McDonnell Douglas F-15E Strike Eagle

The McDonnell Douglas (now Boeing) F-15E Strike Eagle is a remarkable American all-weather multirole strike fighter, meticulously derived from the McDonnell Douglas F-15 Eagle. Conceived in the 1980s, the F-15E was engineered for long-range, high-speed interdiction missions without the need for escort or electronic-warfare aircraft. Its distinctive features, such as darker aircraft camouflage, conformal fuel tanks (CFTs) mounted along the engine intake ramps, and a tandem-seat cockpit, set it apart from other US Eagle variants. The F-15E has seen extensive deployment in military operations across Iraq, Afghanistan, Syria, and Libya, executing deep strikes against high-value targets, conducting combat air patrols, and providing close air support for coalition troops. Its prowess has led to its export to several countries, while Boeing has continued to enhance its design through the Advanced Eagle family, including the F-15EX Eagle II.

The development of the F-15E traces back to the introduction of the McDonnell Douglas F-15 Eagle by the United States Air Force (USAF) as a replacement for the aging fleet of McDonnell Douglas F-4 Phantom IIs. The F-15, unlike its predecessor, was primarily designed for air superiority with minimal consideration for ground-attack roles. This focus on air superiority gave rise to the phrase “Not a pound for air to ground.” Despite the lack of official interest in ground attack capabilities, McDonnell Douglas had quietly embedded a basic secondary ground attack capability in the F-15’s design from its inception, envisioning an F-15-derived interdictor fighter as a potential replacement for the General Dynamics F-111 and the remaining F-4s.

In 1978, the USAF initiated the Tactical All-Weather Requirement Study, which evaluated McDonnell Douglas’s proposal alongside other options, such as acquiring additional F-111Fs. The study concluded with a recommendation for the F-15E as the USAF’s future strike platform. McDonnell Douglas, in collaboration with Hughes, began developing the F-15E’s air-to-ground capabilities in 1979. To aid in its development, McDonnell Douglas modified the second TF-15A prototype, known as the Advanced Fighter Capability Demonstrator, which first took to the skies on July 8, 1980. This demonstrator, initially used to test conformal fuel tanks, was later equipped with a Pave Tack laser designator targeting pod, enabling the independent delivery of guided bombs. It was showcased at the 1980 Farnborough Airshow, marking a significant step in the F-15E’s evolution.

In March 1981, the USAF launched the Enhanced Tactical Fighter program to replace the F-111, later renamed the Dual-Role Fighter (DRF) competition. This initiative sought an aircraft capable of deep air interdiction missions without requiring additional support from fighter escorts or jamming. General Dynamics submitted the F-16XL, while McDonnell Douglas put forth the F-15E. Although the Panavia Tornado was also considered, its lack of credible air-superiority capabilities and non-American origin diminished its prospects. The DRF evaluation, led by Brigadier General Ronald W. Yates, spanned from 1981 to April 30, 1983. During this period, the F-15E logged over 200 flights, demonstrating a takeoff weight exceeding 75,000 pounds and validating 16 different weapons-carrying configurations. Ultimately, on February 24, 1984, the USAF selected the F-15E, citing lower development costs compared to the F-16XL, future growth potential, and twin-engine redundancy as key factors in the decision.

Construction of the first three F-15Es commenced in July 1985, with the first aircraft, designated 86-0183, making its maiden flight on December 11, 1986. This flight, piloted by Gary Jennings, saw the aircraft reach a maximum speed of Mach 0.9 and an altitude of 40,000 feet during a 75-minute journey. The first production F-15E was delivered to the 405th Tactical Training Wing at Luke Air Force Base, Arizona, in April 1988. Production continued into the 2000s, resulting in 236 units for the USAF by 2001.

The F-15E underwent significant upgrades over the years, including the integration of the Raytheon AN/APG-82(V)1 Active Electronically Scanned Array (AESA) radar after 2007. This radar combines the processor of the APG-79 used on the F/A-18E/F Super Hornet with the antenna of the APG-63(V)3 AESA fitted on the F-15C. The new radar, part of the F-15E Radar Modernization Program, includes a wideband radome, enabling operation on more radar frequencies, and environmental control and electronic warfare improvements. In 2015, Boeing and BAE Systems were contracted to upgrade the electronic warfare system of all USAF F-15s, including the F-15E, with the AN/ALQ-250 Eagle Passive/Active Warning Survivability System (EPAWSS). The first retrofitted F-15E with EPAWSS was delivered in 2022.

The F-15E’s robust airframe, rated for 8,000 hours of service life or up to 16,000 hours with proper maintenance, ensures its operational viability past 2025. As of December 2012, the USAF’s F-15E fleet had an average age of 21 years and an average airframe flying time of 6,000 hours. The USAF has considered various future options, with no direct replacement for the F-15E slated at that time.

