For the aviation industry, safety is the primary and most important parameter to consider. The aircraft will employ advanced safety measures to eliminate the risk of failures and accidents. In usual vehicles, a braking system is necessary for stoping or slowing down. But for aircraft, a thrust reverser is also used along with the braking system for a safe landing in unpredicted conditions such as in icy or snow-covered runways. The most important function of the thrust reverser is to reduce airspeed in flight by reversing the direction of the exhaust gas stream. What are the major functions of the thrust reverser system?
- Minimize the wear on the brake
- Reduce taxi distance and landing distance
- Helps to slow down the aircraft just after touch-down
- Reverse maximum thrust
- Reduces the landing run distance
- Provide additional stopping force
- Enhanced safety for transport aircraft operations
The thrust reverser system can be categorized as a cascade type reverser system(cold stream), bucket target system(hot stream), and clamshell door system(hot stream). The pneumatically operated hot stream clamshell door system contains pneumatic rams for reducing airspeed. The hydraulically actuated hot stream bucket target system uses bucket-type doors to reverse the direction of the stream. The cold stream reverser system is actuated by an air motor. These three types use different types of actuation mechanisms and here we will focus on the aircraft thrust reverser system with hydraulic actuation.
At first, we can look into the design of the thrust reverser system. The design of the thrust reverser contains a different set of fixed parts and movable parts. For actuating the doors, the single hydraulic-powered actuator is connected to the drive idler. A mechanical lock is used to align the buckets in their extended position by avoiding uncommanded, asymmetric retraction of the buckets.
Next, we can find where a thrust reverser can be located in aircraft. This system is located at the middle of the engine nacelle under the wing. The thrust reverser will be closed at normal flight condition and for a safe landing, it needs to be opened. Thrust reversers are placed in this position in order to reduce the impact of airspeed and wing load, and to maximize the combat efficiency of aircraft.
The hot stream bucket target system reverses the hot gas stream using the bucket type doors that are actuated by a conventional pushrod system. It is possible to implement this bucket target system in commercial and military aircraft, business jets, and large transport aircraft. The system contains linear hydraulic actuators, control valves, synchronizing flex shafts, locking actuators, hydraulic tubes & hoses, drive assemblies, and more.
The hydraulically-operated bucket type doors can be alternate between deployed/stowed position. The pair of doors will form the propelling nozzle of the engine to create forward thrust. To reduce the aircraft speed while landing, the bucket doors will reverse the stream of airspeed. This hydraulically operated thrust reverser can be controlled by the pilot from the cockpit. It is the pressure of fluid that makes the bucket doors to change the position.