DAYTON, Ohio — The futuristic Next Generation Air Dominance fighter platform now within the works is prone to be one of the vital complex, highest-stakes weapon acquisitions within the U.S. Air Force’s history.
The sixth-generation fighter jet is predicted to incorporate recent technologies starting from cutting-edge adaptive engines to an autonomous drone flying alongside its wings. If NGAD works because the service hopes, it could prove critical in a possible war against China.
But in recent times, the advanced digital engineering techniques the Air Force once thought would result in a revolution in rapid aircraft development and fielding haven’t all the time panned out. The concept allows engineers to create designs or models to check assumptions more quickly and accurately. And with digital engineering expected to play a central role within the NGAD effort, experts say the service can have to make sure the technique lives as much as its promise.
This isn’t the primary time the Air Force looked to a digital design revolution to usher in a brand new generation of aircraft. In the course of the service’s last major recent jet acquisition, the T-7A Red Hawk trainer, the Air Force and manufacturer Boeing promised this system would result in a fresh way of designing and constructing future aircraft.
The service was so bullish on the potential advantages of a future built on digital aircraft engineering that in 2020 it made a short-lived try and rebrand the trainer the “eT-7,” and likewise dub future aircraft designed in this fashion with an “e” prefix.
Since then, a series of missteps and delays have pushed back key milestones on the T-7 — and caused a little bit of the shine to rub off from its much-heralded digital design approach.
In a May breakfast, Air Force Secretary Frank Kendall made clear the extent to which digital engineering had lost its luster within the wake of the T-7′s troubles.
“It’s a major improvement, but it surely has been overhyped,” Kendall told reporters. “More integrated digital designs, higher modeling all help, but they’re not revolutionary. … They don’t replace testing entirely.”
‘Not a magic wand’
Digital engineering has been around in a single form or one other for the reason that Seventies, said Heather Penney, a senior resident fellow on the Mitchell Institute for Aerospace Studies. Computer-aided design helped shape many aircraft in use today, including the B-2 Spirit stealth bomber, F-22 Raptor jet and F-35 Joint Strike Fighter.
The concept evolved as processing, algorithms, modeling and simulation improved, she explained. Now, Penney said, digital engineering can include every little thing from 3D models of individual aircraft parts — fuel pumps, hydraulic lines, electrical system bundles and more — to models of how an aircraft’s various systems interact with each other or the aircraft as an entire.
Having this kind of digital model doesn’t only inform the aircraft’s design, she said, but additionally shapes the tooling and manufacturing of the aircraft. For example of a major advancement this technology can provide, she pointed to Boeing’s “amazing” ability to make use of digital processes to fabricate T-7 components so accurately that they fit together without having shims. And he or she highlighted the B-21 and the LGM-35A Sentinel intercontinental ballistic missile as examples of complex and so-far successful Air Force acquisitions that made tremendous use of digital engineering.
But, she noted, “it’s not a magic wand that waves away any bumps [in] design,” and may’t take the place of solid engineering fundamentals.
An aerodynamic instability within the T-7 often known as “wing rock,” through which its wings could have dangerously rocked back-and-forth in some flight conditions, was fixed in 2021, but was one among several aspects that prompted the Air Force and Boeing to begin to rethink its schedule in 2022.
Additional issues, including an escape system and ejection seat that would endanger the T-7′s pilots, in addition to glitches with its flight control software, led to further delays.
For “the eT-7, digital engineering was going to make this airplane go fast, the design was going to go fast, it was going to knit everybody together, it was going to be a bumpless design process,” Penney said. “What our experience with the eT-7 has been is that digital engineering is only a tool. You continue to need to get the engineering right.”
Penney said blame for the T-7′s problems, like those with its ejection seat system, can’t be laid on the feet of digital engineering — but notably, digital modeling didn’t catch the T-7′s issues upfront.
In roundtables with reporters on the Air Force’s Life Cycle Industry Days, held July 31-Aug. 1 in Ohio, officials described how the service is attempting to expand its approach to digital engineering by spreading the advantages throughout your entire life span of an aircraft — in an idea it calls digital materiel management.
