65.28 Turbine Engine Performance

65.28.2 Define the following terms and describe the relationship between them, and their application to engine operation:

(a) power

Power is the rate at which work is done.

In a turbine engine, power is the rate at which the engine converts fuel energy into useful mechanical output.

In a turboshaft engine, this power is delivered through the output shaft to drive the helicopter transmission and rotor system.

(b) thrust

Thrust is the force produced by accelerating a mass of air or gas in one direction, producing an equal and opposite force on the engine.

In turbojet and turbofan engines, thrust provides the main propulsive force.

In a helicopter turboshaft engine, little useful propulsive thrust is produced by the exhaust because most of the gas energy is extracted by the turbines to produce shaft power.

(c) torque

Torque is the twisting force produced by the engine.

In a turboshaft engine, torque is transmitted through the output shaft and reduction gearbox to the helicopter transmission and rotor system.