Well, thats the problem ,its impossible to get a doppler with big folders, dont know about 7" props, the 7x10 sounds more then the 7x13, so maybee possible for the 7x10..
The best props for doppler is the small ones..
I think sound can play a big factor here, its like the turbines, just the sound of a turbine plabe flying by makes it do 250mph, but it really does 170mph...
I think the big folders like 10x23 and also the 7x13 prop on a F5D goes faster then it lookes just for the quiter sound...
I guess we need a radar gun to be sure, but I guess Doug dont care as long as he is having fun
, I dont care about claimed speed much either as lon as I am happy, and I get what I want out if that setup/plane..
BUT, I can doppler, just make a straigt over the cam/close flyby, I think th 7" props ar managable do doppler..