One of the current battles focuses on a seemingly simple question:
should the Air Force spend a portion of its budget on a new version of its oldest fighter,
the F-15 Eagle, or dedicate every available dollar to the F-35 Lightning,
its newest fighter? Complicating matters is that the two aircraft are built to do different things.
The single-engine F-35A is meant to carry out penetrating strikes into protected enemy airspace,
relying on stealth and powerful sensors to avoid enemy troops.
Whereas the Air Force’s soon-to-be-retired twin-engine F-15C fighters are air-to-air-only
aircraft that patrol the airspace around the United States and foreign military bases,
fending off intruders and potential attackers. The F-15 is non-stealthy as a fighter can get,
but has a 33 percent higher maximum speed of Mach 2.5 and a longer range.
As foreign air forces have ordered more and more heavily modernized F-15s over the last
few decades, Boeing is offering to an F-15EX variant that will incorporate all those new
bits of technology while also incorporating the multirole capability the F-15C lacks. Since the
premature retirement of the F-22 Raptor program in 2009, the F-35 Lightning has been the Air Force's
primary new fighter program. Despite being behind schedule, the program has been a top
Air Force priority for more than a decade and was anticipated to remain the USAF's
only fighter program until a future capability, which has yet to be specified, became operational.
Now, the F-35 is up against an old jet design, a version of the F-15 Strike Eagle; an aircraft
from a different age, built for a different task. Despite the Air Force's denials, the
two planes are competing for a restricted amount of money inside the service's fighter portfolio.
The Air Force has requested $1.1 billion in the fiscal 2020 budget to purchase the first eight
of 144 F-15EX aircraft. The new planes look a lot like the export variants constructed for Qatar.
The F-15EX is a two-seat fighter that can be flown by one or two pilots
and is designed to replace F-15C and D aircraft that are reaching the end of their service lives.
Under the plan, the Air Force would get two F-15EX jets in 2022, six more in 2023,
and a total of 80 planes over the next five years. Separately, the 2020 budget plan includes
$949 million for F-15 upgrades. The decision to buy more F-15s was made by the Pentagon's Cost
and Program Evaluation office, or CAPE, and was backed by former Defense Secretary James Mattis.
The Air Force has justified its intention to buy new F-15s as a method to sustain fighter capacity,
despite its long-held position of investing solely in fifth-generation fighter technology,
given the aging of the F-15C fleet and the slow pace of F-35 acquisitions.
While the Air Force insists that purchasing F-15EXs will not reduce the need for 1,763 F-35s,
history and the Air Force's own budget proposal indicate otherwise. The 2020 budget submission
shows the Air Force buying 24 fewer F-35s over the next five years compared to last year’s plan.
The opening for the F-15EX results from the age and condition of today’s F-15Cs. Designed
as air superiority fighters and first fielded in the 1970s, the F-15Cs were planned to have
retired by now. But the premature termination of the F-22 after acquiring 186 aircraft,
less than half the planned production compelled the Air Force to extend their service.
Now, key structural components are reaching the end of their engineered service life so much
so that many F-15Cs must operate today under significant speed and G-loading restrictions.
The Air Force's argument for the F-15EX is based on capacity preservation.
The F-15Cs will age out of the inventory faster than new F-35s can be delivered,
reducing the available fighter fleet at a time when the Air Force argues it’s already seven
squadrons short of the 62 officials say they need to meet the National Defense Strategy.
The F-15EX, USAF argues, is essentially an in-production aircraft. It has upward of
70 percent parts commonality with the F-15C and E already in USAF service and can use almost all
the same ground equipment, hangars, simulators and other support gear as the Eagles now in service.
At a unit price roughly comparable to that of the F-35, F-15 squadrons could transition
to the F-15EX in a matter of weeks, whereas converting pilots, maintainers, facilities
and equipment to the F-35 takes many months. The F-15EX, though, is a fourth-generation
aircraft which lacks the stealth characteristics and sensor fusion of the F-35 and F-22
and therefore won’t be able to survive against modern air defenses for very much longer.
USAF has said that 2028 is probably the latest the jet could conceivably operate
close to contested enemy airspace. However, CAPE and Air Force officials see viable continuing
missions for the F-15EX in homeland and airbase defense, in maintaining no-fly zones where air
defenses are limited or nonexistent, and in delivering standoff munitions.
Contrary to one might expect, the F-35A is no more expensive than an F-15EX at around
$85 million each. That reflects success in cutting initially alarming F-35 costs thanks
to massive economies of scale in its favor the Pentagon expects to order over 2,000 F-35s.
However, if the F-15EX has a cost advantage, it comes in terms of operating costs.
The F-15EX is forecast to cost $27,000 per flight hour,
while the Air Force is struggling to get F-35 operating costs to $34,000 an hour. As the Air
Force is also very familiar with F-15 after forty years of service, the F-15EX likely benefit from
higher readiness rates than the notoriously low ones currently afflicting the F-35.
In short, The F-35 and F-15EX were designed in different eras for different missions.
The F-15C was designed for air superiority in the pre-stealth era; the F-35 to be the
battlefield “quarterback,” gathering vast amounts of information from behind enemy lines
while executing stealthy strikes and picking off enemy fighters. Yet, as Congress decides
how to invest in future aircraft, comparisons are necessary as the two planes compete for resources.