British Aerospace EAP

British Aerospace EAP
Type:	Experimental airplane
Design country:	United Kingdom  Germany  Italy
Manufacturer:	British Aerospace Messerschmitt-Bölkow-Blohm Aeritalia
First flight:	August 8, 1986
Commissioning:	Flight tests ended in 1991
Number of pieces:	1

The Experimental Aircraft Program (EAP) from British Aerospace (BAe) was an experimental aircraft , the technological foundation for the Euro Fighter put project. Without the EAP, the European Fighter Aircraft (EFA) would not have been possible. The EAP tested the suitability of lightweight materials such as CFRP and Al-Li alloys for long-term supersonic flight , and new, cost-effective manufacturing processes for titanium and CFRP semi-finished products and individual parts .

The EAP was the first airplane in the world to have wings made from bonded CFRP components, and the first European airplane to be made aeroelastic using fiber-reinforced plastic . Originally, the body part of the EAP should consist of CFRP and superplastically deformed, diffusion-welded titanium, and be manufactured by Messerschmitt-Bölkow-Blohm (MBB). MBB presented a fuselage with a cockpit at the Paris Aviation Exhibition in 1983, which was made entirely of CFRP and at that time the largest CFRP structure in the world. The withdrawal of MBB, forced by the German government, forced BAe to fall back on the tried and tested aluminum construction. As a result, the hull of the Eurofighter is also conventionally riveted from aluminum components.

The flight control computer of the EAP formed from the knowledge and experience that previously with the fly-by-wire - Jaguar and the F-104G CCV had been collected. The control commands were adapted, the aerodynamic instability increased and the possibility of override integrated in order to fly higher g-forces . The rest of the avionics were designed according to the USAF's pave pillar architecture , which was also to be used in the Advanced Tactical Fighter (ATF).

Suppliers from Germany and Italy made a significant contribution to the success of the program. These companies only invested their private capital since their governments, unlike the British, made no contribution. Due to the lack of financial participation from the two countries, only one EAP (ZF 534) could be built, although two machines were originally planned.

history

First concepts

In 1983 negotiations continued behind the scenes about a joint European fighter aircraft. British Aerospace continued to promote the construction of an Agile Combat Aircraft (ACA) demonstrator. Only one if the program was to be funded entirely by the UK, or two if Aeritalia and MBB were still involved with their governments. It was hoped to have reached an agreement by the end of 1983 so that the aircraft could take off for its maiden flight in 1985/86 and go into production in 1990. Should ACA gain momentum, it was hoped that France would join as a fourth partner. At the time, France was also planning a fighter aircraft prototype that was similar to the ACA and was looking for MBB as a partner. The federal government planned to cooperate with France on missile, helicopter and aircraft projects, but no money was available and the decision was left to the industry. The government preferred the ACA, which could compete with the Northrop-Dornier ND-102 . In 1983 the Air Force (Bundeswehr) slowly woke up from its hibernation, which suffered from lack of money, but was considering a new fighter aircraft.

In 1983 the Luftwaffe presented the first specifications for the new tactical combat aircraft (TKF). The national defense aircraft should be armed with AMRAAM air-to-air missiles and an on- board cannon and be capable of all weather conditions. The limits of conventional aerodynamics should be overcome, there are no restrictions on the alignment of the aircraft. Specifically, it was required that the aircraft had to withstand as much g-force as the pilot and that it should still be controllable even after a stall . Colonel Rolf Thiemann explained that, in contrast to the Royal Air Force , which was expecting aerial battles over the North Sea , the German Air Force began the aerial combat at a medium distance and would quickly switch to close combat.

Dornier and MBB submitted their designs. The German politicians and the Bundeswehr planned a competition between the two aircraft with flying prototypes, around 1986. However, the financing of two prototypes was unclear. A volume of 700 machines was estimated for a joint European aircraft. Germany wanted to involve British Aerospace and Dassault in a future European fighter aircraft project, but budget planning would not have made it possible to procure a new fighter aircraft until 1996, when the Phantoms would have long been obsolete. In order to avoid a European monopoly, the Air Force wanted to keep the option open of buying off-the-shelf combat aircraft (e.g. F-18 ). The cost of the engine was estimated at 35%, with MBB preferred the RB.199 , the Air Force preferred the GE F404 , and Dassault preferred the Snecma M88 . The AN / APG-65 of the F-18 already emerged as the radar . The main sticking point of the cooperation were the different requirements: Germany and Italy wanted to focus on air-air, France a balanced design, Great Britain more air-ground. The British also wanted to somehow accommodate a vertical takeoff and landing .

In the German industry, MBB and Dornier represented a different philosophy with their designs: The LVJ 90 from MBB focused on performance and viewed post-combustion as indispensable. The Dornier ND-102, on the other hand, did without an afterburner, but was still able to achieve Mach 2 ( super cruise ). The MBB design was advanced and expensive, and according to MBB it should achieve a launch ratio of 2: 1 to 3: 1 in air combat at short and medium distances. An air-to-ground capability was provided for the export, which was supposed to bring in part of the development costs. In addition to low wing loading, the aircraft should enable "unlimited flying" (now called supermaneuverability ): it should also be able to fly after a stall and be free of spin. The combat aircraft should be able to perform any desired movement under all circumstances, which should be ensured by the canards and thrust vector control . Rocket motors and suction / blowing out of the boundary layer were considered.

Start of cooperation

MBB already started with the production of the front fuselage, which consisted of 80% CFRP, and was to be exhibited at the Paris Air Show 1983. Dornier had worked with Northrop for four years and saw the ND-102 as the answer to Air Force specifications. In contrast to MBB, however, more emphasis was placed on low costs. The federal government financed Dornier test flights with alpha jets for a new transonic wing, Direct Side Force Controls (DSFC), new flaps and load-bearing structures made of CFRP. Dornier has already tested a wing in the fatigue test that was made entirely of CFRP. Germany also planned to build and test a tornado with a CFRP tail fin. At the time, the Air Force was already flying CFRP air brakes on the Alpha Jets in order to determine the long-term strength of the material. Dornier favored a collaboration with Dassault.

At the 1983 Paris Air Show, British Aerospace announced that the ACA would be funded by the British government, as a preliminary stage to an Experimental Aircraft Program (EAP) . A mock-up with a double vertical stabilizer had already been shown months earlier in Farnborough . With the (unofficial) £ 70 million, the government wanted to set an example and base the negotiations on something more concrete than feasibility studies. There was talk of up to five ACA prototypes, which should test handling, fly-by-wire, performance, avionics and weapons. Although the German and Italian governments did not share in the costs, MBB and Aeritalia were involved in the EAP. France, however, worked Germany to join the ACX program, and Dassault had talks with MBB. Since MBB participated in the EAP with private funds, there was no pressure from politics. At the Paris Air Show, MBB also presented the fuselage with cockpit, which was made entirely of CFRP and at that time was the largest CFRP structure in the world.

