The Progress of the F-22 Fighter Program

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WEAPONS AND EQUIPMENT, Japan

Date Posted: 01-Mar-1997

International Defense Review

THE PROGRESS OF THE F22 FIGHTERPROGRAM

TEXT: Late in May, Lockheed Martin test pilot Paul Metz is due to take the F22A fighter up on itsmaiden flight from Dobbins Air Force Base, Georgia, next to Lockheed Martin's Marietta plant. Itwill be a longawaited milestone in what has become the US Air Force's (USAF's) most importantprogram of the 1990s, and possibly one of the most significant programs in its history. ThePentagon is currently preparing the Quadrennial Defense Review (QDR), the secondterm followon to the 1993 bottomup review of US military plans. The 1993 review cut the planned number ofF22s from 648 to 442: there is a risk that the QDR will further reduce this. Congress fears a`tactical aircraft trainwreck': a situation in which increasing expenditures on the F22, the USNavy's (USN's) F/A18E/F and the Joint Strike Fighter (JSF) reach a point where it is impossible toretain all three programs. The F22 is the most prominent of these programs and the mosttempting target for budgettrimmers. Annual cuts imposed by Congress and the Pentagon havealready delayed the program and increased its costs. Further cuts will be more expensive in thelong run, while building fewer aircraft at a lower rate will increase its unit costs. The USAF'sdefense of the F22 is farreaching and fundamental. In the latest revision of its postSovietdoctrine, air and space superiority is listed as the primary USAF `core competency'. Air and spacesuperiority is intended to provide US forces with freedom of action, while preventing hostileaircraft and missiles from interfering with US operations and denying them sanctuaries where theycan operate. "Too many people fail to understand how the country depends on air dominance,"Air Combat Command chief Gen Richard Hawley remarked at an Air Force Association symposiumin Orlando in January. "How long will information from Rivet Joint and Joint STARS be available ifthose aircraft are threatened by longrange AAMs [airtoair missiles] launched from sanctuariesprotected by surfacetoair missiles [SAMs]? Will we be able to sustain precision attack operationsagainst adversary fighters? Will ground forces be able to maneuver as they did in Operation`Desert Storm' if the enemy's reconnaissance aircraft can see them?" The USAF's case is that airsupremacy is an unstated prerequisite for US military operations. Consider that the US Armyspends relatively little on its own air defense, mainly using SAMs to defend fixed targets or to dealwith `leaker' aircraft. The USN's air defenses are designed for bluewater operations. Joint forcesrely on force multipliers such as the Airborne Warning and Control System (AWACS) and JointSTARS, carried on vulnerable transports. To put it bluntly: what did more for the ground forces in

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the 199091 Gulf War the USAF's control of the air, or USN deepattack missions? F15s haveshot down 96 adversaries with zero losses in air combat. However, the USAF argues that a morelethal and survivable replacement is needed to counter the proliferation of advanced fighters andSAM systems. Two factors support the need for a fighter which outclasses the threat, rather thanmatching it (as an improved F15 could). First, US and allied forces intheater are likely to beoutnumbered in the early stages of a conflict, as they arrive and establish their bases. Second, theUS public and political leaders expect quick success and minimal losses. A balanced assessment ofthe F22's capabilities and the status of the program suggests that it should win the approval ofthe QDR and Congress. However, as Hawley said: "If the facts are allowed to speak, the outcomewill not be in doubt. At this juncture, I'm not sure that will happen." While Hawley remarked thatmany people do not understand the F22's mission, however, he could also have added that fewpeople understand its capabilities either. The F22 represents the greatest one generationadvance in fighteraircraft capability in 50 years. It brings about the greatest increase in sustainedspeed since the advent of the jet, flying most of its missions at speeds that other fighters attainonly in short sprints, and accelerating and maneuvering at speeds where today's fighters areworking hard to fly in a straight line. It will equal and probably surpass the agility of any otherfighter, including the Su35. It embodies allaspect, widebandwidth radiofrequency (RF) andinfrared (IR) stealth. Its integrated avionics and sensorfused displays are a generation in advanceof anything known to be under test elsewhere. The F22's basic shape was devised in three hecticmonths in 1987, after Lockheed decided that the design with which it had won a place in theUSAF's demonstration/validation (dem/val) program was both technically and competitivelyunacceptable. The fundamental challenge was to reconcile the demands of stealth, supersoniccruise and agility. Stealth influences the shape and angle of all external surfaces, and requires thatall weapons and fuel be carried internally, demanding an airframe of much greater volume than anequivalent nonstealthy design. Supersonic cruise requires low supersonic drag, which usuallyimplies slenderness and thin wing and tail sections, which are not inherently compatible with largevolume. Agility is achieved through a large wing span and area and effective controls: this is hardto reconcile either with the need for a small, thin wing for supercruise, or with the fact that thebest tail for a stealth aircraft is no tail at all. The initial goal was a fighter with a 22.5tonne cleantakeoff weight, but that proved impossible, and the F22 tips the scales at 27 tonnes. In generallayout, the F22 is a moderately swept (42) delta of a kind that has not been seen since theJavelin and Skyray of the 1950s: little of the F22's mass lies behind the line of the trailing edge.The wing and body are highly blended onethird of the total wingspan lies between the wingattachment points making room for the weapons bays and much of the fuel. The delta wingcombines ample volume and a low thickness/chord ratio for supersonic drag with enough area tomeet maneuverability requirements, and still fits in standard NATO aircraft shelters. It isstructurally efficient and stiff. At high g loadings, the ailerons deflect upwards to offload thethinner outer sections. The wing is more sophisticated than it looks; large leadingedge flaps andcomplex camber make it more efficient at low speed and high alpha (angle of attack) than earlierdeltas. The F22 was designed to reach extreme angles of attack while remaining under full

