Graham Warwick/ATLANTA
McDONNELL DOUGLAS (MDC) has detailed its Joint Advanced Strike Technology (JAST) concept for the first time since switching from the original gas-coupled remote-fan vertical-lift concept to a lift-plus-lift/cruise propulsion configuration.
MDC says that the change was implemented after the Advanced Short Take-Off/Vertical landing (ASTOVL) programme was merged with the JAST and affordability became the key issue.
An average flyaway-unit-cost of $30 million (1994 dollars) has been set for some 3,000 aircraft planned for the US Air Force, Navy and Marine Corps, as well as the Royal Navy.
MDC is teamed with Northrop Grumman and British Aerospace. A draft request for proposals (RFP) for JAST concept-demonstration is expected on 18 December, with the final RFP due in February 1996, leading to the selection of two teams to build concept-demonstrators in October. Each will build a conventional take-off and landing (CTOL) and an ASTOVL version.
A separate lift engine installed behind the cockpit allows MDC to use an unmodified Pratt & Whitney F119 as the lift/cruise engine in its proposed concept-demonstrator aircraft, says MDC JAST programme general manager John Stuerer. The 70kN (16,000lb)-thrust Allison/General Electric lift engine used in the USMC and RN ASTOVL versions would be replaced by fuel or a second cockpit in USAF and USN CTOL versions.
MDC has dropped the "hammerhead" canard configuration of its original ASTOVL design and adopted a tailed design with a "lambda"-shaped wing planform. Changes to the baseline USAF version for the USN's mission are limited to additional wing area outboard of the fold, for carrier suitability, Stuerer says. The wing torque-box is common to all variants.
The ASTOVL version has a blocker/diverter valve to deflect main-engine thrust to a vertical-lift nozzle under the fuselage. This nozzle provides lateral and directional control in the hover, while lift-engine thrust can be deflected fore and aft by vanes, Stuerer says.
Some 6,500h of windtunnel testing is under way to assess controllability in the hover and in flight. A model used to determine high-angle-of-attack stability will re-enter MDC's low-speed tunnel in December to test the high-lift devices on the Navy-version wing.
Transonic testing has been completed at ARA Bedford in the UK and inlet-performance testing at NASA Langley. ASTOVL-configuration hot-gas-ingestion and ground-erosion tests are under way at BAe.
Source: Flight International