® OUL JANUARY 2016 S www.kitplanes.com XL Booth Paint Lights Layout Nav Downdraft Switch LED Inthe Shop: • • • SuperSTOL SIGN E M D ISHAPS E M YST S L E ANGAR ANGAR Components 101 Components Expelling the Remains Expelling Gear Collapse ADVENTURE IS GOOD FOR THE THE IS FOR GOOD ADVENTURE H FU EXHAUSTING! The Envelope The Stretching KITPLANES JANUARY 2016 SuperSTOL XL • On a Whim • ULPower Engines • Fuel Systems 2 • Gear Collapse • Exhaust Systems • LED Lighting • Switch Layout • Pre-Trip Maintenance BELVOIR PUBLICATIONS January 2016 | Volume 33, Number 1 Flight Review 6 STRETCHING THE ENVELOPE: Flying the SuperSTOL Stretch XL with a 180-hp ULPower engine. By Dan Horton. Builder Spotlight 14 THE NEW OLD AERO ENGINE! ULPower takes a different approach to air-cooled, horizontally-opposed, direct-drive engines. By Steve Ells. 20 ON A WING AND A WHIM: Flying a scratch-built Sonex is good for the soul. By Kerry Fores. 28 LIGHT AIRCRAFT FUEL SYSTEM DESIGN: Part 2—Every 20 component is there for a good reason! By Ken Krueger. 34 ERROR CHAIN: Gear collapse—not all mishaps happen in the air. By Russ Erb. 38 ENGINE THEORY: Exhaust—expelling the remains. By Tom Wilson. 68 aSK THE DAR: Combining parts from multiple kits, N-numbers, using an amphibian for land-only training. By Mel Asberry. 74 COMPLETIONS: Builders share their successes. Shop Talk 46 AIRCRAFT WIRING: Instrument panel switch layout for Experimental aircraft. 54 THE NEW GUY: Ten universal tips for Experimental aviation. By David Boeshaar. 56 MaINTENANCE MaTTERS: Maintenance for an extended journey. By Dave Prizio. 78 AERO ’LECTRICS: Winging it with LEDs. By Jim Weir. Shop Tip 64 TEMPORARY DOWNDRAFT PaINT BOOTH: By Larry Larson. Designer’s Notebook 50 STREssING STRUCTURE: Buckling of panels. By David Paule. 75 WIND TUNNEL: Horns and spades. By Barnaby Wainfan. 6 Exploring 2 EDITOR’S LOG: Shaving time with Occam’s razor. By Paul Dye. 60 THE DaWN PaTROL: The dropped tool disastrophe. By Dick Starks. 65 CHECKPOINTS: Oshkosh 2015 musings. By Vic Syracuse. Kit Bits 4 LETTERS 69 LIST OF ADVERTISERS 70 BUILDERS’ MaRKETPLACE 80 KIT STUFF: Drawing on experience. By cartoonist Robrucha. 14 On the cover: Just Aircraft SuperSTOL Stretch XL with 180-hp ULPower engine. Photographed by Richard VanderMeulen near Lakeland, Florida. For subscription information, contact KITPLANES® at 800/622-1065 or visit www.kitplanes.com/cs. KITPLANES January 2016 1 EDITOR’S LOG Shaving time with Occam’s razor. Troubleshooting is an art—an art the servo or carburetor and turn on the based on experience, knowledge— fuel pump—does it flow? Airflow is even and sometimes a little luck. I have been easier to determine—is there anything building and fixing things all my life, obstructing the inlet? Does the throttle and there are still times that I run down plate open? If yes, check that off the list. a primrose path that leads me to a des- Spark, of course, needs to be pres- ert devoid of answers. And that is when ent—and at the right time (although I remind myself of Occam’s razor. No, it is astounding how far out of time an you don’t buy it in a drugstore—it’s the engine can be and still “run.” I use quotes name of a process. because it won’t run very well). I had an According to Wikipedia, Occam’s razor unfortunate experience with a used fly- is a principle of parsimony, economy, or wheel once that had me time the mags succinctness used in problem solving 120° off—and it still started! Ran fine at that was devised by William of Ock- about 1500 rpm, but backfired like crazy ham (c. 1287–1347). It states that among when we throttled back. competing hypotheses, the one with the How about if it won’t crank? Well, you fewest assumptions should be selected. need a charged battery, a starter that will Other, more complicated, solutions may engage and then turn, and if there is a ultimately prove correct, but—in the solenoid in between, it has to go “click” absence of certainty—the fewer assump- and conduct massive amounts of juice. To keep small tasks from becoming tions that are made, the better. There aren’t many things that can go large tasks, the first tool you should The razor has many different descrip- wrong, and they are easy to check—so reach for is Occam’s razor. tions, but the way I like to think of it, the why start thinking that you have been simplest possible solution is the one to