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control: the objective was `carefree abandon' handling, allowing the pilot to exploit a very largealpha/airspeed envelope without overstressing the aircraft or causing it to depart from controlledflight. Another goal was to avoid stability and control deficiencies that would require limits on theangle of attack. The F22 is designed to be immune from deep stalls and to recover from highalpha, poststall conditions with both engines flamed out. According to test pilot Metz, the first F22A will fly with a set of flight control system (FCS) laws that address the full flight envelope andall configurations. Although testing will be incremental (as always), the prototype YF22 and windtunnel experience suggests that no major changes will be necessary. Thrust vectoring is not usedto expand the envelope. At low airspeeds, vectored thrust gets the F22 from one maneuver stateto another more quickly, but the aircraft is controllable in any part of the envelope without it andcan always recover with a failed engine. The same benefits could have been achieved withconventional controls, but it would have meant increasing the size of the tails by 30 per cent andadding 180kg to the empty weight. Given that the twodimensional (2D) nozzles were needed tomeet stealth requirements, thrust vectoring added only 1322kg to the aircraft. The nozzles vectoronly in pitch, but they make the F22 more nimble in roll because, with the vectoring systemoperational, the horizontal tails can be exploited more fully for roll control. The fourtailconfiguration was selected because it provides adequate stability and linear control response inpitch, roll and yaw over a wide speed and alpha range. The verticals are located well forward, sothat even at high alpha they are not blanketed by vortices from the body, and stability and ruddereffectiveness are retained. The horizontal tails are carried on booms projecting aft of the nozzles,and their root leadingedges fit into cutouts in the flaperons. The FCS runs the horizontal tails,the rudders, the vectoring nozzles, the wing surfaces (flaperons, ailerons and leadingedge flaps)and even the nosewheel steering. There are no speedbrakes: for inflight deceleration, theflaperons go down, the ailerons deflect up and the rudders move outwards. On the ground, theentire trailing edge deflects up to spoil the wing lift. Almost 17,000h of wind tunnel testing wereperformed during the engineering and manufacturing development program, involving 23 modelsin 15 facilities. The basic program was completed in mid1995, but a further 900h of work on GBU32 and AIM9X weapons (see below) release will be completed this year. No significant changeshave been made as a result of tunnel tests. The F22's stealth design clearly evolved from that ofthe F117, with a preponderance of flat, canted surfaces and a sharp chine line from the nose tothe wingtips. Better modeling and testing techniques have allowed the designers to incorporatesome curvature in the surfaces. In the nowfamiliar manner, surfaces and edges are aligned withone another; large openings such as the landing gear and weapon bay doors have serrated edges,aligned with the wing and tail edges; and small apertures are diamond or rhombusshaped. Gapsbetween control surfaces are delicately sculpted to avoid 90 angles as they move. The object isto concentrate radar reflections in a small number of lobes, using preflight and onboard missionplanning software to minimize the time during which any lobe `dwells' on a known or detected RFthreat. A basic difference between the F117 and the F22 is that radar absorbent material (RAM)is not applied to the entire aircraft, but selectively to edges, cavities and surface discontinuities.

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Lockheed Martin builds all the edges of the aircraft, which probably consist of wideband radarabsorbent structures. Heatresistant ceramicmatrix RAM is likely to be used on the exhaustnozzles. The radome is a `bandpass' type which reflects signals at all frequencies except theprecise wavelengths used by the F22 radar. Radar crosssection (RCS) problems were discoveredduring early fullscale model tests. There was no single reason for the failure to meet thespecification: rather, the problem was traced to the difficulty of maintaining tolerances in a largenumber of apertures and serrations. The result was a detailed redesign of the surface of theaircraft. Access panels and drain holes were eliminated or combined, and some serrated edgeswere modified with fewer, larger teeth. Recent tests of a modified RCS pole model have indicatedthat the problem is solved. The F22 structure includes less composite material than the designersplanned, but the weight goal 25 per cent lighter than an allaluminum airframe was achievedthrough the selective use of highstrength, highstiffness composites and the largescale use oftitanium, which makes up 41 per cent of the airframe weight. Composites account for only 25 percent, mostly in the wings and tails where their stiffness is valuable. The heart of the structure isthe midbody section, built by Lockheed Martin Tactical Aircraft Systems in Fort Worth. Itincorporates the four weapon bays, the main landing gears and the complex inlet ducts (seepicture on left). The midbody accomodates much of the fuel. Apart from the discrete bays for themissiles, landing gear, gun and environment control system, the midbody is plumbed and sealedas set of integral fuel tanks. An onboard inert gas generating system produces nitrogen, which ispumped into the tanks to reduce the risk of explosion from battle damage. The midbody alsoaccommodates much of the fuel. Apart from discrete bays for the missiles, landing gear, gun andenvironmental control system, the midbody is plumbed and sealed as a set of integral fuel tanks.Nitrogen produced by an onboard inert gas generating system is pumped into the tanks to reducethe risk of explosion from battle damage. Attached to the midbody are the forebody,accommodating the cockpit and avionics, which is built by Lockheed Martin in Marietta; and thewings, aft fuselage, engine bay and the tailbooms, built by Boeing. Five massive titaniumbulkheads in the midbody absorb most of the structural loads. The largest measures just under4m between the wing attachment points and 1.8m from top to bottom, and is produced as theworld's largest titanium forging by WymanGordon, weighing 2,975kg. Some 95 per cent of itsmass is removed during machining, leaving a 149kg finished part. The widest of the forgingsmeasures 4.62m from tip to tip. The midbody and rear fuselage include some unusual structuralfeatures. The inlet lip and the fittings that support the wing and rudder are hot isostatic process(HIP) castings, made from titanium alloy powder formed under very high pressure. HIP wasoriginally developed for disks in engines, but is used to form highly loaded, rigid, complexshapedcomponents with a minimum parts count. The tailbooms are electronbeam welded titanium: theaft fuselage is 67 per cent titanium because of high temperatures. Carbonfiber/bismaleimide (BMI)composite is the primary material in the wings. BMI replaced the thermoplasticmatrix compositeused in the YF22 because it was stronger and less expensive. Thermoplastics had previously beentougher and more damagetolerant than BMI, but improved BMI resins became available during

