Translated by BabelFish
the air superiority is the keystone of the doctrines and the mission of the US Air Force. The army is convinced that its priority task is to be able to control the sky whatever the place and the moment. Thus, the enemy planes cannot obstruct the air operations and on the ground, or carry out reconnaissance missions. This mission, accomplished completely honourably since the end of 1970 by the F-15 Eagle de McDonnell Douglas, soon will be entrusted to F-22 de Lockheed Martin. At the time of the service entrance envisaged of F-22 in 2004, there will be more than 20 years that the US Air Force will have created an office in charge of the tactical program of Hunter advanced ATE (Advanced Tactical Fighter), to define the plane intended to replace the F-15. At the beginning of the years 1980, II was obvious that the Soviets had found three manners of countering the threat represented by the new American fighters very operating. First of all, they developed fast, nimble fighters and very heavily armed: Mig-29 and the most imposing Known-27 with large operating range. The development of improved ground-to-air missiles was quite as worrying. It was clear that the Soviet Union also worked on weapons anti-runway.
USAF decided into 1982 that its first priority was to increase the number of its planes of attack at low altitude, by modifying an already existing plane. Thus the F-15E Strike Eagle was created. The second stage was to produce a new fighter which would be higher than the new Soviet hunters, just like the F-15 and F-16 had outclassed the Migone.
the new hunter was to answer the three following criteria: furtivity, supersonic cruising and takeoff and landing courts. The furtivity should make it possible to protect the plane counters the hunters and the ground-to-air missiles and, in combat, would give him the advantage of being the first to see the enemy and to draw - (However, few people knew the secrecies jealously kept of the furtivity, and those which knew them all were not convinced that they can apply to a supersonic hunter very operating.) Supersonic cruising - the possibility of flying at a supersonic speed without using afterburning should make it possible to the pilot to choose to attack or not slower targets, if it wishes it. The DAC (takeoff and landing courts) should complicate the task of an enemy wanting to stop the air operations by bombarding the landing strips.
the US Air Force wanted that the FRA has an operating range larger than that of the F-15. This would enable him to operate starting from bases back in Europe and to intervene in a more effective way in battle fields the such Middle-East where the distances are larger. With these simple elements, USAF could make an estimate of the size of the FRA and start to develop engines (after the problems of design of the engines of the F-15, USAF was well decided to begin the construction of those of the FRA as soon as possible). In September 1983, Pratt & Whitney were charged to conceive the XF119 and General Electric started has to work on the XF120.
During two years which transfer, USAF published several provisional specifications of the FRA, modified them according to the reactions of the manufacturers, and also tried to reduce the technical risks of surprises at the time of the last stages of the development.
Finally, USAF decided to carry out great validation and demonstration program with to the hand two competitors, during which the riskiest technologies would be tested in natural size.
*** * It was in September 1985 that USAF formulated the last proposals for the validation and demonstration program. There were then still seven engineering and design departments of fighters in the USA and all answered has the invitation to tender: Boeing, General Dynamics, Grumman, Lockheed, McDonnell Douglas, Northrop and Rockwell.
Lockheed and Northrop had been much further that their rivals in their integration from the furtivity at the supersonic speeds and the agility. This made it possible USAF to concentrate all the funds of the Démonstration/Validation project on two models, thus allowing the construction of operational prototypes. As it was clear that the money of USAF would not be sufficient to build the plane chosen, and that the manufacturers should provide a substantial contribution of funds, five of the competitors decided to join their forces: Boeing and Lockheed with GD, and Northrop with Douglas McDonnell. In October 1986, the YF-22 of Lockheed and the YF23 of Northrop were selected.
Démonstration/Validation was the longest contest of hunters of the history, it lasted four years and cost almost 2 billion dollars. Each team built two prototypes, one equipped with the YF119 of P&W, the other of the GE YF120. The teams had built systems avionics completely integrated and the avalent one tested on planes of constraint. They had tested equivalent surface radar in size natural and carried out thousands of hours of wind tunnel tests.
the contest commenca badly for Lockheed which, in July 1987, renonça has its original model of wing in fléche because it was too heavy. Other modifications intervened as USAF modified its requests: the specifications of takeoff and short landing (DAC) were softened in order to eliminate the reversers of thorough too heavy and the objectives as regards weight were also modified.
When the YF-22 and the YF-23 were revealed, during the summer 1990, it was clear that the two teams had left in different directions. The trapezoidal wings and the tail out of V of Northrop showed that the stress was laid on the furtivity; the conduits with vectorial push and the more conventional orders of Lockheed indicated the concern of improving the handiness has low speed. Northrop was the first in the airs (August 27, 1990); the first YF-22 stole on September 29, as soon as its engines YF120 accepted their certification for the flight. The two teams made steal their second apparatus at the end of October.
