U.S. Air Force Secretary Frank Kendall announced in June that the service’s Next-Generation Air Dominance program has entered engineering and manufacturing development. This transition from the prototype phase is a crucial step and a surprise, since the schedule remains classified—like almost everything about the program.

But based on what we do know, we have seen this movie before. The Next-Generation Air Dominance (NGAD) long-range combat aircraft is new, large and expensive, leveraging advanced technologies to satisfy an Air Force requirement. That also describes the General Dynamics F-111, developed in the 1960s under the TFX program. The F-111 story may help predict NGAD’s future.

First, NGAD’s price may make it vulnerable. In May, Kendall said it would cost “multiple hundreds of millions of dollars” per airplane, a very worrying figure, putting it between the $130 million Lockheed Martin F-22 and the $600 million Northrop Grumman B-21. As with the F-111, the price inevitably will be higher than expected, the consequence of the Air Force getting all the range and capacity it really wants (coupled with stealth, of course).

The F-111 provides an unpleasant precedent. Program unit costs (including development) went from $3.97 million to a final $15.01 million. That increase was accompanied by a procurement plan collapse from 1,388 jets to just 466, a near death spiral. These pre-inflation values sound quaint today, but the massive price increase almost led to the program’s cancellation.

Fortunately for the F-111, the strategic environment did not change much during its development. The threat, requirement and defense budget remained in place, so the program survived, barely. The strategic driver behind NGAD—the rise of China as a possible peer adversary—is unlikely to change, but it could. This would derail NGAD in much the same way that the Northrop Grumman B-2, F-22 and other single-service programs were stopped by the end of the Cold War after procurement of a small fraction of the planned buy.

Second, the F-111’s optimization for one service and the associated high price killed hopes for a bigger customer base. The Navy considered the F-111B for carrier operations but went with the smaller Grumman F-14 instead. The UK Royal Air Force hoped to buy 50 but cancelled its order. In the end, the only export sale was 28 aircraft to Australia.

With NGAD, this will likely repeat itself: Very few countries will have the requirement or financial resources to afford an aicraft in this class, especially since the key possible markets (Australia and Japan) will have just made budget-breaking investments to buy Lockheed Martin F-35s. A U.S. Navy NGAD variant likely will follow the F-111B to cancellation due to cost, size and other factors. Even the Air Force will not be able to afford as many as it wants, complicating legacy replacement and force structure plans.

Third, there is the technology question. The F-111 was the first production aircraft to use variable-geometry (“swing”) wings. NGAD may be the first production aircraft to use variable-bypass Adaptive Engine Transition Program (AETP) engines. Both of these technologies are a way of reconciling speed and range. While NGAD will offer other features to improve range, the AETP likely will be the best way to exceed the persistent 600-nm combat radius limit on USAF fighters.

Yet those swing wings contributed heavily to the F-111’s technical problems and cost overruns. It has been over 40 years since any new design used them, and when the last Panavia Tornado and Rockwell B-1 are retired in a few years, swing wings will be remembered as an interesting experiment that was not worth the cost, complexity, weight and maintenance expense. While AETP engines are quite promising and offer more than just additional range, there is no guarantee that they will not result in the same outcome. That’s another program risk.

Despite these concerns, the F-111 story also offers hope. It was not much of a tactical fighter, but with its large airframe, the F-111 proved adaptable to a wide variety of other USAF missions. An additional 76 FB-111 bomber variants were built, and 42 of the fighters were rebuilt as EF-111 electronic attack models. In 1985, strategist Edward Luttwak opined in The Pentagon and the Art of War, “today, some 20 years after the controversy, the F-111 . . . remains the most valued of all Air Force aircraft.” The Royal Australian Air Force did not retire its F-111s until 2010. With its F-35A and Boeing F/A-18E/F/G force, Australia no longer has anything like the F-111’s range and payload.

In other words, NGAD development may be risky and extremely costly, but if the F-111 is any guide, it will be a successful enhancement to the U.S. arsenal.