Helicopter rotor speed

Question

I'm writing a novel and, for a specific description, need to know how fast helicopter rotors travel. Rough estimates are fine. (I prefer the unit of measurement to be RPM [revolutions per minute], but beggars can't be choosers. If need be I'll do the conversion.)

Answer 1

that is going to depend on a lot of factors. Typically, about 500rpm is a fair number to use. some can be faster, and some can be slower. The Mil V-12, the largest helicopter ever made (not produced) had very slow spinning rotors, 110rpm I believe.

I think a jet ranger is around 400 rpm. It seems (logically) that the shorter the rotor is the faster its rotation.

Answer 2

Dennis is correct in all.  Actually the tip speed of the main rotor approaches the speed of sound which is what causes the whop whop sound as the air can travel up the rotor blade instead of being cleanly past mach.. it doesn't actually make it. The collective has a direct input on main rotor RPM and the engine rpm tends to remain constant which is why turbine engines do so well for helicopters. With a finer pitch the main rotor would have a higher rpm and store blade energy which is something you will learn about when you start dealing with autorotations after an engine failure...  the helicopter version of gliding.

Answer 3

my happens to have 257 rpm in flight, both engines operating.

the tail rotor goes somewhere about 1400 rpm