The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.59 m and 0.98 m, respectively. The respective rotational speeds are 456 rev/min and 4143 rev/min. Calculate the speeds of the tips of both rotors.

Question

main rotor:
tail rotor:

Compare these speeds with the speed of sound, 343 m/s.
vmain rotor / vsound
vtail rotor / vsound

speedtip= w*r where w=2PI*rev/min*1min/60sec (what does PI mean?)

Answer 1

pi = 3.1416

They provide the formula to use. Just do the calculations and compare the results to the sound speed.

Show your work if you need further assistance.