The Fox 35 Stunt is a great engine as long as you understand it's limitations. This engine needs to be run on fuel with a minimum of 25% castor oil due to it's "old school" iron piston in a steel sleeve and to ensure that the connecting rod bearing surface gets adequate lubrication. The iron/steel technology also requires a prolonged period of break-in running best done for the first couple quarts of fuel on the ground to avoid overheating the engine when new. Once that break-in is past these engines seem to last nearly forever as I have several that are more than 30 years old and still running well. The only real complaint I have about it that high castor fuel does not flow well in cold weather making it more difficult to start when the temps are below 45 degrees (at least several months of the year in Omaha). This engine works well on most control line aircraft with between 300 and 400 square inches of wing area. That includes classic models like the Ringmaster, Flite Steak and Twister.