How Are RPMs Controlled on a Turbo Prop Aircraft?

Turboprop aircraft use jet engines to turn a propeller.

A turbo propeller engine or turboprop uses the mechanical energy derived from a turbine to spin a propeller with greater efficiency than a conventional, reciprocating engine. A turboprop engine typically enjoys greater fuel efficiency than its turbojet counterpart.

Significance

Revolutions per minute (rpms) are controlled on turboprop engines by means of a gear reducer. A turbine engine spins at several thousand rpms just to operate and must be reduced to turn the propellers efficiently.

Function

Rpm reduction is achieved by using different gears of different circumferences working together to slow the rotational force of the turbine engine. A larger gear is employed as it will spin slower around the circumference, thus reducing the faster spin of the smaller circumference turbine shaft.

Benefits

A gas turbine being used to spin a propeller will achieve greater efficiency and fuel economy for the aircraft than using standard jet propulsion. This is because the engine can be operated at a much lower level than would be required if the engine were needed to produce thrust to move the aircraft through the sky.

References

• NASA: Engines
• Team DaVinci: Gear Reduction