are ready to press taining alignment when driving home traction (cold). Parts that are joined by together. The extended stem has a interference-fit parts. But a well-placed thermal process are referred to as having dual purpose: to gauge the hole for the blow with a soft-faced hammer will also a “shrink-fit.” This is often the way propel- correct interference fit and to align the do the trick. An appropriately sized socket ler hubs are joined to crankshafts. parts for final pressing. is used to support the hub and provide clearance for the protruding stem. Heating is usually required on the tightest force fits. Steel has a coefficient • Heavy drive fits are suitable for of expansion of around 0.000006 inch, heavier steel parts or for shrink fits in per inch, per degree Fahrenheit (°F) and medium sections. aluminum 0.000012 inch, per inch, per • Force drive fits are suitable for parts degree F. This tells us that when heated that can be highly stressed or for to 300° F, most hubs will expand suffi- shrink fits where the heavy pressing ciently to allow even the tightest force fit forces required are impractical. to slip together easily. If you’re worried As the descriptions point out, the about overheating a sensitive part, lower type of fit depends on the applica- the temperature a bit and put the mat- tion. For connections that need to be ing shaft in a freezer. What’s important is permanent, use a medium, heavy, or the temperature differential. Heating the force drive fit. A good example would hub to 225°F and chilling the shaft to 0° F be bearing races pressed into wheel (in a typical freezer) gives you the same hubs. These fits are “permanent” in the Section view of the pressed shaft and hub fit as heating the hub to 300° F with the sense that they won’t come apart from assembly after machining off the protrud- shaft at room temperature (77° F). normal use or abuse. Bearing races, of ing stem. Note there is no noticeable delineation between the two parts. The American National Standards Insti- course, are designed to be pressed out tute (ANSI) has established definitions and replaced, so exactly how perma- There are a number of helpful web- for four basic types of interference fits. nent depends on many factors. A gear sites with calculators for sizing parts, They are light drive, medium drive, heavy pressed onto a driveshaft can almost estimators for driving force, and holding drive, and force drive fits. The following is always be removed with a gear puller or power (the holding force is pretty much quoted from the ANSI guidelines: by reversing the assembly forces. A rod equal to force required for assembly). • Light drive fits are those requiring light or shaft pressed into a blind hole can Case assemblies often have alignment assembly pressures and produce more usually be removed with a slide hammer pins press fit into one or both halves to or less permanent assemblies. They or by applying heat to relax the grip. help alignment during assembly, but are suitable for thin sections or long Parts that have been pressed together never both halves. Bolts or screws do the fits, or in cast-iron external members. with a blind mechanical interlock can holding in these situations. • Medium drive fits are suitable for ordi- usually be released with heat. Nothing Don’t mix materials if the assembly will nary steel parts or shrink fits on light is really permanent if you’re determined be subject to temperature changes. The sections. They are about the tightest enough, though the ultimate solution difference in the coefficient of expansion fits that can be used with high-grade might prove destructive to one or both of an aluminum shaft in a steel hub could cast-iron external members. parts of the assembly. cause the press fit to come loose.J
Photos: Bob Hadley KITPLANES August 2018 65 SLSA max empty weight, sailplane condition inspections, licensing a RANS S-7LS as an ELSA. By Mel Asberry Question: Is there a maximum manufacturer never got a U.S. type very careful not to do anything that empty weight for an SLSA? I read on certificate. When it’s time for the violates the ELSA certificate. What a forum about an 890-pound max annual condition inspection, does kind of things are allowed? Can you empty weight, but that’s the first the inspector need to be an IA, or update the avionics, for example? I’ve heard about that. is an A&P certificate adequate, no Answer: Yes, the current owner can Answer: Yes, there is an