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dem/val. Thermoplastics tolerate higher temperatures than BMI, so the change to BMI in the EMDaircraft meant a reduction in maximum Mach number, from 2.0 to 1.8. The wings incorporate sinewave spars in which the web is an undulating curve produced by a resintransfer moulding(RTM) process developed by Boeing and Dow/United Technologies. In the RTM process, drycarbonfiber fabric is laid up in a mould and BMI resin is injected at high pressure. RTM providesbetter yields and lower costs for relatively small, complex parts. One in four of the spars is stillmade from titanium, a change made after livefire damagetolerance tests. Alliant TechSystemsprovides two of the largest carbonfiber/epoxy components on the aircraft: the 2.8m horizontal tailpivot shafts. The tapewound shaft is up to 490 plies thick and blends from a long cylinder (on theaircraft side) to a flattened, sweptback spar buried in the tail. A few thermoplasticmatrixcomposites are still used the largest components are the landing gear and weaponbay doors,where damage tolerance is important. Weight has been an issue, but Lockheed Martin disputesthat it has been out of control and says the projected empty mass is now lower than it was in1994. There is no weight specification for the F22: the requirement is written in terms ofperformance. As a result, some weight growth has been accepted at the expense of small changesin performance. The totally frameless Sierracin canopy is unique. Most canopy specificationsrequire nearperfect optics only in the forward field of view, but the F22 will have a helmetmounted sight and therefore needs `zone 1 quality' throughout. The F22 canopy is made fromtwo 9.5mm sheets of polycarbonate, sandwiched between two sheets of optical glass, fusionbonded in an autoclave, and drapeformed over a canopy blank at 400C. Birdstrike protectionremains an issue. The F22 canopy is not as inherently tough as the multilayer F16 canopy.Although the F22 canopy can withstand a 450kt birdstrike, the impact initiates a wave throughthe canopy which, at its lowest point, strikes the headup display (HUD) combiner, sendingfragments into the pilot's face. HUD supplier GEC Avionics is working with Lockheed Martin ondesigns for a collapsible combiner. The size and cycle of the F22's Pratt & Whitney F119PW100engines was driven by the supercruise requirement. Although the F119 is similar in size to theF100, with a roughly similar airflow (about 125kg/s), it has a very different cycle. The F119'sbypass ratio is 0.2:1 or less, versus 0.7:1 for the F100, so its core handles at least 50 per centmore air. Although the thrust of the F119 is officially quoted as `in the 155kN class', informationobtained by IDR suggests that the actual thrust may be more than 170kN with full augmentor,implying an intermediate (non augmented) rating of 113kN. This is compatible with statementsthat at supersonic speed, on dry thrust, the F119 generates twice as much power as the F100PW200. The F119 has not been shown in public, but General Electric has exhibited the rival F120 inpartly disassembled form, mounted alongside an F110 the difference in the size of the coreblading was considerable. These are huge engines, capable of delivering 180kN withoutafterburning when fitted with a larger fan for the Boeing JSF design. The F119 has completed aformal qualification program at the USAF's Arnold Engine Development Center (AEDC) inTennessee, and initial flight release has been obtained. By late January, the first two flighttestengines had been delivered to Marietta, and preparations were being made for engine runs.Results have been good, says program manager Walt Bylciw, and the engine's early

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developmental troubles (which necessitated an extensive redesign of the turbine and some otherfinetuning) are behind it. The F119 has a threestage fan, a sixstage compressor and singlestage low and highpressure turbines. Each has fewer blades than an F100 stage, so in all theF119 has 40 per cent fewer aerofoils. The counterrotating shafts eliminate a stator between theturbine stages, saving weight, reducing the engine's length and cutting the requirement forcooling air. Integrally bladed disks are used throughout the fan and compressor; the hollow firststage blades are made separately and joined to the disk by linear friction welding, a technique inwhich the blade is rubbed so hard against the disk that it bonds to it. Early in the design process,Pratt & Whitney engineers joined operational USAF F15 maintainers on the flightline. As a result,the designers selected a small set of wrenches, ratchets and sockets and built the engine so thatall exterior maintenance could be carried out with those tools, and restricted themselves to a fewtypes of clips and fasteners. Virtually all the engine's plumbing is accessible without removing theengine itself, and all lines are colorcoded. The F22 inlets are fixedgeometry, one of many waysin which the USAF's decision to forgo a highMach capability (seldom used on the F15) savedtime, weight and money. Boundarylayer turbulence is controlled by drawing air through pores inthe duct wall, and the air is dumped overboard through exhaust grills and a bleed door. Each inletduct has a larger bypass door just ahead of the compressor face, which can open during rapiddeceleration. The philosophy of the design is that no doors are open except during maneuvers orengine transients. The vectoring nozzles can divert the full augmented thrust 20 upwards ordownwards in a second. Twodimensional nozzles are necessary for stealth in both the RF and IRbands: the edges of a 2D nozzle can be aligned with the other edges of the aircraft, and its shapetends to flatten the exhaust plume and promote mixing with the ambient air. In a twinengineaircraft, too, a 2D nozzle helps to provide a smooth, lowdrag aftbody shape. The nozzles arelargely made of burnresistant Alloy C titanium and incorporate a sophisticated internal coolingsystem. The F22's main armament comprises six AIM120C Advanced MediumRange AirtoAirMissiles (AMRAAMs). Three missiles are carried in each of the ventral bays, which are covered bybifold doors. The AIM120C was designed for internal carriage on the F22, with clipped wing andtail surfaces. Its performance is virtually identical to earlier AMRAAMs and it will be the standardversion for all USAF fighters. The AIM120s will be propelled from the weapon bays bypneumatic/hydraulic AMRAAM Vertical Ejector Launcher units. The side bays will each hold oneGMHughes AIM9X Sidewinder, carried on the AIM9 Trapeze Launcher (ATL), a mechanicallyextending rail incorporating an exhaust plume deflector. The ATL will be extended automaticallyas the F22 nears the point of achieving launch parameters on the target, allowing the IR seekerto lock on before launch. A General Dynamics M61A2 20mm cannon, a lighter version of the M61with longer, compositewrapped barrels and a redesigned breech, is mounted above the rightwing root. The muzzle opens on to a shallow trench in the fuselage, covered by a sidehingeddoor. The F22 carries 480 rounds of ammunition in a linear feed system aft of the weapon bays.In 1994, the USAF asked Lockheed to develop an airtosurface capability for the F22, and thelower weapon bays have been modified to accommodate the 450kg McDonnell Douglas GBU32

