LYNN, Mass.—Three decades ago, GE Aerospace tested a technology that could’ve made the F-16 more agile. It worked, but was never fielded. Instead, it sat in a box in a warehouse—until defense tech startup Shield AI called.
“They reached out to us and said…‘Do you still have that capability? And the truth is, we hadn’t fielded it. After we did the demonstration, it basically went into storage,” said Steve “Doogie” Russell, VP and general manager of GE’s Edison Works. “And the solution that we’ve offered to Shield on that is an F110 engine with a nozzle in the back that we call the axisymmetric vectoring exhaust nozzle, or AVEN.”
Not having to start from scratch on the technology was critical for saving time and speeding up flight testing for its collaborative combat aircraft, X-BAT, an autonomous fighter jet designed to take off and land vertically, Shiva Vallabhaneni, senior propulsion engineer for Shield AI, told Defense One.
“X-BAT always needed to have a thrust vector controlled capability to do vertical flight,” Vallabhaneni. “So we really went out and said…where can we get one? Is there technology that already exists?”
The aircraft “needs to be able to move quickly…in any direction,” GE’s Russell told reporters during a visit to the company’s factory here in Lynn.
That comes with a special set of propulsion requirements, so GE paired its 30-year-old AVEN nozzle with its F110 engine found in the F-16 fighter jet for the X-BAT.
The aircraft needs a high-thrust propulsion system “because you’ve got to be able to have that aircraft take off vertically and then, when it comes back, land at high thrust mode. It also needs to have really good gas mileages. So [thrust-specific fuel consumption], once it’s up and away, needs to be able to hit the range requirements that they’re trying to get,” Russell said.
And, he said, when it lands, it needs a nozzle “on the back that can move around to balance the aircraft as it’s coming in to maneuver into position to dock back up. That’s a pretty significant propulsion challenge and pretty unique.”
In under a year, the companies dusted off the AVEN nozzle, refurbished the original hardware, completely rewrote the software code, and have been testing it with the engine.
The hardware was in very good condition, and AVEN One, which is being used for the X-BAT prototype, has “close to 100 percent of the same hardware that was flown from the 90s,” Vallabhaneni said. “That was the biggest key unlock for getting us to an X-BAT prototype flight test this year—100 percent. In some ways, building that thrust vector control nozzle, verifying its technology, and doing it at the speed that we needed to is probably harder than getting an engine.”
The companies recently completed testing the engine integrated with the full AVEN nozzle at GE Aerospace’s test facility in Peebles, Ohio.
Now, the goal is to complete a tethered vertical flight test of the aircraft by the end of the year, to demonstrate that it can hover and remain stable.
Through data collected during testing, engineers can create models that will help develop vertical flight control laws, Vallabhaneni said.
During the planned test, the prototype aircraft will hang from a 180-foot crane to minimize risk. The test will be successful if slack in the tether is created during the hover.
“Shield AI—much like SpaceX, Rocket Lab, all of these other new space companies—the mindset is: be hardware rich, take risks because the faster we get to test, the faster we can learn what the real problems are. And so the tether gives peace of mind that we’re buying off risk, but we’re not buying off risk irresponsibly,” Vallabhaneni said.
But the AVEN nozzle won’t just be in the prototype—Shield AI plans to make more and eventually tweak the technology along the way. Building additional AVEN nozzles that keep the legacy design will help increase testing effort. And any future changes will likely focus on performance, Vallabhaneni said.
“Lighter, faster, more performance, right? Those are the things that we’re going to go and chase and achieve on the future version of AVEN. So the journey doesn’t stop here. This is the starting point, and it’s really great that GE gave us a pretty great starting point back in the ’90s,” he said.
“AVEN sat on the shelf for 30 years. I was born in Cincinnati, so I drive by the hospital I was born in every time I’m at GE—and…AVEN was built before I was born. So for me, it’s very important to recognize all of the people who went and did that and built that within a year…We are giving those people their flowers and being able to pay that forward.”
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