One probation period in flight short and intense followed - both F-22 carried out 74 flight tests in three months. At the beginning of November, the first YF-22 reached a stabilized speed of Mach 1,58 without afterburning. During December, it showed its spectacular maneuverability at low speed by carrying out complete barrels with an incidence of 60°.
the two planes answered the principal criteria and the final decision did not depend only on the promises made by the manufacturers concerning the development and the manufacture of the apparatus, but also of the confidence which had the customers in the capacity of the manufacturers to deliver the apparatus. At the beginning of 1991, whereas USAF was evaluating the prototypes, McDonnell Douglas, the partner of Northrop, was implied in the failure of A12 Avenger, whereas F-117 de Lockheed had become the hero of the war of the Gulf. Moreover, in certain important fields, Lockheed was more advanced in its demonstration programs. Only the YF-22 had flown to great incidence, had drawn from the missiles and had flown with a prototype of very sophisticated cockpit.
*** * All this, associated the fact that the capacities of F-22 in aerial combat were also higher, made that Lockheed gained the contract of construction in April 1991. F119 de Pratt & Whitney were selected like power plant of F-22.
Since, the development is held well, besides some problems concerning the weight and detection radar, mainly solved now. The principal cause of the delay taken was the lack of financing: budgetary cuts delayed the date of the first flight from August 1995 at May 1997 and that of its startup of 2001 to 2004. Moreover, the Pentagon reduced the number envisaged of planes of its fleet of F-22 from 648 to 442 planes.
So F-22 was more expensive. The total cost of the program: development, 442 apparatuses, spare parts, equipment on the ground and construction - rises has 73,5 billion dollars of the time. This figure holds account of at least ten years of estimated inflation. The average price turn-key of F-22 is now estimates at 71 million dollars of 1995 (this price does not include the spare parts nor the weapons). The court of the development rises to 11,5 billion dollars of the time.
Last nine single-seat F-22A and two two-seater F-22B are in the course of construction for the development. The the first four F-22 will be used for the tests of structure, of performance, and of handiness and the fourth will be a two-seater (the member of the team which will find a name for this F-22 will have right to a flight in preview). Fifth F-22 will have identification and navigation, communication systems. The seventh aircraft will be equipped with the System with Integrated Electronic Countermeasures (INEWS), and the eighth will be first F-22 having a system of complete armament and mission; the fifth and the sixth will be equipped with such a system during tests. The ninth and the tenth will be used for the tests of integration and armament; finally the eleventh apparatus will be built in order to carry out the tests of signature radar.
the appearance of this apparatus is very conventional, but appearances are misleading. Its speed and its capacities of acceleration contradict its rather massive form and its size is not representative of its maneuverability and its detectability. Moreover, some of its internal characteristics are as remarkable as its performances of flight.
the form of F-22 meets the need for furtivity, supersonic cruising and maneuverability. So that a plane is furtive, all its weapons and its fuel must be transported in-house, the form of its external surfaces as their angle must answer precise criteria. To fly at a supersonic speed, which implies a relatively accentuated sweptback wing and mean profiles for the wings and the empennage. The agility is obtained thanks to wings of a great scale and great surface and orders effective - these last also make it possible to carry out short takeoffs and landings.
the furtive form of F-22 is inspired by F-117. These two apparatuses have a simple, monolithic form which contrasts with the part before and the separate nacelles of the YF-23. Surfaces and the edges are aligned between them: and the leakage leading edges of the wings and the horizontal stabilizer are parallel, just like the tilted vertical drifts with the tilted walls of the fuselage. The edges of the large trap doors of opening such as those of the landing gear and the compartment of armament are in "teeth of shark". The small openings are in the form of rhombus. This makes it possible to deviate the reflexions radar secondaries on the arrises and the slits far from the radars which light the plane.
*** * Of the techniques of prediction using of the ultra-powerful computers allowed the originators to incorporate curves has surfaces and arrises like using materials advisedly absorbing the waves radar. Thus, one does not find them on all the surface of the apparatus, as on F-117, but simply on the edges, the cavities and discontinuities of surface. New materials absorbing and resistant to heat are used on the conduits engine and of broad band of improved materials absorbing were integrated in the edges of the wings. The radome is a type with band-width which except reflects the signals of all the frequencies those used speaks radar about F-22. A new system of aerodynamic sensors with weak signature radar, including/understanding four probes distributed on before fuselage was installed. F-22 is the first hunter whose canopy does not have the least reinforcement, which eliminates the signature radar from the arch of the windshield.
the wings are of great surface in delta, effective at high speed, light and being able to contain great quantities of fuel. They are sophisticated than they do not have the air of it: shutters of important leading edges and a curve complexes make them more effective, at low speed and great incidence, that the former delta wings.
