Pilatus PC-12 Torque Settings

[Team Blue]

Can anyone help out with an explaination for the "Maximum Climb Torque" Graph for the Pilatus PC-12, and why the torque settings are less than those for the cruise, for any given altitude and ISA deviation. I have heard some explanations regarding everything from the low pitch stop, to propeller blade flapping, but none really seem to make any sence.

[stubby1]

in the ATR the tq figure for climb (82% rpm) is more than the tq for t/o (100 % rpm).
but when you multiply these Tqs with the respective rpms you get the power, and which clarifies the situation -- the power for t/o is more than for climb.

the fundamental is that Power = Tq * rpm

hope this clears up your doubt.

[werbil]

With the Caravan, the maximum cruise torque settings for an amphib are lower than a podded wheeled van which are lower than a clean van. My guess is the lower torque setting is to allow for less ram effect of air entering the compressor at lower airspeeds.

[Team Blue]

Thanks for the feedback, I am happy with the fact that Torque and RPM are functions of Shaft Horsepower. Lets use that line of thought though: The Pilatus PC12's propellor RPM is essentailly 1700RPM for all phases of flight. Bearing this in mind, the torque (essentially shaft horsepower) limitations for any given altitude and temperature are less for the climb, than the cruise.