Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 1 April 2000




(2000), "DERA'S VAAC Harrier", Aircraft Engineering and Aerospace Technology, Vol. 72 No. 2.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited



Keywords: DERA, USA, R&D

The American/UK Joint Strike Fighter (JSF) programme has selected DERA's VAAC (Vectored thrust Aircraft Advanced flight Control) Harrier to conduct further trials in advanced STOVL (Short Take Off Vertical Landing) control law development for shipboard operations.

The contract will run for a year, with effect from January 2000 to a value of £1.6 million. It is collaboratively funded by the JSF programme office and DERA in the UK.

DERA's VAAC Harrier boasts the most capable and unique system in the world for studying control concepts for powered lift aircraft. Detailed modifications to its two-seater format has introduced a digital flight control system that offers advanced, programmable fly-by-wire capabilities from the rear seat. The result gives the rear pilot full-authority, digital control of the aircraft allowing programmable computer simulations of different flying modes to be developed and installed. The controls now determine the flightpath via a computer interface.

The forthcoming JSF trials will build on prior DERA/NASA research into advanced control laws but will represent the first comprehensive shipboard evaluation. DERA is well placed to continue these studies having been the first to achieve a successful fly-by-wire landing of the VAAC Harrier on to the deck of HMS Illustrious in September 1999.

The timing for this research contract is significant as it will help reduce the risk of the JSF STOVL flight control system development efforts as the programme enters the EMD (Engineering Manufacturing & Design) phase in 2001. The VAAC Harrier is well-known to the JSF programme and has been used for both government and contractual evaluations in the past. Colonel Gene Fraser, Systems Engineering Director for the JSF programme, says:

DERA's VAAC Harrier provides us with a unique test facility ... DERA will be able to investigate the design options for shipboard control concepts to help reduce STOVL flight control law development risk.

The VAAC Harrier's digital flight control system has three key implications. First, it allows the testing of different flying modes in real-flight environments. Second, modifications to the software and the flying experience can be swiftly and easily accommodated between flights with significant benefit of incorporating pilot feedback practically instantaneously. Third, it offers STOVL capability without the need for the tricky third nozzle control lever, thus significantly improving flying simplicity.

The use of mechanical detents and computer feedbacks to lodge the stick and throttle, holds the aircraft at existing speed, bank altitude, climb, dive angle, hover height, side slip direction, descent, ascent etc. to give hands-free flying. Flight Lieutenant Terry Parker, DERA's VAAC Harrier Test Pilot, says:

The integrated approach will benefit the JSF programme in a number of ways. It offers the capability for simpler, carefree handling to ensure a lower training burden, a reduction in the risk of pilot error, so saving lives and airframes and an increase in pilot/airframe performance through the optimal use of controls.

Details available from: DERA. Tel: +44 (0) 1252 392809 or +44 (0) 1252 394572; E-mail:

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