In a June whitepaper, Air Force Materiel Command said digital materiel management goals to dramatically speed up and streamline the processes of designing, creating and sustaining aircraft or other systems through the use of digital methods throughout their life cycles, from the initial idea to retirement.
“We’re playing the long game,” said Brig. Gen. Dale White, the Air Force’s program executive officer for fighters and advanced aircraft. “That’s critically vital. If you happen to just have a look at digital through the lens of design and development and test, you’re going to limit yourself. Everyone knows nearly all of the funding is spent on the sustainment tail.”
“And so having the ability to make decisions that you just couldn’t normally make before, since you didn’t have that quantity of knowledge this early in the method, really is a game changer,” continued White, who oversees the NGAD program.
By having a single digital trail following an aircraft through its entire life cycle, officials argue, it’ll be easier to perform techniques akin to predictive maintenance, which helps track exactly how long parts have been on a plane and results in their alternative before they’re prone to fail.
Definitely, the concept can work, however the Government Accountability Office present in a December 2022 report that the military hasn’t taken full advantage of it. Technology limitations are hampering widespread adoption of predictive maintenance, akin to problems with older information systems and an absence of digitized maintenance manuals.
The military reported “predictive maintenance has enabled pilots to avoid helicopter aircraft accidents and discover failures that were undetected by mechanics, avoid maintenance costs, and redirect maintenance personnel to other work creating cost efficiencies,” GAO said within the report. But “the examples are from limited experience. [And] to be able to implement predictive maintenance more broadly, changes can be essential to mainstream business processes to deal with resource challenges from personnel, parts, and technology.”
“In accordance with military service officials, unplanned maintenance — which adversely affects costs and operations — will be reduced through greater use of predictive maintenance,” the report read. “Military service officials acknowledge that, while they’ve examples of improvements they attribute to predictive maintenance implementation, the examples are from limited experience, and the military services generally lack metrics to guage the outcomes of predictive maintenance.”
Next-gen propulsion
In May, the Air Force took its most important public step forward up to now on NGAD when it announced it had sent industry a classified solicitation for an engineering and manufacturing development contract for the secretive program. The Air Force also said it plans to award the contract in 2024, with Lockheed Martin and Boeing widely expected to be the 2 remaining bidders. The Air Force hopes to have NGAD in production by the tip of this decade.
And with Kendall estimating each fighter’s price tag at a whole bunch of hundreds of thousands of dollars, the service can’t afford to get it improper.
To date, little has been said about how digital engineering is contributing to NGAD. In the course of the May roundtable, just a few days after the Air Force’s solicitation announcement, Kendall described a situation where service engineers and other NGAD program officials at Wright-Patterson Air Force Base in Ohio were “living in the identical design space because the bidders.” Program officials have direct access to the databases that the 2 firms vying for this system use to hone their NGAD designs, Kendall said, and use that access to supply their very own suggestions.
In Dayton, Ohio, White — who oversees the creation of NGAD — and other officials offered more insight into how the Air Force and contractors are using digital engineering as they ramp up work designing the aircraft and propulsion systems.
When past fighters were designed, White explained, they were sketched out on paper in two dimensions. Because the designs went through one iteration after one other, he said, those sheets multiplied until reams of paper tracing each step in an aircraft’s evolution piled up.
But as NGAD takes shape, White said, those mountains of paper have been replaced by a always evolving digital design. In years and even a long time to come back, he added, that can make it easier for NGAD to evolve to remain ahead of the threats it’ll face.
“It’s a living thing,” he said. “You may always make informed decisions about where you’re going and where you think that it’s essential to be. … It’s not enough to be digital just from an engineering perspective. You’ve got to have an excellent foundation to know what the threat is doing. And that’s going to permit us greater flexibility.”
“What it’s allowing us to do is turn out to be more informed buyers,” he added. “On this world, there are a number of belongings you don’t need to do physically because you have got greater visibility and a greater grasp and command of the knowledge due to the digital [tools] we didn’t have before.”
And the NGAD’s propulsion system can be the primary entirely recent military propulsion system to be digitally designed and produced, in keeping with John Sneden, director of the Air Force’s propulsion directorate.
