My TT Rare Bear horizontal stab broke off on the 4th flight... right in front of about 40 people... there is nothing left of it worth saving. I was at about 2/3 throttle and straight and level about 50 ft off the ground. We all saw the right stabilizer flutter violently up and down and then 'pop' it broke off. I rolled it to the left and pulled the throttle back and it went in nose down. It destroyed the plane and broke the motor. I have flown and built airplanes since 1958 and I have never until this plane had one to literally fall apart on me. Yes I had opened the bottom of the stabilizer and added extra glue. I think the problem is that this airplane is a marginal design and will eventually cause someone to get hurt. In my opinion it is unsafe to fly around spectators. Had the structural failure occurred 4 seconds earlier the plane would have crashed into the crowd of people. I have contacted ACE and they say they have no responsibility for this and are refusing to return my money for a defective product and fix the engine. I don't understand why they are doing this but it will clearly have an effect on my decision to buy their products in the future.