I have an 8 lb. and a 10 lb. Bob Cat and am interested in your experience. The 10 lb. one has not been flown with prop. At 10 lb. the minimum flight speed (stall speed) is likely to be 35 mph, which will be difficult to achieve from grass and difficult to land.

My experience suggests that a 61 will be marginal at 10 pounds even with a pipe. Normally 8 lb. airplanes will have engines in the 60-size range and 10 to 11 lb. airplanes will have engines in the 90-size range. However if it doesn’t stall after the first 200 feet off the ground it will probably fly OK but heavy. I believe the strongest engine possible is your best choice.

Good luck and let us know the results.

Bill

I continue to wonder if 100 more sq in wing area wouldn’t make the Bob Cat a much more versatile airplane with many engine and prop setups. For the real finished weight the wing area is simply too small.