The Boeing F-15EX Eagle II is an American all-weather multirolestrike fighter derived from the McDonnell Douglas F-15E Strike Eagle.[4] The aircraft resulted from the U.S. Department of Defense' Cost Assessment and Program Evaluation (OSD CAPE) study in 2018 to recapitalize the aging F-15C/D fleet due to inadequate numbers of F-22s, delays in the F-35 program, and maintaining diversity in the U.S. fighter industrial base through Boeing's St. Louis division (former McDonnell Douglas). The F-15EX is expected to replace the F-15C/D in performing homeland and air defense missions and also serve as an affordable platform for employing large stand-off weapons to augment the frontline F-22 and F-35.[5] The first aircraft was delivered in 2021 and operational service is expected in July 2024.[6]
The F-15EX is a member of the F-15 Advanced Eagle family of aircraft, a further development of the F-15E design that began with the F-15SA (Saudi Advanced) which first flew in 2013 and continued with the F-15QA (Qatari Advanced) which first flew in 2020.[7] The Advanced Eagle in the F-15EX configuration represents the current baseline in F-15 production.[8][9]
Development
In the 2010s, the United States Air Force (USAF) was facing a shortfall of its fighter fleet size due to deferred and downscaled modernization plans from budget cuts following the end of the Cold War in 1991, and the focus on asymmetric counterinsurgency warfare after the 2001 terrorist attacks. The USAF's procurement goal of 381 production F-22s to replace its fleet of air superiority F-15A to D fighters was curtailed to just 187, resulting in a planned service extension of 179 F-15C/Ds to the 2030s, well beyond its original retirement date, in order to retain adequate numbers of air superiority fighters. Also referred to as F-15 2040C upgrade or "Golden Eagle", these jets would have upgraded avionics, including active electronically scanned array (AESA) radar, infrared search and track (IRST), and a new electronic warfare suite called the Eagle Passive/Active Warning Survivability System (EPAWSS). Some of these upgrades would be shared with the F-15E fleet, such as EPAWSS whose development contract was awarded in 2015 to Boeing and BAE Systems.[10] However, by the mid-2010s, the F-15C/D fleet was aging beyond the point of economic sustainability, and the F-35 program was facing delays, resulting in a requirement to recapitalize the fighter shortfall as the legacy F-15s retire by the mid-2020s. Restarting F-22 production was considered cost-prohibitive due to the high non-recurring startup costs of rebuilding the production line and sourcing replacement parts vendors.[11][12]
Meanwhile, Boeing had been developing upgrades for the F-15E for export customers and a substantial update to the air vehicle design resulted in the F-15 Advanced Eagle family; the F-15SA (Saudi Advanced) was the initial variant which first flew in 20 February 2013, followed by the F-15QA (Qatari Advanced) ordered in 2017. In 2018, following a series of OSD CAPE studies indicating that a mix of fourth- and fifth-generation fighters would allow the USAF to more affordably recapitalize its fighter fleet, the USAF and Boeing began discussing the F-15X or Advanced F-15, a proposed single-seat variant based on the F-15QA to replace USAF F-15C/Ds.[13] Eventually, both single- and two-seat variants were proposed, called F-15CX and F-15EX respectively, with identical capabilities; the USAF opted for the EX since only two–seat F-15 models remained in production, and in 2019, eight aircraft were included in the FY 2020 budget request.[14] This would enable the use of the existing F-15 production line with minimal non-recurring startup costs to quickly bring additional fighters into service and also was a way to support Boeing's St. Louis division (former McDonnell Douglas) in order to maintain diversity in the U.S. fighter industrial base.[15] The F-15EX improvements included the AESA radar, IRST, and EPAWSS from the existing F-15 upgrade programs while combining the benefits of the F-15QA such as the revised structure with a service life of 20,000 hours, new cockpit and flight controls, and the proposed AMBER (Advanced Missile and Bomb Ejector Rack) system to enable the carriage of up to 22 air-to-air missiles.[16]
A F-15EX on the assembly line, July 2020
Although it is not expected to survive against modern air defenses by 2028 compared to the fifth-generation F-22 and F-35, the F-15EX can perform homeland and airbase defense, enforce no-fly zones against limited air defenses, and deploy outsized standoff weapons in support of stealth fighters at the frontline.[17] In July 2020, the U.S. Defense Department ordered eight F-15EXs over three years for $1.2 billion.[18][19] The F-15EX made its maiden flight on 2 February 2021.[20][21]
