The F-22's cockpit

The F-22's radar is the Westinghouse/Texas Instruments AN/APG-77 navigation and air-to-air radar. The radar emitter is a fixed, oval-shaped flat array. Instead of being one large emitter that must be physically swung around to scan a volume of airspace, the APG-77 has around 1,500 individual Transmit/Recieve (T/R) modules. Each T/R module is about the size of your finger, and, depending on how many are purchased by the USAF, cost about $500. Each T/R module is aimed electronically at an area, so there are no moving parts at all, meaning that there is a lot less chance of things breaking down at the worst possible time. The greatest advantage the T/R modules present is the ability to scan a given volume of airspace much faster than earlier radars. For example, for the AN/APG-70, the radar used on late-model F-15s, to scan an area that was 120° in horizontal aspect from the plane's nose, in a six-bar (a bar is a vertical measurement of 1.5°) search pattern, it would take the array 14 seconds to swing the dish left-right through each bar to form a picture. By comparison, since the T/R modules on the APG-77 are aimed electronically, the same volume of airspace can be scanned in milliseconds.

Another important feature of the APG-77 is its Low-Probability of Intercept (LPI) qualities. The exact techniques are classified, but the most widely regarded theory involves "spread spectrum transmission". On an ordinary radar, a lot of energy is emitted at high power on a very narrow freqency range. Most Radar Warning Reciever (RWR) equipment is set to those frequencies, so any radar emissions will be picked up about two times farther than the distance where the radar's operator can get useful data from the return waves. Spread spectrum transmission uses the opposite priciple: putting out a little bit of energy on a very wide frequency range. When all the low-energy echoes are compiled by the F-22's computers, the picture is more or less as clear as the narrow frequency returns one would get out of an ordinary radar, but it is highly unlikely that any enemy RWRs have picked up the emissions because the energy levels are so low. Another neat APG-77 feature is its unprecented target ID capability. It uses Non-Cooperative Target Recognition (NCTR) techniques to ID a target. Techniques in this area are also classified, but the most widely reported techniques is to use the radar return to count the amount of compressor or fan blades the target's engine has, which can be used to identify the type of aircraft, or at least whether it's hostile or freindly. Another technique speculated upon is to use a very narrow beam Inverse Synthetic Aperture Radar (ISAR) to detect very fine Doppler shifts in the target's signature to actually form a 3D image or "map" of the return, thus analysing the shape. In the cockpit, only targets which have been identified with 99% certainty are shown, along with the aircraft type. If it cannot be positively identified as hostile or friendly, it's shown as "Unknown".

The F-22's own Electronic Warfare (EW) equipment includes a Sanders/General Electric AN/ALR-94 RF warning and countermeasures system. The F-22 has a TRW comm/nav/ID system, including a Mk-12 IFF (Identification Friend or Foe) system. A Litton Inertial Refernce System is part of the F-22's navigational equipment. Over 30 antennas are mounted on the F-22, but instead of comprimising Stealth by having them stick out of the fuselage, they are mounted in conformal "smart skins". The Jammer/RWR antennae are on the wingtips, and the com/nav/IFF antennae are on leading edges of the wings.

In the cockpit, the pilot sits in a standard ACES II Zero/Zero ejection seat, with a -15° angle view over the nose. Before him is a bank of 4 Sanders/Kaiser color liquid-crystal displays (LCDs), mounted in a row of 3 at the top, with one centered underneath. In the center of the top row is the 8" x 8" "God's-Eye" display. This shows the "Big Picture", with the F-22 in the center. It does not show information such as SAM or AAA envolopes, but instead is used just to orient the pilot in relation to the his wingmen and other contacts "out there." The God's-Eye display is usually set to show a larger area, indicating contacts that aren't close enough to be either a theat or a target to the F-22. On the left is the smaller Defense Display which allows the pilot to select data such as the SAM or AAA threat envelopes in his area. SAMs are represented by red pentagons, with a circle around them indicating their effective range against the F-22 at any given time. The computer identifies them based on data such as frequency emissions. The threat envelopes are constantly being updated. For example if there are two identical SAM radars out there, the one forward of the F-22 will have a smaller threat envelope than the one behind, because the F-22 takes into account the fact that the Raptors rear-aspect RCS is greater from behind. Using these threat ranges, the pilot can determine a course that will take him through the gaps in enemy radar coverage caused by the F-22's low RCS. The display to the right is concentrated on attack data. A bar on the left-hand side of the screen will show a target's altitude, and a bar at the right shows the range of the F-22's missiles in relation to the targets. When the target is within optimum firing range, and a fire solution has been calculated by the computer a SHOOT cue appears and the pilot releases the weapon. The display at the bottom is dedicated to aircraft systems such as fuel, weapons status, engine status etc. Most of the conventional dials and strip-gauges have been deleted and replaced by the multi-function LCDs with only 3 analog gauges remaining purely for backup purposes. The F-22 also has a jam-resistant intra-flight datalink which allows all the F-22 pilots to know exaclty how the others are doing: fuel status, weapons status, etc. is shared, and fire solutions are coordinated via datalink so that only one weapon is targeted on any given airplane to avoid wastage.