F-22 was built in order to be able to reach very high angles of incidence while remaining completely controllable, and to be restored without danger after a flight with great incidence without very the assistance of the vectorial push. The wing is located very behind and the horizontal stabilizers are so close the shutters of trailing edge of the wing are indented in order not to interfere with their leading edge. The control surfaces work symmetrically for pitching and by differential action for rolling. When the vectorial conduits function, they provide the greatest part of the control pitch and the empennage of tail are used mainly for the roll control.
the drifts are large in order to improve stability and the handiness with great incidence, phase of flight during which smaller drifts would be masked by the fuselage before very broad. The rudders can be simultaneously directed towards outside in order to be used as air-brakes.
the heart of the structure of F-22 is the central part of the fuselage, built by Lockheed Martin Tactical Aircraft Systems in Fort Worth. (In 1994, Lockheed increased its share in the F-22 program thanks to the aquisition of the unit of tactical planes of General Dynamics.) This section includes/understands the four compartments of armament, the principal landing gears and of the tunnels of air intake sophisticated, which is curved towards the interior and to the top starting from the air intake to mask the front faces of the engines with respect to the radars. The fuselage nose section is attached to the central part of the plane; it includes/understands the cockpit and the avionics, built by Lockheed Martin in Marietta. Also attached to the central part of the plane are the wings, the fuselage tail section, the compartments engine and the beams of tail, built by Boeing. Lockheed Martin is also responsible for the empennage back and the arenas absorbing the waves radar.
Five large frameworks reinforced out of titanium in the central part of the fuselage absorb the greatest part of the structural loads. Largest measures 4,87 meters between the points of fixing of the wings and 1,82 from top to bottom meters. It is also at the beginning the largest forging out of titanium of the world with its 2 975 kg, 95 % of its mass is removed in the course of construction, the finished part weighing 149 kg then. The F-22A uses more titanium and less composite materials than the YF-22, mainly because the titanium parts are much less expensive.
*** * the majority of the coating are out of carbon fibres in composites in bismaleimide. The bismaleimides replaced epoxy composite materials used for the preceding planes. Indeed, they resist better the high temperatures of the coating due to the supersonic cruising speeds. In spite of that, the maximum speed was brought back of Mach 2,0 to Mach approximately 1,8, this in order to still better avoid having recourse to thermoplastics resisting has heat.
On paper, F-22 is slower than the majority of the current hunters. The maximum speed is determined by the temperature of the airframe and by the use of air intake with fixed geometry, the air intake with variable geometry not being also furtive. But F-22 will be able to reach its maximum speed with all its weapons on board and the greatest part of the fuel for its mission, which no other current hunter can do. Without the afterburning - which cannot be used that a few minutes by mission - its speed is higher 50% than that of all the other current hunters. Its capacity of acceleration and its man?uvrability, in particular at high speed, should they also prove to be excellent.
the F119-PW-100 of Pratt & Whitney is the most powerful engine ever designed. It is one of the reasons for which such a large plane is so fast and so nimble. With its maximum push increased of more than 17 tons, F-22 is more powerful than two F-4. But the maximum push is not the only factor to be taken into account. Because the cycle of F119 is close to the turbojet, its "military" power (power without afterburning) represents a more significant part of its maximum power than for the preceding generations of engines. Moreover, it can resist quite higher temperatures of turbine, it is thus not necessary to retard as much throttle at high speed. With Mach 1,4, without afterburning, F119 is twice more powerful than the F100-PW-200.
In spite of its more important push, F119 has 40% of parts of less than F100. New aerodynamic techniques computer-assisted made it possible to draw paddles of compressor and turbine thicker and charged giving thus more compression with less stages. F119 has of a blower on three floors, a compressor with six stages and turbines low and high pressure on a floor. Its attachments are contrarotating: this makes the engine lighter, shorter and more effective.
Over the entire length of the blower and the compressor, the discs and the paddles is parts of only one holding. The large hollow paddles of the first stage, out of titanium, separately manufactured and are assembled on the disc thanks to a welding with linear friction, a technique by which the paddle is rubbed so strongly against the disc that it adheres to it. The axisymmetric conduits can upwards direct the jet wash to full power of 20° or the has in a split second, they also give to the apparatus the characteristics of furtivity on its back sector.
