F-15 Eagle

The McDonnell Douglas (now Boeing) F-15 Eagle is a twin-engine, all-weather tactical fighter designed to gain and maintain air superiority in aerial combat. It was developed for the United States Air Force, and first flew in July 1972. It is one of the most recognized fighters of the modern day. The F-15E Strike Eagle derivative is an all-weather strike fighter that entered service in 1989. The U.S Air Force plans to keep the F-15 in service until 2025.

Development
Origins
In 1967 U.S. intelligence was surprised to find that the Soviet Union was building a large fighter aircraft, known as the MiG-25 'Foxbat'. It was not known in the West at the time that the MiG-25 was designed as a high-speed interceptor, (not an air superiority fighter), so its primary asset was speed, not maneuverability. The MiG-25's huge tailplanes and vertical stabilizers (tail fins) hinted at a very maneuverable aircraft, which worried the Air Force that its performance might be higher than its American counterparts. In reality, the MiG's large fins and stabilators were necessary to prevent the aircraft from encountering inertia coupling in high-speed, high-altitude flight.
The F-4 Phantom II of the USAF and U.S. Navy was the only fighter with enough power, range, and maneuverability to be given the primary task of dealing with the threat of Soviet fighters while flying with visual engagement rules. As a matter of policy, the Phantoms could not engage targets without positive visual identification, so they could not engage targets at long ranges, as designed. Medium-range AIM-7 Sparrow missiles, and to a lesser degree even the AIM-9 Sidewinder, were often unreliable and ineffective at close ranges where it was found that guns were often the only effective weapon. The Phantom did not originally have a gun, but experience in Vietnam led to the addition of a gun. An external gun pod was tried and later the M61 Vulcan was integrated internally on the F-4E.

F-X program
There was a clear need for a new fighter that overcame the close-range limitation of the Phantom while retaining long-range air superiority. After rejecting the U.S. Navy VFX program (which led to the F-14 Tomcat) as being unsuited to its needs, the U.S. Air Force issued its own requirements for the Fighter Experimental (F-X), a specification for a relatively lightweight air superiority fighter. The requirements called for single-seat fighter having a maximum take-off weight of 40,000 lb (18,100 kg) for the air-air role with a maximum speed of Mach 2.5 and a thrust to weight ratio of nearly 1 at mission weight. Four companies submitted proposals, with the Air Force eliminating General Dynamics and awarded contracts to Fairchild Republic, North American Rockwell, and McDonnell Douglas for the definition phase in December 1968. The companies submitted technical proposals by June 1969. The Air Force announced the selection of McDonnell Douglas on 23 December 1969. The winning design resembled the twin-tailed F-14, but with fixed wings. It would not be significantly lighter or smaller than the F-4 that it would replace.

The Eagle's initial versions were designated F-15A for the single-seat configuration and F-15B (originally TF-15A, but this designation was quickly deprecated, as the F-15B is fully combat-capable) for the twin-seat. These versions would be powered by new Pratt & Whitney F100 engines to achieve a combat thrust-to-weight ratio in excess of 1 to 1. A proposed 25 mm Ford-Philco GAU-7 cannon with caseless ammunition was dropped in favor of the standard M61 Vulcan gun due to development problems. The F-15 retained conformal carriage of four Sparrow missiles like the Phantom. The fixed wing was put onto a flat, wide fuselage that also provided an effective lifting surface. Some questioned if the zoom performance of the F-15 with Sparrow missiles was enough to deal with the new threat of the high-flying MiG-25 "Foxbat", but its capability was eventually demonstrated in combat.

The first F-15A flight was made in July 1972 with the first flight of the two-seat F-15B (formerly TF-15A) following in July 1973.

The F-15 has a "look-down/shoot-down" radar that can distinguish low-flying moving targets from ground clutter. The F-15 would use computer technology with new controls and displays to lower pilot workload and require only one pilot to save weight. Unlike the F-14 or F-4, the F-15 has only a single canopy frame with clear vision forward. The USAF introduced the F-15 as "the first dedicated USAF air superiority fighter since the F-86 Sabre."

