I doubt the prop turns at 200,000rpm, the rotax 914 has a max crank rpm of 5800 (limited to max 5 mins) and an internal reduction gear of 1:2.273.
turning a prop at 200,000 rpm just isnt going to happen. That is way beyond supersonic. Also has a 2 speed prop.
Maybe you are confused with the 50:1 glide ratio, whih means for 1 ft drop in altitude you travel forward 50ft