I had a neighbor friend in the 60's that built a Dolphin, and was infatuated in making it a smooth shiny ship. So he used gobs of spackling compound and built a real beaut. He had the combo from America Hobby Center that had a McCoy 40 RC Blue head with the locked throttle plate. The big day came and off to the ball field we went. Cranked it up, ol Mark runs out to the handle and signals a release. And release it did! The Dolphin made a slow ascent in a counter clockwise.The wings seemed level all the way up! By this time the handle was too high in the air for a recovery, so we all were falling down laughing our a**ess off enjoying this unusual FF show! After what seemed like a eternity, the engine quit.It must of been 100-120'in altitude. We all ran for our lives as it headed earth bound.POW! You all know that familiar sound. Nothing to recover but the engine(I still have it) And a pile of white powder(spackling compound). He said the plane was so heavy, it yanked the handle out of his hand. Naw, thats not possible is it? LOL
Moral to the story: Build it light, power it right, good flyer. Repeat.