Reverse aircraft. Reverse engine aircraft.
Reverse - the mechanism for directing part of the jet or jets of air in the direction of the aircraft and the creation of reverse thrust. In addition, the reverse operation is called used aircraft engineWhich involves reversing device.
The device is mainly used after landing, on the run or braking. In addition, reverse is used for reversing the towing means without assistance. Some aircraft include a reverse in the air. Most often, the device operates in the transport and commercial aviation. After planting, the reverse is characterized by noise. It is used together with the wheel brake system that reduces the load on the brake system of the aircraft and reduces the distance, in particular at a small friction coefficient with the runway, and in the beginning of run. The contribution of reverse thrust is very different in different situations and aircraft models.
Reverse produced rejecting all or part of the jet, which comes from the engine, by means of different zatvorok. In various propulsion thrust reverser is implemented differently. Special zatvorki able to block the stream, which is created purely outer loop turbojet (as A320) or spray all circuits (Tu-154M). Design features of the airplane affect the equipment reverse. These can be all the motors, and a certain portion. For example, on trimotored Tu-154 reverse can create only the extreme engines and Yak-40 - average.
Ladle leaf - a special mechanism that redirects the airflow. Such flaps on the engine can be two or more. Outwardly, they look like buckets. For example, in an engine with a high bypass ratio with overlapping flow across the plane as that of the D-30Ku-154 (Tu-154M).
Method reverser, wherein the nozzle and the rear of the engine is a special metal profile called profiled grating. The engine involved in the direct thrust and svorki in grating redirects exhaust gases pass. This design used in many aircraft engines, in particular in the power plants with a low bypass ratio overlapping with the entire flow (Tu-154, Boeing 727).
But the reverse of the system has its drawbacks. Potential troubles include the use of reverse at low speeds (less than 140 km / h). The jet can lift from the surface of the runway debris, which when run at low speeds the aircraft can get into the air intake and cause damage. At high speeds the raised debris does not interfere because of the fact that the height does not manage the inlet.
On IL-76 the reversing device is mounted on four engines, but in practice 2-th and m-3 motor reverse is not applicable, because the process can damage the fuselage skin.
The engine with a propeller
Reverse screw aircrafts have realized by turning the propeller blades (changing the angle of attack of the blades in the negative), namely under unchanging direction of rotation. Therefore, the screw creates a reverse thrust. This type of device is capable of reversing used on the piston and turboprop engines. The reverse is often provided on amphibians and seaplanes.
For the first time the use of the reverse began in 30-ies. Reversi were equipped with passenger aircraft "Douglas DC-2» and «Boeing 247».
Aircraft without reversing device
A huge number of aircraft does not use the reverse of its uselessness or technical complexity. For example, in connection with certain abilities-lift and high efficiency air brakes in the tail BAe 146-200 reverse switch is not required. Accordingly, all 4 motor in the reverse mode is not working. For the same reason the device does not need to reverse the Yak-42.
Most aircrafts with afterburner does not have the reverse of the value after the landing roll. This circumstance forces to build a long runway, after which the device should be installed for emergency braking. Aircraft in this case equipped with effective wheel brakes and parachutes. It should be noted that the pneumatic brake and such aircraft are subject to heavy wear and often require replacement.
Application of reverse air
Part of the aircraft allows for the use of reverse thrust in the air, but such inclusion is dependent on the type of aircraft. In some situations the reverse is activated before landing, and in the other - at the time of the decline, which significantly reduces the vertical speed or braking avoids permissible speeding during a dive, the emergency lowering or carrying out combat maneuvers.
ATR 72 - Turboprop airliner striking example of the use of reverse air. In addition, air reverse may apply turbofan airliner "Trident", the supersonic airliner "Concord"Military transport aircraft C-17A fighter Saab 37 «Viggen", turboprop "Pilatus PC-6" and others.
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