RE: fun51 engine
I started with a Webra 40 black head and it wasn't enough. Went to the OS .46fx which was plenty, but needed a bunch of tail weight to get it to tumble how i liked. It did an awesome climbing inverted spin. With its short moments, it tumbles pretty good and knife edge loops are a breeze, it just doesn't hove or harrier all that well. Fun plane, got lots of flights on mine.