why are we only recommending os engines? i have a ax55 and the thing is a pain in the rear. hasnt deadsticked but the midrange is horrible, it flies slower at half throttle than it does at 1/4 throttle. i have no throttle response between 1/4 and 3/4 throttle, just a lot of gargleing. my idle is spot on, it will idle all day. im rich on the high end but not horribly rich. the engine crazy hot when i land, it easily boils any water put on it (wont boil water after about 2o seconds). its still breaking in i only have 5 tanks through it but for all the talk about os being easy to break, doesnt seem to be true. of my 5 engines the ax has been the worst during breakin, even my magnum 4 stroke runs better than this ax (breaking in the magnum). i also have a os 40fp that will die on me for no reason that i can think of while in flight, it will run great one day then bad the next.
get a gms .47 it has a slight blurble in the midrange if your idle isnt perfect but it is a very reliable engine and will pull that p-51 around quite well. their is no reason to spend 120-150 bucks on a engine that doesnt run much better than a 70 dollar one. espically if you are just learning and have the highest chance of a crash. if you want more power than a gms 47 get a magnum 52.