attacked by cosmic rays, or some com- cylinder walls, so we make up all sorts of pursue. This works especially well with plicated failure has occurred in your bat- excuses like the ring gaps all being lined simple systems or mechanisms—like a tery that allows you to listen to the radio, up, or maybe it was just too cold to do a Lycoming-type engine. So long as the but not crank the engine (that’s not very good compression check. Lycoming says crank is turning freely, the pistons are complicated), or a witch doctor has put you can button it up and go fly an hour going up and down, and the valves are a curse on your machine? Look at the or two, and that’s a good idea. But when opening and closing, the only thing you simple things first. you come back and get the same results, need to get a Lycoming to run is air, fuel, Sometimes, we know in our hearts you might as well get out the cylinder- and spark. If it’s not firing, assume that it that the problem is serious, but we hope base wrenches—the ring gaps lining up is missing one of those three items and against hope that the problem is actu- is just not going to cut it as an excuse. look for the simplest solution. ally minor. A good example is when you Electrical problems are where we Has it got fuel? Well, that’s easy to fig- do a compression check and find a low always try and get creative—electricity ure out—make sure there’s something cylinder, with air coming out of the dip- is, after all, pretty much magic to many, in the tank and the valve is open. Want stick. No one wants to pull a jug and find so why not assume that the problem is to still be sure? Take off the fuel line at that you have a broken ring or glazed magical? When someone tells me that Paul Dye retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the space shuttle. An avid homebuilder, he began flying and working on airplanes as a teen, and has experience with a wide range of construction techniques and materials. He flies an RV-8 that he built in 2005, and an RV-3 that he built with his pilot wife. Currently, they are building a Xenos Paul Dye motorglider. A commercially licensed pilot, Paul has logged over 4800 hours in many different types of aircraft and is an EAA tech counselor, flight advisor, and member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country. 2 KITPLANES January 2016 www.kitplanes.com & www.facebook.com/kitplanes all of the LED indicators in their cockpit light up when they transmit, I don’t start talking about ferrite beads, separat- ing antenna wires from signal wires, or reloading software—I ask if they have a cheap wire-whip antenna in their all- metal airplane. The answer is usually yes, in which case I then point out that they left too much of the core unshielded next to the antenna. No one wants to hear that if the end of the antenna is under the floor, but nevertheless, that is going to be the answer. If you find yourself constructing a complicated rationale to describe a prob- lem, you are violating Occam’s razor and heading down a path that will probably not take you anywhere. Landing gear seem to be loose? Most likely a hole has wallowed out, or a bushing has failed. Problem getting your RV to cool right? Look at what you have changed from the factory drawings; thousands of them are working just fine, built to plans. If you changed something, that is the most likely culprit—not some strange interac- tion of flow and the Vernatherm. You may not like the answer you are going to get when you take the simple path—it sometimes leads to a major struc- tural rework, or an engine overhaul—but Occam doesn’t say you’re going to like his answer—only which is most likely. When a light that has been working stops work- ing, suspect the bulb or a wire that has come undone, or you blew a fuse. I had a crimp come undone on a landing light wire on one of our planes recently. Rather than taking the whole wingtip off to start my troubleshooting, I looked under the panel, assuming that the wire was con- tinuous from the fuselage to the tip. Sure enough, the bad crimp was in a splice six inches from the switch. That saved taking off 60 screws. Use your head—and Occam’s razor— the next time you have a problem. Don’t reach for the wrenches first. You’ll save time and look like a genius to your friends when you go right to the trouble spot without first going down some dead ends.