The thrust reverser is a system that redirects engine exhaust forward upon landing to enhance braking efficiency. Large aircraft almost always include this capability, while light jets usually omit it because the added weight, cost, and complexity outweigh the modest gains on their typically longer runways. By sharing the deceleration task with wheel brakes, reverse thrust shortens landing rolls, curbs brake temperatures, and reduces wear, especially on short or contaminated surfaces.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
Do planes have reverse thrust?
Jet engines are equipped with thrust reversers, piston-engine aircraft tend not to have them. The hardware includes clamshell thrust reversers, cascade thrust reversers, and cold-stream reversers. Cascade type are fitted only to the inboard engines. All versions create noticeable noise.Light jets and Embraer Phenoms do without them because their small mass and short landing runs rarely justify the extra weight and cost. Large commercial airplanes, by contrast, rely on thrust reversers: the braking system is an integral part of certification, allowing the same runway to be used in wet or contaminated conditions while reducing brake wear and turn-around time.
Airplanes do not have reverse gear. Therefore pushback tractors are used for every rearward movement on the ground.
What was the first aircraft with reverse thrust?
Boeing 707 and Douglas DC-8 were the first commercial airliners to feature reverse thrust in the late 1950s and early 1960s. Boeing 707 pioneered bucket-type reversers for thrust reversal, while Douglas DC-8 series entered service in 1959. HS Trident was the first aircraft able to deploy reverse thrusters whilst still in flight.
Which plane has target reverse thrust?
Target-type reversers, also called bucket or clamshell reversers, are hydraulically actuated clamshell-like structures that cover the rear section of the engine exhaust nozzle. They are most typically installed on turbojet and low-bypass-ratio turbofan engines. Early 737 models (737-100/200 with JT8D engines) had bucket reversers, as did the Boeing 707 and Tupolev Tu-154. The Panavia Tornado fighter, an exception among military jets, carries a target system, and the VC-10 uses a clamshell type. Douglas DC-8 pilots deploy thrust reversal anytime in flight for speed adjustment, and some engines with target-type reversers allow such in-flight deployment.
What plane has the strongest reverse thrust?
The aircraft that can generate the strongest reverse thrust is the stretched Boeing 757-300 when it is equipped with the Pratt & Whitney PW2043 engine, an engine that is rated at 43,000 pounds (19,504 kg) of forward thrust and therefore delivers the greatest mass-flow available for re-direction on landing. Close behind comes the Boeing 757 freighter fleet: the PW2040 version fitted to those aircraft is cleared for 41,700 pounds (18,914 kg) of thrust, while the lighter 757-200 carries the PW2037 at 38,250 pounds (17,350 kg). Although the General Electric GEnx-1B64 used on the 787 Dreamliner can produce 284 kN maximum forward thrust, current configurations do not exceed the reverse-energy level already demonstrated by the PW2043-equipped 757-300, leaving that variant the present benchmark for highest reverse-thrust capability.
How do airplanes use reverse thrust?
Reverse thrust uses engines, but not in the usual forward sense. As soon as the wheels touch the runway, pilots use reverse thrust levers to swing mechanical levers and gates that re-route part of the exhaust. Bucket-style reversers, also called cascade reversers, keep the engines at idle power while the airplane is still at high speed. Inside the nacelle, a series of blocker doors extend into the exhaust stream and turn the jet blast forward, so the same thrust that pushed the aircraft forward now helps slow it. Engines slow aircraft down because the reversed exhaust adds direct deceleration without relying solely on wheel brakes.
Clamshell reversers are hinged doors that cover the rear section of the engine exhaust nozzle. When the pilot selects reverse, these clamshell-like structures pivot shut and deflect the jet blast sideways and forward, supplementing the blocker doors. This combined action of bucket and clamshell reversers produces a coordinated surge of drag that shortens the landing roll. Pushback tractors are used because airplanes are meant to go forwards. Reverse thrust is only for stopping, not for backing away from the gate.
When the aircraft lands, the pilot actuates a system that redirects the forwardforce of the engines. Instead of spinning the motors reversed, the principle is to turn the exhaust stream forward, creating a strong counter-force against the aircraft's course of trip. Pails or clamshell doors spread to generate this obstacle, turning back the exhaust motion, so the motor's own force is exploited to slow the airplane. This effort augments the stopping scheme, so wheel brakes are used less, and their fatigue is reduced. Because additional deceleration is achieved, touchdown distances become shorter, which supports operational safety and efficiency.. The function is strong and makes substantial sound, so aviators hire it judiciously, especially during unfavorable statuses when the backward force is essential.
How do turboprop aircraft achieve reverse thrust?
Propeller-driven aircraft generate reverse thrust by changing the angle of their controllable-pitch propellers. This adjustment alters the direction of the exhaust airflow, directing it partially forward. The process is facilitated by a hydro-mechanical system that varies the blade angle, setting the propeller blades to a negative angle in the beta range. As the propeller pitch is reduced from fine to negative, the airflow through the propeller disc effectively creates reverse thrust and acts as a brake. Turboprop aircraft employ this unique method, distinct from traditional thrust reversers, because they do not have large jet exhaust flows to redirect. Instead, they rely on propeller pitch control, using the beta mode to reverse airflow and achieve deceleration.
How does reverse thrust assist a plane during landing?
