Good evening folks,
I just finished building a Great Planes PT-40, took it out to the local club field and asked an instructor for help.
After getting it fuled up and ready to go, he taxied down the runway and took off. Almost immediatly the plane went nose high, the instructor put full trim to lower the elevator then lowered the elevator with the stick. (the trim tab went up then the left stick went up - is this called up trim because the sticks went forward to lower the evelevator or down trim to lower the elevator). Anyway, he got the plane back on the ground with minor, repairable damage. After emptying the fuel, we re-checked the c.g and the plane was fine, not tail heavy. Another club member noticed that the stab was mis-aligned.. He said that I either had to raise the front of the stab or lower the rear.

This sounds like major surgery! Apparantly the stab itself was creating the lift. I'm thinking that it might be better to cut it off, add some shims to the front of the stab to raise it a bit. The question is; how will I know when I have added enough? I only want to do this once! If I lower the rear, then the rudder to fuse hinges will be messed up. It seems to me that the hinges would be less affected by raining just the front of the stab.

By the way, when 'I' look at the stab, I don't see anything obviously wrong!

Any suggestions?

Thanks,
Greg

p.s. this is not an arf, i built it myself.

It is very difficult to give you a reliable answer from a distance. In general, if you built the PT-40 from plans and followed them to the letter, alignment should not be a problem. Did you make any mods in the way the wing is fastened on such as changing to bolt on versus rubber bands or make any changes in the way the wing sets on the fuselage? It could be that the wing has to high an angle of attack; if so put a shim under the trailing edge to raise it up. You could have the thrust line seriously off (i.e. built in some upthrust instead of down thrust). I'm sure that there should be someone in your club who could be trusted to get you off to a good start, check out some of the older members who have been flying a few years. In general, a PT40 is a very stable and good design that almost flys itself with the correct CG location.

Thanks so much for your input. I did not make any changes to the plans of the plane. I build the rubber band, high dihedral begginer wing. I took the plane yesterday to a hobby shop and while making a few purchases, i mentioned it to the owner. He said bring it in, so I did. He said the stab looked fine, didn't see anything wrong with the thrust. He said maybe a gust of wind took it upo like that. Anyway, I'm going to the field tomorrow am (batteries charging now!) for a second-third opinion
Greg