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Reverse thrust is typically applied immediately after touchdown, often along with spoilers, to improve deceleration early in the landing roll when residual aerodynamic lift and high speed limit the effectiveness of the brakes located on the landing gear. Reverse thrust is always selected manually, either using levers attached to the thrust ...
The reverse-thrust ratio (ratio of backward engine thrust to forward reverse thrust) can be as high as 84%. [6] However, this result is obtained with a cowl to attach air flow in a 7° angle and a large enough "target" (deflector door) installed. A reverse-thrust ratio of 55% can be reached on a simple target without the cowl. [7]
The equivalent concept for an airplane is thrust reversal. In a sailing ship astern propulsion can be achieved by the appropriate manipulation of the sails. In square-rigged ships 'backing the sails', that is, aligning the sails so that the wind impinged on the bow surface, could provide sufficient retrograde thrust to slow or reverse the ship.
The propellers on some aircraft can operate with a negative blade pitch angle, and thus reverse the thrust from the propeller. This is known as Beta Pitch. Reverse thrust is used to help slow the aircraft after landing and is particularly advantageous when landing on a wet runway as wheel braking suffers reduced effectiveness.
[citation needed] The NTSB determined that the probable cause was the pilots' failure to use available reverse thrust promptly to safely decelerate or stop after landing, which resulted in a runway overrun. This failure occurred because the pilots' first experience and lack of familiarity with the airplane's autobrake system distracted them ...
A design fault of the DC-8 had caused the thrust reverser of #4 engine to engage when the thrust lever was rapidly set to idle. [1] 13 August 1966 An Aeronaves de Mexico DC-8-51 (XA-PEI, named Tenochtitlan) crashed 21 mi from Acapulco after a descent was made while turning during a training flight, killing the six crew. [1] 24 December 1966
Reverse thrust can be generated to aid braking after landing by reversing the pitch of variable-pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, and vector sum of this thrust fore and aft to control forward speed.
This creates reverse thrust for braking or going backwards without the need to change the direction of shaft revolution. While some aircraft have ground-adjustable propellers, these are not considered variable-pitch. These are typically found only on light aircraft and microlights.