SKI-JUMP

Many Members will remember the dramatic demonstrations of Harrier ski-jump launches given at the 1978 Farnborough and 1979 Paris air shows. Not so well known is the story of the development trials which preceded the public debut.

On the 19th March Dick Poole gave a talk to the RAeS Weybridge Branch entitled "Harrier Ski-Jump Trials, a Flight Test Engineer View." Dick, at the time a senior flight test engineer at Dunsfold, was in charge of these trials so he was well placed to give the inside story.

The talk covered the Ski-Jump origins by Lt Cdr Doug Taylor, its development by Hawker Siddeley Aviation at Kingston, the design of the test ramp, also by HSAK, the performance prediction and vital safety planning involved, the test methods and instrumentation as well as the trials themselves and the outcome. Initially set to a 6 degree exit angle, the adjustable ramp, installed at RAE Bedford, was progressively adjusted until the maximum exit angle of 20 degrees was successfully flight tested.

This was real pioneering work, carried out in 1977-78, requiring constant monitoring of end speeds, launch trajectories and undercarriage behaviour as well as aircraft handling qualities, and control and performance margins. In the event the Ski-Jump and the Harrier proved to be perfectly matched with launches being made with the stick 'fixed' longitudinally from brakes-off to wingborne flight.

The performance gains when compared with a flat deck launch were large: either a 30% increase in load from a 600 ft deck run or a 400 ft reduction in deck run for the same load. Launch safety was also greatly enhanced by the upward trajectory giving much more time for escape in the event of, say, engine failure. Ski-Jumps are installed in Britain's carriers as well as those of India, Spain, Italy and Thailand, all Harrier operators, of course.

Attending the lecture were other prominent members of HSA Kingston's Ski-Jump team including performance engineers Trevor Jordan and Ken Causer and Chief Test Pilot John Farley.