empty weight matter the subcategory? convert an SLSA to ELSA. The local limit for SLSA, but it is not a definitive Answer: The inspector requirements FSDO or a DAR with the proper func- number. Basically, it’s a formula that should be listed in the operating limita- tion code can perform this conversion. says: Add 190 pounds per seat plus a tions for each particular aircraft. To the The only physical changes to the aircraft number equal to 1/2 the rated horse- best of my knowledge, an IA should never are changing the Light-Sport placard to power. Subtract that number from the be required on these aircraft. The primary an Experimental placard, and chang- gross weight. That will give you your purpose of an IA is to confirm compli- ing the passenger warning placard to maximum empty weight. ance with the type certificate. Since these the appropriate Experimental passenger Here’s an example for a two-seat, 100- aircraft do not have a U.S. type certificate warning placard. hp SLSA on wheels: 190 x 2 + 50 = 430. an IA should not be required. After this conversion, the owner 1320 - 430 = 890 pounds. Obviously a Question: I’m helping a friend sell may take the 16-hour LSA repairman/ single-seat aircraft, a different horsepower his RANS S-7LS, which was factory inspection course and obtain the repair- engine, or the addition of floats will pro- built and has an SLSA certificate, as man certificate. This will allow him/her vide a different empty weight limit. well as helping the new buyer get to perform the annual condition inspec- Experimental Light Sport Aircraft situated with the airplane. It’s my tion on an ELSA that he/she owns. (ELSA) do not have this limitation. This understanding that the new buyer Under ELSA, the aircraft may be is the reason SLSA manufacturers using can convert it to ELSA pretty easily, modified without approval from the a 180-hp engine typically go with ELSA. which is a huge personal property manufacturer, as long as the modifica- Question: There are a number of tax benefit here in Kansas and Mis- tion does not take the aircraft outside different subcategories of experi- souri (about $50 per year instead of Light-Sport parameters as described mental aircraft: amateur-built, R&D, of $1,000 to $2,000 per year), in in FAR Part 1.1, General Definitions.J racing, etc. Many foreign factory- addition to being able to take the built sailplanes imported into the training courses to do the annual Please send your questions for DAR U.S. are licensed as Experimental/ condition inspections. However, Asberry to [email protected] with Racing or R&D because the foreign I’ve also read that you have to be “Ask the DAR” in the subject line.
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KITPLANES August 2018 71 The Creative Homebuilder Hardened Steel Mandrels for Close-Quarters Dimple Dies By KITPLANES® Staff Dissatisfied with using the provided mandrels for Cleave- land Aircraft Tool’s close- quarters dimple dies, our Creative Homebuilder uses the hardened steel mandrels from 5/32-inch blind rivets. He feels that blind rivet mandrels The original 5/32-inch blind rivet. are much stronger than those supplied with the dies and do a much better job of actually forming the dimple. When taken to the breaking point, they always load the die faces the same, as they are designed with a frangible stem in order to secure the blind rivet at its design load. This characteris- tic provides consistency in the dimpling process, so he pulls the mandrels to their breaking point. On very thin material (0.016–0.020 inch), he pulls to “feel and experience.” To date, the Creative Home- The blind rivet is nested vertically in a vise, A light tapping with a hammer drives the ready for harvest. mandrel out of the blind rivet shoulder. builder hasn’t convinced a blind-rivet manufacturer to The harvested mandrel, sell stand-alone mandrels ready to slip out of the (and he’s tried!), so he occa- blind rivet and receive the sionally “harvests” the stems close-quarters dimple dies. from blind rivets to ensure an inventory that is stored with the die sets in his tool drawer. The holes in the dies may need to be opened up a bit for the new stems, but the holes are still smaller (0.095 inch) than the #40 hole from which the dimple is made. He further notes that this technique does a good job on 0.020-inch alu- Ready to go! The harvested mandrel with dimple dies installed, waiting for a piece of aluminum minum and thinner. J to dimple.
