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Aviation History
1991
1991 - 0428.PDF
ASTO VL concept Four propulsion systems have been stud ied under the US/UK ASTOVL memoran dum of understanding: vectored thrust, tandem fan, remote augmented lift sys tem (RALS) and ejector augmenter. Ad vanced Studies has produced four airframe concepts around the different propulsion systems. RALS has emerged as the favoured option and an aircraft featuring a mixed/ unmixed RALS-type engine, displayed at last year's Farnborough as the PI 12, is receiving most attention. (A powerplant is either mixed or unmixed depending on whether the bypass and core streams are mixed or kept separate. The Pegasus vectored-thrust V/STOL powerplant is unmixed and an engine such as EFA's EJ200 is mixed. A RALS-type engine is mixed/unmixed because in lift mode bypass air is ducted forward and core air aft to separate afterburning nozzles, while in cruise mode the two streams include the Harrier II Plus radar-equipped nose and cockpit, as well as a higher-thrust version of the Rolls-Royce Pegasus vectored- thrust turbofan. The last 'S' in BAe's trilogy is for stand-off and, with the UK Royal Aerospace Estab lishment (RAE), it is developing the re search vehicle for in-flight submunitions ejection (REVISE), a stand-off dispenser testbed to provide data to guide the UK MoD in defining a weapon to fulfill Staff Requirement (Air) 1236 — originally to have been met by the defunct multinational modular stand-off weapon. "We have set ourselves the target of developing technologies for something that would use a millimetric-wave seeker to fly 200-300km and hit a tank even if it is standing still and it's engine is still off," says BAe's Liddell. REVISE is being built to evaluate three areas of high risk for large stand-off weap ons — air carriage, safe release and submu- nition ejection. Four of the re-useable dis pensers will be flight-tested this year, and about 12 flight tests are planned using a Tornado launch aircraft. BAe is airframe prime contractor and responsible for windtunnel testing, flight- control system manufacture and vehicle certification. RAE sub-contractors Hunting Engineering, Shorts and Thorn EMI are supplying submunition ejection, range safety and telemetry systems. The joint venture with RAE's Attack Weapons department will lead into a REVISE Plus family of stand-off submuni tions dispenser weapons, which BAe could offer to meet the UK MoD's requirement. Development could begin in 1992, leading to a first flight in 1995 and outstanding deliveries in 1998. 26 makes progress mix before exiting through a single aft nozzle.) For each ASTOVL concept made pub lic, a parallel stealth version has been submitted in secret to the UK MoD. As no US/UK accord yet exists on the sharing of stealth technology, the BAe designs are being kept secret to prevent public knowledge of how much progress has been made in the eight years since UK stealth work began. Liddell says only that the stealth ASTOVL designs are "nothing like" the four configurations seen publicly (right). From top-to-bottom the popular PI 12 RALS concept, the PI 15 tandem fan, PI 16 ejector augmentor and the now relatively elderly PI230 concept built around a vectored thrust development of the Harrier. It is possible that they could be variations of the flying-wing design displayed at Farnborough and similar to the recently cancelled US A-12. Outside of its "Three Ss", Advanced Studies also tackles concepts such as future maritime patrol aircraft, using various airframes. It has been heavily involved in defining a version of BAe's ATP regional airliner, the P132, and is working on ways of extending the life of the RAF's existing Nimrod airframes. The Hawk is another airframe with fur ther potential, both as a trainer", and as a weapons system, according to Liddell. "We're looking at something we call the Hawk 2000 for the potential market in the USA for the BFTS [bomber fighter training system] programme," he says. In the training role, Advanced Studies is looking at ways of reducing operating costs (mainly through engine improvements) and bringing Hawk systems more into line as a training basis for EFA. In the weapons- system role, the improved Hawk 2000 would be offered as a potential Northrop Sfeallh and STOVL: BAe spearhead F-5 and McDonnell Douglas A-4 combat- aircraft replacement. Warton's Systems Development depart ment provides backing for Advanced Stud ies' avionics work and spearheads BAe's role as lead avionics integrator for EFA. Lidell highlights Bae's use of rapid proto typing. "This simply uses newly developed software with off-the-shelf hardware. This reduces the cost and time involved in the software requirement because it reduces the amount of chopping and changing needed later on," he says. Work under way on EFA will influence future studies, such as the use of three-dimensional cockpit displays. "In detail, we are already looking at what should be displayed, and how," Liddell says. "On the how side, it will study technolo gies such as advanced computer-generated imagery derived from terrain databases cou pled with cultural/obstacle databases. We're looking beyond just producing contours, we're looking at how you might merge [computer-generated imagery] .with the real outside world." Under study are advanced versions of conventional displays using flat panels. Alternatives examined include using the helmet visor as a display rather than the cockpit. "The key to success is an effective man-machine interface but, as always, it's not just technology for technology's sake," says BAe's Liddell. • FLIGHT INTERNATIONAL 20 - 26 February, 1991
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