There will be cases when the aircraft is required to land on runways that are shorter than those for which the aircraft can normally land. It is also beneficial to use less runway than that available in order to have a safety margin in the event of a failure. Although the brakes on the aircraft are designed to be adequate under all normal operating conditions, the engine can assist in shortening the landing distance by using the thrust reversal systems.In this system the engine thurst is vectored to the front to slow down the aircraft.
On a propeller engine this is very simply done by reversing the pitch of the propeller blades so that they now thrust air forward instead of backwards. Therefore the prop aircraft can change the direction of thrust by 180 degrees. But, This is impossible to achieve with a jet engine, The result of this is that the reversed thrust from a jet engine can never be as fully effective as that from a propeller. The thrust level obtained from the engine can be as high in reverse as it is in forward thrust but, because of the angle involved, the effect can never be the same as the forward thrust.
types of reversers
As far as jet engines are concerned there are three basic types of thrust reverser:
- Clamshell Door
- Retractable Ejector
- Cold Stream Cascade Reverser