The Gold Institute for International Strategy | John C. Wohlstetter and Travis Korson
October 11, 2023
A Congressional Research Service report (RL30563, issued May 2, 2022) tallies the total F-35 Lightning II Joint Strike Fighter program at 2,456 aircraft. Including development costs, this works out to $2.4 trillion, the largest defense aircraft procurement ever.
From the outset, the program has faced daunting technical challenges, with different F-35 versions for the Air Force, Navy, and Marines. In seeking to build planes that encompass all missions conducted by the prior generation of fighters, the Pentagon is ignoring lessons gleaned from the 1960s Tactical Fighter Experimental (TFX) program.
The program was embraced eagerly in 1961 by Robert S. McNamara, President John F. Kennedy’s first secretary of defense. The F-111/TFX faced multiple performance shortfalls and serial cost overruns. It had an underpowered engine that could not meet the speed requirement of supersonic dash for 300 miles. The F-111 could only fly supersonic for — not a misprint — 30 miles. It was the heaviest tactical fighter, and it had the lowest thrust-to-weight ratio and the highest ratio of aircraft weight to wing area. When an upgraded engine was produced, it could only be put into 235 of the 437 F-111s; the others could not be retrofitted for the new engine.
TFX lasted until March 1968, when McNamara’s successor, Clark Clifford, cancelled the joint program. The Air Force ultimately purchased 437 aircraft in no less than eight configurations: one-third its original planned buy at four times the total program cost. The Navy F-111 fared even worse because, as a fleet-defense interceptor, it faced more complex challenges, and, as a result, only eight planes out of a planned 335 were purchased.
Despite these missteps of the past, the Department of Defense is, some 60 years later, once again in the process of procuring a multi-mission fighter to supplant existing aircraft. This brings us to the F-35 today.
Plans to equip the F-35 with multiple enhanced capabilities with the goal of meeting the needs of all the services mean that the thrust, power, and thermal management limitations of the current F135 engine will be exceeded by the end of the decade. With the F135 engine already running twice as hot as the design goal and driving maintenance costs higher, mostly due to the Honeywell-supplied power and thermal management system (PTMS), there is agreement that a propulsion upgrade is urgently needed in order to keep the aircraft mission capable. But two competing views have emerged as to the best path forward.
The current provider of the F135 engine, Pratt & Whitney, has proposed an Engine Core Upgrade (ECU). An upgrade to the existing engine, it would improve thrust and range by more than 10 percent each along with providing a 5 percent boost in vertical lift and a 50 percent improvement in thermal management. This modernization would also be a retrofit, so it would rely on a similar supply chain, infrastructure, and sustainment network.
The Adaptive Engine Transition Program (AETP), meanwhile, would be a wholesale replacement of the Pratt & Whitney F135 engine. GE asserts that its XA100 engine will achieve 25 percent better fuel efficiency, resulting in a 20 percent range gain, 10 to 20 percent more thrust, and, thus, twice the engine-cooling capability (which runs off engine thrust). But there are several hurdles that call into question the viability of adding the GE engine to the F-35.
For starters, the XA100 is incompatible with the Marine Corps F-35B STOVL variant. USAF retired Maj. Gen. John L. Barry has also flagged the fact that the Navy version of the AETP would be different enough from the Air Force that it would require a separate Engineering and Manufacturing Development phase.
Writing in Forbes, national security expert Loren Thompson cites 10 additional reasons why GE’s XA100 would not work with the F-35: (1) weak rationale; (2) excessive cost; (3) joint interoperability; (4) allied interoperability; (5) logistical commonality; (6) technical risk; (7) delayed availability; (8) engine exportability; (9) untapped potential; (10) fiscal responsibility. Most notable among these are technical risk — GE has never built an engine anything like the XA100; and untapped potential, in the form of failing to exploit the modular design of the F135 engine that was intended to facilitate upgrades.
The recent loss of an F-35 over South Carolina, and a GAO report that was released shortly after the incident, illustrates real life consequences and ongoing risks of undetected problems and program management shortfalls currently plaguing the Pentagon vis-à-vis the fighter jet. They also call into question the wisdom of adding more maintenance complexity and cost to the F-35 program at this time.
With only 450 F-35s in service — a mere 18 percent of the total procurement — only 55 percent are mission capable, as the Pentagon is “behind schedule” in maintaining the fighter jets. Attesting to the centrality of ongoing management of the program, of the $1.7 trillion appropriated for the F-35, only $400 billion represents purchase costs, with the remaining $1.3 trillion allocated to maintenance and support. As the GAO surmises, “the preparedness of our military depends upon” charting “an affordable path forward,” and that involves streamlining, not complicating sustainment programs.
The debate on the best way forward currently sits in Congress. Despite the fact that the Air Force has indicated it is committed to moving forward with the ECU, the House of Representatives’ version of the National Defense Authorization Act (NDAA) was recently passed with $588 million in funding for the AETP. Air Force Secretary Frank Kendall reacted to this move by saying, “As often happens, the Hill doesn’t want to let go.”
The House version of the NDAA must now be reconciled with the Senate version, which fully funds the ECU and includes a specific prohibition against integrating any alternate engine, such as the AETP, on any F-35 variant. As negotiators from both chambers of Congress meet in Conference Committee to hash out differences between these two NDAA versions, we will see which pathway prevails.
Looking back, one might ask if McNamara, while CEO of Ford Motor, would have entertained a proposal to build a vehicle combining the carrying capacity of a truck, the comfort of a luxury limousine, and the speed of a racing car. Then again, one might ask why JFK selected as his defense secretary a business leader who committed the auto industry’s most famous flop — $250 million invested over a decade so as to produce 18 Edsel models, at an accumulated sunk cost that as of its 1959 public sales debut would equal $3.6 billion in 2023 dollars.
It all comes down to this: Should the Pentagon make a bet-the-company wager? A strong rule of prudence is to never bet the company. Cost estimates for the AETP range from $6 billion to $40 billion in a F-35 program already $14 billion in the red. Conversely, ECU cost estimates tally $2.4 billion, with a proven technology solution.
The TFX program presents a cautionary tale. Betting on multi-level technology innovations is a crapshoot, a wager that experience teaches is usually a bum bet. Moving forward, leaders at the Pentagon would be wise to minimize unnecessary additional investments in the F-35 program — sticking to the most cost-effective and technologically compatible upgrades — and reserve more technologically ambitious options for a 6th generation fighter.