Lockheed And RTX Are Not At Loggerheads Over F-35 Engine Upgrades

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Last week’s Paris Air Show was punctuated by unusual statements from the two leading members of the F-35 fighter industrial team concerning upgrades to the aircraft’s engine.

The exchange began with an interview in Breaking Defense wherein the head of Lockheed Martin
Aeronautics—the prime contractor responsible for integrating all three variants of the airframe—opined that the government should purchase a new turbofan engine to bolster the fighter’s performance going forward.

Next-generation “adaptive” engines have been under development in an Air Force research program for several years; engine makers General Electric
and Pratt & Whitney have produced rival versions.

RTX, the parent company of Pratt & Whitney and incumbent prime contractor for the F-35’s engine, responded to the interview with a series of blunt criticisms. Pratt’s program chief on the existing engine, designated F135, complained that Ulmer’s comments were “confusing and misleading.”

At that point, the defense trade press piled on, highlighting the apparent split between the fighter’s airframe builder (Lockheed) and the fighter’s engine builder (Pratt). Such technical disagreements often occur behind the scenes on big weapons programs, but they seldom get a public airing.

Both companies contribute to my think tank. It seems there is less to this controversy than meets the eye.

Lockheed Martin released a statement clarifying that while an upgrade to the F-35’s propulsion system is necessary, it does not favor a particular solution. The company is agnostic on how the engine should be upgraded.

Apparently what Lockheed’s Ulmer was trying to say in his interview was that an all-new engine would meet enhanced performance requirements for the foreseeable future, whereas upgrades to the existing engine might at some point in the distant future not be adequate.

It’s not so clear how he framed his views, because much of the original interview was reported as paraphrased statements rather than direct quotes. It seems Ulmer’s intention was to describe what he viewed as the ideal solution to undefined challenges extending through 2070.

Pratt & Whitney, as the incumbent engine producer, was more focused on the near term—in particular, a series of 53 upgrades to the fighter collectively called Block 4 that will require more power, more cooling, and more management of the fighter’s thermal signature. (Stealthy aircraft like F-35 typically limit the heat emitted by engines.)

Pratt contends that if the fighter program upgrades the core of the existing F135 engine, that will be more than sufficient to meet Block 4 needs. If it also elects to upgrade the separate power and thermal management system, the company says it will be able to generate 80 kilowatts of power—enough to support all aircraft upgrades for the foreseeable future. So, there would be no need for a new engine ever on the fighter.

The Government Accountability Office last month released an assessment of the F-35 program that included a detailed discussion of options for boosting engine performance.

It isn’t possible to definitively say who is right in last week’s exchange, because nobody knows what the performance requirements of the fighter will be in, say, 2050. Engineering details have not been fully fleshed out on either the core upgrade or the adaptive engine, so comparisons are speculative. Indeed, we don’t even know which version of the adaptive powerplant might be the better candidate—GE’s or Pratt’s.

What we do know is that the Department of Defense has made a decision, and elected to pursue a core upgrade of the existing engine while killing the adaptive engine program. On March 29, senior officials from the three services using the fighter testified before Congress that they plan to pursue the core upgrade option.

The logic supporting this decision was driven mainly by cost considerations. It would cost much more to operate diverse engines rather than a single common engine across the fleet. The Air Force might be the only user of an adaptive engine, while the sea services and our allies chose to stick with the F135.

Installing an all-new engine on the fighter would not be easy, because the adaptive system weighs more and has a different configuration from the existing engine. It isn’t even certain, as Pratt points out, that the Pentagon would approve export of an advanced engine, given its sensitive technology.

These are not issues that Greg Ulmer addressed in his interview with Breaking Defense, because he was focused solely on the aircraft’s capability, not budget impacts, allied relations and the like. He was simply applying engineering logic to the challenge of staying ahead of adversaries through 2070.

The Pentagon would share his view if it had doubts about the performance of an upgraded F135, but it clearly does not. Within the planning horizon of decisionmakers, the core upgrade answers the mail at a more affordable price.

Congress may elect to keep the adaptive engine effort going until the F-35 program office more clearly defines its performance objectives into the 2040s, but odds are the Pratt solution will in the end be implemented. Lockheed Martin will accept that outcome so long as it is sure the solution meets requirements—which it almost certainly will.

So, what looked to be the most interesting military story coming out of the Paris Air Show is not going to have legs. It will flame out for lack of new fuel. General Electric, the perennial challenger to Pratt’s incumbency, may try to continue stoking the fire, but it has no assurance that its own version of the adaptive engine is the one the government would prefer anyway.

As noted above Lockheed Martin and Pratt & Whitney parent RTX both contribute to my think tank.

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