The Hnager 9 T-34 is pretty heavy for it's size resulting in a high wing loading. It's prone to tip stalling, so I'd say you probably diagnosed the problem.

This one needs plenty of speed before letting it off the ground, and keep the speed up when landing too.

A friend brought his to the field and asked me to maiden it for him. Everything went fine until the new engine in it quit while a long way out from the runway. The plane tip stalled on me at an air speed that really surprised me. I managed to get some speed back and got the plane leveled before it went in, so there was little damage (some torn covering & wing bolt block), but it's not a plane I'd be interested in owning.

Sorry about your's.
Dennis-