I have a GP Reactor 46 with a OS FS55AX engine flying a 13x6 prop. Last week I tried (to correct engine problems I had) witha a 12x8 prop. It was good but couldnt hold the hover.

This week with a 13x6 prop the airplane hovers for a second and then drops the nose even on application of power and full elevator. I am already at the full 3D throws. I dont apply full throttle, just about 80% in the hover. I figure that the engine should have some left to pullout if I get into trouble. Another issue is that in high-alpha nearing the hover, the airplane seems to have a lot of wing rock.

When I checked the CG, the thing is just a bit tail heavy at the recommended CG. Problem is even with a CG machine, it drops the tail if the tail is lower and the nose if the nose is lower at the recommended CG, so I guess I am somewhere close to recommended. I have a larger than stock 320cc (14oz) Sullivian flexitank in the airplane, most of the time when I hover, I have a good amount of fuel (I usually land with 1/8 tank of fuel after a 10 minute flight), so in that configuration it should be nose-heavy.

I tried a 13x4 prop also, the engine overheats and there is really no airspeed in that prop.

Please suggest what I should do in this case?

Ameyam