WASHINGTON — Commercial spaceflight startup XCOR Aerospace and United Launch Alliance (ULA) plan to develop a low-cost liquid oxygen/liquid hydrogen engine that could one day replace the RL 10 that currently powers the upper stage of ULA’s Atlas 5 and Delta 4 rockets, the companies announced March 22.

George Sowers, ULA vice president of business development and advanced programs, noted that the cost of the RL 10, built by Pratt & Whitney Rocketdyne of Canoga Park, Calif., has soared in recent years due to demand uncertainty and an eroding industrial base as NASA’s space shuttle program heads toward retirement this year.

“It gives us options for a next-generation upper-stage engine,” Sowers said in a March 21 interview, adding, “This isn’t the only option we’re looking at. Certainly we’re looking at options for the next generation of RL 10s as well.”

Sowers said the XCOR-built engine would generate 25,000 to 30,000 pounds of thrust.

“The overall performance targets we’re aiming for are very similar to an RL 10 in terms of thrust and efficiency,” Sowers said. “So we’re not really looking to change the basic upper-stage design. What we’re looking for would be an engine that we could drop into existing stages.”

Sowers said the new engine could be operational within five to 10 years.

“We don’t have a specific target time; it’s really as the risks are retired we make decisions and pass various decision gates,” he said.

Jeff Greason, chief executive of Mojave, Calif.-based XCOR, declined to specify development costs for the new engine, but said he expects it to be competitive in the market.

“We have been forced because of our company’s history to innovate in ways to develop engines that are cheaper to produce,” he said. “I have no intention of showing my number but I am looking to supply this engine, should everything proceed as we hope, at a very, very substantially lower price … than other engines on the market today.”

Greason said XCOR has been working with Denver-based ULA for the past couple of years to demonstrate an engine nozzle weighing hundreds of pounds less than the large upper-stage engine nozzles in use today.

The new upper-stage engine would be based in part on the liquid oxygen and kerosene-fueled 5K18 engine XCOR is developing for its planned Lynx suborbital vehicle, which is designed to carry tourists along with research payloads. Greason said recent testing proved the ability of the 5K18’s cryogenic piston-pump technology to pump liquid hydrogen.

Greason said XCOR and ULA have yet to nail down a formal test regime for the nozzle and other engine components, but said the development program would be based on performance milestones to ensure a cost-effective approach.

“I have no idea how many tests we’ll do, but it’ll be a very big number,” he said. “That’s the way we do everything: Test a little, tweak it, test a little, tweak it.”

Greason said recent hot-fire tests of the nozzle validate XCOR’s design, materials and manufacturing processes.

“If you’ve got to build a rocket plane that flies four times a day very efficiently and for very low cost, you have to do things in a very different way with engine technologies and thrusters and things like that,” Greason said. “So it’s got the attention of folks like George. We’ve knocked off a couple of risk reduction items and got to the point where we can move the technology ahead.”

Although XCOR has tested a number of engines on suborbital flights the company has yet to fly anything in the vacuum of space, a challenge Greason said XCOR is eager to tackle.

“We’re not scared of it, the characteristics are understood,” he said. “Really the far more interesting challenge is not the going-to-space part of it; it’s developing a highly cost effective liquid engine technology.”

Sowers said ULA, a Boeing-Lockheed Martin joint venture, finds XCOR an attractive partner because of the agility and innovation a small company can bring to development projects.

“In terms of development cost, one reason we like working with XCOR is they can make rapid progress quickly with a small team,” he said. “We’re hopeful we can dramatically reduce development costs with this kind of approach.”



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