Buzz, are you saying the OS70FS won't be able to pull the Rush out of a hover? Should I lash out and buy the 91?? BTW I see you are at Canberra, the altitude there is 1886ft (at Canberra Airport) whereas I will spend most of my time flying at 67ft. Also, I should mention that this is my third plane but I am confident in my flying skills and ability to exercise some throttle control.

Is there a program which can be used to compare engine performance based on engine size/type, weight, prop, altitude, temp etc...? I've seen this type of thing for electric planes (eg motocalc among others) but haven't heard of one for glow engines.