The F-22's weapons will all be carried internally when Stealth is a concern. The aircraft has 3 internal weapons bays. One is located inside the lower fuselage, with two smaller bays on the side of each inlet duct. The ventral bay will store up to 4 AIM-120A or up to 6 AIM-120C AMRAAMs (Advanced Medium Range Air-to-Air Missiles). The AIM-120C has smaller guidance fins than the A-model, thus taking up less room. The AIM-120Cs are loaded with a standard MJ-1 loader, and is loaded from the opposite side (ie, if it is being loaded on a rack on the port side, the MJ-1 is doing it from the starboard). The AMRAAMs are stored on LAU-142/A AMRAAM Vertical Eject Launcher (AVEL) racks, and are in a staggered pattern, so when one missile is ejected, its fins wont hit another missile on the way down. The AVEL ejects the AMRAAM at 25 feet per second, which translates to a maximum of about 40 Gs. The bay is covered by hydraulically-operated doors that rapidly open to let the missile out, then quickly close up again. Each of the side bays is equipped with a LAU-141/A hydraulic Trapeze Launcher. The bays will each carry one AIM-9M or AIM-9X Sidewinder AAM, and operate in a similar fashion to the ventral bay. In the ground-attack role, two 1,000-lb GPS-guided GBU-32 Joint Direct Attack Munitions (JDAMs) would be carried in the ventral bay instead of four AIM-120Cs.

Raptor 01 flying over Edwards AFB with its ventral weapons bay open.
Note the AMRAAMs inside the bay. (USAF photo)

The F-22's fixed armament is an M61A2 gatling gun. The M61A2 is a long-barreled, lightweight version of the M61A1, and is located in the right fuselage area. The system consists of the gun itself; the Linear Linkless Ammunition Handling System (LLAHS), which includes the gun's 480-round magazine; the 42-horsepower hydraulic gun drive unit; the gun door/port; and the gas purge system. The gun door, there to reduce drag as well as maintain the F-22's Stealthiness, is a hydraulically operated door covering the gun muzzle. When the pilot squeezes the gun trigger the door is activated within milliseconds and swings 90 degrees to allow the bullets an unobstructed path out of the gun. When the last bullet leaves the muzzle, the door snaps shut again. The gun port itself is a steel casting which is shaped to deflect the gun gases away. The aircraft's gun gas purging system uses a door opening at the same time as the gun port door, and rams air into the fuselage area to quickly blow any gun gases out a fixed screened vent on the top of the fuselage. The gun can fire at rate of up to 6,000 rounds per minute. The F-22 also has provisions to carry 4 external stores pylons. These pylons are located 9ft 8in (3.17m) and 13 ft 6in (4.42m) from the fuselage centerline. Each can carry up to 5,000 lbs (2,268 kg) of stores. For example, the 2 inboard pylons could each carry a 600 Gal fuel tank on BRU-47/A racks, while the outboard pylons would each carry 2 AAMs on LAU-128/A racks. These pylons can be jettisoned from the airplane, and since they totally negate Stealth, they would only be used when Stealth is not a concern, such as a ferry mission where all 4 pylons would be carrying fuel, or after Air Dominance over the war zone has been established and combat-air patrols are being executed, requiring maximum firepower and endurance.