We and the planks have different control objectives, so we end up with different control mechanisms. We have highly variable flight regimes and want to maintain rrpm (because it keeps us alive) without having to play with the throttle all the time (because we've got too much else to think about). The planks have much more fixed flight regimes, so they focus on prop efficiency for airspeed (fuel economy). I could turn your question round and say why would you want to target a particular MP setting ?
R22 Clipper, I think you're there on the pulling carb heat, but I think the climb stuff would be better stated along the lines of
"As you climb, atmospheric pressure reduces which reduces (among other things) rotor drag, thrust, manifold pressure, and back pressure on the exhaust. If the governor is on it will sense any changes to rrpm resulting from the balance of changing engine power and rotor drag and adjust the throttle to restore it. The pilot may then choose to compensate for the reduced performance (rotor thrust) by raising the collective, and if she does, the governor will respond by opening the throttle to meet the demand, thus increasing the MP. Exactly how much the pilot needs to raise the collective to maintain performance will depend on a balance of factors, but if the pilot happens to reproduce the MP that existed at lower altitudes then the engine will be producing more power than it was as a result of lower exhaust back pressure"
Great question BTW, really makes you think. It just shows why lawyers end up with such convoluted prose when they try and answer a simple question !
Last edited by puntosaurus; 27th March 2006 at 08:06.