72 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes AERO ’LECTRICS Weir’s Wires In my March 2018 column [“Spread Those Sheets”], I gave you a wire table spreadsheet that allowed you to select a wire gauge for your homebuilt aircraft given the current you needed to draw and factored in the wire temperature and a lot of other elements. Now it is time to put an overcoat on that bare wire and select the external covering or insu- lation for that wire. Fortunately, modern chemistry has given us a wide variety of options from which to choose. Let’s roll the calendar back nearly 70 years to when Uncle Miltie (Milton Berle) was all the rage on that new-fangled invention, the black and white TV set in the front room. Ask anybody who was around at that time, and (s)he will Mil-spec wire isn’t just for military aircraft. It’s the only kind of wire you want to use in your aircraft, too. tell you that the only wire to use on an airplane was double-wrapped cotton, rainbow you wanted—and some colors So, yes, I’m going to suggest that impregnated with a varnish, and covered that weren’t even in the rainbow. You those of you that sprung for a 1000- with a thin nylon outer film (“DCC”). My could easily mold it, extrude it, make it foot roll of Tefzel, figuring that you’d particular bird right now rolled out of as thin or as thick as you wished, and be asphyxiated if your PVC wire got too Clyde Cessna’s Wichita build-it hangar even dip wire in it when liquid, and it hot, are flying around with stuff heavier in 1958 with just a little over 300 yards of would conform to the shape of the wire. than the 1940s era DCC I took out of the the stuff—and yes, just for the record, I Wow, what an improvement. Cessna some 30 years ago. And while measured it when I completely rewired Sort of. While PVC has been rumored the Tefzel will stand up to blowtorch the blue-on-blue 182 when I bought and to give off toxic gases when it burns, you flames, unfortunately, you will not. restored it in 1990. might want to see a scientific study of what Having said all that, what is wrong with That’s over 28 pounds of wire, and temperature you have to get this plas- PVC? It doesn’t burn at relatively low tem- completely rewiring it with modern tic to in order to produce those gases… peratures, but it melts…and gets runny… stuff took less than 8 pounds, saving 20 here you go: https://tinyurl.com/pvc-wires. and lets wires touch when it melts away pounds of payload…or, if you like, well Note that temperatures in excess of from its wire center. And it is horrible when over two dozen cans of beer. 300° F have to happen for these gases to it comes to resisting fuel, oil, or any hydro- Shortly thereafter, some smart chem- be produced. The normal effect below carbon like brake fluid. Absolutely horrible. ists took several isotopes of that new- 1000° F is a simple lung irritant, and sir, if fangled vinyl plastic, treated it with you’ve got temperatures in excess of 300° Improving PVC chlorine and came up with polyvinyl on the flight deck, you’ve got more prob- For nearly 30 years (1960 to 1990), we chloride, or PVC for short. It didn’t burn lems in your hands than simply coughing coated our PVC airplane wire with a like cotton, it didn’t weigh like cotton, a bit. If you’ve got 1000°, I’d start trying to hyper-thin coating of nylon (say, roughly and you could have it in any color of the make peace with your Maker. 1 or 2 mils thick) that was superb for
is the chief avioniker at RST Engineering. He answers avionics questions in the internet newsgroup 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 out their Jim Weir website at www.rst-engr.com/kitplanes for previous articles and supplements.
Photo: Paul Dye KITPLANES August 2018 73 hydrocarbon contamination and was a thin (5 mil) fiberglass braid between the back to something that was bulky and pretty tough abrasion material. Thus was PVC and nylon. Now we had a real aircraft heavy. Sigh. To boot, you could have any married PVC to nylon in the industry- wire that wouldn’t burn with a torch, was color of 5086 you wanted, so long as you standard aircraft wire, MIL-W-5086 or resistant to fuel and oil, fairly inexpen- wanted only white. 