Well I took my TT 91 FS off and slapped on a KRAFT .61 swinging a apc 14 x 4 prop. Flew it this morning and was able to hover pretty easy, and have "what everybody would call" about 1/2 throw left on my NoN-Linear throttle setting. I also have the a prop wrench zipped tied to the firewall because the .61 doesn't weigh as much as my TT 91 FS did. So now I will move the battery to balance it better and remove the prop wrench and see how it flies. LOVE this airplane!