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Joint Direct Attack Munition (JDAM). The F22 can carry two each of JDAMs, AMRAAMs and AIM9s. JDAM is guided by a GPS/inertial system, with a specified circular error probable (CEP) of 13m.Development of a programmable seeker to provide a 3m CEP, equivalent to a laserguided bomb,is due to start in 2002. A synthetic aperture radar (SAR) mode is being added to the F22's radarfor airtosurface operations. Other weapons have been studied for the F22, but not funded. Theaircraft could carry a pair of Wind Corrected Munitions Dispenser (WCMD) weapons for useagainst area targets. A compact version of the HARM missile is under study for the F22. New andmuch smaller weapons are developed for production early next century and are particularlyattractive for the F22. Examples include an operational derivative of the Miniaturized MunitionsTechnology small hardtarget weapon, eight of which would fit inside the F22, and the LowCostAutonomous Attack System, a miniature cruise missile capable of detecting, identifying anddestroying military vehicles. When stealth is not critical, the F22 can carry up to 2,270kg ofexternal stores on each of four underwing pylons. For ferry flights, each of these canaccommodate a 600gallon (2,270liter) fuel tank and a pair of AMRAAMs, reducing the need fortanker and cargo support. However, none of the F22's attributes could be exploited properlywithout the fighter's least visible element: its avionics system. It is revolutionary, in part becauseit has to be. The F22 brings new complexities to the fighter mission. The air battle will unfoldmuch more quickly in front of the pilot, because of the fighter's greater speed. The F22 relies onits stealth for protection against hostile air defenses, but stealth can be compromised by emissionsfrom its own systems. Stealth gives the pilot a new set of variables to consider; the F22 is morestealthy against some radars than others, and its RCS changes according to the radar's bearing.Stealth imposes limitations on sensor design and operation. "I have to minimize power, and buryall my apertures," said avionics team leader Marty Broadwell. "If I don't do it this way [that is, theintegrated and fused approach used on the F22], I can't see anything." Metz looks at the problemfrom a slightly different angle: "If you look at history, very few fighter pilots are effective," hesaid. In the Second World War, only 21 per cent of fighter pilots made kills and about one in six ofthese (3.6 per cent of the total) became aces. During the 195053 Korean War, the 4.8 per cent ofpilots who became aces made 38 per cent of the total kills. "What if we can increase the ratio ofpilots who make kills from one in five to one in two, or three?" said Metz. The implications interms of force effectiveness are clear. Metz outlined three principles in the F22 design which areintended to accomplish that goal. One of these is to eliminate `housekeeping' tasks throughautomation and selftest. Launching the F22 is a matter of inserting a Data Transfer Modulecartridge which sets up the displays according to the pilot's preferences switching the batteryon, holding the auxiliary power switch in the on/start position and setting the throttles to idle. Theengines start automatically and the avionics run through their diagnostic routines, and within aclassified but extremely short time the fighter is ready to go. The second principle is the `carefreeabandon' flying qualities which relieve the pilot from worrying about the flight envelope or possibledeparture. The third principle, and the driving force behind much of the avionics design, is to`maximize information and minimize data'. The F22's sensors and displays meet this challenge in

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three basic, interrelated ways: sensor fusion. Combining data from all different sensors to displayone target on the screen and relieving the pilot of the need to monitor and compare differentdisplays; sensor management. In normal operation, the pilot does not control the sensors. This isdone automatically according to the tactical situation; and emission control (EMCON). One of thetasks of the sensor management system is to keep electronic emissions at the lowest possiblelevel. The F22 cockpit is dominated by four large activematrix liquid crystal display screens.There are no dedicated backup instruments: these are hosted on smaller monochrome LCDpanels. The GEC holographic HUD is designed so that the bulk of the optical system is locatedbehind the panel, allowing the central 203mm{2} Tactical Situation Display (TSD) to be movedupward and making room for three 152x152mm screens left, right and below. The architecturebehind the displays is revolutionary. In the traditional sense, the F22 has no radar, electronicwarfare (EW) system, or communications, navigation and identification (CNI) systems. Instead,like the displays, they are peripherals serving the fighter's GMHughes Common IntegratedProcessor (CIP), which consists of two banks of 32bit liquidcooled computer modules housed inthe forward fuselage. The entire system runs on 1.7 million lines of code hosted by the CIP.Fiberoptic highspeed databuses link the sensors to the CIPs and the CIPs to the displays. Apractice sortie in Lockheed's concept demonstrator a mediumfidelity, securityapprovedsimulator shows how the system works from the pilot's viewpoint. The pilot's main sources ofinformation in the beyondvisualrange fight are the TSD and the screens on either side: the leftfor defense, and the right for attack. These both take a subset of the data on the TSD and addmore detail to it. All the screens use the same symbology and the same perspective: `God's eyeview', with the F22's track pointing up the center of the screen. The symbols are `dualcoded' as far as possible, they differ both in shape and color. This makes them easy to distinguish andensures that the displays will be workable if the pilot has to wear laserprotective goggles. Other F22s in the formation are represented by blue circles, and other friendlies by green circles. Eachsymbol has a vector line which shows its direction and approximate speed. As the practice missionproceeds, four yellow squares appear at the top of the TSD. This symbol indicates thatidentification is incomplete. The targets were probably detected by an AWACS and transmitted tothe F22 by the Joint Tactical Information Distribution System. All the pilots in the formation willsee the same displays. As well as a datalink that can import information from AWACS, the F22 isfitted with an IntraFlight Data Link (IFDL) which can transfer system and target informationamong F22s. The IFDL operates at low power and in an RF band which attenuates rapidly in theatmosphere, so it is difficult for an adversary to detect or track. The F22's NorthropGrumman/Texas Instruments APG77 radar could identify the targets, but it will not do so to beginwith. The F22's sensor management and EMCON functions divide the airspace around the fighterinto concentric zones. In the outer zone, targets are not close enough to be a threat, and thesystem will not break radar silence to identify them. As they get closer and enter the `situationalawareness' zone, the system is programmed to identify and track them. The next zone is defined

