Which engine configuration is described as having no mechanical link between the compressor and the power output shaft?

Which engine configuration is described as having no mechanical link between the compressor and the power output shaft?

• A. Free Turbine
• B. Freewheeling Unit
• C. Geared Turbine
• D. Direct Turbine

Answer: (A)

In a free turbine setup, the engine has two separate shafts: one drives the compressor (gas generator), and a second, separate turbine drives the power output shaft that turns the helicopter rotor. The energy from combustion powers both turbines, but there is no mechanical connection between the compressor shaft and the power-output shaft. This decoupling allows the rotor to operate at a different speed than the compressor, giving smoother starts, easier throttle control, and better response to changing loads because the rotor isn’t tied to the compressor’s speed. The other configurations involve some form of mechanical linkage between the turbines and the output shaft—gearing or direct coupling—so they don’t fit the description of having no mechanical link between the compressor and the power output shaft.

In a free turbine setup, the engine has two separate shafts: one drives the compressor (gas generator), and a second, separate turbine drives the power output shaft that turns the helicopter rotor. The energy from combustion powers both turbines, but there is no mechanical connection between the compressor shaft and the power-output shaft. This decoupling allows the rotor to operate at a different speed than the compressor, giving smoother starts, easier throttle control, and better response to changing loads because the rotor isn’t tied to the compressor’s speed. The other configurations involve some form of mechanical linkage between the turbines and the output shaft—gearing or direct coupling—so they don’t fit the description of having no mechanical link between the compressor and the power output shaft.