7078. It was used on everything from the sive, easy to work with, and chemically So, for those sorts of things that are venerable straight-tail Cessna 150 to the fairly nonreactive. on the people side of the firewall and early space capsules. Unfortunately, we now have to do aren’t likely to encounter any fuel or oil, Even more popular than plain old 5086 a reality check. With all these layers of the military gave us plain old MIL-W-76, was 5086-Type-II, which featured a very plastic, nylon, and fiberglass, we got which was plain old PVC over copper Mil-Spec Wire Types Insulation Inner Outer Temp. #22 Dia MIL-W-xx Type mils thick Sleeve Sleeve Range ° C Mils Colors Abrasion Flame Fuel, Oil 76B LW PVC 10 -40 +80 53 All C A D 76B MW PVC 16 -40 +80 65 All C A D 76B MW-B PVC 16 Glass Braid -40 +80 75 White B A C 76B MW-J PVC 16 Nylon -40 +80 71 All A B B 76B MW-S PVC 16 Copper Braid -40 +80 87 Solid A B D 76B MW-SJ PVC 16 Copper Braid Nylon -40 +80 94 Solid A B A 5086A I PVC 16 Nylon -55 +105 68 White A B A 5086A II PVC 16 Glass Braid Nylon -55 +105 75 White A A 7078A I PVC 16 Nylon Copper Braid -55 +105 90 White* A B B Glass Braid/ 7078A I PVC 16 Nylon Copper Braid -55 +105 95 White* A A B Nylon/Copper 7078A II PVC 16 Braid Nylon -55 +105 100 White* A A A Glass Braid/ Copper 7078A II PVC 16 Nylon Braid/ Nylon -55 +105 105 White* A A A 7139B I & II Teflon Teflon/Glass Teflon/Glass -65 +200 87 White A A A 16878D B PVC 10 -55 +115 51 All C A D 16878D B-J PVC 10 Nylon -55 +115 57 All A B B 16878D C PVC 16 -55 +115 65 All C A D 16878D C-J PVC 16 Nylon -55 +115 71 All A B B 16878D C-JS PVC 16 Copper Braid Nylon -55 +115 93 Solid A B A 16878D D PVC 31 -55 +115 89 B-R-W C A D 16878D D-J PVC 31 Nylon -55 +115 97 B-R-W A B B 16878D E Teflon 10 -55 +115 52 All A A A 16878D EE Teflon 16 -55 +115 62 All A A A 16878D ET Teflon 6 -55 +115 42 Solid A A A 16878D B-X-link PVC 10 -55 +115 50 Solid B A D 16878D C-X-link PVC 16 -55 +115 64 Solid B A D 22759 - Tefzel -65 +200 50 White/S A A A Notes: • There are literally thousands of mil-spec wire varieties. The above are the most common generally available for light aircraft use. • Size is the outer diameter of the insulation in mils ( 1 mil = 0.001 inch). • Colors – All means all 10 solid colors (black, brown, red, orange, yellow, green, blue, violet, gray, white). Some vendors have the capability of doing any solid color with a stripe of another color. Some vendors can only do a stripe on white. – Solid means any of the solid colors but no stripe. – *White is used for multi-conductor cable where the individual wires are white with a color stripe(s) to distinguish the wires. – B-R-W means that the wire comes in black, red, or white. – WH/S is white with a color stripe – Grades for abrasion, flame, fuel and oil are the usual A–F grades, just like school.
74 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes wire, in all the colors of the rainbow, working with Teflon wire know the bad Where to Buy Wire light, easy to work with, and you could news from first-hand experience—it is At this point in most of my columns, I actually put stripes of a second color crystal witch to strip, even with profes- point you to a source for the parts to build over the base color if you wished. This sional ratchet-style cutter-strippers. The my ideas. In this case, I don’t have a par- gave us a mil-spec wire for our airplanes only thing that works well is a hot-wire ticular source for aircraft-grade wire. What that met our needs. stripper that just barely melts the wire I will point out is that most cities that have Over the years, we’ve had versions with a red-hot cutter, leaving hotter- some sort of military base or civilian aero- of MIL-76 with fiberglass covers, coax- than-the-hinges-of-Hades stripped Tef- space industry will have “Honest John’s ial cable out of PVC, and lots of other lon burning a hole through your cotton Surplus Emporium” that sells mil-spec options. However, 76 has one nasty ten- shirt. Or the aircraft carpet. wire at a tenth of the price you pay for that dency that we’ve already talked about: The other bad news is that it is stiff and same wire new from a distributor. The It doesn’t burn easily, but it melts like ice difficult to bend into nice tight corners, it aforementioned Cessna 182 was com- cream at the Oshkosh airshow. is heavy, it is expensive, and it only comes pletely rewired for less than $50 with mil- Back to science: Some bright, white in whatever shade of white you prefer. spec wire throughout from John’s place. shop jacket found that if he nuked the Teflon was invented by one of the So, how do you test Honest John’s MIL-76 wire (irradiated is the proper big chemical companies (DuPont), and wire? Strip a small end of it. If it is copper term), the plastic would no longer they weren’t about to give out the trade colored, it is uncoated copper, and unless melt, but just curl up and go away. This secrets on how to make it, so some other you want to pull it all out in a dozen years spawned a new mil-spec and gave us