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Experimental Aircraft Programme - EAP

Experimental Aircraft Programme - EAPThe Experimental Aircraft Programme (EAP - not Experimental Aircraft Project) was the forerunner of Eurofighter. Experimental Aircraft Programme was a British Aerospace led demonstrator aircraft programme with a major contribution by Aeritalia and involving the equipment industries of the UK, Germany and Italy. The Experimental Aircraft Programme was intended to demonstrate the integration of technologies needed for any new, sophisticated combat aircraft. As of early 1986 the first flight of the EAP was anticipated at Farnborough in September 1986. The EAP demonstrator prototype flew just over two years after the production contract was let. That demonstrator had nearly six years of flying, which allowed much of the development work to be tested before going final on the Eurofighter itself.

The pedigree of the EFA goes back to 1980, when the British, Germans and French together produced the ECA, or the European Combat Aircraft. That collaboration led in the following year to the United Kingdom proceeding alone with the P110. At the same time the Germans decided to go ahead alone, and they produced the TKF-90. Both of these designs were still on paper, and were brought together in 1982 when the ACA, or the agile combat aircraft went on the drawing board. At that time, Italy came in as an additional partner. That led the then Secretary of State for Defence, John Nott, to announce at the Farnborough international air show that the EAP, or the Experimental Aircraft Program, as it had been renamed, would come into being.

Sir John said that this project was to be "a research experimental aircraft programme which would bring together current component elements of demonstrator work and further advance our knowledge of the demanding technology which will be essential to the high performance requirements now foreseen"." It was not to be a prototype. No one would be designing an aircraft that would be required in 10 years' time, but an aircraft that could give the information required to produce, in the light of circumstances and tests, the sort of aircraft needed.

The designers were going to look at high agility, more efficient use of composite materials, artificial stability or "fly-by-wire", and stealth techniques, as well as advanced cockpit and systems design. A demonstrator model would tell much about these matters, and provide information useful in developing the Harrier STOVL aircraft, and to improve the Tornados already in service. There was much more value in producing a demonstrator model than there could ever be in producing a prototype. In the history of the British aerospace industry, far too many prototypes have finished up on the scrap heap.

The programme part funded by UK MoD(PE) was aimed at developing those technologies necessary for any future advanced fighter aircraft. These included an advanced aerodynamic configuration requiring full authority digital computer-based flight controls. A Utilities and Systems Management System integrated by data bus with avionics to provide the pilot with a modern electric cockpit. Plus the use of advanced materials in primary and secondary structure.

The configuration consisted of a high wing layout, with optional 'non interfering strake' to improve high incidence penetration with little detriment to low incidence drag. The Experimental Aircraft Programme flew a cranked delta with foreplane layout, which was the forerunner to Eurofighter. Here the supersonic requirement was severe, demanding a 'Beyond Visual Range' (BVR) capability at Mach 1.6 and requiring excellent transonic performance as well. At the outset it was realised that the canard - delta configuration was a significant departure from previous experience and the first step was to carry out a large low speed experimental programme on a 1/10th scale model aimed at the EULER method. The resulting procedure gave accurate predictions of pitching moment for both stability and zero lift relationship. The search for a configuration with excellent supersonic performance coupled with very good transonic/subsonic performance was difficult. It was found that the best balance was achieved by designing for the supersonic maneuver point. The alternative of designing for the transonic case and decambering to achieve the supersonic case was not as successful.

The experimental aircraft programme was announced by the Member for St. Ives (Sir J. Nott) on 5 September 1982. The timescale from Contract signature to first flight was three years. A £185 million contract was awarded in May 1983 to British Aerospace for development of an agile demonstrator aircraft - not a prototype. The cost was to be shared between the partner companies of the EFA consortium and the UK Ministry of Defence (MoD). The first and only example of the aircraft (ZF534) flew on 8 August 1986. Powered by two RB.199 Mk 104D turbofans, it embraced many advanced features. The beautiful EAP (Experimental Aircraft Programme) aircraft was on display at Farnborough Airshow 1986. The first two Development Aircraft (referred to as DAs) started construction in Germany and Britain. The first of these, DA-1 98+29 powered by two RB.199-22 engines flew on 27 March 1994 while the British prototype, DA-2 ZH588, flew on 6 April of the same year.

Experimental Aircraft Programme - EAP Technology Demonstrators are physical or virtual (computer-based) entities, simulating systems or subsystems. They are used throughout industry and universities not only to demonstrate and validate, in a practical environment, promising technology that has emerged from the laboratory, but also to test the integration process of several technologies into one system. It is this technology integration process that is often the most problematic and risky part of the product development; therefore, Demonstrators are a critical part of the risk-reduction process in taking base technologies through to products. Only technologies that have a reasonable chance of maturation are subject to Technology Demonstration. In this respect, Demonstrators have a focus on the technologies' end use. They should not be confused with prototypes, which are designed to be working versions of the final product and form part of the subsequent development process.

It is estimated that the £190 million investment in the Experimental Aircraft Programme Technology Demonstrator saved the Industry and Government £850 million in development costs for the resulting Eurofighter and shortened the development time by one year. Similarly, the XG40 Demonstrator for Eurofighter's EJ200 engine cost £135 million but saved £650 million from the development programme. Demonstrators may sometimes appear expensive, but are in fact a fraction of the total development cost—typically less than 10 percent.

  • Reduced Risk of Quadraplex FCS for Delta wing/Canard Configuration.
  • Expanded knowledge and capability of agile highly unstable fast jet configurations.
  • Encompassed and flight tested new materials (eg Aluminium Lithium and CFC Honeycomb) with a large weight saving.
  • Development of CFC Wing and Foreplane (learning from experiences with JAS wing).
  • Proved ability to demonstrate complete aircraft systems at low cost and at short timescales.
  • 1st Glass Cockpit on UK aircraft.

Much of the basic design of the Eurofighter was derived from EAP [and its preceding projects (P.106, P.110, TFK-90]. However there were some notable differences between the operational Eurofighter and the experimental EAP. For example, while the EAP utilised a cranked delta layout, the Eurofighter instead uses a standard delta configuration. Other differences include the inclusion of in the Typhoon of conformal recessed fuselage weaponry, a wide mouthed curved intake and a bubble type canopy.

CREW11 or 2
ENGINE2 x 40.0-75.7kN
Turbo-Union RB 199-34R Mk,
2 x 9185kg
Eurojet EJ.200 turbofans
Empty weight10,000 kg lb
Empty weight22,000 lb lb
Take-off weight14,515 kg21,000 kg
Take-off weight32,000 lb46,300 lb
Wingspan11.77 m10.50 m
Wingspan39 ft 7 in34 ft 5 in
Length17.72 m14.50 m
Length58 ft 2 in48 ft 7 in
Height5.70 m4.00 m
Height19 ft 8 in13 ft 1 in
Wing area51.66 m2
Wing area556.06 sq ft
Max. speed2M2M
Max. speed2125 km/h
Max. speed1320 mph
Ceiling18,280 m
Ceiling60,000 ft
ARMAMENTnone1 x 23mm cannon, weapons on 13 hardpoints

Experimental Aircraft Programme - EAP

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Page last modified: 16-05-2013 18:40:56 ZULU