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The United Launch Alliance’s first Vulcan Centaur rocket returned to its launch pad at Cape Canaveral for a critical test of its Blue Origin-built BE-4 main engines as soon as Wednesday, a test that was delayed since last month by a problem with auxiliary engine ignition system.

ULA plans to load methane, liquid hydrogen and liquid oxygen propellants into the Vulcan first stage and its Centaur upper stage Wednesday afternoon. If fueling procedures go well and the rocket igniters pass a readiness check, the ULA launch team should proceed with test firing the BE-4 engines sometime after 6:00 PM EDT (2200 UTC) .

The engine test window extends over several hours Wednesday evening, but ULA did not provide a schedule of events. A ULA spokesman said the company would not release a timeline because the engine firing is a test, and the company declined a request for an interview to discuss plans and goals for the test firing.

Live video of the engine test, called Flight Readiness Firing, will be available on this page.

ULA technicians rolled the Vulcan Centaur rocket from its vertical hangar at pad 41 on Tuesday at the Cape Canaveral Space Force Station in preparation for a test launch.

The Flight Readiness Firing will demonstrate launch day timing and procedures, propellant loading operations and countdown sequence for the Vulcan Centaur rocket by firing the booster’s twin BE-4 engines, according to ULA. The test is intended to verify the performance of the launch vehicle, engines, ground systems and software.

After exiting one last built-in outlet, the automatic countdown timer ticks off the final minutes until the BE-4 engines are fired. The Vulcan Centaur rocket will switch to internal fuel and the propellant tanks will rise to flight pressure before the valves open to allow methane and liquid oxygen to flow into the thrust chambers of the BE-4 engine.

The twin engines will flash, accelerate and fire for approximately six seconds, sending a plume of exhaust out of the east-facing fire trench at Pad 41. The fastening systems will keep the Vulcan rocket attached to its mobile launch pad throughout the test shot.

Then the rocket’s flight computer will command the motors to shut down when the test is complete.

“The engines will perform a nominal terminal count, then ignite and hold the throttle, maintaining confidence before the engines begin to throttle to simulate in-flight throttling before booster engine shutdown, then perform a similar shutdown in flight,” he said. said RJ Sansom, ULA’s Vulcan Chief Engineer, in a blog post on the company’s website.

The Flight Readiness Firing will be the culmination of a series of tests and countdowns at Cape Canaveral to prepare for the first Vulcan test flight. Most recently, the ULA launch team loaded methane, liquid hydrogen, and liquid oxygen propellants into the Vulcan booster and its Centaur upper stage during a May 12 fueling test. The countdown to Flight Readiness Firing will follow a similar timeline to that of the May 12 tanking test, including propellant loading operations, integrated holds and launch team readiness surveys.

The ULA returned the Vulcan Centaur rocket to the Vertical Integration Facility after its May 12 refueling test to make modifications to the vehicle. The changes included adjusting a setting with hydraulic ground pressure, changing the top-up rate for liquid oxygen, and changing the flow of purge and coolant gases to the BE-4 engine igniters, according to Tory Bruno, CEO of ULA.

With these modifications complete, the ground crews planned to perform the Flight Readiness Firing on 25 May, but ULA postponed the test after discovering a problem with the BE-4 engine’s ignition system. This prompted the rocket’s return to the hangar for troubleshooting before the ULA returned the Vulcan launcher to pad 41 on Tuesday.

ULA stacked the first stage for the Vulcan rocket’s first test flight on a mobile launch pad Jan. 25 inside the Vertical Integration Facility at Cape Canaveral Space Force Station. Here the two BE-4 engines of the first stage are visible. Credit: United Launch Alliance

“FRF is really concerned with confirming the operational readiness of the integrated system: launch vehicle, ground systems, facilities and the associated software. In addition, we will demonstrate the ability to successfully execute the engine start sequence and validate our hot-fire abort response procedures,” said Dillon Rice, ULA’s Vulcan launch host, in a post on the website. of the company.