On 7 April 2021, its official name Eagle II was announced.[22] The FY2021 defense appropriations bill funded F-15EX procurement at $1.23 billion for 12 aircraft, bringing total orders to 20 aircraft with 144 total planned.[23] By May 2022, the USAF reduced its orders to 80.[24] The first operational F-15EXs are not to receive conformal fuel tanks.[25] The Air Force's proposed budget for fiscal 2024 includes funds to buy 24 more F-15EXs,[26] which would bring the planned fleet up to 104 aircraft.[26]
The F-15EX is a variant of the F-15 Advanced Eagle family of aircraft, a further development of the F-15E Strike Eagle design beginning with the F-15SA for the Royal Saudi Air Force. The Advanced Eagle consolidated several upgrades to the F-15E developed for export customers, including full integration of the General Electric F110-GE-129 and the AN/ALQ-239 Digital Electronic Warfare System (DEWS) that replaced the legacy TEWS, and introduced a revised wing structure for increased service life, an enhanced cockpit originally proposed for the F-15SE Silent Eagle, and digital fly-by-wirecontrol system that replaced the original hybrid electronic/mechanical system and enables the activation of two additional wing pylons;[27] the fly-by-wire eliminated flutter modes causing stability issues that resulted in the two outboard wing pylons being deactivated in earlier F-15 variants.[28] Starting from the F-15QA for the Qatari Emiri Air Force, the Advanced Eagle introduced a further revised wing structure that increased service life to 20,000 hours, the new Advanced Display Core Processor II (ADCP II) mission computer, and a new cockpit with a 10 in × 19 in (25 cm × 48 cm) large area display (LAD) each for the pilot and weapon systems officer (WSO). Based on the F-15QA, the F-15EX incorporates the AN/APG-82(V)1 AESA radar, AN/ALQ-250 EPAWSS in lieu of DEWS from which EPAWSS draws heavily from, and the Legion Pod with AN/ASG-34(V)1 IRST21 sensor; in contrast to some other Advanced Eagle variants, the F-15EX does not have the AN/AAR-57 Common Missile Warning System (CMWS), although the blisters for these sensors were retained in order to minimize production changes and maintain the same aerodynamic profile for the fly-by-wire system.[29][30]
While not as survivable as the stealthy F-22 or F-35, the F-15EX nevertheless incorporates advanced integrated avionics and protective countermeasures systems to improve the pilot's situational awareness and increase survivability. The F-15EX's APG-82(V)1 radar, initially designated APG-63(V)4, combines the AESA antenna of the APG-63(V)3 with the processor of the APG-79(V) found on the F/A-18E/F Super Hornet as well as a new cooling system and Radio Frequency Tunable Filters (RFTF) to enable simultaneous radar and electronic warfare functions while integrated with the AN/ALQ-250 EPAWSS electronic warfare suite. Leveraging the work and experience from AN/ALQ-239 DEWS, the EPAWSS is a digital system that provides all-aspect radar warning receiver function and threat geolocation; it is also integrated with the AN/ALE-47 chaff/flare countermeasures dispenser system. Both the pilot and WSO can use the Joint Helmet Mounted Cueing System (JHMCS) to cue weapons at high angles off boresight. The Legion Pod's ASG-34(V)1 IRST21 sensor provides the F-15EX with a passive means of threat detection, especially against low-observable threats in the radio-frequency spectrum; the F-15SA and F-15QA mounts the AN/AAS-42 "Tiger Eyes", the precursor to the IRST21 sensor, on the targeting pod pylon. While the aircraft can be operated by a single pilot for basic air superiority missions, the back seat is fully missionized to support a WSO for complex missions and can potentially support the manned-unmanned teaming coordination with uncrewed collaborative combat aircraft.[31] Although employed primarily as an air superiority fighter to replace the F-15C/D and complement the F-22, the F-15EX can employ the LANTIRN and Sniper XR pods like its F-15E precursor to perform ground attack. The avionics has an open systems architecture to facilitate potential future upgrades.[30]
The F-15EX's large payload capacity enables a high level of flexibility. In a typical air superiority or escort configuration, the Advanced Eagle can carry twelve air-to-air missiles, either the AIM-120 AMRAAM or AIM-9 Sidewinder short-range missiles; the AGM-88 HARM can also be carried. Using proposed expanded racks and CFT weapons stations, it can potentially carry 16 AIM-120; 4 AIM-9; and 2 AGM-88 HARMs, although this has not been tested or funded. For precision strike, it can carry 16 GBU-39 Small Diameter Bombs; 4 AMRAAMs; one 2,000 lb Joint Direct Attack Munition; 2 HARMs; and 2 fuel drop tanks.[28] The F-15EX can carry multiple large standoff munitions such as the AGM-158 JASSM, or outsized munitions like the AGM-183 ARRW to bring additional firepower behind the frontline F-22 and F-35.
