ORIGINAL: Dav0012
Currently i have been running a os 70 fl 4 stroke in this plane, which i switched for an os 46 ax i had sitting on another plane, now what my question is neither of these motors seem good enough for this plane, i mean basic aerobatics it can do, but some other manuevers i'd say it struggles,
What?!!!! < just surprised> [sm=spinnyeyes.gif]
With which manoeuvres in the particular does it struggle?
What does it weigh (dry)? Probably more importantly, what prop have you got fitted to the 46 AX? That engine
should have more than enough poke with that model even if it weighed in at a whopping 6+ lb dry to complete the sportsman pattern sequence including verticals like the top hat, stall turn with ¼ rolls, ½ Immelman continued into a ½ reverse immelman, consecutive upward outside loops from inverted or downward from upright all with ease. It's not going to have 'unlimited' vertical, but it should have 'solid' vertical. If it doesn't, something's wrong.
if a os 61 fx which i could buy, is too much for this plane,
IMO, yes. Well you could certainly fit one, but it's going to stress the structure, require a bigger tank, alter the CofG forward and increase the wing loading.
Really, adding weight or excess power isn't going to help improve the AX+CAP combos overall aerobatic performance even if it does afford you more outright vertical punch. And don't forget, you'll have to carry more fuel to get it which is also going to worsen the overweight situation at take-off and for the first 30% of the flight time. If you really must have more grunt to mask some apparent problem or just to achieve a typical 3D like vertical performance expectation which is unrealistic of this model and any .46 combo, then my recommendation would be to go with a powerful over-bored .46 cased unit like an Irvine .53, ENYA CX50, Magnum 52, JEN .56 or MVVS .49, O.S. 50SX or <choose one of many> similar. Forget the ST G50 ring though. It's a .50in² in capacity and designation only, and not in the same performance league as the others.....in my humble opinion of course.