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as that within which the F22 pilot has the option to engage or avoid the threat. The inmost zoneis bounded by the range of the threat's missiles. In each case, the system uses the radar only asmuch as is necessary to maintain a track. As the target gets closer, the radar will revisit it moreoften. In the simulated engagement, one of the targets gives the game away by using radar. TheF22's LockheedSanders ALR94 EW sensor suite "does not compare with anything out theretoday it's vastly superior," remarks a Lockheed engineer. It can determine the target's bearingand, to some extent, its range. CIP software compares the incoming radar signal with other targetdata. Its source correlates with the unidentified targets being tracked by AWACS, so it is placed inthe same `track file'. The software selects the highestquality data from each sensor to build thedisplay. The target symbols change to red triangles hostiles. The CIP computes the detectionenvelope of the hostile's radar against the F22 at its current bearing. It appears on the defensescreen as a blue cone emanating from the target. The CIP will do the same for any SAM radars,placing a circle around them on the defensive display. If the F22 turns to present its morereflective side or rear to the radar, the envelope will expand visibly. The pilot can choose whetherto risk detection or change course. As the targets enter the engageoravoid zone, the F22 pilotsteers a cursor over them and presses a bar on the throttle. This activates a `shoot list': thetargets are placed in order of priority and tracked for engagement. The targets may be dividedamong the formation using the IFDL, and only one radar at a time need be used for tracking.Targets on the shoot list are represented by numbered circles. The pilot can override the shootlist. It is one of a number of techniques pioneered by the USAF Pilot's Associate. One of the goalsof Pilot's Associate was `adaptive aiding' in which automation would be there to help the pilot inhighworkload situations, but would not take over against the pilot's wishes. The objective is tohelp the pilot make good decisions quickly, rather than automating the decision process. Similarly,the defensive screen will show countermeasure and maneuver options against an imminent threat.The target formation appears in a larger scale on the righthand attack display. On the left of thescreen is an altitude display. On the right, the targets appear on a range scale, compressed to onedimension, which shows the maximum range of the F22's missiles and the lethal envelope of thetarget's missiles. The F22 pilot can use that information to decide whether to fire as soon aspossible and break away earlier or whether to allow the range to close and give the target lesschance to escape. The shootlist function selects and arms missiles. A `SHOOT' cue appears onthe attack display and HUD when the target is within range. Once the missile is in the air, thesystem steps to the next target. The withinvisualrange (WVR) fight has not been ignored. TheHUD regarded as a primary flight display, for the first time on a US fighter uses a combinationof UStype symbology, emulating verticaltape displays, and counterpointer symbols. The F22 willenter service with the Joint HelmetMounted Cueing System (JHMCS) and AIM9X missile for offboresight engagements. (Elbit/Kaiser and Honeywell/GEC teams are competing to produceJHMCS.) The displays and datalink will be important in WVR. Simulations have shown that thedatalink reduces ambiguous voice calls. It also means that a target that is within the radarenvelope of one aircraft in the formation is visible on the displays of all of them. Anothertechnology which may well be added to the F22 is threedimensional (3D) sound. The F22 has a

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Bose audio system to provide active noise reduction, and research is showing that 3D audioprovides a very accurate and reliable bearing and elevation cue. The F22 display system has beenextensively simulated since the late 1980s, including many realtime sorties using multipleinterlinked dome displays. The results, says Lockheed Martin, show that the F22 system isintuitive and easily learned, and raises the performance level of an inexperienced pilot. Lockheedengineers say that it would not be easy to emulate the F22 avionics system on an existingaircraft. The system works, they say, because the barriers between the different sensors havebeen broken down. The most powerful sensor is the APG77. Its activearray antenna consists ofnearly 2,000 fingersized transmit and receive modules (produced by Texas Instruments)embedded in a fixed array. The cost of these modules has been the critical issue in the radar'sdesign since the USAF decided to aim for an activearray radar in the Advanced Tactical Fighterprogram in the early 1980s. They have entered production for several programs and the USAF issatisfied that the APG77 will be affordable. A pair of the EMD modules weighs a mere 15g andputs out over 4W of power. The modular design of the APG77 antenna and power supplyeliminates the cause of many radar failures. The APG77 is also expected to be extremely agile,and capable of changing the direction, power and shape of the radar beam very rapidly to acquiretarget data while minimizing the chance that its signals will be intercepted or tracked. The F22could be described as bristling with CNI and EW antennas if any of them had been visible. The 30plus apertures are all flush with the surface of the aircraft, including largeaperture arrays in thewing leading edges. The EW system includes azimuth and elevation arrays to provide 3D targetdata. Windows for the electrooptical Missile Launch Detection system are located around theforward fuselage, and four dispensers for flare, chaff and active radar decoy cartridges areinstalled in the lower wing surfaces. An IR search and track (IRST) system was part of the originalATF requirement. It was deleted during dem/val, but the Avionics Directorate of the USAF WrightLaboratories has continued its development with Lockheed Martin as the contractor, and space,weight, power and cooling provisions for IRST are still on the aircraft. A lowobservable IRSTwindow for the F22 was tested for stealth and durability last year. IRST is valuable for raidassessment, because of its high angular resolution. It is also useful against tactical ballisticmissiles, and it can double as a thermal imaging system for ground attack. The F22 is the firstUSAF fighter in many years to have a specially developed life support system. It includes the HGU86P helmet, developed by Helmets Integrated Systems of the UK. The antig garment covers moreof the body than earlier gsuits and can exert pressure on more of the body's blood supply. Theoxygen mask and counterpressure vest are designed for positivepressure breathing and arecontrolled by a breathing regulator and antig garment (BRAGG) valve which reacts to the rate ofg onset. Research at the USAF's Brooks Laboratory in San Antonio has shown that positivepressure breathing, the smart valve and improved antig suit increase g tolerance, reduce the riskof ginduced loss of consciousness and allow the pilot to sustain g with less physical strain and