In December 1983 Spain joined the EAP partner countries Germany, Italy and Great Britain for talks, although Great Britain continued to finance half of the project. The remaining half of the cost was paid out of pocket by the industry. The first flight for the EAP was set for spring 1986. The program should demonstrate fly-by-wire, CFRP wings and a modern cockpit. In addition to voice input and output, CRT screens were also planned for the cockpit . In addition, we worked with a “non-European partner country” on the cockpit development. Warton also had the idea of ​​using the simulator dome as a trainer. The two simulator domes in Warton made it possible to fight virtually any opponent. The machines of all NATO countries and their possible opponents were programmed in for this, and, as a little gimmick, the Supermarine Spitfire . The simulator domes were also used to develop Tornado and EAP. For Warton, the EAP was necessary to keep it busy after the end of the tornado program. Germany and Great Britain could now agree on air-to-air as the main task, with air-to-ground as a secondary task.

Departure of France

After Bonn had signed the five-nation catalog of demands for Future European Fighter Aircraft (FEFA) at the end of 1983, the Kohl government pressed MBB out of the EAP project at the turn of the year 1983/1984 . MBB had to reduce its share from 40% to less than 1%. MBB was supposed to manufacture the fuselage and Aeritalia the wings. For MBB, only the aircraft's flaperons remained as a production part. Germany wanted to play a neutral role between the EAP (Great Britain) and ACX (France) and saw both of them only as technology demonstrators. The hope of a five-nation fighter was not given up, and the work share was unsolved. There was also the question of whether a five-nation engine should be developed.

In May 1984, Peter Fichtmüller, Chairman of MBB, warned that an agreement on an aircraft that meets the five-nation catalog of requirements would have to be reached next year in order to have a series-production aircraft by 1995. While France and Great Britain were building technology demonstrators, Germany did not get off the ground. The reason was that the Air Force gave the procurement of Patriot FlaRak systems a higher priority than the TKF-90. However, at the beginning of the year the Air Force had drawn up its own catalog of demands under the title “Jäger 90”, which was more specific than that of the FEFA (now called EFA). A fighter aircraft with STOL properties, the ability to use 500 m long makeshift landing sites , stealth technology , 50 km TWS radar range , six BVR air-to-air missiles and an on-board cannon was required. The maximum speed should be Mach 1.8 and the sustained turning rate 4 g at Mach 1.4-1.6 and 12 kft. The operating radius should be 600 nm for air-to-air and 300 nm for air-to-ground operations. From the point of view of the industry, the European Fighter Aircraft (EFA) should initially fly with an engine that is already available in order to avoid development problems. Nevertheless, European agreement on precise performance parameters was difficult. Germany made the highest demands on the aircraft, France the lowest. MBB, on the other hand, was frustrated to be left with virtually no participation in either program. Since the federal government refused to participate in the EAP, it was clear that only one aircraft would be built. While MBB therefore concentrated on the flight control of the F-104G CCV and carried out research on materials, Dornier continued to lobby for its ND-102. If Germany wanted to build a prototype, it was hoped that it would be an ND-102 with ATF engines .

Although the arms industry put pressure on the governments to come to an agreement, the meeting of defense ministers broke down in March 1985. Great Britain and Germany lacked the money, and the Federal Republic of Germany also had no plan as to what share should be accepted in a development. Neither Germany nor Great Britain were willing to be the leading nation. Only France had a clear goal of aligning the aircraft for export without diluting the national requirements. These delays increased the pressure on countries to go their own way in fighter aircraft development. Great Britain would then continue on the basis of the EAP, and France on the basis of the ACX, or join the ND-102.

In 1985 the Netherlands, Belgium, Norway and Denmark also showed interest in the EFA. Since the EFA specifications were secret, it was only known that the single-seat, two-engine aircraft should be extremely maneuverable in order to meet the Air Force's JF-90 requirement. The empty weight should be 9.5 t. As an engine, the Air Force saw an option in the F404, with MTU applying pressure to develop a completely new engine for the fighter aircraft. MTU wanted to take a 25% stake in this European joint venture, as did West Germany in the overall project. MBB and Dornier were now working on their JF-90 concepts and wanted to present them at the Paris Air Show. MBB worked with McDonnell Douglas for the JF-90 (later X-31 ), Dornier with Northrop ( ND-102 ). Germany wanted to connect a German JF-90 airframe to the F404 as an emergency solution in the event that European cooperation should fail. The purchase of the F-16XL was discarded. Great Britain developed the P.120 concept, which came very close to the later Eurofighter, with 94 kN of thrust per engine. France became more and more a problem case, not only because of the different performance expectations. French industry demanded up to 50 percent work share, politics at least "only" 31%. France also wanted the competence competence , the technical team in France, the test flights in France (under French control) and the construction of all mock-ups in France. The sub-components should not be advertised, but should be assigned by the (French-dominated) project management team. France also demanded control over exports and marketing, but risks should be shared. In the other countries there was resentment about this (interview) "chauvinistic" behavior. It was assumed that France only wanted to delay the EFA as much as possible in order to go its own way with the ACX. The poor performance of the Snecma M88 would hardly have made it possible to meet the EFA requirements.

As a private project

The EAP, which began in 1983, was completed unimpressed by the political quarrels. The front fuselage was fitted out at the end of 1984 and final assembly began in early 1985. The wings were fitted to the fuselage in August and September. At the end of 1985 the cabling was ready, and the refueled EAP was put on the scales in November 1985 to determine the center of gravity for the flight attitude computer. In December the starboard wing was subjected to acoustic vibration tests in a test stand. In January 1986 the first tests were carried out with the RB.199 Mk 104D. The effective radar reflection area was measured in Warton .

In March, Aeritalia, British Aerospace, CASA and MBB agreed on the weight limit for the EFA. Reluctant Germany previously raised concerns that the aircraft might be too heavy and wanted more time to test the ND-102 one more time. Germany finally abandoned the ND-102. The companies previously offered various options for the EFA in order to coordinate weight, performance and costs. So the idea was born to reduce the maximum load factor in order to reduce the curb weight. The companies agreed to found a joint company to manage the EFA. Like NAMMA, the company should be based in Munich. In April, however, it was clear that the development of the EFA would be delayed because the election campaign in Germany intervened. At the same time, Germany feared that the EFA could exceed the agreed weight limit of 9.75 t. Therefore, Germany called for further studies on the ND-102 and P.110 in order not to break the weight limit. At the same time, the EFA company was named Eurofighter .

