I have a new Extra 1.8m Wing with a .90 Super Tigre which I flew (maiden) last weekend that does a complete roll when the top part of the loop is reached (plane upside down at its lowest speed). The plane seems to stall ? and I have absolutely no control of it; but after the roll and when it gains a little speed its back in control again. What can it be ?? CG ?? Wing Balance ?? I am thinking of balancing the wing and pushing the CG a bit forward. I maybe thought it could be overcontrol of the elevators ?? Well lots of questions but not many answers this side. Any ideas on what can be done from someone who has gone through this before ?


Regards

Sounds like it's tipstalling from to much el. throw. Try doing a bigger loop without using full elevator. That will tell you if it's to much throw. Ideal is to back off the throw till it doesn't snap out.

snap roll -anyway you slice it -
Unfortunately, it is far too common on the BARFS of aerobatic models .
Sometimes, the model is underpowered and overweight- done to the manufacturer's recommended setup.
When the very first ARFS hit the US, this was the rule -not the exception.

If you stall the aircraft inverted at the top of a loop it will snap roll upright. This is true for both full scale and models. Really leaves you wondering what the heck happened when you are sitting in the airplane. Make the loop smaller so you keep up the speed on the top side. Also back off the nose up pressure on the stick in the upper quarter of the loop then incrase it on the down side.