65.4 Turbine Engine Types

65.4.2 Compare the working cycle of a turbine engine and a piston engine. 

Gas Turbine Engine

• combustion occurs at a constant pressure
• induction, compression, combustion and exhaust occur continuously
• continuous action and is not enclosed so pressure is constant and volume increases
• no peak or fluctuation pressures
• requires light fabricated combustion chambers
• low octane fuels

Piston Engine

• occurs at a constant volume
• induction, compression, combustion and exhaust occur intermittently
• only one stroke is utilised in the production of power
• no continuous action and is enclosed so pressure rises and volume is constant
• peak pressures in excess of 1,000 lb. per sq. in.
• requires cylinders of heavy construction
• high octane fuels

65.4.4 Describe the comparative advantages of turbine engines versus piston engines for helicopters.

Compared with piston engines, turbine engines provide several advantages for helicopter operations:

High power-to-weight ratio:
A turbine engine produces considerably more power for its weight and size. This allows the helicopter to carry a greater payload without an excessively heavy engine.

Compact installation:
Turbine engines are relatively small for the power they produce, making them well suited to helicopter airframes.