F-22 is armed with six advanced air-to-air missiles of average carried (AMRAAM) AIM-120C in the ventral compartments. The armament had been the subject of controversies. In the ideal, a hunter having internal missile compartments should have a compact missile with folding control surfaces; but that would mean that F-22 could not take along conventional missiles, and that the folding control surfaces of the missiles of F-22 could not resist the constraints of external carrying on conventional hunters. The AIM-120C is a compromise: its wings and its empennage are shorter than those of the preceding AMRAAM; thus it can be transported in an internal compartment but its performances are almost identical and it will become the standard missile of all the hunters of USAF. The AIM-120 will be propelled out of the compartments by hydropneumatic ejectors.
*** * At the beginning, the side compartments will transport each one a missile AIM-9 Sidewinder. However, the future AIM-9X will have small empennage instead of the large wings of the current AIM-9; it is thus extremely probable that F-22 will be able to take along two on each side of them. The AIM-9 will be launched starting from a slope in trapezoid which will be spread before the missile is not fired, so that the infra-red homing head of the missile is locked on the target before the shooting. A gun M61A2 of Lockheed Martin, version lighter of old M61 with longer composite material tubes, is assembled above the root of the right wing. A door opening towards the interior covers the opening in order to preserve qualities of furtivity of the hunter.
In 1994, USAF required of Lockheed to develop an air-to-ground capacity for F-22. The lower weapon compartments were modified to accomodate a bomb GBU-30 Direct Joint Affan Munition (JDAM) of 500 each side kg. The GBU-30 is guided by a simple GPS/inertiel system, but the later versions will have a homing head programmable radar for the attacks of precision. A radar mode with synthetic opening (SAR) is currently added to the radar of F-22 for the air-to-ground missions.
For the operations where the furtivity does not play a paramount part, F-22 can transport up to 2 270 kg of external load on each one of its four pylons of aerofoil. The latter can also receive each one a fuel tank of 2270 liters.
F-22 innovates in as well fields as the sensors and the conventional display systems are unsuited. The aerial combats will be held more quickly for the pilot of F-22, because of his higher speed. The apparatus counts on its furtivity to protect itself from hostile air defenses, but this furtivity is likely to be compromised by the emissions of its own systems. The furtivity gives to the pilot new factors to be considered; F-22 is more or less furtive according to the radars and the waves radar are not considered same manner according to the orientation of the radar.
the furtivity gives the initiative to F-22 in the combat in BVR (Beyond Visual flange - out of reach visual) what makes it possible to the pilot to attack or to avoid an apparatus before being detected to him-méme. Moreover, thanks to supersonic cruising, the pilot can reduce the time of approach to the beginning of a combat and escape and release at the end of a combat.
the sensors and visualizations of F-22 also innovate in order to answer this challenge. The fusion of the sensors coordinates the data coming from all the sensors in order to visualize a target with the screen. Thus the pilot does not need to compare various visualizations to have a good representation of the battle. Thanks to the management of the sensors, the pilot does not have â to control leradar, except exceptional case. Indeed, this control is carried out automatically according to the tactical situation. The function of management of the sensors carries out also the control of emissions (EMCON), it automatically maintains the electron emissions on low the possible level.
the technology of the liquid crystal display with active matrix (AMLCD) allowed to install in the cockpit of a hunter of large readable color screens in full sun. The central shield is a tactical screen of 20 cm broad situation; under this screen, on the left and on the right three 15 cm broad are screens.
*** * This visualization is a revolutionist. On the current hunters, the radar, the electronic system of combat and the identification and navigation, communication systems are separated and each one has its own calculators. On the other hand, the sensors of F-22 are not independent systems but, just as the screens of posting, in fact peripherals supply the common calculator integrated of GM-Hughes, Common Integrated Processor or CIP, including/understanding two banks of modules of calculation 32-bits to liquid cooling placed in the fuselage nose section. This system as a whole functions thanks to 1,6 million lines of Ada code in the CIP. The principal sources of information of the pilot are the tactical screen of situation and the screens being each side: the screen of left for defense and that of right-hand side for the attack. The latter take again a subset of the data of the tactical screen of situation and add details. All the screens use the same symbols and the same prospect: a sight of top, F-22 being represented in the center of the screen in the shape of an arrow directed upwards. The symbols use a system of double coding: as much as possible, they differ the ones from the others by their form and their color; they are thus easily locatable and the screens will be usable even when the pilot must carry safety goggles laser.
the functions of management of the sensors and control of the emissions automatically control the sensors and the communication systems in order to detect and to follow the targets and to coordinate the attacks without betraying the presence of the hunter. The most important sensors are radar APG-77 of Westinghouse/Texas Instruments and the systems monitoring electronic passivates built-in with the electronic system of combat of Lockheed/Sanders. The APG-77 has an antenna with electronic sweeping (electronically steered antenna or AESA), which includes/understands more than 1 000 modules of transmission and reception of the size of a finger, embedded in a fixed antenna. The whole of these modules was a crucial problem in the design of the radar. A pair of modules of transmission and reception of the radar under development weighs only 15 G and provides more than 4 W of power. The goal is cause a drop in the court so that all the defective modules can be thrown and replaced easily.
