Unlike the last two air shows at Paris, where the talk among military-engine makers was dominated by budget cutbacks, consolidation and survival, this year's discussions will welcome decisions to proceed with some military programmes. Leading the drive is the US/UK Joint Strike Fighter (JSF) which, as the US Department of Defense's number-one project for the next century, is becoming the focal point for renewed activity on both sides of the Atlantic.
The show kicks off within days of the first run of Pratt & Whitney's advanced turbine for its two F119-based JSF derivative engines in the company's CAESAR research engine. The turbine incorporates P&W's Superblade/Supervane advanced cooling technology, which it believes will be key to meeting the high temperatures associated with the increased thrust levels needed by the short take-off/vertical landing (STOVL) version of the JSF.
Guaranteeing performance
Guaranteed performance levels for the STOVLJSF have recently taken on even more importance since the US Navy has shown an increased level of interest in the variant as a possible alternative to the carrier-capable version.
The JSF concept-demonstrator aircraft (CDA) to be flown by Boeing and Lockheed Martin in 2000 will be powered by derivatives of the F119, which was developed by P&W for the Lockheed Martin/Boeing F-22 fighter. The first flight of the F-22 was due as Flight International closed for press. The construction of the first parts for both CDA engines began early in May when the first chips were cut from titanium forgings which will be shaped into integrally bladed-rotor fans. Large structural castings have also been poured for the two engines. Assembly of the SE614 version, for Boeing's X-32 CDA, and the SE611 for Lockheed Martin's X-35 CDA, is due to begin in October. Ground tests could begin in February 1998, up to two months ahead of schedule, according to P&W.
P&W is conscious of the need to protect its lead position on JSF, particularly since the JSF programme office's selection of the General Electric YF120-FX as the basis for an alternative engine. F119s will power the two CDAs to be built by each team for flight testing in 2000, and the engines will continue to power the winning aircraft (which is due to be selected in 2001) during development and into initial production. As with the Lockheed Martin F-16 and McDonnell Douglas (MDC) F-15 before it, however, P&W will face competition from GE.
Risk-reduction effort
P&W has, therefore, embarked on a major risk-reduction effort, much of which is naturally linked to the continuing F119 development plan for the F-22. Even though the new engines will run at higher temperatures, P&W has completed a 1,000-cycle test on the baseline F119 at turbine temperatures within 40¹C of that required for the CDAs. It has also demonstrated the engine life needed for flight tests, and says that it is "two-thirds" towards meeting the full-life requirement for production JSF engines. The advanced turbine, as well as other new developments, will be incorporated in two F119 engines, which will be ground run in 1999 before P&W submits its JSF engine-development proposal.
Trailing P&W, but not by much, is the GE/Allison Advanced Development and Rolls-Royce team, which was awarded a $96 million JSF contract in February to develop the alternative engine. The group, which had its roots in the 1993 teaming of GE and Allison to demonstrate advanced engine technology for the US Government-led Integrated High Performance Turbine Engine Technology (IHPTET) programme, was joined by R-R in March 1996 as the UK stepped up its formal JSF commitment. With the YF120-FX selected in phase one, the team is now well under way on the second phase, a four-year core-engine development and technology-maturation effort.
Crucial milestones are already looming large, with a preliminary design review scheduled for the turn of the year, critical design review set for early 1999 and a full demonstration of the production-representative core engine scheduled for 2000. Phase three, beginning around mid-1999, culminates in early 2002, when the Ìrst full engine goes to test. The team hopes to be awarded the full turbofan-engine ground-demonstration contract later this year.
Phase four, which will begin in the third quarter of 2003, will get under way when the team is awarded an engineering and manufacturing development contract.
The first flight tests in the selected JSF airframe are planned to start in mid-2006 and last until early 2008, when a critical operational evaluation of the engine is scheduled. The period coincides with the procurement timescale for the fourth production batch of JSFs. If successful, the first F120-powered production JSF would be delivered in 2010.
