How Does Helicopter Engines Work?

Like all other powered aircraft, helicopters rely on engines to generate the power they use to achieve flight. Helicopters use two different types of engines, reciprocating and turbine, to do so. Reciprocating engines, or piston engines, are typically used in smaller helicopters, such as trainers, because they are relatively simple to operate and inexpensive to maintain. Turbine engines are used in a wider variety of helicopters, and are more powerful. However, they are also more expensive to operate. In this blog, we’ll explore just how these two types of engines work.

Reciprocating engines consist of a series of pistons connected to a rotating crankshaft. As the pistons move up and down, the crankshaft rotates, which gives the engine its name. Most helicopter reciprocating engines are four-stroke engines, which refers to the four different cycles the engine goes through to produce power. When the piston moves away from the cylinder head on the intake stroke, the intake valve opens and a mixture of fuel and air is allowed into the combustion chamber. As the cylinder moves back to the cylinder head, the intake valve closes, and the fuel-air mixture is compressed.

When compression is almost complete, the spark plug fires and the compressed mixture is ignited to begin the power stroke. These burning and rapidly expanding gasses from the controlled burning of the fuel-air mixture drive the piston away from the cylinder head, and provide power to rotate the crankshaft. The piston then moves back toward the cylinder head on the exhaust stroke where the burned gases are expelled through the open exhaust valve, completing the cycle. This four-stroke cycle occurs hundreds of times every minute even at low power operations, and provides the energy to the helicopter’s main and tail rotors.

Turbine engines are made up of a compressor, combustion chamber, turbine, and gearbox assembly. The compressor compresses air as it enters the engine, which is then fed to the combustion chamber where it mixes with the injected fuel. This fuel-air mixture is ignited and expands, then is forced through a series of turbine wheels to make them turn. These turbine wheels provide power to the engine compressor and the main rotor system through and output shaft, and is then expelled via an exhaust outlet.

1. alex marsh
2. Posted on January 13, 2020
helicopter