Experimenter

March 2013

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.

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When Is a Cozy III Not a Cozy III? the numbers, then hold 75 knots on final and over the fence. I touch down at 70 knots. The airplane is very solid at that speed. It is, however, a pavement-only airplane because the front gear and strut are not designed for unpaved runways." No one who builds an airplane is happy with its final empty weight, and Dennis is no exception. "Empty weight is 1,320 pounds," he said. "My design target was 1,250, but I blew that when I added 20 pounds of paint and 50 pounds of Tempur foam seats and upholstery. No complaints, though. Those seats, with ultra leather upholstery, are extremely comfortable and nice looking, too. Useful load is 680 pounds. Details of engine bafing and exhaust pipe cooling air seals.  Te oil cooler (lower right corner of picture) is mounted to the af face of the center section spar with composite brackets epoxied to the spar.  Te composite brackets serve as anchor points for the aluminum arms to which the cooler is attached.   Jim Voss, was especially helpful in making my first flight as safe as it could possibly be. "My first flight went very well, with only one relatively small squawk. Although I had plenty of pitch authority, the pitch trim system that I had designed was not very good; it required constant stick pressure during flight. After using stiffer springs and redesigning the system with a more favorable mechanical geometry, I was able to do fully trimmed, hands-off flight." After putting more than 160 hours on it, including four long cross-countries, including one to EAA AirVenture Oshkosh 2012, Dennis is now in a position to evaluate its handling in all areas. "The airplane flies great!" he said. "It is fast, stable, and reasonably responsive in both pitch and roll. I have to be careful with the rudders, especially close to the ground, since they are more powerful than I expected. Other than that, the flying characteristics are very similar to those published for the Cozy IV. Takeoffs and landings are a little different than they are in conventional airplanes because I am overly conscious of my limited propeller and winglet ground clearance. They dictate using a flatter attitude on takeoff and landing than flown in conventional airplanes. I avoid wing-low crosswind landings to protect the lower winglets. Instead I use a crabbed approach, with a little rudder to straighten out just before touchdown. These procedures are per Nat Puffer's recommendations in the Cozy III POH. "At altitude I'm cruising at 171 knots and 8 gph. I'm using 80 knots on downwind, deploy speed brake, when abeam 18 Vol.2 No.3 / March 201 3 "For fuel, I have 25 gallons useful each side for a total of 50 gallons. At economy cruise of 150 knots, fuel burn is 7 gph with the mixture set to 50 degrees lean of peak. This makes six-hour flight legs possible, but that's much longer than I like to fly without stopping to stretch my legs." No airplane is ever perfect, and it's often after flying it for a while that you realize there are some things you'd change if building it again. Dennis said, "A friend built a Legacy with an all-glass cockpit, and if I were to do it again, I'd go that way. Although, since I started building in 1990, the instrumentation available to the sport aviation market has progressed wildly. "Another change I'd make would be to make the bottom of the winglets easily replaceable, streamlined wooden tips because they sometimes get scraped. I may yet do that." Just as no homebuilt aircraft is ever truly completed, no homebuilder is ever done building or looking for new projects. In Dennis's view that means, as Thoreau said, "Simplify, simplify." Dennis said, "The next thing I want to do is fly a Cub." How's that for extremes? Now we just have to watch to see whether he's going to be happy just flying a Cub. Do we see another building project in his future? Budd Davisson is an aeronautical engineer, has flown more than 300 different types, and has published four books and more than 4,000 articles. He is editor-in-chief of Flight Journal magazine and a flight instructor primarily in Pitts/tailwheel aircraft. Visit him on www.AirBum.com.

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