Trying to match up the prop with an electric motor for a given airframe is a bit of work. I have had the same type of problem with my stingray, it did well with a 6 inch prop but thus far hasn't been able to get past 120 with a 5 inch prop. The best flight and speed was with a 6X5.5 apc with the 5 inch props I have had very high rpm turnning upwards of 27-28 k rpm but the airframe just has to much drag for the prop to even get the plane to 85% of prop pitch speed.
Last edited by iron eagel; 11-10-2013 at 09:58 AM.