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Aviation History
1994
1994 - 0022.PDF
EUROFIGHTER bird" test rig at Ottobrunn, outside Mu nich. Development Aircraft One (DAI) has been taxied at speeds up to 80kt (150km/h), but, for speeds above this, flight-certificated software is required. The structure of the DFCS development with system-design authority residing with DASA, and GEC Marconi Avionics (GMAv) acting as prime contractor and providing the flight-control computer, had from the outset all the potential of "an accident waiting to happen". Political aspirations in the form of German desires Thepov The setbacks plaguing the Eurofighter 2000 programme may be a source of tacit relief for the Eurojet consortium, developing the aircraft's EJ200 power- plant. With the Eurofighter's in-service date delayed four years and continual re-scheduling of the prototype's first flight, few will notice a six-month delay of an engine due to be flown only in the third development aircraft, the DA3. The restructuring of the programme, and the consequent delays, have allowed Munich-based Eurojet — a consortium of Italy's FiatAvio, Industria de Turbo Pro- pulsores in Spain, MTU in Germany and Rolls-Royce in the UK — to announce, with some satisfaction, that the engine is "...ahead of the needs... if we are consider ing the whole programme". Indeed, al though the EJ200 was qualified on 14 December for preliminary flight release (PFR), Eurojet's publicity machine has been trumpeting its product as "ready to fly" since PFR testing was completed at the end of October. This assertion is still not quite true. Although PFR means that all functional, endurance, and control checks which can be completed in a test cell have been successful, the engine must be installed and integrated with the airframe and systems before it receives flight clearance. This is already being done by Alenia in Italy, where the DA3 was fitted with one German- and one UK-built engine in September 1993. This work will continue well into 1994, leaving Eurojet to concen trate on further refinements of its new- generation combat engine. The EJ200 is a twin-spool, re-heated turbofan engine, built largely in titanium alloy and designed to be operated near Mach 2. It has three low-pressure and five high-pressure (HP) compressor stages, powered by two single-stage turbines. While in the same 1,000kg weight class as the Turbo Union RB.199 — the three- spool turbofan which powers the Panavia Tornado and which is fitted in the first two Eurofighter prototypes — the EJ200 has a lower bypass ratio (0.4) and gener- to capture a DFCS capability, rather than purely technical considerations, have hamstrung the design and development approach. Vincent, despite an engineering background, recognises the inevitability of industrial politicking as an intrinsic ele ment of collaboration. "You can't have a purely engineering approach. Germany wanted the DFCS and, equally, BAe wanted the avionics. Neither of them could have it all, so, in the rules of collaboration, SDR [system- design responsibility] for different things was shared among the partners." The wider German agenda on garnering technology from its involvement was the ability to pump prime development of DFCS technology for its civil sector. The then-MBB had worked on a relaxed- stability Lockheed F-104 Starfighter, with a second horizontal stabiliser bolted on just behind the rear of the cockpit. It was akin to the UK's Sepecat Jaguar fly-by- wire demonstrator and considerably less sophisticated than the computerised flight controls on the EAP. The final Eurofighter rerplant ates substantially more thrust — 60kN (13,5001b) dry and 90kN with reheat, against the RB.199's 40.5kN dry and 71kN with reheat. Strong emphasis has also been placed on maintainability and simplicity of con struction. The EJ200 is "in the order of twice as good" in terms of required maintenance man-hours per flying hour as the RB.199, says Eurojet. Larger, more efficient, blades have cut the number of aerofoils to 1,800, against the RB.199's 2,848. Maintainability in combat conditions was demonstrated in Italy in April 1993, when an Italian-built engine was fitted to the DA3 and mock-maintenance exercises were carried out by technicians in full nuclear, biological and chemical protec tive clothing. Built-in health-monitoring and test equipment allows maintenance "on-condition" — as the needs of the engine dictate. The engine has an overhung fan with no inlet guide vanes, which the company claims offers high stability, efficiency and low weight, as well as resistance to bird strike. The use of integrally bladed disks (blisks) in the third stages of the fan and HP compressor boost performance further while trimming weight. Each compressor is driven by a turbine with single-crystal blades and the HP turbine utilises a pow der metallurgy disc. Eurojet is investigat ing the use of lighter alloys and composites in some of the engine components, to reduce weights. Managing di rector Mike Roberts says that the work is expected to result in a percentage saving in "single figures". According to The EJ200 engine is "ahead of the needs" Roberts, the engine has already surpassed specifications for thrust and fuel con sumption under some of the 15 flight conditions tested. The full-scale de velopment prototypes have been run for nearly 2,500h, meeting or exceeding the performance and endurance requirements of the project's development milestones. "We have shown really quite a signifi cant recovery from the delays of the last year or so," says Roberts. The develop ment "milestone" missed in mid-1993 is one of two due for completion before the beginning of 1994. Later stages of the programme will shift emphasis increas ingly from performance to endurance. The remainder of the project is being rescheduled in co-operation with Euro fighter and has not yet been finalised. Eurojet sources say, however, that initial certification of the engine is due by the end of 1998. The stretching and re-structuring of the programme, brought about by political manoeuvring among the participating na tions in 1992, has spared Eurojet the need for expensive firefighting measures to get back onto the schedule defined in 1988. "We are 50% of the way through the project in terms of total spend," says Roberts. "In terms of spend versus level of achievement — forget timescales — 20 FLIGHT INTERNATIONAL 5-11 January. 1994
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