How Helicopters Work

By: Tom Harris & Talon Homer  | 

Anatomy of a Helicopter: The Blade Are Spinning and the Engine Is Running

helicopter illustration
This diagram details the basic parts of a helicopter.

Sikorsky and a few of his contemporaries brought a technical rigor to the field that finally made vertical flight safe, practical and reliable. As the flight-crazy Russian continued to refine his helicopter designs, he worked out the fundamental requirements that any such machine needed to have to be successful, including:

  • a suitable engine with a high power-to-weight ratio,
  • a mechanism to counteract rotor torque action,
  • proper controls so the aircraft could be steered confidently and without catastrophic failures,
  • a lightweight structural frame, and
  • a means to reduce vibrations.

Many of the basic parts seen on a modern helicopter grew out of the need to address one or more of these basic requirements. Let's look at these components in greater detail:


Main rotor blade — The main rotor blade performs the same function as an airplane's wings, providing lift as the blades rotate — lift being one of the critical aerodynamic forces that keeps aircraft aloft. A pilot can affect lift by changing the rotor's revolutions per minute (rpm) or its angle of attack, which refers to the angle of the rotary wing in relation to the oncoming wind.

Stabilizer — The stabilizer bar sits above and across the main rotor blade. Its weight and rotation dampen unwanted vibrations in the main rotor, helping to stabilize the craft in all flight conditions. Arthur Young, the gent who designed the Bell 47 helicopter, is credited with inventing the stabilizer bar.

Rotor mast — Also known as the rotor shaft, the mast connects the transmission to the rotor assembly. The mast rotates the upper swash plate and the blades.

Transmission — Just as it does in a motor vehicle, a helicopter's transmission transmits power from the engine to the main and tail rotors. The transmission's main gearbox steps down the speed of the main rotor so it doesn't rotate as rapidly as the engine shaft. A second gearbox does the same for the tail rotor, although the tail rotor, being much smaller, can rotate faster than the main rotor.

Engine — The engine generates power for the aircraft. Early helicopters relied on reciprocating gasoline engines, but modern helicopters use gas turbine engines like those found in commercial airliners.

Stay with us. We'll learn to steer this baby next.