The businesses working on the Next Generation Adaptive Propulsion system, or NGAP — primarily GE Aerospace and Pratt & Whitney, alongside Lockheed Martin, Boeing and Northrop Grumman — are only now stepping into a spot where they will start designing it in a very digital, 3D environment, he said. Given the last fighter engines designed for the Air Force were created a long time ago for the F-35 and F-22, Sneden said, this can be a recent approach.
“All of that predated the digital environment,” he explained. “There really hasn’t been a requirement that’s on the market for [digital engine designers] to essentially sink their teeth into until we got to NGAD.”
Having the propulsion system digitally designed and built, from the bottom up, will make it easier to update and further develop at pace with evolving threats, Sneden added.
NGAP remains to be within the early design stages, he said, but because it moves into the testing phase, the digital-based modeling will help fine-tune digital tests and mix various models to see the second- and third-order effects of design changes.
“If you start stepping into testing models, you may have one which’s different for structures, you could have one other one which’s different for thermodynamic properties of the engines,” Sneden explained. “Can we pour those together so we are able to higher see, if you make a change here, here’s the way it impacts you downstream?”
When the time comes to begin prototyping or constructing the engines, he added, the contractors can send 3D digital blueprints to their very own suppliers to make components, as a substitute of counting on 2D drawings.
‘Physics gets a vote’
Penney stressed that for digital engineering to yield advantages, a program must take the effort and time from the beginning to know exactly how it’ll use digital tools.
“If you happen to don’t have that foundation, that can leave you with technical debt as you start to maneuver forward,” Penney said, and will inadvertently cause problems further on down the road. “You’ve got to get it right initially.”
In Dayton, officials agreed with Kendall’s comments that advancements in digital modeling — while vital — can’t entirely replace real-world testing. They described how they hope future programs can use each techniques to fill within the gaps a single approach would offer.
The Air Force, together with GE Aerospace and Pratt & Whitney, already conducted an incredible deal of design and development on adaptive engines that were regarded as replacements for the F-35 under the Adaptive Engine Transition Program, or AETP.
The Pentagon ultimately decided not to place AETP within the F-35, as a substitute choosing an upgrade of the fighter’s current engines. But AETP engine technology — akin to the adaptive fans that can allow the engine to shift to probably the most efficient configuration for a given situation — will likely be folded into NGAD’s engine development process.
Sneden said by leveraging existing AETP technology, NGAP can reap the perfect of each worlds on the subject of testing. NGAP will use digital modeling, he explained, but those digital tests can be shaped by real-world results from prior tests conducted for AETP.
“Once we’re testing an engine, we’re actually testing a series of technologies to learn the way they work so you’ll be able to actually craft a testing baseline,” Sneden said. “We’ve done real-world testing [on the XA100 and XA101 engines] so we are able to see how adaptive engine technology runs across the portfolio, how those materials delay, how the adaptive fan works — all of that.
“Now what you’ll be able to do is take that testing baseline and begin incorporating it into your NGAP understanding, and begin to merge those worlds of ‘real world’ and ‘digital’ together so you have got this nice fusion that happens.”
White, in his own roundtable, underscored the Air Force’s intent to make use of digital testing to buttress real-world testing. His office hopes that combining the 2 types of testing will allow it to cover gaps and yield a much richer set of information.
“We’re using the virtual elements of the model to ensure that that we’re filling within the blanks of the info,” White said. “After which as you try this, it’s form of like a puzzle. The puzzle starts to fill its way out, and also you turn out to be more comfortable.”
Having multiple ways to conduct testing is useful when attempting to put fledgling aircraft through among the more extreme flying conditions they could encounter, said Col. Kirt Cassell, chief of the Air Force’s T-7 Red Hawk program office.
“Irrespective of how good your digital engineering is, physics gets a vote,” Cassell said. “If you’re at high angles of attack … it’s still very difficult to get advanced models” to predict the real-world physics.
Sneden noted the Air Force hasn’t even begun to achieve the boundaries of how digital tools might help keep an engine running throughout its entire life.
For instance, he said, digital tools could help find ways to make spare parts for an engine more easily or efficiently with additive manufacturing. Or it could help discover a recent solution to repair a broken part as a substitute of taking the lengthy and expensive step of replacing it with a wholly recent one, he said.
“We’re just beginning to lean into that technology,” he added.
Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.