Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/113663
algorithms to extrapolate to a 10-percent bigger airplane, while preserving the original structural margins of the standard Cozy III. "I also used as much Brock-produced Cozy III hardware as I could. For example, bell cranks, torque tube inserts, nose strut mounting hardware, heavy-duty nose wheel and pivot structure all came from the Cozy. "My goal was to enlarge the aircraft 10 percent in all areas, including the cockpit, which went from 38 to 42 inches. To do the rest of the airplane, I built a huge pantograph and mounted it on an old ping-pong table. For those not familiar, a pantograph is a very simple mechanical device used to trace a drawing and produce a scaled version of the drawing; it was invented about 400 years ago, and the original design concept worked fine. The scaling is set by varying the length and pivot points of the arms." Te af end of lower boat-tail cowl was extended as far back as possible to minimize curvature and reduce airfow separation. Af end of upper cowl was cut as far forward as possible to allow relatively unimpeded engine cooling air to exit. Quite often, homebuilders are more or less isolated and have to make an effort to seek out knowledgeable help. Dennis, however, didn't have that problem. "Jim Voss lived almost across the street from me, and he was building a Long-EZ," Dennis said. "Not only that, but he was an EAA technical counselor and flight advisor; so that gave me firsthand knowledge of how the structure worked, and he was there to help me when I was stuck. He was invaluable in so many ways. "As I laid out the rear of the fuselage, I made some changes because I was never happy with the way the Cozy not only looked in that area, but also I was certain the airflow wasn't optimal for a pusher prop. So I straightened everything out and made it into a boat tail where the bottom was as long as possible. I shortened the top of the cowling because I wanted the hot air flowing over the engine to cool before exiting. The whole design was aimed at decreasing the back pressure the prop presented at the cooling air exits. "When it came to the canopy, I was originally going to have one made, but I lucked out and was able to modify a Mk. IV Cozy canopy/windshield that I bonded into a frame of my design. However, I didn't like the rear windows and wanted much more visibility. So I made a male form with the intent of heating a sheet of cast acrylic and draping it over the mold. I built an oven and heated it with two electric tent heaters. I had the material laying on the mold and stood there watching as it got hotter and hotter, but nothing was happening. Nothing! Then, almost without warning, it suddenly relaxed and flowed perfectly down over the form. It Photography by Jim Raeder Lots of room inside, with ultra-leather covering Tempur foam seats, back rests, and head rests. Te small leather pouch located between the seats contains the crank used to lower the nose gear if the electric deploy/retract mechanism were to fail. EAA Experimenter 15