It's not real easy to do, since there is a long flat portion of the flight
trajectory at the top and it's difficult to judge the highest point. First
the top of the flight trajectory must be brought down to the floor by winding
and backwinding down to about half of maximum turns. (47% of the optimum
motor) For a plane that flies slowly enough to walk beside, catch the plane when
it seems to be flying level. Catch a few when it seems to have just leveled
off and a few when it seems to be just starting down. If the plane is
flying at eye level and there are horizontal lines in the background (bleachers,
wall panels, windows, stage) you may be able to judge altitude changes very
closely. Measure the torque. Be careful your bow wave and body heat do not
disturb the model. Bill Gowan's paper describes this method.
For a faster plane, wind, measure torque, let the plane fly a circuit, catch
it and measure torque. If it climbs, start with a lower number of turns, if
it descends, start with more turns, until you get a flight that leaves and
returns to your hand at the same elevation. The average of the beginning and
ending torques is very close to the level flight torque.
This is an important point of the flight trajectory. This torque
corresponds to the highest point on the flight trajectory. You want to set this point
to coincide with the ceiling height. You know turns and torque at launch and
landing. This point divides the energy into that used in the climb and that
used in the descent. Plotting these three points on the torque and energy
curves will help you select cross section and length of motor for best flight.
Gary Hinze
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Received on Thu Mar 15 2007 - 15:32:49 CET