Reversethrust

Reversethrust, commonly referred to as thrust reversal, is a propulsion feature on certain aircraft that redirects engine exhaust forward rather than backward. The primary purpose is to provide additional deceleration after landing and to assist braking during an aborted takeoff, by converting part of the engine’s thrust into a forward-directed force that opposes the aircraft’s forward motion. Thrust reversers are designed to be used only when the aircraft is on the ground.

In jet and turbofan engines, reversers typically employ blocker doors and cascade vanes inside or near the exhaust nozzle to deflect the hot exhaust forward. When deployed, the redirected flow generates a braking force that supplements wheel brakes and spoilers. There are two main designs: cascade-type, which uses a set of hinged doors and channeling vanes, and bucket-type (less common on modern airliners), which physically blocks and redirects the nozzle flow. In turboprop aircraft, reverse thrust is produced by pitching the propeller blades toward negative angles, creating backward-directed reaction forces that slow the aircraft.

Operational considerations include shutdown timing, speed limits, and crosswind handling. Reversers are typically activated after touchdown and when the aircraft’s wheels are on the runway; they are not used for takeoff and are generally avoided during high-speed aborts unless the situation permits safe, controlled deployment. Their effectiveness depends on engine power, weight, runway conditions, and system maintenance. Reversers introduce added noise and can complicate directional control in some conditions, and they must be stowed before the aircraft proceeds taxi or repositioning.

Overall, thrust reversers are a complementary braking system used in many types of aircraft to reduce stopping distance and improve controllability on landing.