While the F-15EX's strengthened structure makes it heavier than earlier F-15 variants, the digital fly-by-wire control system and the increased dynamic thrust envelope of the F110-129 engines provide it with substantially improved maneuverability and handling characteristics over legacy F-15s and enables the pilot to maneuver aggressively with no angle-of-attack limits. The fly-by-wire also makes the aircraft much more departure-resistant and tolerant of asymmetric loads.[32][33]
The first F-15EX was delivered in March 2021 and flown to Eglin Air Force Base in Florida. A fleet of six aircraft formed the test force to support development and operational flight testing. The first two aircraft conducted weapons separation tests and participated in Northern Edge and Combat Hammer in May and August 2023. The third aircraft was equipped with additional communications equipment, a redesigned forward fuselage specifically for USAF requirements, and was the first equipped with EPAWSS. The F-15EX test program is able to save time and money because many systems such as the fly-by-wire and cockpit displays were already tested on the F-15SA and F-15QA with export customer funding by Saudi Arabia and Qatar.[34][6]
In August 2020, the USAF announced plans to replace F-15Cs of Air National Guard units in the Florida and Oregon with F-15EXs.[35][36] On 18 April 2023, the USAF announced that the California and Louisiana Air National Guards would replace their F-15C/D fleets with the F-15EX.[37] On 25 May 2023, it was announced that the 173rd Fighter Wing at Kingsley Field ANGB, Oregon, would become a Formal Training Unit (FTU) for the F-35A rather than the F-15EX. Basic F-15 training, for both the F-15E and F-15EX, will instead take place at Seymour Johnson AFB, North Carolina, from 2026 onwards.[38]
Potential operators
Egypt
A U.S. agreement to sell F-15 Advanced Eagles to Egypt for the Egyptian Air Force was announced in March 2022. A contract needs to be finalized after price and delivery date are determined.[39]
Israel
The Israeli Air Force ordered 25 F-15IA fighters based on the F-15EX and plans to upgrade 25 F-15Is to the F-15IA standard.[40]
Indonesia
In February 2022, the U.S. State Department approved the sale of up to 36 F-15IDs and related equipment to Indonesia.[41] As of 21 November 2022, Indonesia's planned purchase of F-15s is in advanced stages and awaiting final sign-off from the government, as stated by the Indonesian Minister of Defense. Speaking after meeting his U.S. counterpart Lloyd Austin in Jakarta, Prabowo Subianto said that Boeing had agreed to the financial offer proposed and he is confident the package is affordable.[42] In June 2023 during a Ministry of Defense press conference it was stated that the contract for the F-15 aircraft is still in the discussion stage with the U.S. government.[43] On 21 August 2023, Boeing and the Indonesian government signed a Memorandum of Understanding for the purchase of 24 F-15EX fighters.[44]
Poland
At MSPO 2023 in September 2023, Boeing pitched the F-15EX to Poland.[45] However, there were no specifics on price or delivery.[46]
Saudi Arabia
In addition to the 84 F-15SA purchased in 2011, Boeing discussed the sale of 54 F-15EXs to Saudi Arabia during the 2024 World Defense Show in Riyadh.[47] If the deal goes ahead, Saudi Arabia will look to upgrade their fleet of F-15SAs to the same standard as the EX.[48]
Thailand