On April 18, 1986, the EAP was rolled out, accompanied by a laser show. Up to that point the project had cost £ 180 million. Originally the project was supposed to be 50% financed by industry and governments, but with the withdrawal of Germany and Italy, industry had to bear a large part of the costs. 80 million pounds came from the government of the kingdom, 100 million had to be contributed by BAe, MBB and Aeritalia. The EAP's airframe with the modified Tornado ADV fin cost £ 115 million of which 70% was provided by British, 23-24% by Italian and the remainder from German sources. The fly-by-wire system cost £ 65m and was 65% funded by the British, 30% MBB and 5% Aeritalia.

EAP at Farnborough Airshow 1986

With a large majority of the Warton employees voting in early June 1986 to continue the strike for higher wages, the viewing date at the Farnborough International Airshow was in jeopardy. The strike started four weeks before the first flight in late May. On June 20th the strike ended. It was unclear whether the EAP would fly in Farnborough due to the time pressure. In mid-July, BAe announced that the EAP would fly by the end of the month and be ready for Farnborough International Airshow. The static test with the RB.199-Mk-104D engines was completed in early July. The first flight was delayed by hydraulic problems and bad weather and took place on August 8, 1986 with Dave Eagles at the controls. By August 13th, seven flight hours had already been accumulated on six flights, including a supersonic flight with Mach 1.1 on the first flight, as well as Dutch rolls and 4g maneuvers. A mock-up of the EFA was exhibited at the Farnborough International Airshow and the founding of Eurojet Turbo was announced, which was to develop a supercruise engine for the EFA with the EJ200. The EAP also flew at the air show. The costs for the demonstration flight, as well as for further test flights, had to be borne entirely by the industry. Follow-up funding for the EFA was also unclear, as there were general elections in early 1987 . BAe was therefore forced to carry out further test flights on its own account. At the end of 1986, the two Aeritalia test pilots Ed Nappi and Napoleone Bragagnolo flew the EAP for the first time.

In May 1987 a consortium made up of GEC, Aeritalia, Inisel and MBB submitted an offer for the EFA's fly-by-wire system, with MBB taking the lead. The basic things for this were tested with the EAP: Software updates increased the maximum angle of attack and the instability of the EAP. For the test campaign from May, which was of course fully financed by the industry, the instability was increased from 12% MAC to 15% MAC, and the maximum angle of attack was set to 25 °. Great Britain, Germany, Italy and Spain had meanwhile agreed that the EAP should become an official part of the EFA development program. In February 1988, with Peter Weger, MBB test pilot, a German pilot climbed into the cockpit of the EAP for the first time. Funding remained difficult, but BAe sought to be compensated by the other EFA partner countries if the EFA was given the green light. On March 26, 100 flight hours and 140 flights were completed with the EAP. Twelve pilots have already flown the machine, with speeds up to Mach 1.7. Pressure probes were now attached to the fuselage, rudder unit and port wing to collect data for the EFA. Overall, tests were planned for the next two and a half years.

Gleanings

EAP hull being transferred to the RAF Cosford Museum

When the EAP completed its last flight on May 1, 1991, a total of 259 flights with over 195 hours had been flown. Speeds of up to Mach 2 and angles of attack of up to 33 ° were achieved. The EAP was then transported to Loughborough University's Department of Aeronautical and Automotive Engineering and Transport Studies on June 27, 1996 on a long-term loan. On March 26, 2012, the EAP was transferred to the Royal Air Force Museum Cosford at the request of the RAF . The university received a BAE Hawk 200 in return . In late 1995, the press started rumors that an EAP Mk 2 was planned for the Future Offensive Air System . For details, see ibid.

The Eurofighter, which emerged from the EAP, has a few significant differences to the EAP: The articulated delta was replaced by a delta with a constant 53 ° bearing, which reduced the wing area by 1.66 m² and the wingspan from 11.77 m to 10 .5 m shortened. The aspect ratio was reduced from 2.4 to 2.2, which lowered the maneuvering and straight flight resistance in supersonic. The area of ​​the slats was also reduced from 3.81 m² to 2.4 m².

The override option has been retained and enables the Eurofighter to reach up to + 12g. The operational flight envelope therefore largely depends on the pilot's anti-g suit . Due to the measurement data of the structural load at the EAP, the loads for the EFA could be estimated much better, which is why it was decided to reduce the safety factor from 1.5 to 1.4 in order to save weight. At the same time, the Eurofighter was dimensioned to only 90% of its design load in order to avoid over-construction due to overly conservative load assumptions. The unusual step was crowned with success, uncertainties only arose with the leading edge flaps: Due to the delay in extending and folding down during fast pitch-up maneuvers in the transonic range , the loads were difficult to estimate. On the one hand, the leading edge flap has to withstand the dynamic pressure of the flight, on the other hand, when maneuvering at the physical maximum, an 80 percent vacuum is formed on the leading edge flap. The result pushed the tolerance range to the limit, so that a reassessment of the design loads of the leading edge flap was necessary.

technology

aerodynamics

The EAP / EFA concept was based on the assumption that the aerial battles of the future could begin with fire-and-forget missiles out of sight of the pilot . In this case, the defender has to accelerate quickly from the air surveillance mission to give his air-to-air missiles maximum energy and range, and turn hard after launch without losing energy in order to force the enemy guided missiles to make hard changes of course at the end of their orbit to shake it off. As the battle progressed, the combat range would quickly shrink to line of sight where short-range missiles would be deployed. Whereas in the past, infrared-guided short-range weapons could only lock onto the enemy's rear, and correspondingly high short-term turning rates were required in order to be the first to get into the opponent's rear, modern infrared-guided short-range weapons can target the enemy from any position. Now the sustained rate of turn is crucial, as everyone will always shoot everyone as soon as they are within range. While high acceleration and supersonic maneuverability are required in long-range combat, close combat requires maximum lift and a high thrust-to-weight ratio in order to quickly compensate for energy losses.