The F-15E’s design has also seen success on the international stage, with Boeing developing upgrades for international customers. Notably, the F-15 Advanced Eagle family began with the F-15SA for the Royal Saudi Air Force, featuring a digital fly-by-wire control system, additional wing pylons, and a revised wing structure. Further variants include the F-15QA for the Qatari Emiri Air Force and the F-15EX Eagle II for the USAF. In fiscal year 2020, the USAF began procuring the F-15EX to replace the aging F-15C/D fleet and supplement the F-22 Raptor, leveraging the existing export production line for a cost-effective and rapid introduction of additional fighters. The F-15EX is also a potential replacement for the F-15E in the future.

Additionally, the F-15E was involved in the Airborne Launch Assist Space Access (ALASA) program, which aimed to reduce the cost of launching microsatellites into orbit. Under a contract awarded to Boeing in March 2014, the F-15E was to serve as the carriage vehicle for ALASA launch vehicles. However, the project was terminated in late 2015.

The F-15E’s design represents a significant departure from the original F-15’s air-superiority focus, showcasing the airframe’s versatility to evolve into a highly capable strike fighter. While primarily designed for ground attack, the F-15E retains the air-to-air lethality of its Eagle lineage, capable of defending itself against enemy aircraft. The F-15E prototype, a modification of the two-seat F-15B, incorporated substantial structural changes and more powerful engines. The rear cockpit is equipped with controls for the weapon systems officer (WSO), who manages the air-to-ground avionics via multiple screens, monitoring radar, electronic warfare, and thermographic cameras, selecting targets, and navigating with an electronic moving map.

For extended range, the F-15E is equipped with conformal fuel tanks (CFTs) that hug the fuselage, providing lower drag compared to conventional drop tanks. These CFTs carry 750 U.S. gallons of fuel and house six weapons hardpoints. The Tactical Electronic Warfare System (TEWS) integrates all countermeasures, including radar warning receivers, radar jammer, and chaff/flare dispensers, offering comprehensive defense against detection and tracking. The TEWS was replaced by the AN/ALQ-250 EPAWSS digital electronic warfare suite in 2022, enhancing performance with lighter and more capable digital components.

The F-15E’s radar capabilities, initially provided by the APG-70, allow crews to detect ground targets from long ranges. The AN/APG-82(V)1 AESA radar, introduced in 2010, further enhances these capabilities, achieving initial operational capability in 2014. The aircraft’s inertial navigation system, using a laser gyroscope, continuously monitors its position, providing data to the central computer and other systems, including a digital moving map in both cockpits.

The LANTIRN system, mounted externally under the engine intakes, enables the F-15E to fly at low altitudes, at night, and in adverse weather conditions, delivering precision-guided and unguided weapons with exceptional accuracy. The AN/AAQ-13 navigation pod, containing terrain-following radar and a forward-looking infrared system, allows the pilot to safely navigate at very low altitudes. The targeting pod, equipped with a laser designator and tracking system, marks targets for destruction from up to 10 miles away, automatically handing off targeting information to infrared homing air-to-surface missiles or laser-guided bombs.

The F-15E can carry a wide array of air-to-ground weapons in the USAF inventory, along with AIM-9 Sidewinders and AIM-120 AMRAAMs, maintaining its counter-air capabilities. It is also equipped with an internally mounted General Electric M61A1 20 mm cannon, effective against enemy aircraft and soft ground targets.

Since 2004, South Korean firm LIG Nex1 has manufactured the F-15’s Head-up Display (HUD), delivering 150 units by 2011. Korea Aerospace Industries (KAI) has produced the F-15’s wings and forward fuselages, establishing a production line for Singapore’s F-15SG in 2008. KAI is also involved in the design and manufacture of the Conformal Weapons Bay for the F-15 Silent Eagle.

Early F-15Es were powered by Pratt & Whitney F100-PW-220 engines, with later batches featuring the more powerful P&W F100-PW-229 engines. Saudi Arabian and Israeli aircraft initially used P&W F100-229 engines, but in 2008, Saudi Arabia re-engined their F-15S and F-15SA fleets with General Electric F110-GE-129 engines. The South Korean F-15K had two different engines, with the first batch powered by GE F110 engines and the second batch by P&W F100 engines. The Singapore Air Force equipped their F-15SG fleet with GE F110 engines.

The F-15E has spawned several variants, including the F-15I operated by the Israeli Air Force, known as the Ra’am, featuring different avionic systems to meet Israeli requirements. The F-15K Slam Eagle, operated by the Republic of Korea Air Force, includes components outsourced to South Korean companies and differs from the F-15E with features like an infra-red search and track system and advanced radar. The F-15S, supplied to the Royal Saudi Air Force, is almost identical to the USAF F-15E, with minor differences in radar performance. The F-15SG, ordered by the Republic of Singapore Air Force, was chosen over the Dassault Rafale and features advanced radar and weapon systems.

In summary, the F-15E Strike Eagle’s rich history and continuous evolution underscore its enduring significance as a versatile and formidable multirole strike fighter. Its adaptability, advanced avionics, and extensive operational history make it a crucial asset for the USAF and its international partners, ensuring its relevance well into the future.