There are two important measurements of turbine engine power output. The one published in basic specifications, and tossed around when pilots get together to talk, is the takeoff power rating. And that’s important. But a more difficult to define, and equally important, measure of turbine enginepower is how much is available at useful cruise altitude. The new TBM 850 has the same takeoff power rating as the previous model, but delivers considerably more thrust at high cruise altitude to increase its effective cruise speed by 25 knots or more.
The actual cruise power increase in the new TBM 850 is variable when you consider altitude and air temperature for the comparison, but it is nominally 150 shaft horsepower (SHP), thus the name change from TBM 700 to 850. Because the extra fuel needed to generate the extra power up high is offset by the cruise speed increase, range remains about the same with no fuel capacity increase. And when boring into a strong headwind, the higher true airspeeds actually improve range because a smaller percentage of the true airspeed is lost to the wind.
