United Launch Alliance (ULA) has picked Blue Origin, the secretive Seattle-based space-vehicle company founded and funded by Amazon.com chief Jeff Bezos, to complete development of a 550,000-lb. thrust rocket engine that could replace the Russian-built RD-180 at the Atlas V power plant in the coming decade.

ULA will pay Blue Origin an unspecified but "significant" sum to help defray the cost of developing its BE-4 engine, which has been in the works under wraps for the past three years in Seattle and at the Blue Origin test facility near Van Horn, Texas. The launch services company selected the BE-4 after kicking off a search for an RD-180 replacement when political tensions over events in Ukraine threatened continued supply of the big Russian engine.

"To develop a liquid rocket engine takes a solid seven years, sometimes longer," says Tory Bruno, ULA president and CEO. "Blue is already several years into that cycle. So by partnering with them we have the opportunity to really cut that cycle in half, which means that, say, about four years from now we would be in a position to begin flying rockets with this engine technology."

Air Force Space Command chief Gen. John Hyten, speaking at the 2014 Air and Space Conference and Exhibition Sept. 17, calls the partnership a "pretty amazing piece of news" that is particularly welcome because of the "ease of acquiring and supporting and operating" the engine due to its use of methane.

Similarly, Lt. Gen. Ellen Pawlikowski, military deputy to the Air Force procurement chief, told Aviation Week at the same conference she is "excited about the news" of private investment going toward a government requirement.

Developed for Blue Origin’s planned Orbital Vehicle, the BE-4 (designating the fourth Blue engine) is an oxygen-rich, staged combustion, single-shaft rocket engine designed to burn liquefied natural gas (LNG).

"Liquefied natural gas is almost 100% methane; it has a few other hydrocarbons in it," says Bezos, who appeared with Bruno at a Washington press conference to announce the deal. "We’re designing the engine to run on liquefied natural gas or methane. They’re both roughly the same density, but methane is considerably more expensive because to remove the last little bit of other kinds of hydrocarbons is costly. Cost/operability is what drives us designing the engine."

Development has benefited from modern computer modeling techniques, additive manufacturing and other new approaches to design, the two executives say. Staged combustion testing of the preburner and main injector assembly has been conducted, and turbopump and main valve tests are in preparation. Full-scale testing of the BE-4 is scheduled to begin in 2016, according to Blue Origin.

Bezos has been using his own deep pockets to endow development of the new engine and everything else Blue Origin is doing, and he stressed that the engine-development effort is "fully funded" to avoid a costly "start-and-stop" work flow. The company plans to offer the BE-4 engine commercially once it is ready, and to make it reusable for eventual vertical takeoff and landing operations with its own vehicle, drawing on the "self-cleaning" properties of liquefied hydrocarbon fuel to avoid soot and other byproducts, Bezos says.

That application is in the future, however. Near-term plans call for "feathering" the BE-4 into the Atlas V vehicle set as needed, in conjunction with the RD-180.

"The BE-4 is not a one-for-one replacement for the RD-180, which is a kerosene-burning engine," Bruno says. "What we intend to do is pair these in our baseline Atlas vehicle, and provide actually higher performance, higher thrust levels together than we have now. The RD-180 is a great engine; it’s a real workhorse, it’s high-performance, but this is an opportunity to really jump into the 21st century with modern technology so we can achieve more performance and a lower cost."

The two-bell RD-180, built by NPO Energomash, generates 860,000 lb. thrust. The BE-4 thrust level is comparable to the AR-1 engine under development as a possible RD-180 replacement by Aerojet Rocketdyne (AJR), which would also be twinning for the Atlas V application. AJR is responding to a U.S. Air Force request for information (RFI) on what it would take to replace the Russian engine by arguing that risk reduction work done with NASA funding will dramatically cut the time to get a prototype of that engine – also a hydrocarbon-fueled, oxygen-rich staged-combustion configuration – on the test stand.