How the F-15 and F-22 should inform the F-47’s procurement

The US Air Force needs to make some hard choices about its fighter aircraft to avoid ceding air superiority to China. Two new stealth aircraft have appeared in Chinese skies, and rising J-20 production rates mean China could have up to 1,000 5th-generation fighters by 2030. 

The Air Force’s F-47 promises to help offset some of these Chinese gains, but it can only do that if Pentagon planners make an informed decision on how much to spend on the new fighter, how many to buy and when to buy them. 

The history of the F-15 and F-22 illustrates some of the choices lying ahead for the Air Force as it pursues the F-47 and reveals that, although the Air Force should consider buying more of the new fighters, a rush to acquire them could come at the expense of the service’s other procurement priorities.

The Air Force is still figuring out how to approach the cost and procurement schedule of the F-47. Cost estimates range from less than $100 million to as much as $300 million per aircraft. Other than naming 2028 as the goal for a debut flight, the procurement schedule for the F-47 is hardly discussed at all.

It is unknown exactly how many F-47s the US is seeking to buy. In 2023, then-Air Force Secretary Frank Kendall indicated the service plans to buy around 200 of what was then known as NGAD, but that was before the Trump administration’s program award to Boeing for the jet, as well as several years of real-world knowledge that could potentially change that figure. Still, for the sake of argument, we’ll use 200 as a baseline assumption. 

Past spending on F-15 and F-22 can help shed light on questions surrounding F-47 costs. From 1973 to 1991, the Air Force purchased more than 1,000 F-15s at an inflation-adjusted average unit cost of almost $84 million in fiscal 2027 dollars. Funding for the F-15 took up an average of around 32% of the Air Force’s aircraft procurement budget during this time. From 1999 to 2009, the Air Force bought fewer than 200 F-22s with an average price tag of $291 million each in FY27 dollars. This accounted for 27% of the Air Force’s aircraft procurement budget. Regardless of whether the cost of a single F-47 falls closer to high- or low-end estimates, historical data show that the Air Force should expect the fighter program to account for roughly 30% of its annual aircraft procurement budget.

Today’s threat perceptions and strategic priorities vis-à-vis China much more closely reflect those of the Cold War than the Global War on Terror. Thus, the Air Force should aim to purchase more F-47s than it did F-22s. Advancements in stealth, networking and munitions since the Cold War means the Air Force does not need to buy over 1,000 F-47s, either. Recent analysis recommends buying at least 300 F-47s to meet the operational requirements necessary to counter China. Irrespective of specifics, the Air Force should treat 200 F-47s as a floor, not a ceiling.

The F-15 and F-22 also give the Air Force two different acquisition schedules to apply to the F-47: “go fast” or “go steady.” The first five years of F-15 procurement consumed an average of more than half of the Air Force’s aircraft procurement budget during that time. In contrast, the F-22 only made up an average of around 22% of the aircraft procurement budget in its first five years of procurement. 

If the Air Force follows the go-fast example of the F-15, most of the money for buying new aircraft would go towards the F-47 in the first five years of the program before leveling off to around 30% in later years. Based on trends in new aircraft procurement spending over the last ten years and assuming F-47 procurement begins two years after its first flight, the Air Force would spend an average of more than $10.5 billion per year from 2030 to 2035 on the new fighter by following the go-fast model. For comparison, the Air Force spent an inflation adjusted average of nearly $6 billion annually on the F-35A procurement from 2020 to 2025. 

The primary benefit of the go-fast model is that it gives the Air Force significantly more sixth-generation fighters sooner. Assuming a high-end unit cost of $300 million, the go-fast model could give the Air Force around 210 F-47s by 2035. The main downside of this approach is that programmers may have to reduce funding for other major aircraft acquisition programs to account for increased spending on the F-47. 

Alternatively, the Air Force could follow the F-22’s go-steady model and keep the proportion of F-47 funding constant at around 30% of its aircraft procurement budget. Taking the go-steady approach with the F-47 would not be an aberration in historical spending patterns. Under this model, the Air Force would spend an average of about $5 billion from 2030 to 2035 on the F-47, which is below the annual average it spent buying F-35As from 2020 to 2025. The go-steady approach would lead to fewer F-47s entering service in the first five years of procurement than the go-fast model — only 100 fighters compared to around 210 — but it would leave funding available to continue to buy other types of aircraft. 

The two models highlight the main tradeoff facing the Air Force when it comes to the F-47: should it prioritize getting as many new fighters as soon as possible, at the expense of acquiring other aircraft? 

Without considerable and consistent increases to the aircraft procurement budget, the importance of other aircraft programs makes the F-22’s go-steady model better for the Air Force’s future needs. The Air Force cannot risk shifting funding from important aircraft procurement programs — like the B-21, collaborative combat aircraft (CCA) and air mobility aircraft — to the F-47. 

CCAs have been developed in part to bolster the capabilities of the F-47 at a much lower cost, so cutting the CCA fleet for more F-47s would be entirely counter to its intended purpose. The F-47 lacks the strike capacity necessary for the Indo-Pacific compared to the longer-range and higher-payload B-21. Plus, the bomber’s role in the air leg of the triad makes the B-21 crucial to maintaining nuclear deterrence. Dedicating a greater proportion of spending to the F-47 could also force the service to reduce the planned expansion and upgrade of its tanker and cargo aircraft inventories, thereby further limiting an already-constrained fleet of crucial enablers.

Some may see an increase in the budget as a panacea for F-47-related budget tradeoffs. Yet, Congress’ appetite for higher defense budgets appears to be waning after a recent historic uptick in defense spending. Throwing money at the problem will not suffice even if Congress revives their interest in higher defense spending, as the F-47 would still compete with other expensive priorities for funding, like Golden Dome or Golden Fleet.

The Air Force needs to assess its F-47 plans to keep ahead of China’s growing air superiority capabilities. Historical lessons from the F-15 and F-22 can help the service anticipate the decisions it will face when acquiring the F-47. If the Air Force can learn from the past, it can acquire a significant number of F-47s without sacrificing other critical aircraft procurement programs.

Casey Nicastro is a Senior Analyst at the Center for Strategic and Budgetary Assessments. His work primarily focuses on the defense budgets and force structures of the United States and its allies.