US airframer Boeing has delivered two more F-15EX Eagle II fighter jets to the US Air Force (USAF), marking the 3rd and 4th examples of the type to enter service globally.
The delivery took place on 20 December at Florida’s Eglin AFB, according to Boeing, which confirmed the delivery to FlightGlobal on 21 December.
The company says it is working to deliver two additional F-15EXs to the USAF before the end of 2023.
The delivery of tail numbers 003 and 004 comes 12 months after the originally planned date of December 2022. A report by the US Government Accountability Office blamed the delay on manufacturing issues at Boeing and sub-contracted suppliers, as well as budgetary uncertainty around the F-15EX programme.
The USAF has repeatedly changed its Eagle II procurement plan, with the fleet size dropping from an original 144 aircraft to as low as 80 jets at one point.
That number has subsequently rebounded to the current plan to acquire 104 of the twin-engined fighters.
Funding for six additional F-15EXs had been proposed by the US House of Representatives, but was rejected by the Senate in the 2024 National Defense Authorization Act (NDAA) – maintaining the planned for a 104 aircraft fleet.
Despite the F-15’s sterling service record, the latest iteration of the air-superiority-turned-multi-role fighter has previously attracted scrutiny in Congress – particularly over the jet’s price tag.
In the latest USAF contract with Boeing, the service will pay Boeing $3.9 billion for 48 F-1EXs, with a per-aircraft cost ranging from $90 million to $97 million over three production lots.
Those figures make the fourth-generation F-15EX more expensive than the fifth-generation Lockheed Martin F-35As flown by the USAF, which have an average cost of $82.5 million per fighter in the latest contract.
The higher cost and lack of stealth technology have previously generated scepticism in Congress about the efficacy of making substantial investments in the F-15EX.
However, Boeing has countered that the Eagle II’s massive 13,300kg (29,500lb) payload, combined with the latest avionics and an advanced suite of electronic warfare countermeasures, make the EX both more survivable than previous F-15 versions and better able to support fifth-generation fighters like the F-35.
In recent flights at Eglin, air force test pilots have proven the Eagle II capable of carrying up to 12 air-to-air missiles or three long-range Lockheed AGM-158 Joint Air-to-Surface Standoff Missiles.
By contrast, the F-35 boasts a payload 8,160kg, according to the USAF. The single-engined type typically carries weapons and fuel internally to maintain its low-observable profile, limiting capacity.
The F-35 can boost its weapons payload by carrying missiles externally, albeit at the expense of stealthiness.
Despite any past doubts, the NDAA passed by Congress on 14 December expresses continued support for the F-15EX acquisition programme.
“The conferees applaud the air force’s effort to field F-15EX across the active duty, reserve, and air national guard components,” the legislation states.
“But [we] remain concerned that tactical fighter capacity is not sufficient to meet combatant commander war fighting requirements at an acceptable level of risk,” Congress adds.
The USAF is in the process of retiring older F-15C/D models, withdrawing some of the longest-serving examples from squadrons in Japan this year.
The 2024 NDAA will allow the service to retire up to 68 F-15Es, under the assumption these will be replaced with F-15EXs already on order with Boeing.
The USAF currently has commitment for 56 Eagle II fighters.
Boeing is also marketing the F-15EX to overseas customers, with some success thus far.
Indonesia in August signed a memorandum of understanding to acquire up to 24 Eagle II fighters, although that deal has not been finalised.
US arms regulators in 2022 approved the sale to Indonesia of 36 F-15ID fighters – an Indonesia-specific variant based on the F-15EX. That sale was valued at $13.9 billion by the Defense Security Cooperation Agency.
Boeing is also pitching the F-15EX to Poland, as that country seeks to dramatically expand its air-combat capabilities. Warsaw plans to acquire 32 F-35As from Lockheed; those jets are currently under production.
Poland is also acquiring 48 Korea Aerospace Industries FA-50 light fighters as a means to rapidly modernise its current fleet from Soviet-era fighter aircraft.