Optimum Rotor RPM?

[rehler]

Is there a way to figure the optimum rotor rpm? My rotor is pitch adjustable and I want to set it at the pitch needed to get the best rotor RPM.

Rotor Description: 27' diameter, 8.5" chord
Gyro Description: 805 pounds all up weight (with pilot and fuel)
Best Rotor RPM: ???

It now turns 290 RPM, which seems rather slow.

[birdy]

Im just a pilot Ken,but with the little experiance I'v had I'v found that it depends on wot you want.
Fuel efficiancey
Best lift
Speed
or control responce speed.
All of the above is impossable,but a balance is acheivable.
IOW,I like as high rpm as possable,but not everybody is do'n wot I'm do'n.

High rpm gives me good fuel efficiancy and fast control responce,but im probably loos'n out on speed and lift.

[Aussie_Paul]

Ken, Chuck B has posted from time to time the recommended rotor tip speed. You can then determine the RRPM for your particular rotor system diameter.

Aussie Paul. :)

[rehler]

Thanks for your help. I found a post by Chuck Beaty, which I think recommends that the desired top gyro speed be 35% of the rotor tip speed. So ...

At my present 290 rotor rpm my top flying speed is 97 mph.

If re-pitched to get 310 rpm my top flying speed will be 104 mph.

Birdy, as I read Chuck's post, your fast rotor speed hurts your fuel efficiency and helps your top flying speed. I don't think it changes the lift - but I'm not sure.