Calculating Thrust
 

I' m hoping someone can advise me if the following method will indicate the approximate thrust being delivered from a turboprop engine:

1 Calculate a torque co-efficient eg 70 of max 107= 0.654

2 Calculate a RPM co efficient eg 1230 of max 1384 = 0.889

3 0.654 x 0.889 = 0.581 of maximum sea level rated power
eg 1394 kW x 0.581 = 810 kW

4 810 kW x typical propeller efficiency 0.8 = 648 kW "delivered' by the propeller

Would this methodology hold for typical cruise levels ie FL150 ?

Greedy