This sounds like a snap, which is probably the biggest enemy of the learner (and, it could be argued, the biggest friend of the 3d flier, but that's another story!!)

It was almost certainly caused by trying to get airborne too early, before enough airspeed had been reached, and the wing was flying properly. Try to keep the plane of the ground a little longer before taking off.

When a wing stalls, it doesn't stall equally across the whole wing, and sometimes one wing will partially stall when the other is still providing normal lift. Partly due to the air bleeding off the tip, the tip on some wings tends to stall first. This is called, believe it or not, a tip stall! It can be avoided in the design of the wing, and also when flying.

Lets say you are lining up to land, flying an aircraft that tends to tip stall... When you slow down, you will see one wing drop (the tip on the dropped side has partially stalled), the reflex is to give opposite aileron. This sometimes makes the situation even worse, as the dropped aileron (that is trying to push the dropped wing up) increases the drag on that side, making the plane turn towards the dropped wing (not away from it, which is what you meant to do!) and the plane dives in even faster! This is called a snap, and, when you get a bit more proficient, is great fun to actually induce if you are high enough!!!.

Getting back to the unwanted snap on landing . .The only way to handle this situation is to use a yaw control surface that hasn't stalled . . that is . . the rudder. Giving opposite rudder will not only have the tendency to bring up the dropped wing, but could also increase the speed of that side of the plane slightly which, if you are lucky, might bring the wing out of stall.

So, that's an answer to your other question. It is often better to use the rudder than the ailerons to control the model at slow speeds.

I shouldn't worry about all this just yet though. It only happens with more sensitive planes, and shouldn't happen with a trainer, where the stall speed of the wing is so slow due to the low wing loading.

-David C.