The design focus of the EAP was on the maximum and permanent turning rates, as well as a high specific power surplus, i.e. the ability to gain speed and height. Like any aircraft, the EAP is a compromise between supersonic and subsonic requirements. The double delta with an internal sweep of 57 ° , a thin profile and a large profile chord reduces the supersonic drag when flying straight ahead and when turning. The moderate outer sweep of 45 ° reduces the induced drag when constantly turning in subsonic mode, while the more heavily swept inner section improves lift thanks to bag vortices at a high angle of attack. In order to achieve a high permanent turning rate and short landing distances, the wing area is 52 m² and the span is 11.7 m, whereby weight and supersonic resistance should be relatively low according to BAe. The curvature of the profile was dynamically changed by the flight control computer via the leading and trailing edge flaps in order to achieve the best lift-to-drag ratio in the subsonic, while the computer tries to minimize the wave resistance in the supersonic. Pitch control was ensured by canards and (computer-optimized) trailing edge flaps, roll control by flaperons , whereby only the inner ones worked at high speeds.

Since a stable aircraft would have a front center of gravity and a high canard wing loading with unacceptable air resistance when maneuvering, the configuration was designed to be aerodynamically unstable with a rear center of gravity. In the supersonic, when the pressure point moves backwards on both aerodynamic surfaces and the EAP becomes stable, the long lever arm of the canard can ensure more efficient trimming. By doing without pendulum elevator, it was also possible to reduce the stern drag, which makes up around 40% of the total drag at supersonic levels. The EAP was designed according to the area rule in supersonic.

The vertical stabilizer was taken over from the Panavia Tornado; a curved tip was added for cosmetic reasons. In order to reduce air resistance, in addition to Kuchemann wing tips, fuselage-mounted LFKs were carried as external loads . The launch pylons at the wing tips were preferred by BAe. Compared to launch pylons on the wing tips, it doesn't matter aerodynamically whether the rocket sits on the rail or not. The lower hull inlet was optimized for high angles of attack, and was a novelty for BAe. It was supposed to convey clean, non-turbulent air to the engines even at high angles of attack. The turned down lower lips improve the air supply at high angles of attack and low speed, while the perforated surface on the top is used for boundary layer suction. At high speed, the lower lip rotates upwards to reduce overflow resistance. No consideration was given to the radar signature of the inlet.

Flight control computer

The flight control computers of the EAP were supplied by GEC Avionics. Although MBB was responsible for the fly-by-wire system (FBW), the British press likes to refer to the BAe Jaguar, which British Aerospace has equipped with an FBW system for testing purposes. Although fighter aircraft such as the F-16 or Mirage 2000 were designed to be unstable before, the BAe Jaguar was the first aircraft to be equipped with a digital fly-by-wire system. The instability of the aircraft was successively increased in test flights until finally 10% of the mean aerodynamic wing depth (MAC) was reached - far more than with the F-16 or Mirage 2000. The output of the four FCC was passed through two further computers, which recorded the results of the four summed to form a pseudo-sixfold FCS . MBB's F-104CCV was extremely unstable at 20% MAC, but retained the mechanical controls of the starfighter as reassurance.

As with the Jaguar, there was no mechanical contact between the control stick and the control surfaces of the EAP. Compared with the EFA's FBW computers, the EAP's system was relatively primitive; Thus, with the EFA, twice the computing power could be accommodated in half the building volume. Compared to the Jaguar, the two summing calculators were omitted, and instead more emphasis was placed on improved fault isolation and detection, the computing speed tripled and BITE integrated. The digital quadruplex fly-by-wire system guaranteed a loss of control with a maximum probability of 1: 10,000,000. The system worked by adding up and averaging the output values, whereby errors of up to two lanes could be controlled. If a third lane also fails, a defective lane must be recognized as such within milliseconds. Experience has shown that the software errors on the first flight of the EAP were an order of magnitude less than that of the FBW Jaguar, although with 13 considerably more control surfaces had to be controlled. The software update took place in May 1987 and all problems were resolved. At the same time, the instability was increased from 12% MAC to 15% MAC, and the maximum angle of attack increased to 25 °. The computer network was able to handle angles of up to 30 °.

While in the fly-by-wire Jaguar the time to amplitude doubling was around 0.25s, the EAP was much more difficult to control at 0.18s. In addition to the linear systems of equations that were necessary to control the aircraft, non-linear characteristics also had to be taken into account. A method known from FBW-Jaguar was chosen using root locus curves and frequency response analyzes. The trim distribution, the balancing of control forces and the variation of the stability remained non-linear, but were sent through amplifiers, filters, integrators, switches, etc. and packed together with the others into a simple, executable file . The resulting source code was used for simulation and analysis. This was another step away from the FBW Jaguar, where the control laws were seen as part of the hardware . Due to the high aerodynamic instability, the EAP would have been difficult to control, since the control loop would pay close attention to the stability of the flight attitude, which would weaken the input commands. As a solution, the control loop and command path were separated. The command path is fed with precontrol and digital filters before the signal is released for the dynamic calculations. This idea made it possible to align the handling of the aircraft precisely to the characteristics of the aircraft, while the stability loop works independently of this. This practically eliminated Pilot Induced Oscillation (“Pilot” in this case the flight control computer). Although angles of attack of up to 34 ° and speeds of up to 100 knots were demonstrated without stalling, the pitch control at under 200 knots was perceived as (original sound) "jagged". Periodic nodding with the control stick led to the angle of attack limit being exceeded.

Since the partner countries agreed to make the EAP a development program for Eurofighters, further experiments with the FBW system became necessary. While the EAP used bit-slice ICs , Motorola 68020 microprocessors were planned for the EFA , as twice the computing power should be available for future increases in maneuverability. The flight control computers (FCC) of the EFA should be able to send the movement and air data to other subsystems via data buses. It was also considered that the FCCs of the Eurofighter should not only provide data, but also energy for electrical rudder control. With the FBW Jaguar, the pilot commanded the pitch rate and angle of attack with the control stick. With EAP and EFA, three parallel systems were used for pitch control, angle of attack control and g-control via control stick inputs, the control commands of which were interlinked. In principle, small stick movements (practically straight flight) are controlled according to the pitch rate; with increasing deflection, commands are given according to the angle of attack (limit) and g-load. An amplitude-dependent command input filter was also tested with the EAP in order to be able to aim more precisely with the on-board weapon . Like the Eurofighter, the EAP had the option of override in order to exceed the standard g-limit. This is not a mystical ability, but the EAP / EFA control stick only has to be pulled backwards over a force feedback limit. The EAP also demonstrated carefree handling . H. the structural and aerodynamic limits of the aircraft were never exceeded by the pilot.