The F-15 would be favored by customers such as the Israel Air Force and Japan Air Self-Defense Force, and the development of the F-15E Strike Eagle would produce a strike fighter that would replace the F-111. However, criticism from the fighter mafia that the F-15 was too large to be a dedicated dogfighter, and too expensive to procure in large numbers to replace the F-4 and A-7, led to the Lightweight Fighter (LWF) program, which led to the USAF F-16 Fighting Falcon and the middle-weight Navy F/A-18 Hornet.

Further development
The single-seat F-15C and two-seat F-15D models entered production in 1978 with the models' first flights in February and June of that year. These new models have Production Eagle Package (PEP 2000) improvements, including 2,000 lb (900 kg) of additional internal fuel, provision for carrying exterior conformal fuel tanks and increased maximum takeoff weight of up to 68,000 lb (30,700 kg).

The F-15 Multistage Improvement Program (MSIP) was initiated in February 1983 with the first production MSIP F-15C produced in 1985. Improvements included an upgraded central computer; a Programmable Armament Control Set, allowing for advanced versions of the AIM-7, AIM-9, and AIM-120A missiles; and an expanded Tactical Electronic Warfare System that provides improvements to the ALR-56C radar warning receiver and ALQ-135 countermeasure set. The final 43 included the enhanced-capability Hughes APG-70 radar, which was carried forward into the F-15E. The earlier MSIP F-15Cs with the APG-63 were later upgraded to the APG-63(V)1, which significantly improves reliability and maintainability while providing performance similar to the APG-70. The improvements were retrofitted to existing F-15s.

Recent upgrades include retrofiting 178 F-15C fighters with the AN/APG-63(V)3 Active Electronically Scanned Array (AESA) radar with delivery beginning in early 2009. Additionally, the Air Force also plans to upgrade other F-15s with the Joint Helmet Mounted Cueing System (JHMCS).

Design
The F-15 has an all-metal semi-monocoque fuselage with a large cantilever shoulder-mounted wing. The empennage is all-metal twin fins and rudders with all-moving composite horizontal tail surfaces outboard of the fins. The F-15 has a spine-mounted air brake and retractable tricycle landing gear. It is powered by two Pratt & Whitney F100 axial-flow turbofan engines with afterburners mounted side-by-side in the fuselage. The cockpit is mounted high in the forward fuselage with a one-piece windscreen and large canopy to increase visibility.
The F-15's maneuverability is derived from low wing loading (weight to wing area ratio) with a high thrust-to-weight ratio enabling the aircraft to turn tightly without losing airspeed. The F-15 can climb to 30,000 ft (10,000 m) in around 60 seconds. The thrust output of the dual engines is greater than the aircraft's weight, thus giving it the ability to accelerate in a vertical climb. The weapons and flight control systems are designed so that one person can safely and effectively perform air-to-air combat. The "A" and "C" models are single-seat variants that make up the bulk of F-15 production. "B" and "D" models add a second seat behind the pilot for training. "E" models use the second seat for a bombardier/navigator.
A multi-mission avionics system includes a head-up display (HUD), advanced radar, inertial guidance system (INS), flight instruments, ultra high frequency (UHF) communications, and Tactical Air Navigation (TACAN) and Instrument Landing System (ILS) receivers. It also has an internally mounted, tactical electronic-warfare system, "identification friend or foe" system, electronic countermeasures suite and a central digital computer.

The heads-up display projects, through a combiner, all essential flight information gathered by the integrated avionics system. This display, visible in any light condition, provides the pilot information necessary to track and destroy an enemy aircraft without having to look down at cockpit instruments.

The F-15's versatile APG-63/70 Pulse-Doppler radar system can look up at high-flying targets and down at low-flying targets without being confused by ground clutter. It can detect and track aircraft and small high-speed targets at distances beyond visual range (the maximum being 120 nautical miles (220 km) away) down to close range, and at altitudes down to treetop level. The radar feeds target information into the central computer for effective weapons delivery. The capability of locking onto targets as far as 50 nautical miles (90 km) with an AIM-120 AMRAAM enables true beyond visual range (BVR) engagement of targets. For close-in dogfights, the radar automatically acquires enemy aircraft, and this information is projected on the head-up display. The F-15's electronic warfare system provides both threat warning and automatic countermeasures against selected threats.

