14x13.5. I'm surprised the engine stayed with the airplane. Not sure what the actual cause was. Earlier in the day I had the mount come loose. I epoxied it back and added some screws between rounds. The following round went well with 14x13N and 30%. Made it into the trophy race and knew that 30% was not going to beat Mick and Mark. James Gale gave me a tank of 55% and I changed to the bigger prop. Mick and I were trading the lead back and forth. Virginia tells me I was leading when all I knew was the engine had quit. I had just thought I popped a plug. The look on her face when she retrieved the airplane said more was wrong. Upon inspection the front of the airplane is chewed up but worst is the stress damage to the wing. After pulling the engine I found that the needle valve assembly has vibrated loose, throttle arm was loose and the ratchet clip on the needle valve is gone.