The Royal Thai Air Force is seeking multirole fighters to replace the F-16A/Bs it has in service. On 31 December 2021, the RTAF Commander-in-chief announced that the Air Force proposes to buy 8 to 12 F-35 Lightning IIs in 2023. On 12 January 2022, the council of ministers approved the first batch of four F-35As.[49] On 22 May 2023, a Royal Thai Air Force source stated that the United States Department of Defense implied it will turn down Thailand's bid to buy F-35As, and instead offer F-16 Block 70 and F-15EX Eagle II fighters.[50]
F-15Cs from 44th Expeditionary Fighter Squadron along with RSAF F-15SAs in flight formation
The F-15SA (Saudi Advanced) is the initial Advanced Eagle variant for Royal Saudi Air Force and the baseline from which the F-15EX would be developed from. The F-15SA has the older AN/APG-63(V)3, AN/ALQ-239 Digital Electronic Warfare System (DEWS), AN/AAR-57 Common Missile Warning System (CMWS), and AN/AAS-42 "Tiger Eyes" IRST mounted on the targeting pod pylon.[51]
F-15QA "Ababil"
The F-15QA (Qatari Advanced) is the direct predecessor of the F-15EX, further development of the Advanced Eagle for Qatari Emiri Air Force with the introduction of the improved cockpit with large area display (LAD) and ADCP II mission computer. The F-15SA has AN/APG-82(V)1, DEWS, CMWS, and AN/AAS-42 IRST. In June 2017, Qatar signed a deal to buy 36 F-15QAs for US$12 billion (~$14.2 billion in 2022) which included weapons, support, equipment, and training, with up to 72 approved by the U.S. State Department.[52][53][54] On 22 June 2021, Boeing announced that it will integrate an Elbit Systems anti-jamming systems into the F-15QA, allowing it to fly into heavy electromagnetic interference environment uninterrupted.[55]
F-15EX
Two-seat variant for the U.S. Air Force. The F-15EX has AN/APG-82(V)1, AN/ALQ-250 EPAWSS, Legion Pod with AN/ASG-34(V)1 IRST21 sensor, but no CMWS.
F-15IA
The F-15IA (Israel Advanced) is a variant for the Israeli Air Force based on the F-15EX.[56] The Israel Defense Forces approved the plan to acquire 25 new-build F-15IA and upgrade 25 F-15Is to the F-15IA standard in February 2020.[56]
F-15IDN
The F-15IDN (formerly F-15ID) is a proposed export version of the F-15EX for the Indonesian Air Force.[44] In February 2022, the U.S. State Department approved the sale of up to 36 F-15IDs and related equipment to Indonesia worth around $13.9 billion.[41]
Proposed variants
F-15CX
Proposed single-seat variant for the U.S. Air Force with equivalent capability as the F-15EX, not procured due to single-seat Eagles are no longer in production.[14]
F-15GA
Boeing offered 90 F-15GA (German Advanced) fighters to Germany as replacements for its Tornado IDSs and ECRs.[57] Luftwaffe chose 35 F-35A Lightning II and 15 Eurofighter Typhoon (ECR EW variant) instead.[58]
Hardpoints: 4 wing pylons, fuselage pylons, bomb racks on CFTs with 23 hardpoints with a capacity of 29,500 lb (13,400 kg) of external fuel and ordnance
^Tirpak, John A. (18 April 2019). "F-15EX vs. F-35A". Air & Space Forces Magazine. Archived from the original on 3 August 2021. Retrieved 1 August 2021.
^Perrett, Bradley; Sweetman, Bill; Amy Butler (26 August 2013). "South Korean Fighter Order: AF Backs F-35". Aviation Week. Space Technology. Archived from the original on 27 March 2018. Retrieved 26 March 2018.
^ ab"Indonesia – F-15ID Aircraft". Defense Security Cooperation Agency. 10 February 2022. Archived from the original on 22 April 2022. Retrieved 11 February 2022.
