View Full Version : "Typical" Rotor RPM
extreme P
2nd Dec 2006, 02:23
If there is such a thing what would typical rotor RPM be in cruise for an S76 or similar?
NickLappos
2nd Dec 2006, 03:22
It really isnt the RPM, its the speed of the rotor blade tip that counts. For most helos, the tip speed is about 675 to 750 feet per second. Obviously, the smaller the radius the faster the RPM to get that tip speed.
For an S76 it is 725 fps, 314 RPM for the 22 foot radius.
Gomer Pylot
2nd Dec 2006, 03:23
Between 100% and 108%, depending on the exact model. The A++, B, and C series normally operate at 107%. 100% is 293 rpm, and 107% is 312 rpm. Most helicopters operate in the vicinity of 300rpm for the main rotor.
extreme P
2nd Dec 2006, 03:24
Thanks guys.
Camp Freddie
2nd Dec 2006, 15:24
just for info I worked out years ago when a student asked and because the info was not in the POH, that an R44 RRPM was about 400 and the R22 was 500.
but the tip speed was similar on both which I seem to recall equated to about 400kts
age may have changed this figures but thats what I remember
regards
CF
Similar questions asked before and it is interesting to see the difference in speeds between different helicopters. As has been mentioned, tip speed is the same but rotor rpm ranges from 192 on the Mi-8, a few more on the S-61 up to 485+ on the smaller machines.