A variety of air-to-air weaponry can be carried by the F-15. An automated weapon system enables the pilot to perform aerial combat safely and effectively, using the head-up display and the avionics and weapons controls located on the engine throttles or control stick. When the pilot changes from one weapon system to another, visual guidance for the required weapon automatically appears on the head-up display.

The Eagle can be armed with combinations of four different air-to-air weapons: AIM-7F/M Sparrow missiles or AIM-120 AMRAAM advanced medium range air-to-air missiles on its lower fuselage corners, AIM-9L/M Sidewinder or AIM-120 missiles on two pylons under the wings, and an internal M61A-1 20 mm Gatling gun in the right wing root.

Low-drag conformal fuel tanks (CFTs) were developed for the F-15C and D models. They can be attached to the sides of the engine air intake trunks under each wing and are designed to the same load factors and airspeed limits as the basic aircraft. However, they degrade performance by increasing drag and cannot be jettisoned in-flight (unlike conventional external tanks). Each conformal fuel tank can hold 750 U.S. gallons (2,840 L) of fuel. These tanks increase range thus reducing the need for in-flight refueling. All external stations for munitions remain available with the tanks in use. Moreover, Sparrow or AMRAAM missiles can be attached to the corners of the conformal fuel tanks. The 57 FIS based at Keflavik NAS, Iceland was the only C-model squadron to utilize CFT's on a regular basis due to its extended operations over the North Atlantic. With the closure of the 57 FIS the F-15E is the only U.S. variant to carry them on a routine basis. The American CFTs were also provided to Israel and Saudi Arabia but only Israel uses them (as needed) on their entire fleet.

The F-15E Strike Eagle is a two-seat, dual-role, totally integrated fighter for all-weather, air-to-air and deep interdiction missions. The rear cockpit is upgraded to include four multi-purpose CRT displays for aircraft systems and weapons management. The digital, triple-redundant Lear Siegler flight control system permits coupled automatic terrain following, enhanced by a ring-laser gyro inertial navigation system. For low-altitude, high-speed penetration and precision attack on tactical targets at night or in adverse weather, the F-15E carries a high-resolution APG-70 radar and LANTIRN pods to provide thermal imagery.

The APG-63(V)2 Active Electronically Scanned Array (AESA) radar has been retrofitted to 18 U.S. Air Force F-15C aircraft. This upgrade includes most of the new hardware from the APG-63(V)1, but adds an AESA to provide increased pilot situational awareness. The AESA radar has an exceptionally agile beam, providing nearly instantaneous track updates and enhanced multi-target tracking capability. The APG-63(V)2 is compatible with current F-15C weapon loads and enables pilots to take full advantage of AIM-120 AMRAAM capabilities, simultaneously guiding multiple missiles to several targets widely spaced in azimuth, elevation, or range.

Operational history
The largest operator of the F-15 is the United States Air Force. The first Eagle (F-15B) was delivered November 14, 1974. In January 1976, the first Eagle destined for a combat squadron, the 555th TFS, was delivered. These initial aircraft carried the Hughes Aircraft (now Raytheon) APG-63 radar.

The first kill in an F-15 was by IAF ace Moshe Melnik in 1979. In 1979–81 during Israeli-Lebanese border disputes, F-15As downed 13 Syrian MiG-21 "Fishbeds" and two Syrian MiG-25 "Foxbats", the latter being the aircraft the F-15 was designed to kill. F-15A and B models were used by Israel during the Bekaa Valley operation. During the 1982 Lebanon War, the Israeli F-15s shot down 40 Syrian jet fighters (23 MiG-21 "Fishbeds" and 17 MiG-23 "Floggers") and one Syrian SA.342L Gazelle helicopter. Later on, in 1985, IAF Eagles, in Operation Wooden Leg, bombed the PLO headquarters in Tunisia. This was one of the few times air superiority F-15s (A/B/C/D models) were used in tactical strike missions.

Royal Saudi Air Force F-15C pilots shot down two F-4E Phantom IIs flown by the Iranian Air Force in a skirmish in June 1984, and shot down two Iraqi Mirage F1s during the Gulf War.