chemical companies came out with their when it corrodes on you, pass on it. If it the standard that exists to this day— own version of the stuff. For those of us is silver colored, dip the wire into a very MIL-W-16878 for a plain, lightweight, weaned on the Gilbert Junior Chemistry diluted (about 100:1) solution of water irradiated PVC-covered copper wire Set, we all know that an ethylene—fluo- and battery acid. If, after a day of drying that doesn’t melt. rocarbon plastic polymer—was chris- out, there is a black coating (silver sul- We had been making another plastic tened Tefzel. The military liked the stuff fide) on the wire, you have silver-coated that was really nice for coaxial cable for so much they created a new MIL-W-22759 wire (lucky you), and if there are no black quite some time that didn’t have all the category for it. specks or coating, you have tin or solder- nice capabilities of PVC, but was instead Tefzel has exactly the same good stuff plated wire, which is just fine. treated with the same stuff we use to and the same exact bad stuff that Tef- As for the insulation, take a sample of make high-test gasoline: poly-ethyl-ene lon has going for it. Exactly the same. It it and lay it across a hot soldering iron. (polyethylene). It is very low loss at very is expensive, heavy, and a witch to work If it immediately melts and runs, you high frequencies, so coax cable is made with. But it is nearly indestructible. have un-irradiated PVC. If it just curls of a copper center conductor, a polyeth- What do I personally do when working up and deforms, it is irradiated PVC (no, ylene insulator, a copper braid, and a with a (re)wiring situation? it will not trigger a Geiger counter; it is black outer jacket of irradiated PVC. • If it is for purely electrical stuff and not radioactive). If it does nothing, burn with current measured in amperes it with a match. If it still does nothing, it Teflon and Tefzel (incandescent lights, motors, starters, is fiberglass, Teflon, or Tefzel. If it flames Polyethylene is pretty poor in the heat generators, and the like), I fall back on up immediately, it is either cotton or and flame department, so in the early good old 5086A, unless it is going into nylon over cotton. days of the space program, some bright the engine compartment and likely to Rarely do I tell you not to use the avia- chemist decided to try and blend four be severely thermally stressed. Here, tion department of Honest Ed’s Auto fluorine atoms into the ethyl ring in and only here, will I spring for a few Parts Store, but in this case I will do that. polyethylene, giving us poly-tetra-flu- feet of the good Tefzel stuff. Most auto wiring you get from them will oro-ethylene (polytetrafluoroethylene), • If it is for modern avionics and instru- be solid copper, not stranded. Same for which was immediately shortened into ments with currents measured in milli- house wiring using Romex. Solid cop- “Teflon.” All the manufacturers of MIL- amperes, I’ll use the 16878 wire so that per doesn’t cut it for airplane wire. I pre- W-16878 jumped onto the Teflon band- I can color-code all the wiring (battery fer 22-strand but will accept as low as wagon and brought out their versions of plus is red, ground is black, micro- 7-strand for aircraft wiring. There’s too 16878 Type E with Teflon insulation. phone key is brown, microphone much vibration in an aircraft to go with Teflon wire is impervious to nearly audio is shielded 16878C-JS, and so solid wire. Way too much. everything known to man, including on). Actually, to tell you the truth, if it is Finally, I want you all to be aware of the gasoline, alcohol, flame, ketones, ace- non-flight-critical, I’ll use cheap RG-174 overriding military specification that we tone, ethylenes, and I suspect that ter- coaxial cable for stuff (like microphone all work to as best we can—MIL-TDD-41 mites can’t do much damage to it either. audio) that needs shielded wire. Yes, (Make It Like The Damned Drawing For That’s the good news. Most of us who RG-174 also comes in a mil-spec ver- Once). Later, until next month…Until have hung upside down in small spaces sion if that is important to you. then…Stay tuned… J
KITPLANES August 2018 75 WIND TUNNEL Design Process: Initial Weights Last month we introduced the con- cept of “size, bones, balance” and started on the initial layout of the airplane. We now turn our attention to the next step in sizing the airplane, which is to get an idea of how much it will weigh.
Known Weights At the outset of the design, there are cer- tain weights that are chosen as part of the requirements for the airplane.
