F-15D

The McDonnell Douglas (now Boeing) F-15 Eagle is an 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. 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.^[2]

Development

Origins

During the mid-1960s U.S. Air Force intelligence was surprised^[3] to find that the Soviet Union was building a large fighter aircraft, known as the MiG-25 'Foxbat'.^[4] 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;^[5] as such, 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.^[4] 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.^[6]

The Phantom did not originally have a gun, as it was intended that only missiles would be used to engage slowly moving and maneuvering Warsaw Pact bombers and fighters at longer ranges. Experience in Vietnam showed this not to be the case and led to the addition of a gun. At first an external gun pod was tried but that proved inaccurate and increased drag. Later, the 20 mm 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.^[7] Four companies submitted proposals, with the Air Force eliminating General Dynamics and selecting 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 December 23, 1969.^[8] 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"; its capability would eventually be 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.^[9]

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."^[10]

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.

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.^[11] 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).^[12]

Improvements

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.^[13]

Design

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 feet (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.^[7] 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.

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.^[15]

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.^[16]

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.^[17]

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.^[18]

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.^[18] 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.^[19] 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.^[12] 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.^[20] 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.^[16]

The APG-63(V)2 Active Electronically Scanned Array (AESA) radar has been retrofitted to 18 U.S. Air Force F-15C aircraft.^[21] 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.^[22] In January 1976, the first Eagle destined for a combat squadron, the 555th TFS, was delivered.^[22] 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.^[23] 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.^[24]

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.^[28] 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.^[29] Another one was damaged on the ground by a SCUD strike on Dhahran air base.^[30]

As of 2008, the F-15 in all air forces has an air-to-air combined kill record of 104 kills to 0 losses in air combat.^[32] 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.^[33] 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 feet (11.6 km). 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 statute 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.^[34]^[35]

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 interpret 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; however, the missile was not known to have entered service. The program was officially terminated in 1988.^[33]

Grounded by USAF

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 November 2, 2007. The newer F-15E fleet was later cleared for continued operations. The U.S. Air Force reported on November 28, 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.^[36]

F-15A through D-model aircraft were ordered grounded until the location received more detailed inspections and repairs as needed.^[37] The grounding of F-15s received media attention as it began to place strains on the nation's air defense efforts.^[38] The grounding forced some states to rely on their neighbors' fighter jets for air defense protection, and Alaska to depend on Canadian Forces' support.^[39]

On January 8, 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.^[40] 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.^[41] In a report released in January 10, 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."^[42] On February 15, 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.^[43]

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 its different air-to-ground role and the lower number of hours on their airframes.^[2] On September 26, 2006, at the Air Force Association's Air & Space Conference and Technology Exposition in Washington D.C., the USAF announced their plan to upgrade 178 F-15C fighters with the AN/APG-63(V)3 AESA radar. Additionally, the Air Force also plans to upgrade other F-15s with the Joint Helmet Mounted Cueing System (JHMCS).^[44] In keeping with that plan, the Air Force then contracted with Boeing to retrofit F-15Cs with the AN/APG-63(V)3 Active Electronically Scanned Array (AESA) radars with delivery beginning in early 2009.^[45] The Air Force will keep 178 F-15Cs as well as the 224 F-15Es in service beyond 2025.^[2]

Variants

Basic models

F-15E and related

Research and test

Operators

Notable accidents and incidents

On May 1, 1983, during an Israeli Air Force training dogfight, a F-15D collided with a A-4 Skyhawk. Unknown to pilot Zivi Nedivi, and his copilot, the right wing of the Eagle was torn off roughly two feet (60 cm) from the fuselage. The pilot managed to regain control of the aircraft and prevented it from stalling, ultimately landing the crippled aircraft successfully. The F-15 was able to stay in the air because of the lift generated by the large horizontal surface area of the fuselage, the large and effective stabilators and the surviving wing. Landing at twice the normal speed to maintain the necessary lift, although the tailhook was torn off completely during the landing, Zivi managed to bring his F-15 to a complete stop approximately 20 feet (6 m) from the end of the runway. He was later quoted as saying "(I) probably would have ejected if I knew what had happened."^[56]^[57]

On November 22, 1995, during air-intercept training over the Sea of Japan, a Japanese F-15J was shot-down by a AIM-9L sidewinder missile accidentally fired by his wingman. The pilot, Lt. Tatsumi Higuchi, ejected safely. Both F-15Js involved were from JASDF 303rd Squadron, Komatsu AFB.^[58]

On November 2, 2007, a 25-year-old F-15C (s/n 80-0034 of the 131st Fighter Wing) crashed during air combat maneuvering training near St. Louis, Missouri. The pilot, Maj. Stephen W. Stilwell, ejected but suffered serious injuries. The crash was the result of an in-flight breakup due to structural failure. On November 3, 2007, all non-mission critical models of the F-15 were grounded pending the outcome of the crash investigation,^[59] and on the following day, grounded non-mission critical F-15s engaged in combat missions in the Middle East.^[60] By November 13, 2007 over 1,100 were grounded worldwide after Israel, Japan and Saudi Arabia grounded their aircraft as well.^[61] F-15Es were cleared on November 15, 2007 pending aircraft passing inspections.^[62] On January 8, 2008, the USAF cleared 60 percent of the F-15A-D fleet for return to flight.^[40] On January 10, 2008, the accident review board released its report stating the November 2 crash was related to the longeron not meeting drawing specifications.^[41] The Air Force cleared all its grounded F-15A-D fighters for flight on February 15, 2008 pending inspections, reviews and any needed repairs.^[43] In March 2008, Stilwell, the injured pilot, filed a lawsuit against Boeing, the F-15's manufacturer.^[63]

Specifications (F-15C Eagle)

Data from USAF fact sheet,^[64] Jane's All the World's Aircraft,^[65] Davies 2002,^[66] GlobalSecurity^[67]

Popular culture

The F-15 was the subject of the IMAX movie Fighter Pilot: Operation Red Flag, about the RED FLAG exercises. In Tom Clancy's nonfiction Fighter Wing (1995), a detailed analysis of the Air Force's premier fighter aircraft, the F-15 Eagle and its capability is showcased.^[69]

Contents