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3 Answers

Rated rpm with throttle fully open

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General Aviation

Why is it not possible to achieve rated rpm with throttle fully open?

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3 Answers



  1. John D Collins on Jul 15, 2014

    For most fixed pitch propellers, there is too much air resistance to motion with full throttle and the aircraft not moving, for the engine to achieve the rated RPM. As you commence the takeoff roll, you will note that the RPM will increase and at some speed will be able to achieve the rated RPM during a static run up. A propeller pitched for best climb or one that is under sized for the aircraft might be able to achieve rated RPM during a static run up.

    For a constant speed propeller, depending on the pitch stop settings and the engine power available, it may be able to achieve rated RPM during a static run up.

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  2. Danna danna on Jul 19, 2014

    thank you! So the aircraft can’t be on full throttle because of too much air resistance?

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  3. John D Collins on Jul 20, 2014

    Danna,

    The engine can be at full throttle, it just can’t achieve the full RPM because of the wind resistance to the motion of the propeller. RPM at full throttle without the aircraft moving is termed static RPM and usually there is a maintenance specification for what this value should be.

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