XCOR-ULA Engine Project Taking Page from Auto Industry

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CAPE CANAVERAL, Fla. — At first blush, there may not be too much in common between driving a car and maneuvering a satellite in orbit, but that may be changing. 

With backing from United Launch Alliance (ULA), privately owned XCOR Aerospace is working on a type of piston engine for a prospective upper-stage rocket motor that is similar to what is used in cars and motorcycles. 

“It’s a dramatically different kind of upper-stage engine,” said Jim Sponnick, ULA vice president of Atlas and Delta programs.

“Instead of rotating turbo-machinery, it’s basically a piston-type engine, more like in a car, except operating with liquid hydrogen and liquid oxygen. You gain some manufacturing efficiencies. The indications are that it would be a much simpler and less expensive engine to build,” he said.

“The development is actually going well, but it’s truly a future capability,” Sponnick added. “This is something that wouldn’t be flying on the rockets until sometime in the next decade.”

The underpinning technology, however, is in line for a test drive — and operational service — far earlier than that. XCOR plans to use piston pumps in its Lynx suborbital passenger spaceships. 

“The underlying technology is all the same, but the hardware is all different,” said Jeff Greason, XCOR’s co-founder and president. “It’s a different size engine, using different propellants. But it’s not a different kind of engine in the sense that we had to invent a whole lot of new stuff. It was more learning how to adapt the engines we had made for our own purposes to this new application.” 

This year, the focus of the ULA-backed project has been on refining the hydrogen pump and designing a subscale hydrogen engine. Based on funding next year — the project is renewed annually — XCOR would then work on integrating the components. 

Ultimately, in addition to building its own Lynx vehicles, XCOR could find itself in the business of providing 25,000-pound-thrust-class upper-stage engines to ULA. The company, a Boeing and Lockheed Martin joint venture, presently uses RL10 engines built by Aerojet Rocketdyne for upper stages on both the Atlas 5 and Delta 4 rockets. 

“Each Lynx vehicle has four engines on it and each Lynx has 12 reaction control thrusters on it and our plan has been to scale up with the demand of the market to a production rate of four to six or those per year over time, so even a fairly large amount of demand for these engines by ULA is not a high-volume production problem,” Greason said. 

“If we made 10 of them a year, that would be a lot of engines by the standards of the large U.S. rocket engine business but nobody in any other industry views 10 a year as being a lot,” he added.

A key component of the technology is to leverage manufacturing investments made by other industries to cut production costs. 

“Our own projects simply do not permit us to use the industrial base that’s been traditional for aerospace manufacturers. Traditional aerospace suppliers are very high cost, not so much because of anything unique about them, but because the specialty processes that they use have very few customers. So when you have expensive equipment divided by very few customers, the cost to each customer is high,” Greason said.

“We’ve always designed all of our hardware to be manufactured by a wide range of relevant machine shops. That’s probably most significant with the pump because the pumps are piston pumps. We have those fabricated by the kinds of shops that make car engines or motorcycle engines. While those are still specialty manufacturing processes, there’s a lot more car and motorcycle engines made than there are rocket engines made so we don’t have to carry the fabrication costs of the entire industry just to make an engine,” he said.