The diameters of the main rotor and tail rotor of asingle-engine helicopter are 7.64 m and0.98 m, respectively. The respectiverotational speeds are 454 rev/min and4136 rev/min. Calculate the speeds of thetips of both rotors main rotor: tail rotor: Compare these speeds with the speed of sound, 343 m/s. vmain rotor /vsound: vtail rotor /vsound: The diameters of the main rotor and tail rotor of asingle-engine helicopter are 7.64 m and0.98 m, respectively. The respectiverotational speeds are 454 rev/min and4136 rev/min. Calculate the speeds of thetips of both rotors main rotor: tail rotor: Compare these speeds with the speed of sound, 343 m/s. vmain rotor /vsound: vtail rotor /vsound:
Explanation / Answer
linearspeed v = radius* angular speed v = r * a. mainrotor = 454 rev/min = 454* 2 /60 = 47.52 rad/s vmainrotor = 7.64 *47.52 = 363.05 m/s tailrotor = 4136 rev/min = 4136*2/60 = 432.90 rad/s vtailrotor = 0.98 *432.90 = 424.24 m/s b. vmain rotor /vsound = 363.05 /343 = 1.058 vtailrotor /vsound = 432.90 /343 = 1.262