15.12.2021

"These are really big, heavy, complicated pieces of machinery."

A full-power test of the BE-4 rocket engine in April 2019 in West Texas.

Blue Origin is unlikely to deliver two flight-ready versions of the BE-4 rocket engine to United Launch Alliance (ULA) before at least the second quarter of 2022, two sources say. This increases the possibility that the debut flight of ULA's much-anticipated new rocket, Vulcan, could slip into 2023.

Vulcan's first stage is powered by two BE-4 engines, which burn methane and are more powerful than the space shuttle's main engines. The sources said there recently was a "relatively small" production issue with fabrication of the flight engines at Blue Origin's factory in Kent, Washington.

As a result of this, the engines will not be completed and shipped to the company's test stands in West Texas until next year. Once there, each engine must be unpacked, tested, and then re-configured to be moved to ULA's rocket assembly facility in northern Alabama. A reasonable "no-earlier-than" date for the engines' arrival at the rocket manufacturer is now April 2022, and this assumes a smooth final production and testing phase.

A lot riding on these engines

ULA declined to comment on specifics about the production issue. However, the company said it was disappointed that it did not receive these two flight engines in 2021 as anticipated.

"We are disappointed that we will not be receiving Vulcan flight engines from Blue Origin by the end of the year, but they will be arriving early next year," the company said in a statement. "The certification program is moving along very well, and the production engines are being manufactured. We look forward to Vulcan’s first launch in 2022."

However, it now seems far from certain that Vulcan will make its debut in 2022. And there is a lot riding on this rocket and its timely debut, which will replace both the Atlas and Delta rockets that ULA has flown. The US military is counting on Vulcan to lift about 60 percent of the nation's national security payloads into space from 2022 to 2027.

Due to delays in development—at one point, the Vulcan rocket was expected to debut in 2020—the US Space Force and ULA have already agreed to move the first military mission assigned to Vulcan, designated USSF-51, onto an Atlas 5 rocket. However, ULA has since said that all of its remaining Atlas rockets, which are being phased out due to reliance on the Russian-built RD-180 engine, are allocated to other missions. It is not clear, therefore, that other military missions can be moved off of Vulcan and onto an Atlas.

Assuming the BE-4 engines arrive at ULA in April, the company would have about eight months to prepare the rocket for a test flight in 2022, which will carry a small lunar lander built by a private company, Astrobotic.

This is the first time that ULA, which was formed out of the launch divisions of Boeing and Lockheed Martin in 2005, has taken delivery of a brand-new first-stage rocket engine as part of booster development. However, when Boeing and Lockheed first used the RS-68 and RD-180 engines for their Delta and Atlas rockets, it took an average of 19.5 months from engine delivery to first flight.

Vulcan is not expected to require this much time to incorporate the BE-4 rocket engine, however. During a reporters roundtable in December 2020, ULA Chief Executive Tory Bruno explained why in response to a question from Ars. Earlier that year, ULA had taken delivery of "pathfinder" engines, which are nearly identical to the flight engines but not designed to be ignited.

Value of a pathfinder

Bruno said these pathfinder engines have allowed ULA to do a lot of the work that is involved in preparing a rocket for launch, in terms of assembling the propulsion end of the booster, sending it to the launch site, and ensuring that it links up with the ground systems there for fueling and other operations.

"These are really big, heavy, complicated pieces of machinery," Bruno said. "So they have custom tooling that handles them in the factory and aligns them and helps us to install them in the rocket. We don't really like to ad-lib anything in our rocket factory, so every move that is made is in a process instruction that has been proved, certified, and then locked down in configuration. What we're doing in this initial pass-through, that I call pathfinding, is making sure that all of that is exactly perfect."

So over the last year or so, ULA has used the pathfinder engines to test the vehicle-assembly process, move it into the transport ship, travel to Cape Canaveral Space Force Station in Florida, transfer it onto the Mobile Launch Platform, and test ground systems. As a result, Bruno said, the 19.5-month yardstick from the earlier Atlas and Delta development programs is not comparable.

"All of these pre-launch activities were part of that big span that you looked back on, and we are able to work off almost all of that with these pathfinder engines, right up to just literally short of the flight readiness firing," Bruno said. "And then, at the last minute, we're able to bring in the flight engines, take them through that whole evolution that has already been trailblazed for them. And so that's why you don't need them as early."

This means there's still a chance for Vulcan to launch in 2022 if everything goes right. ULA must receive the BE-4 engines soon. Its integration process must go smoothly. And according to one person, ULA must also resolve issues with the Vulcan rocket's Centaur upper stage, which is using a new variant of the RL-10 engine. So a lot has to go right for Vulcan to launch in 2022.

If there is some comfort ULA can take from this, it's that the latest development version of the BE-4 rocket engine has been performing very well. The engine has racked up thousands of seconds of continual hot-fire time on the Blue Origin test stands at full power.

All evidence to date suggests that Blue Origin builds quality products. The reusable, suborbital New Shepard launch system just launched its third human mission in five months this weekend and appears to be highly reliable. New Shepard is an elegantly engineered solution to address space tourism. And the BE-4 engine also seems to be maturing nicely. It almost certainly will be a quality engine for both ULA's Vulcan rocket and Blue Origin's New Glenn rocket.

Quelle: arsTechnica