Full Scale Test of a Transport Aircraft Thrust Vectoring System

VSTOL transport aircraft pose unique thrust vectoring control requirements. The control moments have to be very large in comparison with VSTOL fighter aircraft because the moments of inertia are so much larger due to a high aspect ratio wing and distributed payload in the fuselage. To obtain the desired angular accelerations a bleed air control system like the one used in the Harrier is no longer adequate, and consideration has to be given to controlling by moving the thrust vector away from the center of gravity.

A full scale test of such a thrust vectoring system was successfully completed in the fall of 1996. A single engine installation using a 30,000 pound thrust V2500 engine was tested. The thrust vectoring hardware was nearly 100% graphite epoxy composite construction. It held the engine operating line in both forward and vertical thrust. The data showed high efficiency, low thrust losses, in both forward and 90 degree vectored thrust. The ability to vector the thrust for control was also demonstrated. Composite structure held up well during several hours of testing. The only structural problem was caused by differential thermal expansion of the steel bearing attachment fittings.