Since then, the company has worked with NASA under an unfunded Space Act agreement that allows it to draw on the agency's expertise and test facilities. The next major milestones include a review of the subscale propulsion tank assembly later this month, and a full space vehicle subsystem interim design review in March 2014. Blue Origin is scheduled to present its final CCDev-2 briefing to NASA in May 2014.
The BE-3 was assembled at the Kent facility, largely from parts manufactured there. The design is based on the combustion “tap-off” engine cycle, sometimes known as the “topping cycle” or chamber-bleed cycle, in which the combustion gases from around the walls of the main chamber are bled-off, partially cooled and used to power the engine's turbopumps.
Blue Origin says the cycle, which produces a relatively high specific impulse, is simpler than options such as pre-burning staged-combustion, and is well suited to human spaceflight because of its single combustion chamber and “graceful” shutdown mode. Despite the challenges of the cycle—including potentially complex start-up systems and high-temperature turbine-drive gases—Meyerson explains, “It is different because it only uses the one combustor, so it has a tendency to shut down rather than feed the combustion process.” Although Rocketyne developed the experimental J-2S tap-off variant of the Saturn V upper-stage J-2 engine in the 1960s, Meyerson says the BE-3 is the first engine of its type developed to fly.
The company also is focusing on development of modifications to adapt the baseline engine to the expendable upper-stage BE-3U version. “We demonstrated very high efficiencies on the core injector and that allows us to put on different nozzles, including a short design for deep throttling for landing, and a large-expansion-ratio nozzle design for the upper stage, which will give the higher performance and efficiency you need for that. But we are also looking at other things we can do in terms of expendables and lower-cost manufacturing,” he adds.
Still to be determined is the powerplant for the reusable first stage of the orbital vehicle. Meyerson says it could be a cluster of BE-3s, or something entirely different. Performance drove the decision to use hydrogen fuel in the BE-3, he says, but the company's engineers have not ruled out a different approach on the orbital first stage.
“We selected the BE-3 as our first orbital launch vehicle engine because it provides us with options to go with an all-hydrogen architecture if we choose to,” he says. “We have ideas. Some things are in development for other engines that we're developing, but we're not ready to discuss those today. Those would provide other options and other architectures.”
Overall, Blue Origin has received $25.7 million from NASA for CCDev-1 and -2 work, of which only a small portion went into the BE-3 engine, according to Meyerson. The company also developed a peroxide/kerosene BE-2 engine for early flight tests over Texas. A vehicle powered by that engine reached 45,000 ft. and Mach 1.2 before it was destroyed by range safety officers when signs of flight instability were noted (AW&ST Sept. 12, 2011, p. 39).
So far, the company has tested the Space Vehicle's biconic shape at Lockheed Martin's high-speed wind tunnel facility in Dallas to validate computational fluid dynamics models of its performance. Meyerson notes that while there is nothing particularly unusual about the manufacturing techniques that go into the BE-3, computer modeling also played an important role in the engine's development.
“One of the key things is the design process we went through using computational methods and our in-house analytical techniques to come to a turbopump design that worked, essentially, out of the box,” he says. “I think that is unique.”