To compensate for its late start, the alternative-engine team is leveraging as many technologies as possible from the demonstrator engines developed for the IHPTET effort. The high-pressure compressor, for example, is derived from both the original YF120-100 and the XTC 45-1/2, an earlier core from the advanced Turbine Engine Gas Generator (ATEGG) element of IHPTET. The combustor, high-pressure turbine and low-pressure turbine designs are similarly taken from past, present and even future ATEGGs, including the yet to be run XTC 76/3. R-R brings its fan and lift-system expertise to the team, while the afterburner is derived from GE's YF120/F414 design. Some discrete elements of the Joint Technology Demonstrator engine (JTDE) effort are also due to be used, including the design of some bearings, to be based on the XTE 76/1 - expected to be tested in late 1998.
Thrust vectoring
Another vital part of the proposed design is the stealthy, thrust-vectoring, exhaust. Tests of a technology-demonstrator system, GE's low- observable axisymmetric (LOAxi) exhaust nozzle, were run earlier this year on an F110-100 powered F-16C of the South Dakota Air National Guard. Follow-on flight demonstrations are planned for later this year, lasting into 1998. The LOAxi is based on a relatively simple modification of the existing F110 nozzle.
The JSF engine development is the first to enjoy significantly the fruit of the ATEGG and JTDE technology programmes, and is a timely spur to the US engine manufacturers as they work towards the IHPTET goal of producing a next-generation fighter engine with twice the thrust-to-weight ratio of engines now in use. A crucial milestone towards these goals will be reached only weeks after the Paris show, when the ATEGG XTC-76/2, a variable-cycle engine-core demonstrator, is due to begin test runs at Allison.
Pending a successful run, the XTC-76 core will be mated to the XTE-76, a low-pressure spool developed under the JTDE effort, and run at GE in late 1998. This Phase II engine demonstration will culminate in late 1999 with tests at NASA of the 76/3 engine.
Production contracts
While all the companies appreciate the huge value of research and development, their continued survival depends on production contracts. After a depressingly dry period, some have finally begun to materialise. In May, for example, the US Navy awarded limited production qualification to GE's F414 turbofan for the MDC F-18E/F. The USN approved low- rate initial production of 12 F-18E/Fs and 27 F414 engines in March and the first engines will be delivered in June 1998. Production will increase from three to ten a month, when the aircraft enters full-scale production. Rated at 98kN (22,000lb)-thrust, the F414 has 35% more power than the F404, which powers more than 1,200 older F-18s. Within weeks of the USN decision, however, GE's silver cloud developed a black lining when the Quadrennial Defense Review (QDR) slashed procurement of F-18E/Fs to a minimum of 548 from a planned total of 1,000.
P&W's F119 plans for the F-22 have been similarly overshadowed, but not as dramatically as with the F-18E/F. The QDR also reduced the US Air Force F-22 requirement by 99 aircraft to 339, but this could also slowly rise again as the USAF considers replacing MDC F-15Es and Lockheed F-117As with F-22 variants after 2015.
Another US manufacturer suffering ups and downs has been AlliedSignal which shipped the first F124 turbofans to Aero Vodochody for the L-159 light attack/trainer, but lost out to Rolls-Royce/Turboméca over the long-waged battle to power the Royal Australian Air Force's British Aerospace Hawk fleet. AlliedSignal continues to hunt for new homes for the F124 and its afterburning sibling, the F125. With production of the Taiwan Aerospace Industrial Development's (AIDC) Ching-Kuo Indigenous Defence Fighter (IDF) now capped, the engine maker is helping AIDC push the concept of a new variant of the IDF configured as an advanced twin-engined trainer.
The gradual slow-down of the IDF is balanced by the continuing deliveries of Dassault Mirage 2000s to Taiwan. The 60-strong order is providing work for Snecma, with its M53-P2 engine, while much of the company's hopes centre on the Dassault Rafale fighter, which is powered by two 75kN M88s.
China is reportedly interested in the Rafale, and particularly its engines. The country's long-term aim is to find a modern Western military turbofan for possible licensed manufacture, thus relieving China of its dependence for combat-engine know-how on Russia.
The Eurojet EJ200 development for the Eurofighter EF2000 has been overshadowed by political problems surrounding the programme, but the engine programme appears to be progressing smoothly.
The first prototype to be flown with the EJ200 is development aircraft (DA)3. The Turbo-Union RB199 was used on the DA1 and DA2. Five of the seven prototype aircraft, all of which have now flown, are fitted with EJ200s. Test-pilot reaction to the EJ200 has been uniformly positive. The engine offers up to a 25% thrust increase over that of the RB199.
Source: Flight International