The USAF deployed F-15C, D and E models to the Persian Gulf in 1991 in support of Operation Desert Storm where they accounted for 36 of the 39 Air Force air-to-air victories. F-15Es were operated mainly at night, hunting modified SCUD missile launchers and artillery sites using the LANTIRN system. According to the USAF, its F-15Cs had 34 confirmed kills of Iraqi aircraft during the 1991 Gulf War, mostly by missile fire: five MiG-29 "Fulcrums", two MiG-25 "Foxbats", eight MiG-23 "Floggers", two MiG-21 "Fishbeds", two Su-25 "Frogfoots", four Su-22 "Fitters", one Su-7, six Mirage F1s, one Il-76 cargo plane, one Pilatus PC-9 trainer, and two Mi-8 helicopters. After air superiority was achieved in the first three days of the conflict, many of the later kills were reportedly of Iraqi aircraft fleeing to Iran, rather than actively trying to engage U.S. aircraft. The single-seat F-15C was used for air superiority, and the F-15E was heavily used in air-to-ground attacks. An F-15E achieved an aerial kill of another Iraqi Mi-8 helicopter using a laser-guided bomb during the air war. The F-15E sustained two losses to ground fire in the Gulf War in 1991. Another one was damaged on the ground by a SCUD strike on Dhahran air base.
They have since been deployed to support Operation Southern Watch, the patrolling of the No-Fly Zone in Southern Iraq; Operation Provide Comfort in Turkey; in support of NATO operations in Bosnia, and recent air expeditionary force deployments. In 1994, two U.S. Army UH-60 Black Hawks were downed by USAF F-15Cs who thought they were Iraq Hinds in the Northern no-fly zone of Iraq in a friendly fire incident. USAF F-15Cs shot down four Yugoslav MiG-29s using AIM-120 missiles during NATO's 1999 intervention in Kosovo, Operation Allied Force.

The F-15 in all air forces had an air-to-air combined record of 104 kills to 0 losses in air combat as of February 2008. To date, no air superiority versions of the F-15 (A/B/C/D models) have ever been shot down by enemy forces. Over half of the F-15's kills were made by Israeli Air Force pilots.

Satellite killer
From January 1984 to September 1986, two F-15As were used as launch platforms for the ASM-135 anti-satellite (ASAT) missile. The F-15As (76-0086 and 77-0084) were modified to carry one ASM-135 on the centerline station with extra equipment within a special centerline pylon. The launch aircraft executed a Mach 1.22, 3.8 g climb at 65° to release the ASAT missile at an altitude of 38,100 ft (11,600 m). The flight computer was updated to control the zoom-climb and missile release. The third test flight involved a retired communications satellite in a 345-mile (555 km) orbit, which was successfully destroyed by kinetic energy. The pilot, USAF Major Wilbert D. "Doug" Pearson, became the only pilot to destroy a satellite.

The ASAT missile was designed to be a standoff anti-satellite weapon, with the F-15A acting as a first stage. The Soviet Union could correlate a U.S. rocket launch with a spy satellite loss, but an F-15 carrying an ASAT would blend in among hundreds of F-15 flights. The ASAT program involved five test launches. The program was officially terminated in 1988.

Structural defects
All F-15 aircraft were grounded by the U.S. Air Force after a Missouri Air National Guard F-15C came apart in flight and crashed on 2 November 2007. The newer F-15E fleet was later cleared for continued operations. The U.S. Air Force reported on 28 November 2007 that a critical location in the upper longerons on the F-15C model was suspected of causing the failure, causing the fuselage forward of the air intakes, including the cockpit and radome, to separate from the airframe.

F-15A through D-model aircraft were ordered grounded until the location received more detailed inspections and repairs as needed. The grounding of F-15s received media attention as it began to place strains on the nation's air defense efforts. The grounding forced some states to rely on their neighbors' fighter jets for air defense protection, and Alaska to depend on Canadian Forces' support.

