we always powered our cubs to go straight up but here in the last few weeks i built a g.p. arf cub, put a new 52 magnum. it was so much more fun with the smaller engine, you have to use full power to get it moving so it has the straining sound like the real ones do. my friend that i putt-putt around with pulled his o.s. 70 and put an old saito 45 on his. lot's more fun and it really gets the wing loading down.