Comment on "503 rotax pukes- Engine Out over 2 years ago now"
...start the engine. (i've had quite a few 'engine outs', flew hirth for several years,!and in the...5secs to plan , arrange and execute an arrival due to my trusting that hirth crank not to seize., that win...Comment on "Efficiency: Perfect pitch UAVs and airboats lead to new propellers (at least some good from UAVs / Drones)"
...the speed of sound. It's more noisy and its dangerous to the prop's structure. Because a lot of small aviator engines are 2 stroke (Rotax, Hirth) and they operate at high RPM...