Reverse thrust helps slow an aircraft after landing and provides additional deceleration during the landing rollout. Immediately after touchdown, thrust reversers redirect the exhaust forward, giving the biggest helping hand for the first few seconds when residual aerodynamic lift and high speed limit the effectiveness of the wheel brakes. By shortening landing distance up to twenty per cent and reducing landing roll on wet or slippery runways, reverse thrust assists wheel braking and improves deceleration early in the landing roll. It also reduces brake wear by sharing the stopping effort and compensates for reduced friction on contaminated surfaces. Extra stopping power is useful for landing on short runways and maintains better control during landing rollouts.
Nevertheless, airplanes can land safely without reverse thrust. Wheel brakes provide deceleration, spoilers are deployed after touchdown, and the entire weight of the aircraft eventually settles on the wheels, so the brakes take full responsibility for the remainder of the rollout.
Reverse thrust is an essential security aspect that makes a good and sure halt. It decreases the strain and temperature created in the wheel brakes, and it dramatically expands the speed at which the aircraft decreases. By contributing to deceleration, reverse thrust acts as an additional braking force. This lessens the danger of brake fade, a hazardous status where brakes decline efficacy appropriate to overheating. On damp or frozen surfaces, brakes alone may not provide sufficient deceleration, so reverse thrust offers additional control. As an essential associate to the wheel constraints, rearward force stretches the lifetime of these crucial portions and contributes to maintaining the frame's parts.
Can a plane use reverse thrust in the air?
For modern aircraft, its use in flight is prohibited, so reversers cannot be used in flight. An electromechanical lock ensures that reverse thrust is applied only when weight-on-wheels is determined on the runway after landing. In the 1991 crash of Lauda Air flight 004, the number one engine reverser deployed uncommanded in mid-air, sending the aircraft into a steep left dive and killing all 233 passengers and crew onboard. Such fatal accidents have been caused by the inadvertent use of thrust reversal in flight when one or more reversers unlock and deploy uncommanded.
The main purpose of thrust reversal is to slow the aircraft after landing on the runway. The configuration and functional processes for contemporary aircraft are based on the principle that reverse propulsion remains idle until the landing gear is securely on the ground. Employing opposite force while an aircraft is airborne would be a dangerous move. The ban against in-flight propulsion reversion is an underlying dogma of air security. The huge thrusts engaged are not intended to counterbalance the intricate mechanics of continuous flying. Deploying these systems in flight would create significant disturbances to aerodynamic forces.. The disturbance to the aerodynamic pressures dealing upon the airfoils and active surfaces is dangerous. Such an action could cause a serious decline in altitude. The chance for ruinous functional strain or a whole failure of regulating far exceeds any possible advantage. The security of everyone on board would be endangered. It is a testimony to the stringent discipline and regulatory criteria that such a preventative standard is universally prescribed.
Can a plane move backwards with reverse thrust?
On the ground, some jets can use thrust reversers to move backward in a maneuver known as powerback. The maneuver is called powerback. Pilots can taxi aircraft backward by directing thrust forward rather than backward. American and Eastern Air Lines practiced power backs with Lockheed L-1011 and Boeing 757, showing that some aircraft can do powerback.
Yet reversers are not designed for precise movements, and airplanes are meant to go forwards. After a deadly event when an engine reverser deployed and sent an aircraft into a steep dive, killing all 233 passengers and crew, operators stopped routine power-back. Today, pushback tractors are used to move airplanes backwards from the gate, so there is normally no need for an airplane to go backwards under its own power.
Thrust reversers do not propel aircraft backward. Their main function is to slow the aircraft after touchdown. Turn propulsion action is an interim high-stress process perfected for ahead propulsion, and opposite force would put remarkable stress on engines.
Why don't planes use reverse thrust?
Low effectiveness is one reason pilots don't use reverse thrust to bring the aircraft to a complete stop. At high speeds, reversers can only provide up to around 40% of the total deceleration effort, so wheel brakes shoulder most of the work. Because every aircraft already has brakes fitted to its wheels, certification rules require that an aeroplane must be able to stop safely using only those brakes. The extra hardware for thrust reversal then becomes an optional source of weight and maintenance cost rather than a necessity.
Deploying reverse thrust close to the terminal building is judged too risky for the airport, the ground crew, and the aircraft itself. High power settings create jet blasts strong enough to injure ground crew, and reversing without precision is dangerous, especially since pilots cannot see where they are going when using reverse thrust away from the gate. Older aircraft with tail-mounted engines used the technique called powerback more often. However, the maneuver is now generally avoided for practical and safety-related reasons. Commercial aircraft require short turnaround times, and a routine that flings debris, ingests loose equipment, or stresses engines is incompatible with that goal.
Commercial aircraft do not utilize reverse thrust on every landing because the mix of wheel brakes and control surfaces is more than adequate to bring the aircraft to a safe standstill. Airlines rely mainly on wheel brakes, reducing wear on engines that reverse thrust would otherwise impose. Service expenses are considerable, so reserving the mechanism for shorter touchdown rolls maintains safety while minimizing operating costs.Deployment of backward force generates a huge number of cacophonies, a leading worry for neighborhoods adjoining aerodromes, airlines can therefore decrease disturbance footprint on flight path and arrival.This approach balances community considerations while keeping the system available for urgent runway conditions.
