Question for the Motor Heads

[DK-nme]

Originally Posted by Dutch_851

No, not Lemmy's gang!
Thanks in advance!

Hmmm they are good though...

Originally Posted by Dutch_851

Also is the RPM gauge telling you prop RPM or engine RPM?
Thanks in advance!

RPM is for the engine, I think. And this is why. A quick calculation:

If prop lenth is 1.5 meters (too long, too short?)
And max RPM is 2400-2500 r/min (too much?), then, the speed of the propeller tip will be:

2*radius*Pi (m/r) * 2400 (r/min) * 60 (min/h) *1/1000 (km/m) = 1357 (km/h), which is a bit above speed of sound.

Edit: Oooops, a small bug in the calc. Now it has been fixed

The propeller should not exceed the speed of sound, cause the compresability will eliminate the lift (of the propeller, that is) and thus, the RPM must logically represents the revolving of the engine...