Overall Propulsive Efficiency of Turboprop

Discussion in 'Firewall Forward / Props / Fuel system' started by Albertiumoxide, Sep 4, 2019.

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  1. Sep 4, 2019 #1

    Albertiumoxide

    Albertiumoxide

    Albertiumoxide

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    Does anyone know why does the turbopropeller engine reach the same overall propulsive efficiency at a higher mach number than the supercharged piston-propeller engine?

    The attached picture is a graph that indicates this trend, it was found in "The Design Of The Aeroplane" by Darrol Stinton.

    Many thanks
    Albert Propulsive Efficiency.jpg
     
  2. Sep 4, 2019 #2

    pictsidhe

    pictsidhe

    pictsidhe

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    Turbine engines get more efficient as speed increases. It increases the pressure ratio. Piston engines cannot take advantage if this as they are knock limited.
     
  3. Sep 4, 2019 #3

    Swampyankee

    Swampyankee

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    Most turboprop engines get some of their thrust from engine exhaust, as the exhaust isn’t expanded fully. This will tend to improve their propulsive efficiency as speed increases.
     
    Last edited: Sep 4, 2019

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