5-5 Turboprop and Turboshaft Engines SQ

  1. Describe the basic construction of a turboprop engine.
    Gas generator with a reduction gearbox, torquemeter assembly, and a propeller assembly.
  2. What component produces the majority of thrust in a turboprop?
    Prop (90% of total thrust)
  3. Why are reduction gears required in a turboprop?
    • To keep the blade tips subsonic.
    • Converts high RPM/low torque to low RPM/high torque.
  4. How much thrust is produced from the exhaust gases of a turboprop?
  5. What are the advantages and disadvantages of a turboprop in comparison with a turbojet?
    • Advantages:
    • Low TSFC
    • high thrust at low airspeed
    • able to carry more load requiring short runways.

    • Disadvantages:
    • Heavier and more complicated
    • limited to 450 knots.
  6. How is a turboshaft constructed?
    Gas generator with a free air/power turbine.
  7. What is a free turbine?
    A turbine that is not mechanically connected to the compressor and aft of the gas generator turbines.
  8. Describe the sections of a turboshaft and its function.
    • Gas generator:
    • Provides exhaust gas to drive the free/power turbine.

    • Free/power turbine:
    • Connected to the main transmission, it converts the heat energy to mechanical energy to drive the rotors.
  9. What percentage of a turboshaft's thrust comes from the exhaust?
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5-5 Turboprop and Turboshaft Engines SQ
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