notenoughtime

I have a GP super decathalon and in order for level hands off flying I end up with some noticeable up elevator at most all throttle settings. If everything was perfect wouldn't a plane with all control surfaces level with airfoils and stabilizers fly straight and level. The plane seems to fly good once trimmed. The wing has an incedence of 0 when the horizontal stab is level. I was wondering if I could shim the bottom of my motor mount (adding a little up thrust to help pull the nose of the plane up) to help with the trim situation. Ground handling is not real good either. When the tail comes up I have to give up elevator to keep the prop out of the ground. I think it all has to be related.

I am not sure if I was clear on my problem but for level flight my elevator is pitched up noticably a lot more than my trainer was when trimmed for level flight.

FHHuber

visit www.nsrca.org see thier aircraft trim table.

Remember... if it is not a symetrical airfoiled 0-0-0 design, then the table will be off a little in the dive tests. EXPECT a flat bottom airfoil semi-scale Cub to pull out of the dive on its own fiarly quickly as speed builds. That Decathalon... should be close to the chart.

notenoughtime

thanks, I will test according to chart

Flypaper 2

Nose heavy plane will do this also. Try moving the CG back a bit to see if it straightens out. Another way to tell if it's a CG problem is wether it takes a lot of down elevator when flying inverted. Should take very little.

MinnFlyer

My Feedback: (4)

The GP Decathlon has a fullt Symmetrical airfoil, so speed shouldn't be a factor. I would also try shifting weight back, but CAREFULLY! This plane gets too tail heavy very quickly!