Swashplate (aeronautics)

In aeronautics, a swashplate is a mechanical device that translates input via the helicopter flight controls into motion of the main rotor blades.

Today, on most modern aircraft the swashplate is above the transmission and the pushrods are visible outside the fuselage, but a few early designs, notably light helicopters built by Enstrom Helicopter, placed it underneath the transmission and enclosed the rotating pushrods inside the mainshaft.

The stationary (outer) swashplate is mounted on the main rotor mast and is connected to the cyclic and collective controls by a series of pushrods.

An anti-rotation link prevents the inner swash from rotating independently of the blades, which would apply torque to the actuators.

Push rods or hydraulic actuators tilt the outer swashplate in response to the pilot's commands.

Conventionally, each control mechanism, (roll, pitch, and collective) had an individual actuator responsible for the movement.

However, some newer model helicopters remove this mechanically complex separation of functionalities by using three interdependent actuators that can each move the entire swashplate.

Swashplate on a radio-controlled helicopter . 1. Non-rotating outer ring (blue). 2. Turning inner ring (silver). 3. Ball joint. 4. Control (pitch) preventing turning of outer ring. 5. Control (roll). 6. Linkages (silver) to the rotor blade
In 1907 before the flight test of Cornu's helicopter. Can be seen wheels (plates) with levers controlling the pitch of the propellers.
A scaled model of an exhibition full-size mock-up of a single-rotor helicopter, proposed in 1912 by students of the IMTS headed by Boris Yuriev (1889-1957). No details of the mechanism are shown on the mock-up.