Materials

One of the most critical decisions for the EAP was the choice of materials. Humidity and high temperatures due to frictional heat during the long-term supersonic flight limit the possibilities. The problem of the stagnation point temperature was solved by using an aluminum alloy leading edge of the wing. The remaining fuselage surface would be exposed to a recovery temperature of 136 ° C at Mach 2.4 at 35,000 feet if Mach 1.2 were possible in low-level flight and the aircraft would always fly at the limit of thrust and drag. By moving the lower right area of ​​the flight envelope slightly upwards (approx. Mach 2.32 at 36,000 feet), the recovery temperature could be reduced to 120 ° C, which increases the compressive strength of the carbon fiber-reinforced plastic by 11%. On the ground, CFRP materials absorb humidity, which leads to a marginal increase in weight (1%), but reduces compressive strength by 30% and tensile strength by 5%. During the supersonic flight, the water evaporates from the material. Since combat aircraft are only on the ground for most of the year, there is no long-term decrease in moisture. The crux of the matter was the matrix, which should be able to tolerate at least 120 ° C as well as possible. Bismaleimides can be used up to 220 ° C (e.g. Harrier nozzle regions), but are brittle and difficult to process. Ultimately, the decision was made to use PEEK with a glass transition temperature of over 140 ° C for the EAP. Individual CFRP elements were test flown with SEPECAT jaguars and tornadoes.

The EAP was the first aircraft in the world to use a glued wing. The individual parts, i.e. the frames and the upper and lower shells, are glued together from smaller parts. The lower shell and ribs are then wetted with glue at the contact points, a non-adhesive agent is applied between the upper shell and the ribs and the total work of art is clamped together. This allows the adhesive to harden in the wing. After the successful operation, the upper shell can be removed and fits precisely onto the rest of the wing. Since the wings are also tanks at the same time, inspectability can be guaranteed. The upper shell was fastened with rivets. According to its own statement, BAe was thus a world leader. The wing was designed using Aeroelastig Tailoring, which was supposed to guarantee the optimal rotation for the lowest possible air resistance. For this purpose, up to 200 layers of laminate were laid on top of one another. It was the first time that a European aircraft was made aeroelastic by changing the thickness and direction of the fiber mats. The left wing was made by Aeritalia, the right wing by BAe.

In the case of metallic materials for permanent supersonic flight, the challenge lies in corrosion. According to British Aerospace, the experience with the Concorde could be used directly. While in previous supersonic machines such as the BAC TSR-2 and aluminum-lithium alloys have been used, they bribed there rather by their extremely short critical crack length. The new type A alloy , developed by the Royal Aircraft Establishment in Farnborough, was supposed to combine high strength with low density and was used in the EAP. A higher-strength type B alloy was supposed to be used for the wing spars at the EFA, but had development problems. Alloy Type A is around 10% lighter than equivalent, previous aluminum-lithium alloys. Since the material was only produced in small quantities at the time, only the front and rear edges and some panels were made from it. According to program manager John Vincent, only the suitability of the alloy should be shown.

Due to their susceptibility to corrosion, magnesium alloys should only be used in easily accessible areas such as cockpit surrounds and arches. New titanium alloys were not developed, instead the focus was on reducing costs through new manufacturing methods such as superplastic forming and diffusion bonding (cold welding). British Aerospace took the alloy TI6A14V as its working material. The result of the research and development work was the construction of the duck wing of the P.110 concept. The titanium variant with bearing journals, thin top and bottom surfaces and a zigzag internal structure made of titanium sheet was only slightly heavier than a CFRP variant with titanium journals (5%), but significantly cheaper (30%). Originally, the middle and rear fuselage part of the EAP should consist of CFRP and superplastically deformed, diffusion-welded titanium (SPF / DB), and be manufactured by MBB. However, the withdrawal of MBB forced BAe to fall back on the tried and tested aluminum construction. SPF / DB-Titan was also used for the firewall between the engines. Ultimately, however, the canards of the EAP were made of CFRP.

Although steel is a popular material for supersonic aircraft, BAe calls it the XB-70, it was not an option for the EAP and EFA due to the high density and manufacturing costs. Metal matrix composites such as SiC flakes in aluminum alloys were seen as future options, as were SiC fibers in diffusion-bonded TI6A14V.

Cockpit and avionics

The EAP had fully integrated avionics in which individual subsystems were connected to one another via data buses . The flight control system, avionics, displays and the network of the Utilities Management System (UMS) were integrated into it. The cockpit was dominated by a refractive wide-angle head-up display , three colored multifunctional displays and HOTAS . The position of the central stick was chosen to gain space for the right side panel and because combat damage could obstruct the pilot's right arm. A switch on the central control stick was used to reset the displays to factory settings (engine status / primary flight display / warnings). The wide-angle HUD came from GEC Avionics and was taken from the F-16 LANTIRN program and ensured a field of view of 18 ° vertically and 30 ° horizontally. The three multi-purpose CRT displays were installed by Smiths Industries, which mastered 14 different presentations. With 21 fixed keys attached around the screens, the pilot could change the settings and displays. The two waveform generators for the displays were supplied by VDO, with each waveform generator having four processors for reasons of redundancy. The left panel was used for navigation and communication. a. a number pad. The displays previously flew for testing on the BAe One-Eleven. The pilot sat on a Martin Baker Mk 10LX Zero-Zero ejection seat that was tilted backwards by 25 °.

Four Aircraft Motion Sensor Units (AMSU) and four Actuator Drive Units (ADU) controlled and steered the aircraft. Canard, air inlet and leading edge flaps were controlled by the flight control computer (FCC), but flaperons and rudders were controlled by the rear-mounted ADUs, which were connected to the FCC via data buses. The AMSU determined pitch, roll and yaw rates, and sent the data to the avionics and engines via buses. The Actuator Drive Units were supplied by the Bodenseewerk , and Litef was responsible for the Aircraft Motion Sensor Units . All systems were networked via double redundant MIL-STD-1553B data buses. In addition, the inertial navigation system FIN1070 from Ferranti, the audio management system RA80 from Racal, and the TACAN AD2780 from GEC Avionics were installed.

