What would a formula look like for calculating the rotor blade tip speed on a helicopter? I.e. a blade on an R44, or a blade on a micro helicopter that's only 360mm. -
![drag - At what rpm does the tip of a 54" propeller start to incur mach losses? - Aviation Stack Exchange drag - At what rpm does the tip of a 54" propeller start to incur mach losses? - Aviation Stack Exchange](https://i.stack.imgur.com/0cdls.jpg)
drag - At what rpm does the tip of a 54" propeller start to incur mach losses? - Aviation Stack Exchange
![aerodynamics - What is the correct formula to calculate propeller efficiency? - Aviation Stack Exchange aerodynamics - What is the correct formula to calculate propeller efficiency? - Aviation Stack Exchange](https://i.stack.imgur.com/vcgpZ.png)