Hello guys, I have been following this thread with quite a bit of interest as it has rekindled my interest in the Groovy 50 F3A which I have sitting in the basement. I believe that the planes are very similar and I am starting to think that I might have put the Groovy into mothballs a little too soon.

I just have a quick question. I would like to get an idea of what props are being used on the Spot On as well as what RPM's are being achieved. My Groovy is an electric conversion and I want to get a sense of whether I am in the ball park or not. The power system I was going to put on the plane will spin a 13x10 prop at about 7700 rpm giving me a pitch speed of about 72 mph and about 130 oz of thrust. The plane weighs about 95 oz. The input power is of about 650 watts. The set up is geared and I can change the ratios to either turn a bigger prop or to get higher RPM and power.

Just for reference, a 12x5 prop spining at 12K RPM requires close to 1000 input watts (850 watts at the prop) and generates a pitch speed of about 58 mph and about 127 oz of thrust. My set up will generate about the same amount of thrust, but at a somewhat higher pitch speed. Any one using higher pitched or larger props?

Any input would be appreciated.

Thanks,

Teo