On 8 January 2008, the USAF Air Combat Command (ACC) cleared a portion of its F-15A through D-model fleet for return to flying status. It also recommended a limited return to flight for units worldwide using the affected models. The accident review board report was released on January 10, 2008. The report stated that analysis of the F-15C wreckage determined that the longeron did not meet drawing specifications, which led to fatigue cracks and finally a catastrophic failure of the remaining support structures and breakup of the aircraft in flight. In a report released on 10 January 2008, nine other F-15s were identified to have similar problems in the longeron. As a result of these problems, General John D. W. Corley stated that "the long-term future of the F-15 is in question." On 15 February 2008, ACC cleared all its grounded F-15A-D fighters for flight pending inspections, engineering reviews and any needed repairs. ACC also recommended release of other U.S. F-15A-D aircraft.

Future
The F-15C/D model is being supplanted in U.S. service by the F-22 Raptor. The F-15E, however, will remain in service for years to come because of their different air-to-ground role and the lower number of hours on their airframes. The USAF will upgrade 178 F-15Cs with the AN/APG-63(V)3 AESA radar, and upgrade other F-15s with the Joint Helmet Mounted Cueing System. The Air Force will keep 178 F-15Cs as well as the 224 F-15Es in service beyond 2025.

Variants
Basic models
F-15A
Single-seat all-weather air-superiority fighter version, 384 built 1972-79.
F-15B
Two-seat training version, formerly designated TF-15A, 61 built 1972-79.
F-15C
Improved single-seat all-weather air-superiority fighter version, 483 built 1979-85.
F-15D
Two-seat training version, 92 built 1979-85.
F-15J
Single-seat all-weather air-superiority fighter version for the Japan Air Self-Defense Force 139 built under license in Japan by Mitsubishi 1981-97, 2 built in St. Louis.
F-15DJ
Two-seat training version for the Japan Air Self-Defence Force. 25 Built under license in Japan by Mitsubishi 1981-97, 12 built in St. Louis.
F-15N Sea Eagle
The F-15N was a carrier-capable variant proposed in the early 1970s to the U.S. Navy as an alternative to the heavier and, at the time, considered as "riskier" technology program: F-14 Tomcat. The F-15N-PHX was another proposed naval version capable of carrying the AIM-54 Phoenix missile. These featured folding wingtips, reinforced landing gear and a stronger tail hook for shipboard operation.
F-15E Strike Eagle
See F-15E Strike Eagle for F-15E, F-15I, F-15S, F-15K, F-15SG, F-15SE and other F-15E-based variants.

Research and test
F-15 Streak Eagle (72-0119)
One stripped and unpainted F-15A, demonstrated the fighter's acceleration – broke eight time-to-climb world records between 16 January and 1 February 1975. It was delivered to the National Museum of the United States Air Force in December 1980.

F-15 S/MTD (71-0290)
The first F-15B was converted into a short takeoff and landing, maneuver technology demonstrator aircraft. In the late 1980s it received canard flight surfaces in addition to its usual horizontal tail, along with square thrust-vectoring nozzles. It was used as a short-takeoff/maneuver-technology (SMTD) demonstrator.

F-15 ACTIVE (71-0290)
The F-15 S/MTD was later converted into an advanced flight control technology research aircraft with thrust vectoring nozzles.

F-15 IFCS (71-0290)
The F-15 ACTIVE was then converted into an intelligent flight control systems research aircraft. F-15B 71-0290 is the oldest F-15 still flying as of January 2009.

F-15 MANX
Concept name for a tailless variant of the F-15 ACTIVE, but the NASA ACTIVE experimental aircraft was never modified to be tailless.

F-15 Flight Research Facility (71-0281 and 71-0287)
Two F-15A aircraft were acquired in 1976 for use by NASA's Dryden Flight Research Center for numerous experiments such as: Highly Integrated Digital Electronic Control (HiDEC), Adaptive Engine Control System (ADECS), Self-Repairing and Self-Diagnostic Flight Control System (SRFCS) and Propulsion Controlled Aircraft System (PCA). 71-0281 was returned to the Air Force and became a static display at Langley AFB in 1983.
F-15B Research Testbed (74-0141)


Current operators of the F-15 in light blue, F-15E in red, both in dark blue
Acquired in 1993, it was an F-15B modified and used by NASA's Dryden Flight Research Center for flight tests.