RAE HS.748

The Utilities Services Management System (USMS) was developed by Smiths Industries for eight years and, as a kind of janitorial system, monitored around 30 subsystems such as fuel, inlet de-icing, chassis, control hydraulics and sensors. The UMS could process 500 to 600 different input / output signals. The system had four processor cards as LRU, two in the front in the avionics bay, two in the rear fuselage. These were connected to around 100 actuators via a double redundant MIL-STD-1553 B data bus. Changes in position, altitude, temperature and pressure are also recorded. The cards and modules of the system were standardized; The structure of the system corresponded to the USAF's Pave Pillar concept. While all components of the UMS were connected via the data bus, the four processors were collectively connected to the avionics via a further MIL-STD-1553B data bus. The system was supported on the ground by a computer that could be connected to the system to read out and change data that could be stored in another external database. The function monitoring of individual systems could thus be combined, which is practical and saves weight. If problems arose, the system could show them on each of the three displays or indicate them via voice output. The latter, however, was limited to a few words. The pilot could use the softkeys to view the status of the system more closely. The UMS flew in 1984 in HS.748 of the Royal Aircraft Establishment as a test.

Engines

Two RB.199 Mk 104 from Tornado ADV were taken over as engines. Later experimental engines of the type XG-20 were to be used, but this did not happen. The engines achieved about 75 kN afterburner and 40 kN dry thrust . Compared to the ADV engine, the flame tube was lengthened and a FADEC from Lucas Industries was installed, and the thrust reverser was removed. Aeritalia accounted for 17% of the work on the modified engine, MTU for 7% and British companies for 76%.

Test program

The main aim of the test flights was to test the flight with high angles of attack at low speeds, to test the transonic acceleration and supersonic flight, to assess the low-level flight quality (due to the low wing loading), the ability to take off and land quickly ( STOL ), to demonstrate the effectiveness of the air intake, as well as to show the low-resistance transport of external loads . Practically all test flights were therefore flown with external training weapons, as was the first flight. 2 ASRAAM and 4 Skyflash were carried along.

In the test break between 1986 and 1987, the instability was increased from 12% MAC to 15% MAC, and the wings were reinforced because they were bent too much. In addition, higher angles of attack have been released. In 1988 a load measuring system was installed that consisted of 400 pressure measuring probes. This was to ensure that the EFA would not be oversized. The fold-out table lists all flights from the flight log . The pilot was usually Peter Orme ( BAe ) with 132 flights, followed by Chris Yeo (BAe) with 57 flights, Peter Gordon-Johnson (BAe) with 24 flights, Don Thomas (BAe) with 21, Keith Hartley (BAe) with 6, David Eagles (BAe) with 4, Peter Wegner ( MBB ) and Derek Reeh (BAe) with 3, Ettore Nappi ( AIT ), Napoleone Bragagnolo (AIT), Colin Cruikshanks ( RAF ) and Murco Zuliani ( AM ) with 2, and Bernie Scott (RAF) on a flight.

