When Will Roper, the top acquisition and technology official at the Air Force, first saw how Boeing and Saab came up with the design for the Air Force’s new training jet, he realized the way the military devises new weapons, planes, satellites and missiles needed to change.

When designing the T-7 Red Hawk trainer aircraft, Boeing and Saab relied heavily on computer models to test system designs and iron out inconsistencies, a far less time-consuming approach, Boeing executives said in an interview, than physically piecing together the plane’s advance system. Though the company has long employed various forms of digital modeling, Boeing executives said the T-7 relied more heavily on it than any of the company’s previous aircraft.

Now Roper wants to make this sort of process a requirement for companies building any of the Air Force’s premier systems in the future. He is hoping to usher in a new era of weapons development in which computer-generated models — owned by the government and enabled by artificial intelligence technology — can test millions of possible designs in a virtual format before ever creating a prototype.

In this case, the outcome that seemed to impress him the most was the plane’s low price. Boeing’s Arlington-based defense division is known in the aerospace world for underbidding its rivals.

“For me, the Sputnik moment was looking under the hood at T-7,” Roper said. “The airplane came in at a much lower cost than we expected, which begs the question: How? That took me on the odyssey of how it was designed and assembled.”

What surprised Roper about the design process for the T-7 was the use of what’s known as “digital threading,” in which designers created a digital twin for the jet before manufacturing it. Starting in a virtual format means they can modify and test the plane’s systems with various configurations over the course of its design.

For Boeing, seeing a top Air Force official hold up the T-7 as a model for aircraft design should come as a welcome reprieve at a difficult time. The company’s reputation for sound engineering has been called into question over design flaws in the 737 Max commercial jetliner, which went undiscovered until a pair of plane crashes killed 346 people. Boeing’s defense and space division, despite problems with the KC-46 tanker and the Starliner capsule, has been more stable by comparison.

Roper recognized that a mostly digital design process represented a significant departure from the traditional way of doing things.

“There is an old adage in defense acquisition called ‘fly before you buy.’ It’s a caution that you ought to build something and test it out before you commit to buying it,” Roper said. “Today, you can digitally buy and fly before you even commit to buying that first prototype. Let’s do that in the military and then we can design things more frequently.​​”

Using a digital thread in the design process allows automated checks to happen in the background as the product is modified, essentially ensuring that as different parts of a plane or missile system are designed, they all fit together and don’t face integration problems.

Roper said that in the past, with the manual design of aircraft, small differences in parts that don’t fit together well can end up becoming big problems ― like when you are trying to put together a piece of furniture from Ikea and for some reason the holes don’t line up. Even a variance of a thousandth of an inch within a complicated system can create expensive headaches.

Mechanics can also learn how to assemble the plane digitally. For the Red Hawk, Roper said, mechanics were trained in a simulator to build the aircraft before it was ever put together in the real world.

“They achieved the same quality on their first airplane that would normally be achieved on the hundredth,” Roper said, because they came with the experience of having built the plane digitally.

Because of the approach, Roper said, the Air Force has been able to complete assembly and subsequent maintenance of the T-7 in record time, which he described as “off the charts, not near any other airplane in recorded history.”

It remains to be seen whether the T-7 will live up to expectations. It’s possible the low price and faster assembly process could entail trade-offs in other areas.

The U.S. Space Force, which was created out of the Air Force last year, also will apply this method to new system designs, including the missile system that will replace the Minuteman III ICBM fleet. Roper said Northrop Grumman created a digital twin and tried out over 6 billion different variants of the new ICBM using artificial intelligence and machine learning to weigh the trade-offs between cost and different possible characteristics.

It is also employing it to design a futuristic fighter jet meant to follow current aircraft such as the F-35 Joint Strike Fighter, under a program called Next Generation Air Dominance, or NGAD. That program has progressed to the point where a physical prototype ― already designed, assembled and tested in a virtual system ― has been flown, Roper said Tuesday.

If this approach is expected to become the norm, it will require a significant shift for U.S. weapons makers. An Air Force spokeswoman said the department does not yet have a written policy requiring digital design processes but is working on one. Roper says he considers the new approach to be a mandate for which any exception requires his personal sign-off.

This kind of process shift ― particularly the related requirement that the digital technology be fully owned by the government ― could be controversial for large defense companies that prefer to own and profit from the intellectual property underlying their products.

Hawk Carlisle, a retired Air Force general who now leads the National Defense Industrial Association, said a range of proprietary digital engineering efforts are already underway. He added that the defense industry on the whole would do well to transform its development process accordingly.

With digital engineering, “you can produce an airplane that is much faster, has fewer challenges in the manufacturing process, and is much more accurate and perfect. This is the way we have to go, and it’s about getting speed and capability out to the warfighter quickly,” he said.