If you change the angle of the blade, you can have lower rpm. This increased push is a drawback on a normal propeller because more air it pushed outward (loss).

If you change the angle of the blade, you can have lower rpm. This increased push is a drawback on a normal propeller because more air it pushed outward (loss). This design could solve both of the problems. So airplane propellers can have more push and lower rpm. Some years since I last designed propellers and did run CFD-analysis on them. Could be fun to try it again. This was my last attempt: https://no.m.wikipedia.org/wiki/Sivilingeniør#Utdanning https://no.m.wikipedia.org/wiki/Sivilingeniør#Utdanning