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fatigue (an important factor in sustaining high sortie rates). Positivepressure breathing alsoprovides altitude protection. USAF fighters are normally limited to 50,000ft because, if power andcockpit pressure are lost, the pilot will lose consciousness before the aircraft descends into thickerair. The F22 lifesupport ensemble has been chambertested to 66,000ft and its emergencyoxygen system will function long enough to reach lower altitudes. The lifesupport system includesan aircooling garment underneath the gsuit and counter pressure vest, and optional suits thatprotect the pilot from chemical and biological agents and cold water immersion. Up and halfwayThe F22's first flight marks only the midpoint between the start of EMD and the fighter's entryinto service. Nine EMD aircraft are being built. The first three (40014003) are dedicated toairframe and engine testing and weapon release clearances. The second of these is due to fly inApril next year and the third the following September. They will have nonstandard displays, nomission avionics and simpler, flighttestdedicated communications equipment. Conducting the firstflight at Marietta was cheaper than disassembling the completed prototype and transporting it toEdwards AFB, which had been considered. A mission control center has been set up at Marietta,and the first flights have been rehearsed extensively using the pilotandhardwareintheloopsimulator in Fort Worth. Lockheed Martin plans a physical rehearsal of the first flight, using an F15 escorted by F16 chase aircraft. After eight flights, the F22 will be ferried to Edwards AFB nonstop, with inflight refueling. In July last year, the USAF deferred development of the F22B twoseater to save money and eliminated two F22Bs from the test program. This was not a `painless'decision, says Metz, but the fighter's carefree handling and straightforward flying qualities shouldmake it easy and safe to fly, while recording devices and the debriefing functions built into theBoeingdeveloped training system allow a pilot's performance to be reviewed on the ground. Thefourth to ninth aircraft (40044009) will fly between April 1999 and May 2000, and are alldedicated to avionics testing. The plan calls for all these aircraft to be kept identical: as newhardware and software is available, all the aircraft will be retrofitted at the same time. Softwareand hardware will be released in blocks. The first three test aircraft will fly with Block 0, whichincludes the inertial reference system, the stores management system and the displays. The firstmajor milestone in avionics testing is Block 1, which includes radar and CNI. Altogether,comments Broadwell, Block 1 includes almost half the lines of code in the final system, and itssuccessful completion will prove a number of principles. "If we survive Block 1, we'll know a lotabout software integration, and we'll know how to debug the system. We won't be wrestlingfunctional and infrastructure issues at the same time." With radar and CNI, too, Block 1 willdemonstrate the first elements of sensor fusion. Block 1 will be available for testing almost a yearbefore F22 4004 is ready, and will fly first aboard the Boeingbuilt Flying Test Bed (FTB), amodified 757 airliner fitted with the APG77, other sensors, CIPs and displays. If the FTB tests gowell, Broadwell hopes that the F22 test aircraft can be updated quickly to the Block 2configuration, which adds radar modes and some EW functions and should be available in mid1999. Block 3, originally planned as the final preinitial operating capability (IOC) release of thesoftware, should be released in April 2000 and includes all EW functions. It will be followed in late

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2000 by Block 3.1, which includes provision for JDAM. Although the task of developing such aradical system is not trivial, Broadwell believes that solid progress is being made. "We surprised alot of people," he said, by keeping the current total of 1.7 million software lines of code (SLOC)relatively close to the 1.3 million SLOC that was predicted in December 1990. "If we can hold thegrowth to 25 per cent we'll amaze the world." Every piece of hardware intended for the systemhas been built and is working in the laboratory, including a complete radar array, which is lookingout over the airport at Northrop Grumman's Baltimore plant and is linked to a CIP. Softwaredevelopment so far has stayed on track, and the Block plan is mostly cumulative: "When you adda block in CNI, you add a function. When you add a block in radar, you add modes. It's done, andit doesn't change." Flight tests should confirm that the F22's `conservative' looks belie itsperformance. Details are classified: however, the immense thrust should provide remarkableacceleration and speed. A chart published in 1991 shows that the F22 is slightly faster onintermediate power than an F15C on full burner, when both aircraft have eight AAMs on board.(The speeds are probably around Mach 1.61.7.) "We expect that this will be one of the thingsthat surprises the air force," said Metz. "If you don't know what you're doing, you'll besupersonic." Unlike most fighters, too, the F22 achieves its highest rate of climb at supersonicspeed. It is almost as fast with afterburner as without. The augmentors will be used mainly foracceleration and supersonic maneuvering. Metz believes that the "afterburner will generally not berequired", and that when it is used it will be in bursts of seconds and tens of seconds, at theoutside. The principal breakthrough in terms of straightline performance is supercruise. The USAFhas stated that "about 30 minutes in a onehour mission" can be flown at supersonic speed, threeto six times the supersonic endurance of any fighter using augmentors. On a typical mission, the F22 can sustain supersonic speed for most of the time that it is over hostile territory. Supersonicendurance varies with speed: a supercruising F22 may vary its speed between Mach 1.1 to Mach1.5plus according to the tactical situation. Supercruise has many tactical advantages. A fasteraircraft retains engagement control: if its pilot chooses to fight, the adversary cannot run, and ifthe F22 pilot disengages, the adversary cannot sustain the pursuit. The F22 can maneuveraround a slower adversary to engage it from the rear, and enters the fight with greater energyand overtaking speed. Supersonic speed goes along with a higher altitude capability: both shrinkthe lethal envelope of SAMs. Firstlook, FirstShot The F22's reduced headon RCS is claimed toguarantee a firstlook, firstshot advantage against any contemporary fighter radar. However,where the F22 differs from any other aircombat fighter is in the importance placed on allroundRCS, which is described as being in the same order as the slower and less agile F117 and B2. Allround stealth is aimed primarily at the SAM threat. Stealth and supercruise are synergistic: theaim is not to be invisible, but to reduce detection range to the point where the system cannotcomplete an engagement against a fastflying target before the range begins to increase. Thephilosophy of `balanced observables' mandated that the F22's IR signature be reduced so that IRand radar sensors would have a similar detection range. The most prominent source of IRradiation from an aircraft is its exhaust plume. On the F22, plume radiation is reduced by minimalafterburner use, the 2D nozzles and bypass mixing. Much of the remaining IR signature

