The First Launch of ULA’s Vulcan Is Getting Close
For months now we have seen progress ramp up as United Launch Alliance and the Vulcan rocket approach its maiden flight. While there have been a few different delays thanks to explosive tests and various reasons, the company is still on track for a launch very soon. As ULA phases out other rockets Vulcan is meant to become the new workhorse and has a lot riding on its success.
In the last few days, we saw the completion of different tanking tests on the full test article. This is in preparation for the final main test before launch, the flight readiness firing. Based on current progress and updates from Tory Bruno, in only days from now, this test should be attempted. This will see the two BE-4 engines fire on the rocket for the first time and ensure Vulcan is ready for flight.
Depending on the results of this test, Vulcan’s maiden flight could be only weeks away. This being said, other important factors like payload delivery and the investigation of the test tank anomaly will also play a big part in the rocket’s schedule. Here I will go more in-depth into the recent testing completed by ULA, the final steps before Vulcan’s maiden flight, what to expect in the coming days, and more.
Static Fire Preparation
Less than a week ago on the 15th, the Vulcan test article rolled off the launchpad and back into the Vertical Integration Facility (VIF). Just before that, the rocket had been on the pad for a few days undergoing testing of both the first and second stage tanks. Overall it looks like the testing went well but a few things need to be attended to. Related to this, on the 15th ULA CEO Tory Bruno tweeted saying, “Good #VulcanRocket Flight Tanking Tests last Friday & Saturday. Will need to adjust a handful of parameters and set points for a reliable FRF count. (Which is the purpose of this run). Rolling back to the VIF today to work on that. FRF in a few days or so.”
By now we still haven’t seen the static fire but based on the tweet it should only be in a few days. This test will feature a full Terminal Countdown sequence, followed by igniting the engines and demonstrating a hot-fire abort recycle and saving. After the FRF, the rocket will return to the VIF for installation of two solid rocket boosters and its payload for launch. The first launch will send Astrobotic’s Peregrine commercial lunar lander to intercept the Moon, deploy two Project Kuiper prototype broadband satellites into low Earth orbit for Amazon and carry a Celestis memorial payload into deep space.
Another thing that ULA has been testing is the pad and general infrastructure supporting Vulcan. Some of the changes include upgraded Vertical Integration Facility (VIF) platforms, decks and crane to accommodate all Atlas and Vulcan configurations, liquefied natural gas (LNG) ground systems, increasing the fuel and oxidizer storage capacity, and increasing acoustic water suppression system capacity. They even upgraded former solid rocket assembly facility, now known as Spaceflight Processing Operations Center (SPOC), to accommodate Vulcan Launch Platform (VLP) construction and storage. All of which is important because it has an impact on the test schedule and the launch of Vulcan.
On May 16th during an interview after the Humans to Mars Summit here, Bruno said that work involved a combination of minor adjustments to both pad infrastructure and the vehicle. The former includes adjusting set points in a hydraulics system and changing the rate of liquid oxygen flowing into the rocket to top off tanks after recycling the countdown. Those adjustments, he said, could be done in software.
However, on the booster, he said there was an issue during the pad tests with flowing gas through spark torch igniters used to ignite the BE-4 engines. The gas is intended to make sure that the igniters are dry and can light, but the timing was off. That could involve some combination of adjustments on the rocket and ground infrastructure. While slightly concerning, he said in a quote that “There’s nothing wrong with the engines. We’ve lit the engines a zillion times on the test stand at Blue.” As of right now, the launch date is expected to happen in July after the May timeframe was missed. If the upcoming tests go well this date is realistic and not far away. If various problems get in the way after testing with either the rocket or pad infrastructure, it could be quite a bit longer.
More Test Concerns
As many know by now, early last month images came out, and eventually videos were released of a different Vulcan Centaur upper stage exploding during a tanking test. While right after the anomaly happened we were told it would have little to no effect on the maiden flight, it seems that the company wants more information on exactly what went wrong.
In this test, Hydrogen leaked from the structural test article and ignited, creating a large fireball. Bruno mentioned that the investigation was delayed because it took time to remove equipment on top of the Centaur, such as a payload adapter and mass simulators for the payload and payload fairing. Only in the last week and a half was ULA able to get access to the dome section of the Centaur where the leak was located. He also pointed out that engineers isolated a small region on that dome where they believe the leak came from, as well as the likely ignition source. “I’m pretty confident that we’re going to find the leak, and once we find the leak we’ll know if we have to take corrective action or not on the flight vehicle,” he said.
As far as a specific impact on the launch date, Bruno commented if ULA doesn’t need to modify the Centaur, that would allow the Cert-1 launch to take place in early summer. “If we do, it could take longer, but I don’t expect it to get out of the year.” This quote is slightly concerning as it seems there might be a few too many unknowns for an early summer launch date to be realistic. At the end of the day, Vulcan has never lifted off before which means there are bound to be a few kinks and issues along the way. Combine this with an explosive test and it’s going to be hard to stay on track for its first launch.
The BE-4 engines for example are about to attempt a host of firsts related to this launch and final testing. If anything were to go wrong it would push the date back significantly. These engines were designed from the beginning to be a medium-performing version of a high-performance architecture. This was a conscious design choice made to lower development risk while attempting to meet performance, schedule, and reusability requirements. In the past few weeks, we have seen a significant increase in production of these engines as both Vulcan and New Glenn are expected to need them.
Not only are the engines playing a big role in this maiden flight and adding to the list of new hardware but the payloads are also complicating things. Specifically, the Peregrine lunar lander from Astrobotic, has a launch window that is open only for a few days per month. The start of this month was the start of a window about four days long. On the bright side, while initially there were delays with this payload, by now they seem to be ready and will be installed on Vulcan after it completes its testing.
The tanking tests completed just days ago was not the first time we have seen the test article out on the pad with propellant. Back in March pathfinder tests filled the Vulcan first stage and Centaur V upper stage with cryogenic propellant on separate days to validate performance of the stages, Vulcan Launch Platform (VLP), Space Launch Complex-41 facilities and ground support systems. The transfer lines at the pad and the flight hardware underwent chill down procedures to thermally condition equipment against the harsh temperature shock of the propellants. Once that was achieved, the cryogenics began flowing into the rocket. The Vulcan booster uses Liquefied Natural Gas (LNG) and liquid oxygen; Centaur V is powered by liquid hydrogen and liquid oxygen.
For both tests, the “Preps and Tanking Team” shift of launch console operators initiated the countdown to power up the rocket, perform testing and complete final configurations for cryogenic propellant loading. During the planned countdown hold, the launch pad was verified clear of all personnel and the authorization was given to proceed into tanking of the rocket. A shift change in the control room saw the “Detanking and Securing Team” take over to drain the propellants back into the pad storage tanks, safe the rocket and power it down. After, engineers reviewed the tanking test data collected and information gained in test objectives aimed at characterizing performance of hardware and confirming analytical predictions.
As partially mentioned before the other important step before launch will be adding the two solid rocket boosters. In this case, Vulcan integrates up to six Northrop Grumman Graphite Epoxy Motor (GEM) 63XL Solid Rocket Boosters (SRBs). They are constructed out of a graphite-epoxy composite with the throttle profile designed into the propellant grain. GEM solids supported the Delta II and Delta IV rockets, and the GEM 63 variant has already flown on ULA’s Atlas V.
Conclusion
ULA could be only weeks away from a launch or months depending on the outcome of a few different things. This mainly includes the Centaur anomaly investigation and the Vulcan test results from recent tanking tests and the upcoming static fire. We will have to wait and see how it progresses and the impact it has on the space industry.