One expects has what the APG-77 is very nimble, able to change the direction, the power and the form of the beam radar very quickly in order to obtain data on the target while minimizing the risks of interception or continuation of this beam. It should also be reliable: many breakdowns of radar are nowadays caused by problems of transmitter to feed in energy, but these breakdowns are mainly eliminated by the modular concept from the antenna from the APG-77 and its food.
the system of electronic countermeasures is much more sensitive and precis that that of all the current hunters. Thanks to large aerials suppressed in wing tips and the external leading edges, it can determine the direction of the target and, to a certain extent, its distance.
the hunter includes/understands also a system of data transmission sophisticated which can receive information on a target starting from planes AWACS behind of the zone of combat. It also has a system of data transmission with short range, not easily detectable, which can transfer from information on the system and the targets between of F-22 so that all the pilots of the same patrol can see same visualizations.
the functions of management of the sensors and control of the emissions divide the airspace around F-22 into concentric zones. In the external zone, the targets are not sufficiently close to represent a threat and the system will not break silence radar to identify them. As they approach and enter the "zone of appreciation of the situation", the system is programmed to identify them and follow them.
*** * the following zone is defined as being that where the pilot has the choice between engaging or avoiding the combat. The lower limit is defined by the range of the missiles of the enemy. In these two cases, the system uses the radar minimum time necessary to the follow-up of the target. As the target approaches, the radar will more often light it.
When the targets are detected - by the AWACS, the radar of F-22 or by measurements of electronic monitoring - the software of F-22 assigns a file of follow-up to them. When the other sensors also detect them, information is placed in the same file of follow-up and the best given is extracted from the file and is posted. For example, visualization will post information of distance and speed obtained by the APG-77 and the information of direction obtained by measurements of electronic monitoring.
the integrated common calculator will identify the hostile planes and will calculate the field of detection of the hostile radar and its missiles compared to F-22 with its current raising. The NCV will act in the same way for any radar of system of ground-to-air missile.
the computers help also the pilot to draw up a "list of targets to be drawn": the targets are placed by set of priorities and are followed for the attack. The screen of attack posts the maximum range of the missiles of F-22 - by holding account the speed and the altitude of launching - and the effective range of the missiles of the target. The function lists targets selects and arms automatically the missiles.
the pilot of F-22 can see when the target will be with range and when it must release. It can thus use this information to decide if it must draw as soon as possible - and to release more quickly - or if it wants to approach the target and give him less chances to escape. Simulations showed that F-22 often manages to fire its missiles AMRAAM in their field from sure effectiveness (not leaving any chance with the target) before even as the latter did not detect its attacker.
a helmet with integrated posting (CAI) was not planned for F-22, but a CAI is to be developed thanks to a distinct program and it should be available to the moment when F-22 will enter in service.
In spite of its remarkable capacities, F-22 should not be an apparatus eccentric, difficult to maintain. Upon the departure, the principal goal of the program was to produce an apparatus requiring less personnel of maintenance and less logistic support than the F-15. Each part of F-22 was designed by an integrated production line team which includes/understands engineers and specialists in the production and maintenance. The avionics is conceived by modules which can be removed and replaced without tools. The external maintenance of F119 can be carried out with a set of screw spanners, ratchet spanners and socket spanners. With less parts détachéeset more equipment car-tested, a unit made up of 24 F-22 needs only eight C-141B charged with equipment for deployment a 30 days, compared to 18 for the same number of F-15.
It is easy to be blasé, here a long time that the advanced tactical hunter is under development and few people realize that when it enters in service, he will represent the largest technical projection ever carried out in the field of the fighter force. F-22 will profit from the greatest increase cruising speed since the use of the engine. It takes the maneuverability of F-16 and extends it to the supersonic field. It uses with full all the possibilities with furtivity during the aerial combat and associates it a ultra-sophisticated avionics which gives to the pilot means of appreciation of the situation without precedent. If it is shown with the height of its potential, this apparatus will be the uncontested Master of the airs during the first décénies of the 21st century.