Ok here is the deal. I have a GP PT-40 that I built from a kit and the wing is a scratch built from the plans. Everytime I try to take off the plane pulls right when the wheels start to come off the ground. It usually ends with the plane nose over in the dirt on its back. When I do get it off the ground, it SEEMS to fly ok. I don't feel that I am adjusting to keep it going in line. I have checked the control surfaces and they seem to be OK. I buddy of mine said that there may be too much right thrust causing it to pull over when it leaves the ground. I am using a OS .46fx with a APC 10 X 6. I put a .40 on the plane last night thinking that I would see if a smaller engine will create the same result.

Any thoughts? I have looked at the wing and to my untrained eye, it looks to be pretty strieght.

Thanks!

Honestly this may be very difficult to diagnose over the internet without pictures. Do you have access to an instructor or experienced builders/flyers? I'd suggest employing their assistance - it will likely go much better for you.

... probably not what you wanted to hear ...

-MA

How does it end up on it's back?

If there is too much right thrust it should yaw right, but this should not cause it to roll over, even with the built in dihedral.

From the all too brief description it sounds like the plane is rolling too, more so than you ( the pilot ) is able to compensate for.

Usually on a new plane, during the first flight, you trim the plane out so it does not roll, etc. in flight. Has this been done before by a more experienced flyer?

I have a couple of (or had a couple - lost one this season) of PT-40s, good flyers overall, I hope you did not build the beginner wing, it has way too much dihedral.

It sounds to me like you did build the big dihedral wing, with that wing there is a tendancy to have the wind pick it up and flip it at slow speeds. You may also be pulling up too hard on rotation and stalling it. The first thing I would do is ease off on the elevator during take off, and step on the left rudder a bit more, that should null out the right yaw. I would also try to get a bit more speed up when you are taking off, that should help with the problem as well.

Good luck!

Manks

Check the play in your main wheels. They should both spin freely. If the right wheel is much tighter than the left, it act as described.

Nevermind, I misread the question and thought you said as soon as they start rolling.

Thanks for the replies.

I went out just now with a .40 and it still is doing it! I have had several people look at it with no answers. I have flown it several times and, once in the air, it flys nicely. You just have to fly right to get up in the air. My solution was to fly perpendicular to the runway (no one else was around) which gave me enough space to pull it back left. My experienced buddy flew it once it was in the air and found nothing wrong. We shimmed the motor to the left a little and it seemed to help a little but only a little. Lateral balance-OK, wheels-Ok. It is wierd because it happens just as soon is it gets light on the wheels. That is when I have to give it full left aileron to try to bring it back. The ring wing has about 1/8ish of an inch more wash out than the other but not too much that I can tell.

I made a mistake and built the beginner wing first, but then scratch built the "sport" wing. I tried to be very careful when building. Several people have looked at and are stumped as well.

The way it ends up on its back is, after the "tip stall" the wing digs in and over she goes!

Sounds like you may be pulling it off the runway too quickly and inducing a tip stall/snap roll on take off.

Brad

Did you check the balance? The right wing may be heavier.

when it pulls right are you in the air or not???

I might have found part of the problem. When replacing my .46fx I noticed that the back of the engine is ever so slightly cocked to the left, pulling the front of the engine to the right. I must have drilled the holes off by a little. It is not noticable when looking from the top, only when looking at the bottom of the engine. It is not very much off, maybe 1/32 to 1/64 of an inch. Maybe that combined with newbe building skills (the thrust line might be too much right) will cause this problem.

Here is the question now. The plane pulls right just about the time that it gets light on the wheels. Could the combination of too much right thrust, left wing traveling slightly faster than the right cause the problem at take off only to dissappear when both wings get enough lift? Like I said, the plane flies fine when I get it in the air and it lands fine.

???

Sounds like a wing tip stall, or you are pulling the the right stick down and to the right when adding elevator on takeoff setting your ailerons for a right turn/roll. Make sure you are pulling straight back.