People The first consideration is the weight of the pilot and passengers. The airplane will be designed to be capable of car- rying a certain number of people. How many depends on the mission of the airplane. The designer must choose a “typical” weight to use for each occu- pant of the airplane. At one time the Back in the day, the FAA specified 170 pounds as the weight of a “standard human” FAA specified 170 pounds as a “stan- for weight calculations. These days, they use 200 pounds for an adult male and 179 dard human” for weight calculations. pounds for an adult female in summer, plus an additional 5 pounds for each in winter. (Photo: George Louis [CC BY-SA 3.0 via Wikimedia Commons]) In modern times we know that this is too light to properly represent the well advised to use at least the summer choose a baseline set of equipment and U.S. population. For American males, adult male weight (200 pounds) as a use actual weights for our design esti- the 50th percentile weight is just over typical occupant weight. mates. As the design gets more refined, 180 pounds, while the 75th percen- we must also then take into account tile is slightly over 200. If the airplane Baggage and/or Cargo the weight for mountings and wiring to is required to carry full-sized adults in Another weight chosen at the outset power the avionics. every seat, the designer would be well is the cargo/baggage weight. Airlines advised to use a weight in this range use 50 pounds per person as baggage First Weight Estimate for initial weight calculations. Note that weight. If the airplane is intended more Once the cabin and cargo hold or bag- these weights do not include cloth- as a cargo hauler than a people trans- gage compartment are defined, these ing or personal items carried in pock- porter, then the design specification components have essentially con- ets. The current FAA advisory circular must define the weight of the cargo the stant weight as the rest of the airplane used for calculating passenger weights airplane must carry. evolves. In order to get started on siz- for airlines (AC 120-27E) specifies 200 ing wing, engine, and fuel capacity, we pounds for an adult male and 179 Instruments and Avionics need an initial estimate of the gross pounds for an adult female in summer The mission of the airplane implies a weight of the airplane. and adds 5 pounds to each for winter. minimum suite of instruments and avi- A common method of doing this is to A general aviation designer would be onics. For preliminary design, we can use statistical analysis of similar airplanes
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 Barnaby Wainfan unconventional airplanes including canards, joined wings, flying wings, and some too strange to fall into any known category.
76 KITPLANES August 2018 www.kitplanes.com & www.facebook.com/kitplanes that are already flying. If we take the takeoff weight for every pound of arbi- size will allow a preliminary estimate of combined weight of the occupants and trary weight added. the size of the tail surfaces to be made. baggage, and divide it by gross weight Fortunately for clever designers, the With that done, we have enough infor- for existing airplanes, we can determine weight wrap rate works both ways. mation to make a more refined weight a typical percentage of gross weight for Every pound of fixed weight saved estimate and then generate an initial these known items. We can then use this yields an attendant larger reduction in estimate of the drag and performance percentage to estimate the gross weight gross weight. of the airplane. of our new design. For example, suppose we are design- Initial Wing and Engine Sizing Iterate, Iterate, Iterate ing a new 2-seat, fixed-gear airplane. If Once we have our first weight esti- With the first performance calculations we use the “standard” weights discussed mate, we can move on to our first esti- in hand, the designer can compare the above, we will be carrying 400 pounds of mate of wing size and engine choice. In performance of the initial design to the human and 100 pounds of baggage, for a some respects, initial engine sizing is design requirements. Inevitably, the first total of 500 pounds. I did a quick (and by easier because the designer has only a cut at the design will not meet the per- no means comprehensive) look at 2-seat relatively few discrete choices. Engine formance specifications exactly. fixed-gear kit airplanes and found that manufacturers make specific engines, For each design cycle, the designer will the “people plus baggage” as a percent- and the designer must choose one of make changes to the airplane to bring age of gross weight ranged from 24% to them. As with our initial gross weight its performance in line with the design 28% for the airplanes I surveyed. Accord- estimate, a good first step is to look sta- requirements. Note that this does not ingly, if I use this to get my initial weight tistically at the power-to-weight ratio always mean that the initial design falls estimate for my new airplane, the gross of existing airplanes. For the two-place short of requirements. It’s entirely possi- weight will range between: airplanes I surveyed, power-to weight ble to find out that you have overshot the 500/0.28 =1785 pounds ratios varied from a low of 16 pounds requirement, and your initial concept has And: per horsepower to a high of 12 pounds more range or more speed than required. 