Test flight	date	Details
#1	August 8, 1986	Test flight with Tornado and Hunter companion
# 2	August 10	Handling
# 3
# 4	12. August	Handling and engineering studies
# 5
# 6
# 7	August 14th	Handling and demonstration maneuvers
#8th
# 9		Supersonic handling
# 10	August 19th	Engine test flight and exercises
# 11		Handling and demonstration maneuvers
# 12
# 13	20th of August
# 14
# 15		Demonstration and practice
# 16	August 21	Handling
# 17	August 22nd	Photo exercise with jet stream
# 18	August 24th	Demonstration and exercise at low speed
# 19		Fast climbs
# 20	August 25	Demo flight in bad weather
# 21	26th of August	Transfer to Farnborough
# 22	August 27	Demonstration and practice
# 23
# 24	August 28th
# 25
# 26	29th August
# 27
# 28	August 31, 1986	Flight at the Farnborough Air Show
# 29	September 1
# 30	September 2nd
# 31	September 3
# 32	September 4th
# 33	5th September
# 34	September 6th
# 35	7th of September
# 36	September 8th	Return flight to Warton via Hamble, Filton, etc.
# 37	September 10	N / A
# 38	September 11
Minor inspection after 21.5 hours of flight
# 39	October 22nd	Test flight, Emergency Power Unit (EPU) test ignition and handling
# 40	October 24th	EPU test ignition and handling
# 41	October 29th	EPU test ignition during flight test
# 42	30th of October	Handling
# 43	October 31	Level flight and flyby
# 44	November 5th	Formation and low-level flights, fast taxiing
# 45	15th of November	Introductory flight new pilot (Nappi)
# 46	November 17th
# 47	November 18	EPU test ignition, re-ignition of the engines
# 48	November 19th	Engine handling and flutter tests
# 49	20th November	Introductory flight new pilot (Bragagnolo)
# 50		Handling
# 51	21st November	Performance test level flight and taxiing
# 52		Air-to-air tracking, climbs and turns
Preparation for high alpha tests after more than 37 hours of flight, with a braking parachute attached
# 53	May 1, 1987	Calibration of the air data sensors (ADD), braking parachute release at the airfield
# 54	May 4th	Calibration ADD, engine test and brake parachute removal
# 55	May 6th	Calibration ADD, braking parachute release
# 56	May 7th	First high alpha test, ADD calibration, screen drop test
# 57	8th of May	High alpha test
# 58		High alpha test and roles
# 59	May 9	Flight demonstration due to Family day in Warton
# 60		High alpha test and Flight demonstration due to Family day
# 61	10th of May	High alpha test
# 62	May 13th
# 63
# 64	May 13th
# 65
# 66	May 16
# 67	May 18
# 68		General handling
# 69	May 19th	High alpha test with thrust lever idling -> maximum
# 70	May 20th	Carefree Maneuvering u. Thrust lever idle -> maximum
# 71
# 72	May 21
# 73	28th of May	Flight without limiters
# 74	May 29th	High alpha handling
# 75		High alpha handling and combat maneuvers
# 76		High alpha handling and fast rolling
# 77	30th May	High alpha handling and floor checks
# 78		Practice flights for air show
# 79
# 80
# 81	31. May
# 82
# 83	2th of June
# 84
# 85
# 86	3rd of June
# 87
# 88	June 4th
# 89
# 90
# 91	June 5th
# 92
# 93
# 94	8th June	Transfer flight to Paris
# 95	June 9th	Practice flights for air show
# 96
# 97	June 10th
# 98	June 11th	Demo Paris Air Show 1987
# 99	June 12
# 100	14th June
# 101	15th June
# 102	June 16
# 103	17th of June
# 104	18th of June
# 105	June 19th
# 106	20th June
# 107	June 21st
# 108	June 22	Flight back to Warton
# 109	June 30th	Flight with pressure measuring probes
# 110		Vibration tests
# 111	2nd July	Cruikshanks (MoD) as test pilot
# 112
# 113	3rd of July	Zuliani (IAF) as a test pilot
# 114	July 6th
# 115		Fuel delivery with negative "g"
# 116	7th of July	Scott (MoD) as test pilot
# 117	December 7th	Handling test
# 118	December 14th	Handling and incline tests
# 119	December 17th
# 120	December 18th
# 121	21st December
# 122	January 11, 1988	Supersonic loads
# 123	January 18th	Trim and tilt tests
# 124	January 19th
# 125	January 20th	Introductory flight new pilot (Weger)
# 126	21th January
# 127	January 27th	Introductory flight and handling of new pilot (Hartley)
# 128	January 28th	Handling and inclination test
# 129	February 2nd	Handling
# 130	3 February
# 131	February 16
# 132	February 17th	Trim check and load measurements
# 133	19th of February	Handling and trim checks
# 134	February 24th	Performance measurements
# 135	February 25	Performance and inlet measurements
# 136	February 26th	Run-in and handling tests
# 137	1st March	Performance measurements and combat maneuvers
# 138
# 139	2nd March	Combat maneuvers
# 140	4th of March	Threads on the tail unit and guide vanes "off"
# 141	March 22	Guide vanes "off", no more threads on the tail unit
# 142	March 23	Night flight
# 143	March 24th	Run-in tests
# 144	25th March
# 145	28th March	Performance and handling tests
Installation of load measuring system after 104 flight hours
# 146	July 27th	Test flight
# 147		Photo shooting
# 148
# 149	August 1st	Load measurements
# 150	8th August	Inlet measurements
# 151	August 16	Load measurements
# 152	17th August
# 153	August 19th
# 154	August 22nd
# 155	August 23	Measurement of the infrared signature
# 156	5th September	Vibration measurements
# 157	September 6th
# 158	13.september	Load measurements and demo exercises
# 159	September 14th
# 160	16th September	Load and vibration measurements
# 161	September 26th	Vibration measurements and various loads on the flaps
# 162		Load measurements during demo maneuvers
# 163	September 27th	Vibration and load measurements
# 164	September 28th	Transfer flight to Filton, AMSU drift measurement
# 165	September 29th	Demo in Bristol at Rolls-Royce
# 166		Transfer flight Bristol to Warton, AMSU drift measurement
# 167	30. September	Vibration and load measurements
# 168	5th October	Various loads on the flaps
# 169	October 6th
# 170	October 10th
# 171	October 11th
# 172		Load measurements in supersonic
# 173	October 12th
# 174	November 2	Load measurements on the tail unit and fuselage
# 175	November 4th
# 176	November 7th
# 177	November 8th
# 178	November 10th	Load measurements on the tail unit and fuselage (supersonic)
# 179	November 11th
# 180	November 24th	Supersonic trim and vibration excitation
# 181	25. November	HRH demo and hull subsonic trim
# 182	November 28th	Load measurements on the tail unit and fuselage (supersonic)
# 183	November 29th	Measurement of the infrared signature
# 184	December 1
# 185
# 186	2. December
# 187	December 5th	Supersonic trim and noise measurements
# 188	12th of December	Tail vibrations at high angles of attack and pressure measurements
# 189	December 14th	Supersonic trim and pressure measurements
Air brake was mounted on the back after 141.7 flight hours
# 190	April 24, 1989	Test flight and trim test
# 191	26th of April	Air brake extended up to 15 °
# 192	April 27	Navigational flight and trim tests
# 193	2.May	Air brake extended up to 30 °
# 194	May 4th	Air brake extended up to 45 °
# 195
# 196	5th of May	Trolling test, followed by Buccaneer and Tornado
# 197	June 1st	Missile drop
# 198
# 199	June 5th
# 200	6th of June
# 201	September 27th	Test flight, EPU ignition and demo
# 202	September 29th	Test demo flight for RAF Scampton
# 203	October 2nd
# 204	October 3	Transfer flight to RAF Scampton
# 205	4th of October	Demo flight for RAF Scampton
# 206	5th October	Transfer flight to Warton via Brough
# 207	October 6th	Photo flight with Red Arrows in Scampton
# 208	November 28th	Noise measurements and transfer to Boscombe
# 209	December 14th	Transfer flight to Warton
# 210	January 19, 1990	Gear test with negative "g"
# 211	April 5th	Hydraulic actuator test
# 212	June 1st	Gear test with negative "g"
# 213	October 12th	Handling in slow flight
# 214	October 18	Supersonic Envelope Expansion
# 215	November 6th	Supersonic envelope expansion and engine tests
# 216	November 7th	Supersonic Envelope Expansion
# 217	November 8th	Supersonic run-in tests
# 218	November 9th	Supersonic Envelope Expansion
# 219	November 26th	High alpha testing
# 220	December 14th
# 221	19. December
# 222	January 8, 1991	Envelope expansion, PE check and flutter check
# 223	January 9th
# 224	11th January
# 225	21th January	Supersonic envelope expansion and flutter tests
# 226	January 24th
# 227	January 25th
# 228
# 229	31 January
# 230		Termination for technical reasons
# 231		Envelope expansion
# 232	February 18
# 233
# 234	19th of February
# 235
# 236	21st of February
# 237	February 22
# 238	February 25
# 239
# 240
# 241	February 26th
# 242	February 28
# 243
# 244	12. April	IFSME, SIFT and regression
# 245	April 15th
# 246	April 16
# 247
# 248
# 249
# 250	17th April
# 251	April 18	Flight in wake vortices
# 252		IFSME, SIFT
# 253	April 23
# 254
# 255
# 256	April 24th	Combat maneuvers
# 257	April 25	IFSME and SIFT
# 258		Combat maneuvers
# 259	1st of May	IFSME, SIFT and Carefree Handling
Total flight time 195 hours and 21 minutes

Technical specifications

Parameter	Data
crew	1 pilot
g limits	like EFA
length	14.7 m
span	11.7 m
height	5.52 m
Wing area	52 m²
Empty mass	10,000 kg
Max. Takeoff mass	14,515 kg
Wing loading	minimum (empty weight): 193 kg / m² maximum (max. takeoff weight): 279 kg / m²
Engines	2 × Turbo-Union RB199 Mk 104
Thrust	with afterburner: 2 × 75 kN without afterburner: 2 × 40 kN
Top speed	Mach 2 1
Thrust-to-weight ratio	Maximum (empty weight): 1.5 Minimum (max.start mass): 1

¹ RAND Corporation states Mach 2+

Web links

Commons : British Aerospace EAP  - collection of images, videos and audio files

• BAE Systems: EAP Official EAP site
• BAE Systems: Experimental Aircraft Program Direct link to the flight video