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comprises reflected solar IR radiation and emissions caused by skin friction heat. IRabsorbentpaint reduces solar reflection; it is analogous to normal paint except that it absorbs in the IRband. Friction heat cannot be absorbed by paint, but coatings have been developed that changethe emissivity of a surface: that is, they make it less efficient at emitting IR. To some extent,coatings may also be able to shift the wavelength of the emitted IR energy into wavebands whichattenuate most rapidly in the atmosphere. Heat from electronics and other systems can cause IRemissions. The F22's specialized environmental control system stores peak heating loads in heatsinks and removes it from the aircraft through airtofuel heat exchangers. The F22's visualsignature will be managed by a new camouflage scheme, an overall grey with darker, softedgedareas on the wings, body and tail. The base color is intended to match the luminance of the sky attypical combat altitudes and extreme visual range, while the darker patches send mixed signals tothe eye or to an electrooptical seeker with an edgerecognition algorithm. Metz prefers not to bedrawn into the debate over the value of the lowairspeed, highalpha maneuvers demonstrated bythe Sukhoi Su37 at the Farnborough air show last September, or by the X31. Some pilots believethat the ability to fire a shortrange AAM in almost any direction, by changing the fighter's bodyangle independently of its flightpath, will be critical in future combats. Others disagreevehemently, arguing that poststall maneuvers kill so much airspeed that they are `suicidal' in amanyonmany fight. Whatever the outcome of the debate, the F22 should be able to acquit itselfwell, with a very large flight envelope that is actually usable in combat. (At least some spectacularairshow maneuvers have involved disabling safetyrelated limiters.) Alphas to 60 weredemonstrated in the YF22 program, and some roll maneuverability was retained at that extremepitch angle. The acual inservice alpha limit has not been released. However, the fact that 60was demonstrated in flight tests, and the F22 fuel system simulator is built to emulate 60alphas, suggests that the fighter will indeed be designed to attain 60 in service more than twicethe service limit of any other fighter. At alphas of 15 and above, the F22 rolls at least twice asfast as the F15, and the gap widens until the F15 hits its roll limit of 30 alpha. Maximum pitchrates are up to twice as fast as the F16. The F22's pitch rate is so fast that it is inhibited by asoft stop in the aft movement of the sidestick. Pulling the stick through the stop overrides a limitin pitch acceleration, and it is considered best for the pilot to be aware that the F22 is about torespond very fast and that the BRAGG valve will respond in turn. The F22 pilot who decides thatthe tactical situation warrants highalpha, lowspeed maneuvering may be reassured by thefighter's controllability and thrusttoweight ratio. The F22 should be able to end a maneuverrapidly when required, and will accelerate quickly to a safer combat speed. The fighter will beevaluated against `actual and simulated adversary aircraft' during its flighttest program, Metzstates. "It will be a great airshow airplane, too," he added. The F22 is claimed to have more thantwice the range of the F15C at subsonic speed, with a greater margin when the mission includessupersonic flight. Such numbers have to be treated with caution. In this case, the comparison isprobably based on a full missile load and internal fuel only. The F22's internal fuel load is greater

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than that of an F15C with three 2,300liter tanks, and it has much less drag, so it should have agreater combat radius on a similar mission profile. Despite its remarkable capabilities, the F22should not be a hardtomaintain, exotic aircraft. Every part of the aircraft has been designed byan integrated product team that includes engineers and specialists in production and maintenance,and the goal is an aircraft that requires onethird as many maintenance hours per flight hour asthe F15. Builtin test equipment replaces offboard test equipment, and more items are designedto be replaced on the flightline rather than repaired in an intermediatelevel shop on the base. A24aircraft unit of F22s requires only eight C141Bloads of equipment for a 30day deployment,versus 18 for the same number of F15s. It requires half as many people to support the F22 asare needed for the same number of F15s. So far, developmental problems have been minor, withthe exception of the turbine redesign, and program managers note that preflight testing and tightconfiguration control have unearthed problems before rather than after first flight when therehas been time to solve them at reasonable cost. The main cause of delays has been funding.Since the EMD program started, budget cuts have moved the first flight from August 1995 to May1997, and have IOC from 2001 to 2004. These actions have made the F22 more expensive. Thetotal program cost development, 438 aircraft, spares, ground equipment and construction stands at US$73.5 billion. Much of this total includes 10 years or more of projected inflation, and ithas increased as IOC has slipped. Lockheed Martin's development contract for the airframe wasestimated late last year at US$12 billion. A review last year showed that costs were likely to risemore than predicted, because defense industry costs are expected to rise faster than thegovernmentwide inflation rate on which the Pentagon's budgets are based. The Pentagon hasresponded by slowing initial production and adding a US$1.45 billion reserve to the EMD program.This is expected to fund investments in production and program changes (such as the earlyprocurement of some avionics components) that will reduce costs in the future, and includes theintegration of the AIM9X and JHMCS. The total EMD cost, including Lockheed Martin and Pratt &Whitney contracts, and work done by the USAF, now seems likely to exceed US$17 billionincluding the sums already spent or committed. The projected average flyaway price of the F22 isnow US$71 million in 1996 dollars. (This price includes a fullyequipped aircraft but no spares orweapons.) Some of the added investments being made now, and other proposals made by thecontractors including multiyear procurements are intended to ensure that this numbercontinues to track the budgeted rate of inflation, rather than with defense industry costs.Lockheed Martin managers argue that export sales would reduce the cost of the F22 to thePentagon, and the sooner the better. Department of Defense policy precludes final contracts untilinitial operational test and evaluation is complete, in 200102, but that does not prevent LockheedMartin from briefing export customers. The company planned to do this at the Farnborough airshow, but the Pentagon withheld permission until the cost picture became clearer. USAF DeputyChief of Staff Gen Tom Moorman noted in January that "I have no doubt that the F22 will bereleased for export, and we have some authority to do that now." An executive committee cochaired by the US Under Secretary of Defense for Aquisition and Technology Paul Kaminski and

