Commercial airplanes today use complex control systems consisting of hundreds of dials, knobs, buttons, switches, levers and more. Whether it’s a short flight across state lines of an intercontinental flight to the opposite side of the world, pilots must engage these controls to achieve and maintain their course. But there’s a specific type of control that often goes unnoticed to non-aviation professionals: reverse thrust. So, what is reverse thrust, and how does it work exactly?
Overview of Reverse Thrust
Also known as thrust reversal, reverse thrust is a control system found in many airplanes with jet engines that changes the direction in which air is exhausted from the engine. Upon reading this, you may assume that reverse thrust is the equivalent to a car or truck’s reverse control, but this isn’t necessarily true. Airplanes can’t reverse direction in midair. Rather, reverse thrust is used primarily to assist pilots in decelerating their airplane prior to landing. When engaged, it changes the direction in which air comes out of the airplane’s engines, allowing the airplane to slow down in preparation of landing.
How Reverse Thrust Works
All reverse thrust systems are designed to change the direction in which air is exhausted from the engine. However, there are different types of reverse thrust systems, some of which work in different ways. Smaller airplanes, for example, use reverse thrust to reverse the flow of air entirely. Larger airplanes, on the other hand, only reverse the flow of air partially.
A typical commercial jet airplane features a high bypass ratio engine that utilizes fans for reverse thrust. The airflow produced by the engines’ fans is reversed, so rather than pushing out behind the airplane, it pushes air in front of the airplane.
There are also target-type thrust systems. With this type of system, the pilot engages bucket-style doors to change the direction in which gas steam is exhausted. Target-type reverse thrust systems are very common, and you can even find them in commercial Boeing 707 airliners. Another common type of reverse thrust system is clam shell. Clam-shell reverse thrust systems are characterized by the use of doors that open or close to change the direction of airflow.
Reverse thrust is essential control mechanism found in modern-day airplanes. While it doesn’t allow airplanes to reverse their direction midair, it does allow them to decelerate prior to landing. When approaching a destination airport, pilots will typically engage reverse thrust to slow down to a more appropriate speed.