Remarks

1. ↑ ^{a b} Measure with the ruler from diagram Fig. 1 on page 233.
2. ↑ According to the Flugenveloppe, the BAC TSR.2 could fly at Mach 2.05 in 37,000 feet without an afterburner, Mach 2.35 was achievable with an afterburner. The Rolls-Royce Olympus engines were later used in the Concorde. (Tim McLelland: TSR.2: Britain's Lost Cold War Strike Aircraft. Classic Publications, 2010. ISBN 978-1-906537-19-7 )
3. ↑ The aim of Pave Pillar was to provide standardized computer / processor cards for various avionics functions. Individual avionics systems then represent "islands" which are connected to their subsystems via a local area network . The "islands" are networked via high-speed data buses.
4. ↑ SIFT = S ystem I dentification F rom T racking: Greatly simplified, specifically, a modal analysis to the response of the aircraft (or a portion thereof) to measure the entire aircraft, to pilot inputs. (AGARD-AR-279: Handling Qualities of Unstable Highly Augmented Aircraft . NATO, 1991) IFSME was the recorder.

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o p q r s t u v} Henry Matthews: Prelude To Eurofighter: EAP . HPM Publications, 2000. , passim
2. ^ The Crystal Ball. In: Flight International. January 1, 1983, accessed February 13, 2014 .  
3. ↑ ^{a b} Military targets conflict. In: Flight International. April 16, 1983, accessed February 13, 2014 .  
4. ↑ ^{a b c d} Industry looks at the European fighter. In: Flight International. April 16, 1983, accessed February 13, 2014 .  
5. ^ Bill Gunston: Warplanes of the Future . Crescent, 1986, ISBN 0-517-46960-X .
6. ↑ BAe gets ACA go-ahead. In: Flight International. July 4, 1983, accessed February 13, 2014 .  
7. ^ Tornado and beyond. In: Flight International. December 31, 1983, accessed February 13, 2014 .  
8. ^ Political decisions required. In: Flight International. March 3, 1984, accessed February 13, 2014 .  
9. ↑ Germany treads Fefa tightrope. In: Flight International. March 3, 1984, accessed February 13, 2014 .  
10. ↑ 1984: Germany's year of decision. In: Flight International. May 19, 1984, accessed February 14, 2014 .  
11. ↑ EFA under threat. In: Flight International. February 23, 1985, accessed February 14, 2014 .  
12. ↑ EFA - will it happen? In: Flight International. May 25, 1985, accessed February 14, 2014 .  
13. ↑ EAP weighs in. In: Flight International. November 9, 1985, accessed February 14, 2014 .  
14. ^ Acoustic test for EAP wing. In: Flight International. December 7, 1985, accessed February 14, 2014 .  
15. ↑ EAP tries RB.199 for size. In: Flight International. January 25, 1986, accessed February 17, 2014 .  
16. ↑ EFA clears weight hurdle. In: Flight International. March 29, 1986, accessed February 17, 2014 .  
17. ↑ Germany sounds EFA stall warning. In: Flight International. April 19, 1986, accessed February 17, 2014 .  
18. ↑ Eurofighter. In: Flight International. April 19, 1986, accessed February 17, 2014 .  
19. ↑ BAe uncovers EAP. In: Flight International. April 29, 1986, accessed February 17, 2014 .  
20. ↑ Strike pushes EAP off course. In: Flight International. June 7, 1986, accessed February 22, 2014 .  
21. ↑ Warton work force returns. In: Flight International. June 28, 1986, accessed February 22, 2014 .  
22. ↑ July first flight for EAP. In: Flight International. July 12, 1986, accessed February 22, 2014 .  
23. ↑ EAP progresses as Farnborough looms. In: Flight International. August 23, 1986, accessed February 22, 2014 .  
24. ↑ Eurofighter progresses as EAP and Rafale joust. In: Flight International. September 13, 1986, accessed March 5, 2014 .  
25. ↑ EAP looks for funds. In: Flight International. September 13, 1986, accessed March 5, 2014 .  
26. ↑ No money for EAP says MoD. In: Flight International. September 13, 1986, accessed March 10, 2014 .  
27. ^ Italians fly EAP tests. In: Flight International. September 13, 1986, accessed March 10, 2014 .  
28. ↑ ^{a b c d e f} EAP team bids for EFA fly-by-wire. In: Flight International. May 2, 1987, accessed March 10, 2014 .  
29. ↑ MBB pilot flies EAP. In: Flight International. February 6, 1988, accessed March 10, 2014 .  
30. ↑ EFA awaits clearance. In: Flight International. April 30, 1988, accessed March 10, 2014 .  
31. ^ Air Britain News, May 2012
32. ↑ Invisible HALO. In: Flight International. November 8, 1995, accessed April 15, 2014 .  
33. ^ Fighting for Air. In: Flight International. June 16, 1993, accessed April 15, 2014 .  
34. ↑ Clere et al .: Current Concepts on G-Protection Research and Development . In: NATO AGARD-LS-202 . January 1995.
35. ↑ ^{a b} Carballal et al .: Loads and Requirements for Military Aircraft . In: NATO AGARD-R-815 . January 1997.
36. ↑ ^{a b c d e f g h i j k l m n o p q r s t u} EAP - Fighter blueprint. In: Flight International. April 19, 1986, accessed April 8, 2014 .  
37. ↑ ^{a b c d e f g h i j k l} BAe shows off EAP technology. In: Flight International. May 25, 1985, accessed April 8, 2014 .  
38. ↑ ^{a b c} Computers have control. In: Flight International. October 5, 1985, accessed April 8, 2014 .  
39. ^ ^{A b c d e} Mark A. Lorell: The Use of Prototypes in Selected Foreign Fighter Aircraft Development Programs . In: RAND AR-214 500 . August 1989.
40. ↑ ^{a b c} Wunnenberg et al .: Handling Qualities of Unstable Highly Augmented Aircraft . In: NATO AGARD-AR-279 . January 1991.
41. ↑ ^{a b c} Tischler et al .: Advances in Aircraft Flight Control . Crc Pr Inc, 1996, ISBN 0-7484-0479-1 , pp. 321-343 .
42. ↑ ^{a b c d} RJSellars / British Aerospace plc: Materials for Figher Aircraft (p. 231ff) . In: AGARD REPORT No.740 Special Course on Fundamentals of Fighter Aircraft Design . January 1988.
43. ↑ Eurofighter avionics: how advanced? In: Flight International. October 4, 1986, accessed April 10, 2014 .  
44. ↑ ^{a b} Management by micro. In: Flight International. October 25, 1986, accessed April 10, 2014 .