What Does Air Force Interest in More Powerful Engines for CCAs Mean?

The Air Force has been looking at drones to mix with manned fighters as Collaborative Combat Aircraft (CCAs). Now, it’s signaling something about what it wants to buy.

The signal came in the form of a modest Request for Information (RFI) it issued last week. In two brief paragraphs the RFI asks industry for information on “off-the-shelf, modified off-the-shelf, derivative, and new engine designs” for “3000-8000 lbf thrust class engines” for CCAs.

The request stands out because the current crop of potential large-class CCAs from Kratos, Boeing, Anduril and others generally have 2,000 lb-thrust class engines.

In the RFI, the Air Force says its interest in higher thrust powerplants lies in evaluating “increased range, reduced runway take-off distance, increased Mach capability, increased power and thermal capacity, and increased payload”.

It’s worth considering that would-be CCA makers have based their designs and engine choices on what they have heretofore thought (via informal discussion) the Air Force wants in terms of performance from such aircraft. But the RFI indicates that may have changed and OEMs with horses in the running are almost universally mum about what it means.

Boeing, which makes the MQ-28 Ghost Bat, had no comment on the RFI with respect to its import or how the Ghost Bat might integrate a higher thrust engine. Kratos Turbine Technologies, and Anduril (formerly Blue Force Technolgies) similarly had no comment. Lockheed Martin
LMT
had not responded as of press time.

General Atomics Aeronautical Systems Inc. (GA ASI, which has put forward its Gambit series concept CCAs) did offer some general thoughts on the RFI, asserting that it is not surprised by the Air Force’s request. Company spokesman, C. Mark Brinkley, said;

“The Gambit Series was designed, from its inception, to use any one of 11 different engines already on the market. There are pros and cons for each engine, and they have varying thrust outputs. I can’t get into the specifics, but the idea is provide the government with access to a deep supply base from the beginning and offer flexibility by design.”

The lack of specifics and the radio silence from GA ASI’s counterparts obviously reflects competitive reluctance to offer any information they may put forward in their RFI responses. But it also potentially reflects some unease with the Air Force’s query and what it portends.

In asking for higher thrust engine information, the Air Force’s self-described interest in increased range, speed, power, thermal capacity and payload shows its desire for larger, longer range CCAs to operate across long Indo-Pacific distances, short takeoff capability notwithstanding.

The logical knock-on effect of that desire for more power, payload and range is more fuel consumption and the need for more onboard fuel. This alone suggests the possibility that aircraft like the XQ-58 Valkyrie and MQ-28 Ghost Bat aren’t large enough to meet the Air Force’s requirements.

It also suggests the Air Force has shifted to a more strategically-oriented view of CCAs than put forward in previous years wherein collaborative aircraft were depicted as relatively low-cost, “attritable” machines to team with manned fighters/bombers.

If that is the case, large-class CCAs will be more expensive than anticipated, America will build fewer of them, and potential industry winners from among the pool above will be fewer. This possibility likely has OEMs hurrying behind the curtains as they recognize that the stakes have gone up.

Richard Aboulafia, managing director at AeroDynamic Advisory, agrees that the focus may now be centered on fewer, larger CCAs.

“Larger, longer-ranged CCAs also helps solve the deployability problem,” Aboulafia says. “In the Pacific, it wasn’t really clear where shorter-ranged CCAs were going to be based.”

Aboulafia has also recently pointed out that the artificial intelligence-enabled autonomy that is supposed to underpin small and large CCAs may not be panning out. This may be another factor in USAF interest in larger aircraft which may need to operate with a balance of autonomy and remote human input tilted toward less of the former.

“If AI limitations keep the smaller size class from reaching its full potential through autonomy, then the larger size class might be more relevant, and might be faster to enter service in larger numbers,” Aboulafia observes.

“It’s all about the ratio. If we have AI-driven autonomy, then having multiple smaller CCAs per piloted jet makes sense. But if AI limitations keep the ratio to 1-1, then larger CCAs might be more effective.”

A potentially related point is that despite all the noise about the Pentagon’s Replicator program for masses of small autonomous drones, there is not a clear funding stream nor explicitly identified new funding for Replicator. The Defense Innovation Unit (which will manage the program) is expected to weigh in on this in a week or two but its strategy is unknown for now.

Aboualfia also opines that this RFI could indicate a market about to skew. “Smaller CCAs promised a lower barrier to entry for new companies like Kratos. Bigger air vehicles, with more complex systems and capabilities, definitely favor incumbent combat aircraft primes.”

As for off-the-shelf engines that might fit the interest expressed in the RFI, Aboulafia pointed to Honeywell’s F124 turbofan (6280 lbs-thrust) which already powers manned trainer aircraft like the Navy’s T-45 Goshawk and Leonardo M346 Master as well as the Czech Aero L159 light combat jet and which powered Boeing’s X-45A unmanned combat aerial vehicle (UCAV) demonstrator in the early 2000s.

Reviews of potential engine candidates and what such choices may mean for existing airframe designs are moving forward with urgency at potential CCA OEMs. The Air Force/DoD is expecting responses by 5:00 pm EST on November 15.