You should have read the review in RCM.

First of all. the CG is WAY off. :angry: The instructions call for 100mm. It should be 30 to 33 % of the wing chord (I don't have mine anymore or I'd tell you exactly). Mine balanced without added lead with an MVVS 49 or HP 61.

As far as engine, you will need either an HP Gold Cup .61, a Saito 72 or a YS .63 for passable 3D or a 91 four stroke for awesome acceleration out of a hover. The 91 will be heavy though, and will make some of the other 3D maneuvers harder to do.

Jim