Constant Speed Tach Time

[raj_singh]

I had a question regarding tach time on aircraft using a constant speed propellar. I know many clubs that charge tach time which is great. But what about the aircraft that have a constant speed propeller. Can't you theoretically get the same power output on a lower rpm. What if you lower the rpm and increase manifold or does that over stress the engine and you shouldn't do it. Do you have to increase the rpm when you increase the power, and lower rpm when you lower the power. Because after understanding little bit about how the constand speed prop works, I wondered that wouldn't somebody just lower the rpm to save on tach time. But I have heard at the same time that when you increase power, you increase the rpm as well, and when you lower the power you lower the rpm.

Any thoughts!

[kenmod]

Gentlemen,

The best source of info is the POH. I have never seen one that requires rpm in hundreds to be above mp in inches even though this was taught to me. Use any combinaation of mp and rpm thqt is approved in the poh.

Ken