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Gen Joe Ralston, vicechair of the Joint Chiefs of Staff, is reviewing the security issues raised bythe possible export of a stealthy aircraft. Some of the stealth features of the F22 are `modular' innature and could be selectively removed or downgraded for export. Potential customers include F15 operators such as Israel, Japan and Saudi Arabia. South Korea is considering a highend fighterto complement the F16, and Lockheed Martin is looking at the possibility of selling small `silverbullet' F22 fleets to operators of modern but nonstealthy fighters; even Eurofighter members arenot ruled out. Granted that cost definitions are fraught with a lack of international consistency, theF22's flyaway cost of US$71 million does not appear widely different from the US$50 million toUS$60 million figures recently quoted (by the German government audit office) for theEurofighter, as well as those for Rafale. Eurofighter's claim, repeated at Farnborough, that itsaircraft is "less than half the price" of the F22 appears to rest on a comparison between a flyawaycost and a unit program cost. Lockheed Martin executives appear reasonably confident that the F22 will survive the QDR and this year's budget deliberations. Production may be cut to 300350aircraft, but it would not materially affect the program until 2008 three US elections and at leasttwo presidents hence. Both Lockheed and the USAF caution against deeper cuts, partly becauseexperience with AWACS and similar `force multiplier' assets is showing that the limiting factor maybe the ability to sustain and retain essential people for small, highvalue forces that spend monthson end away from home. This year is pivotal for the F22. If it survives the QDR, it is likely tosurvive through the tenure of the administration, and by 2001 it should be well established: but bymaking the air superiority mission and the need for the F22 its top priorities in the QDR, the USAFis nailing its colors to the mast. If the F22 does not survive, and the F/A18E/F emergesunscathed, the USAF will not see another new aircraft before the JSF arrives in 2010. It will be avictory for the advocates of seabased airpower, and a setback for the concept of an independentair arm. The continuation of the F22 program, however, would be the starting point for a new,more forwardthinking airpower doctrine for the 21st century.

CAPTION: An artist's rendition of a visual range confrontation. The F22 in the picture has pursuedtwo adversary aircraft to low altitude, destroying one (the `fireball' at the top right of the picture),and has launched one of its six AIM120C airtoair medium range missiles at the remaining enemyfighter. The visible camouflage scheme is one indication that the US Air Force has not ignored thecertainty of visualrange combat (the retention of a 20mm cannon and 480 rounds of ammunitionbeing another). Lockheed Martin

CAPTION: The F22 team is using a unique vertical modular tooling process for assembly of themidfuselage, which incorporates the four weapon bays, the main landing gears and the inletducts. Made of carbonfiber/epoxy, the ducts curve sharply upwards and inwards to mask theengine faces from radar, changing section smoothly from rhomboidal to circular, and their innercontours must be smooth and accurate to maintain their stealth characteristics. Lockheed Martin

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CAPTION: F22 versus surfacetoair missile attack. A conventional fighter is detected at point A.The SAM system projects its track and launches towards intercept point B. The missile retainsenough energy to counter target maneuvers. The stealthy F22, by comparison, is flying equallyclose to the SAM system, but is not detected until point C. The missile will take longer to reach itsaltitude because the slant range is greater. Coupled with the F22's greater speed, this means thatthe first possible intercept point is D a lowenergy, longrange tail chase against a target at thelimits of the system's tracking range. A moderate supersonic `jink' at D runs the missile out ofenergy. Source: Lockheed Martin

CAPTION: The F22 canopy is approximately 3.5m long, 1m wide and 0.7m tall, and weighs about160kg. This test canopy will be mounted on the rocketpowered multiaxis seat ejection vehicle,and launched along rails to simulate canopy jettison and seat firing in an aircraft traveling atvarious speeds. Lockheed Martin

CAPTION: Pratt & Whitney's F119PW100 twinspool augmented turbofan engine was selected topower the F22 in April 1991. The first production engine is due in late 1999. Pratt & Whitney

CAPTION: An airtosurface capability has been developed for the F22. The aircraft's lowerweapon bays have been modified to carry two McDonnell Douglas GBU32 1,000 lb (450kg)classJoint Direct Attack Munitions. The GBU32 is a nearprecision standoff weapon guided to its targetby means of an inertial measurement unit updated inflight with data from Global PositioningSystem satellites. In this artist's rendition, an F22 pilot releases both GBU32 bombs against anenemy airfield's surfacetoair missile site.

CAPTION: The tactical display system that will provide unsurpassed situation awareness for F22pilots. The defense display on the left gives pilots the information they will need to protectthemselves against threats. The display in the middle provides an overall situation awareness andnavigation information, while on the right is the target attack display. Boeing

CAPTION: Boeing has modified a 757 airliner into a flying avionics testbed for the F22.Modifications include installing a wing shape geometrically identical to the F22 on the crown ofthe fuselage. This sensor wing will include F22 electronic warfare and communication, navigationand identification sensors. There are also various apertures to replicate F22 antennas, and the F22 forward fuselage structure housing a prototype radar. Boeing

8 Images

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F222804

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vertical modular tooling process2805

F22 versus surfacetoair2806

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F22 canopy2807

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F119PW100 twinspool2808

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F22 releases GBU32 bombs2810

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tactical display system2811

Boeing 7572812

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Copyright IHS Global Limited, 2015

THE PROGRESS OF THE F22 FIGHTER PROGRAM

The Progress of the F-22 Fighter Program

Documents

Transcript of The Progress of the F-22 Fighter Program