500/0.24 = 2083 pounds. per horsepower. Accordingly, for our While this might seem, at first blush, to For an average of 1934 pounds. average-weight example airplane (1934 be a good thing, it also means that the Depending on how optimistic the pounds), my initial engine choice would initial design is larger, heavier, and more designer is, or how well-understood the range between 120 and 160 hp. If the expensive than an optimized design that configuration and structural materials of designer is a fan of Lycoming engines, just meets the design requirements. the new design are, any one of these 3 this would mean a choice between an Since cost is also a “performance param- weights might be a reasonable estimate O-235 and an O-320. eter,” this is where it falls short. with which to start detailed design. Once we are in the ballpark with sta- After making changes, we repeat the One caution is in order here. The tistical analysis, some initial consider- weight estimation and performance above analysis illustrates one of the most ation of desired performance and/or cost calculations. Because each change important issues in airplane design: Add- might drive the initial determination one affects multiple variables, the perfor- ing weight adds even more weight. Each way or another. mance may change more than our additional pound arbitrarily added to the Wing sizing is more complex and will initial estimate. airplane carries with it a “wrap weight” be discussed in detail in a subsequent Assuming that the requirements that is usually greater than the initial edition of “Wind Tunnel.” While it is pos- are meetable, and the changes to the weight increment, once all of the effects sible to get a rough initial estimate by design are in the right direction, each of the initial weight increment are taken using a statistically derived wing loading cycle brings the design closer to the into account. from other airplanes, this will likely prove design requirements. (This is not always Using our example airplane, suppose too crude an initial estimate to be par- the case. It’s possible to get in a situ- our passenger and pilot each want to ticularly useful. Accordingly, the first bit ation where a design will not be close, add 5 pounds to their baggage alloca- of more detailed design that should be and each iteration leads to the airplane tion. For our average case above, that done after the initial layout is the prelimi- getting worse, not better. If this is hap- additional 10 pounds will increase the nary design of the wing. pening, either the requirements are not takeoff gross weight of the airplane realistic, or some element of the design by about 38 pounds. Carrying the 10 First Performance Estimate approach is not suitable to the mission.) pounds of additional baggage will At this point in the design, we have a After several cycles, the calculated require an additional 28 pounds of air- preliminary layout of the airplane. The performance of the airplane will be close plane and fuel to fly the same mission. basic shape of the fuselage has been enough to the design requirements to This wrap rate varies depending on the defined. We have chosen an engine to be acceptable. At this point, it’s time to type of airplane and its mission, but in start with and have a first design itera- move into detail design and start think- some cases it can exceed 5 pounds of tion completed on the wing. The wing ing about building it. J
KITPLANES August 2018 77 REAR COCKPIT An Inside Look Aircraft interiors were recently sug- gested as a suitable subject for this column. Anyone who’s seen my open- cockpit rat rod knows why, as the box kite I habitually aviate has a hopefully unique hole du habitation. Product of the 1970s and trimmed in the sort of blue velour a French hote- lier might wince at, gilded with bass boat gold metal flake panel inserts, and left to decay for 37 years in the gentle Southwest ultraviolent rays, my Starduster’s cockpit is at least rodent- proof, as no self-respecting kangaroo rat would dare be seen in it. In fact, most people might say it’s ugly, except airplane people are typically well-mannered. Personally, I consider it historical, if any recollection of the disco era could be elevated to such status. It is, after all, a faithful testament to the blessedly brief baroque period in mid- American taste, when the yearning for upscale status ingrained by the depres- sion peaked in the ’60s, then lingered into the malaise era of oil embargos and Like a messenger from a time long gone, this cockpit shows the wear of 37 years of adventure. declining national pride. In any case, I simply don’t see the inte- unusual emphasis on the artificial. The bring more money in an antique shop, rior any more, repetition having dulled VSI has never worked, the surprisingly but in my cockpit it at least means there any sensitivity to the glittering metal accurate tachometer is in the right arm- is an evenness of wear. Put something flake and tattered blue velour. It’s only rest, and the radios are especially visu- new in there and it would shine like a when someone new to the plane walks ally abhorrent. They work well, but the ruby in a goat’s ear. up to it that my toes curl in embarrass- faces are bleached like whale bones, and The other advantage—and it is an ment inside my Italian racing booties. the plastic film in the windows where advantage in an open-cockpit air- Besides its visual offense, just about the frequencies are displayed are better plane—is no one is going to steal any of everything in this cockpit is old, techni- described as gnarled plastic curls remi- this junk, so you don’t feel so bad leaving cally obsolescent, or simply worn out. niscent of old Chinese royalty fingernails. it outside and overnight at some place In other words, I’m carting around a There are two advantages to this, far from home. bunch of useless weight in the form of however. For one, the majority of items Curiously, even with the interior fully a VOR with glideslope, a gyro compass in the cockpit are equally thrashed, lend- paneled with walls of blue fuzz, there is that pinwheels given a half-aggressive ing a visual cohesiveness. This would be no storage room in the immediate cock- turn, and an artificial horizon with an called patina in arty circles and might pit environment, not even a pencil holder.
