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down aileron that causes most of the adverse yaw. So you know it’s not going to require as much rudder in a turn as an airplane where the ailerons move the same amount in each direction.”


While at the engine the Kings consider the propeller, including ground clearance (“That’s tells me where I can take this airplane, what I can do with it,” John said.) and on multi-engine aircraft, direction of prop rotation (“Are they counter-rotating propellers, or do they both go in the same direction?,” Martha asks. “That tells you a lot about the handling characteristics if you lose an engine on one side versus another.”) They also note engine position on the wing, for handling characteristics in engine-out situations. (“If it’s farther out, it’s going to have a higher Vmc (Minimum controllable airspeed on one engine),” Martha noted.

“If the airplane has more up aileron travel than down aileron, it isn’t going to have as much adverse yaw as an airplane where the ailerons move the same amount in each direction.

Pilots often focus on an aircraft’s horsepower but the Kings downplay its significance. “Unless it’s got a turbine or a turboprop on the front, the power is really going to mostly be proportionate to what the aircraft needs, based on the drag of the wings and the fuselage,” Martha said.

“The certification of an airplane requires that it be able to climb at a certain angle and a certain rate,” John noted. “So if you’ve got an FAA certificated airplane, it’s going to have an engine of a certain capability in order to make that airplane climb at a certain rate and climb at a certain angle.” “It takes four times the horsepower to double the speed,” John continued, noting that the Piper Comanche, originally a 180-hp aircraft, ultimately included a 400-hp Cherokee variant that was only about forty knots, or 25 percent faster, than its 180-horsepower cousin. “So adding horsepower doesn’t make it a whole lot faster,” John said. “It makes it climb better.”

Fuselage & Empennage After checking out the wings, John and Martha advise stepping back and taking in the airframe as a whole. “One of the things you would look at is the length of the fuselage relative to the size of the rudder,” Martha said. “The farther back the rudder is, the more effect it will have. With a relatively long fuselage you can have a smaller rudder and still have plenty of rudder authority.”

m ay / J u n e 2 0 1 0


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PilotMag-May/June 2010  

Aviation magazine

PilotMag-May/June 2010  

Aviation magazine

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