Originally posted by faisalk
I have a 40 size trainer and a 46 size engine installed. Its usually very windy where i fly. At full throttle the plane climbs steeply and at even half throttle it climbs. I trimmed the elevator to down and i can literally see the elevator down from the neutral position but still the plane climbs. At 1/4 throttle it is level. Any idea if this is unusual or usual with trainers?
If you have a flat bottom wing trainer, and the stab is mounted along the fuse centerline, then you already have positive wing incidence. The wing chord line starts at the center of the wing's leading edge, not the bottom of the wing. Aerodynamically the stab is already set with *up* elevator when flat, and will load the wing to a positive angle-of-attack (AOA) which produces lift.
Your problem requires engine down-thrust. Many trainers have some, many don't.
Reset your engine to 5 to 8 degrees DOWN from the fuse. (stab.)centerline.
You said the plane does not climb at 1/4 throttle. With the downthrust, additional power will pull the plane down and you will trim the elevator for level. When you retard the throttle, the "pull down" goes away but the trim setting should allow a fairly smooth transition to the low power glide. Experiment a bit.
Some old timers that I fly require up to 12-15* down thrust depending on Glide CG arrangements that I set up. Pattern ships use CG to arrange near same.
Flat bottom wings fly their aerodynamics, sym. fly theirs and all others in-between. For example, washing out the wing tips will reduce the Down-thrust required. The PILOT controls a plane, airplane-drivers wonder what's wrong.