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 August 2018 www.kitplanes.com & www.facebook.com/kitplanes Built when WAC charts were the answer storage compartment. It’s also some- to biplane cross-countries (try unfolding thing of a camouflaged safe, as when a paper chart with one hand in an open tied down outside during food stops cockpit sometime), it’s near criminal there or fly-ins, the portable GPS and other isn’t a single pouch, pocket, bag, cubby, or desirables can be secreted within, and hideaway for cockpit incidentals. There’s with the seat in place there’s not a hint some storage in the headrest—my wife’s anything is behind it. purse was once sucked out of this thanks If all this sounds unique, what many to a lazy latch—but it’s not accessible in find the most unusual fitment is the flight, except by the wind. cigarette lighter and ashtray, the latter Another area useful for small-item in the right floorboard. Smoking is not storage but also completely inacces- the first thing that comes to mind with sible in flight is a curious recess under open cockpits, but it’s entirely possible the seat cushion. Seemingly designed if you can get the coffin nail out of its for a seat pack parachute but too small pack using one hand. Dusty, the crusty for that, the main effect of this depres- aerial applicator in our area ages ago, sion is to allow the seat cushion to crush never left the ground without a sto- down into a hole. Unfortunately well gie clamped in his jaw, and he flew an past my waif stage, the submerging seat open-cockpit N3N with an R-985 provid- cushion means the excess of my poste- ing the breeze. Even better, a previous rior—actually the hip joints—ends up owner liked to go very long distances in perching on two very distinct pressure the Starduster and, for better economy points. There’s a third hard ridge along at altitude, had a turbocharger fitted for the lower back as well, such that around 98 hours of operation. What could be an hour in the air you begin to think of better than cruising along at 140 knots little else, and after two hours you’re true while sitting outside at 12,000 feet ready to fly the approach inverted to and having a puff? To each their own. relieve the pain. So, the interior could have been bet- A partial answer is to pack the cav- ter back when it was built. So could ity under the seat cushion with the some interiors today, although the shirts you plan on wearing when you well-developed planes from the major get there. This keeps the hips slightly kit makers mean there is less of the elevated, solves the issue of where to free-form execution described here. put the shirts, and ensures they stay Above all, comfort is on my to-do list creased for eternity. when the Starduster eventually gets Another feature of these molded stripped and rebuilt, and I recommend fiberglass seats is they simply lift out of it for your build. For me that means the cockpit, being held in by the com- all-new seats with no pressure points, bination of your person and the five- although the lift-out feature is some- point safety harness. This is extremely thing I’m sure to retain, and it looks like handy during condition inspections I’ll have room for under-seat compart- and such, and allows wide-open access ments. The second is storage. There’s behind the seat backs. In the front never enough in our small planes, cockpit, that means generous access and if you’re gluing together your first to behind the rear cockpit’s lower build, spend some time identifying just instrument panel area, while in the how you’ll use your interior and install rear cockpit it allows reaching the “cat the water bottle holders and gum dis- carrier.” This is a canvas storage com- pensers where you want them. partment—it has a fiberboard floor— Third on my list is style—why else do of sufficient capacity to accept a pair the cross-country thing in a biplane? I of socks, boots, and a stuff-it-in-there could stay period correct and find some jacket. It is suspended by rope from new blue velour…and a mini disco ball the primary structure’s tubing in the would be a real trip at dusk in the glint aft fuselage and has a zippered front of the instrument lights. Or maybe I’ll door. This is, in fact, the aircraft’s main chicken out and go with tan leather. J
Photos: Tom Wilson KITPLANES August 2018 79 KIT STUFF BY ROBRUCHA
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