The U.S. Air Force has begun the process of buying its first new F-15 Eagle fighters in more than 15 years.
The initial purchase of new, twin-engine F-15EXs from Boeing’s St. Louis production line could lead to a wider modernization of the Air Force’s Eagle fleet. Chicago-based Boeing last delivered an F-15, an E-model Strike Eagle, to the Air Force back in 2004.
The Air Force on Jan. 28, 2020 alerted Boeing and General Electric in Ohio of the service’s intention to order F-15EX jets from Boeing and the fighters’ F110-129 engines from General Electric.
A contract could follow as early as May 2020.
The GE F110-129 is a popular fighter engine. It powers half of the Air Force’s roughly 900 F-16s and most of the service’s 200 F-15Es, according to Air Force Magazine. Pratt & Whitney in Connecticut also makes fighter engines for the U.S. military, but the latest F-15 models are incompatible with Pratt’s engines.
The Air Force got Congress’s approval to spend $1.1 billion in 2020 buying eight F-15EXs. The service wants as many as 144 new Eagles to replace most of the Air Force’s roughly 240 1980s-vintage F-15Cs and Ds.
The flying branch is proposing to buy 18 each F-15EXs in the years 2021 to 2024, for a total of 80 new Eagles over the next five years, according to Air Force budget documents.
In the years after 2024, the Air Force has proposed to purchase another 64 F-15EXs. The new planes in total would cost $7.8 billion. The likely result, by the mid-2020s, would be a mixed fleet of old F-15Cs, Ds and Es and new F-15EXs.
Nine squadrons fly the F-15C and D for air-to-air missions -- three in the active force and six in the Air National Guard. Another nine units, all but one of which are in the active force, operate the F-15E in the air-to-ground role.
The F-15Es mostly date from the 1990s. The F-15Cs and Ds are 1970s- and 1980s-vintage aircraft. Each has racked up more than 8,300 flight hours, on average, the Air Force stated. That's roughly double the service-life that builder McDonnell Douglas, later Boeing, designed the plane for.
The F-15Es have tougher airframes than the F-15C and Ds have. The flying branch is upgrading the Strike Eagles with new radars as part of a plan to keep the fighter-bombers in service for decades to come.
Many of the F-15Cs, however, suffer from structural fatigue that limits their top speed. "Many F-15C/Ds are beyond their service life and have serious structures risks, wire chafing issues and obsolete parts," the Air Force stated. "Readiness goals are unachievable due to continuous structural inspections, time-consuming repairs and ongoing modernization efforts."
The F-15C and Ds "won't make it to 2030," Air Force major general David Krumm, the service's director of strategic plans and requirements, told Air Force reporters John Tirpak and Brian Everstine.
The Air Force plans to swap out old Eagles for new ones in squadrons that already fly F-15s, thus minimizing disruption to operations. Replacing the oldest and more tired F-15Cs and Ds for combat missions could allow the healthier old Eagles to continue flying in the training role.
The service also is considering arming the new F-15s with a hypersonic missile, potentially making the Eagle force the branch's first units to perform a new kind of specialist strike mission.
The F-15EX purchase has not been without controversy. The Pentagon’s Cost Analysis and Program Evaluation office advocated for the Boeing plane as a means of quickly replacing some of the oldest fighters in the Air Force’s inventory while the service also buys new F-35 stealth fighters.
Some lawmakers worried that F-15 purchases would rob the F-35 program of resources, but Air Force leaders have insisted the F-35 is their top priority. So far the new F-15 buy has had no impact on U.S. F-35 orders.