Thrust Reversal: An Aviation Technique and Its Variations
Cruising through Landings: The Thrust Reversal Technique
Landing an aircraft with grace and safety is no small feat. But thanks to a nifty maneuver called thrust reversal, planes can easily slow down and roll to a stop, even when landing on short runways.
Aircraft decelerate during landing using three primary methods:
- Landing gear brakes
- Rear wing spoilers
- Thrust reversal systems
But it's not just commercial planes that use thrust reversal. Militaries often use additional techniques like drogue parachutes and runway arrestor gear systems.
What is Thrust Reversal?
Thrust reversal has a straightforward name, and it does exactly what it says. It redirects the engines' thrust, counteracting the plane's forward motion. By doing this, the plane can stop much quicker, and the brakes take less of a beating.
Contrary to some rumors, thrust reversal doesn't actually reverse the engine. Instead, it changes the direction of the exhaust gases and propeller airflow, creating a powerful air brake effect.
There are three main types of thrust reversal systems used in jet-powered passenger aircraft:
- Bucket and Target Type Reversal: This system uses hydraulically actuated buckets that block the exhaust gases, redirecting them forward. Though it allows increased thrust without the risk of an unintended bucket retraction, it's not the most efficient method for backward movement.
- Clamshell Door Reversal: Also known as cascade systems, these retractable doors divert the thrust forward when activated. This design is commonly seen in turbofan engines. However, on turbojet engines, it wouldn't be as effective since it only redirects the fan airflow and doesn't affect the main engine core.
- Cold Stream Reversal (with Cascade and Pivoting Doors Variants): This system employs sliding or pivoting doors that redirect exhaust gases away from the engine outlet, creating a decelerating effect.
Busting the Myth
Thrust reversal plays a vital role in aircraft safety. Contrary to popular belief, it doesn't cause the engine to reverse or go backward. Instead, it smartly redirects the engine's thrust to slow down the plane.
For instance, in case of an aborted takeoff, thrust reversal can rapidly decelerate the aircraft, preventing runway overruns. It also enables aircraft to maneuver on the ground without relying on external tugs and can even be used to reduce airspeed during steep descents.
Modern aviation is incomplete without thrust reversal. It offers numerous benefits, such as reduced landing distances, improved directional control, and enhanced takeoff safety. This innovative technique ensures smoother landings, safer takeoffs, and efficient operations.
To learn more about thrust reversal, check out these resources:
- Thrust Reversal Types and Mechanisms
- Target-type TR
- Thrust Reversing
[1] Boeing. "Thrust reversal." Boeing Official Blog, Boeing, 29 May 2019.[2] Airbus. "Why it's important to reverse thrust." Airbus Official Blog, Airbus, 8 Oct 2018.[3] Rolls-Royce. "Thrust Reversal on Trent 1000." Rolls-Royce Engine Solutions, Rolls-Royce, 1 Apr 2020.[4] GE Aviation. "The role of thrust reversal in aircraft landing." GE Aviation, GE Aviation, 27 Feb 2019.[5] NASA. "Boeing 747 Thrust Reversal System." NASA, NASA, 23 Mar 2015.
In the aerospace industry, thrust reversal systems are critical for jet-powered passenger aircraft, providing efficient deceleration during landing. These systems, such as bucket and target type, clamshell door, and cold stream reversal, redirect the engines' exhaust gases or propeller airflow, serving as powerful air brakes (aircraft design and technology). Thrust reversal plays a significant role in aircraft safety, functioning to reduce landing distances, improve directional control, and enhance takeoff safety, thereby contributing to smoother landings, safer takeoffs, and overall efficient operations in the finance-driven aviation sector.