ULA says it has installed additional instrumentation on the rocket to monitor engine performance during Flight Readiness Firing.

In parallel with preparations for Flight Readiness Firing, ULA engineers continue to investigate a hydrogen explosion in March that disrupted a structural test of the Centaur upper stage of Vulcan rockets at NASA’s Marshall Space Flight Center in Huntsville, Aug. Alabama. The explosion damaged the test rig and a Centaur upper stage test article. The Vulcan rocket will use a larger, updated model of the Centaur upper stage currently flying on ULA’s Atlas 5 rocket.

If engineers determine that no modifications to the Centaur upper stage on the first Vulcan rocket are needed, the test flight could take off this summer. In remarks last month, Bruno said the mission could be delayed until later this year if corrective actions are needed on the Centaur.

ULA is a 50-50 joint venture between Lockheed Martin and Boeing, who merged their Atlas and Delta rocket programs in 2006. The Vulcan rocket will fly in several configurations, with varying numbers of strap-on solid rocket boosters and different sizes of available cargo fairing available on each flight, depending on mission requirements.

The Vulcan rocket for the program’s first test flight sports a colorful paint job with a bright red flame emblazoned on the side of the 5.4-meter (17.7-foot) first stage. For tanking tests and Flight Readiness Firing, the Vulcan rocket is not equipped with solid rocket boosters or payload fairing. In that configuration, the vehicle is approximately 50.7 meters tall.

Once the test launch is complete, ULA will drain the rocket’s propellant tanks and return the Vulcan Centaur to its hangar for inspections. Technicians will install two of the Northrop Grumman-built solid rocket boosters and payload shroud provided by Beyond Gravity, formerly known as Ruag Space.

ULA ground crews will also inspect the Vulcan rocket and its engines after returning the vehicle to the hangar, and technicians may need to adjust or replace thermal blankets around engines that could be burned by test fire. ULA will also replace the disposable igniters on the BE-4 engines before proceeding with final launch preparations.

The maiden flight of the Vulcan rockets will be the first launch to use the new methane-fueled BE-4 engines from Blue Origin, founded by billionaire Jeff Bezos. At full throttle, each BE-4 engine can generate approximately 550,000 pounds of thrust. Two of them will power each Vulcan core stage, with zero, two, four or six solid rocket boosters to add thrust in the first two minutes of flight.

The Centaur upper stage of Vulcan rockets, called Centaur 5, is an upgrade of the upper stages currently flying on ULA’s Atlas 5 rocket. The Centaur 5 has a larger diameter to accommodate larger oxygen and cryogenic propellant tanks, along with two Aerojet Rocketdyne RL10 engines. The Centaur flying the Atlas 5 rocket typically flies on a single engine.

ULA’s first Vulcan Centaur rocket on its launch pad last month at Cape Canaveral Space Force Station. Credit: United Launch Alliance

Once all Vulcan rocket configurations are operational, the new rocket will completely replace and augment the lift capacity currently offered by all ULA rockets. The largest variant of the Vulcan rocket, with a single core stage, will have a higher payload lift capacity than ULA’s Delta 4-Heavy, which has three liquid-fueled first stage boosters linked together.

Ultimately, ULA plans to salvage the repurposed BE-4 engines from Vulcan launches, but not the entire first stage.

ULA unveiled the Vulcan rocket in 2015, therefore aiming for an initial launch of the new vehicle in 2019. The company selected the Blue Origins BE-4 engine for the first stage propulsion system in 2018. At that time, ULA aimed to launch the first Vulcan test flight in 2020.

But the delays, mainly caused by problems discovered in the production and testing of the BE-4 engine, forced the first Vulcan test flight to be postponed by several years. Bruno said earlier this month that Blue Origin and ULA completed final qualification tests of the BE-4 engine ahead of Vulcan’s first launch, clearing a hurdle that still threatened to delay Vulcan’s debut earlier this month. ‘year.

On its maiden flight, the Vulcan rocket will launch a commercial lunar lander developed by Astrobotic, which will attempt to deliver a variety of NASA experiments and technology demo payloads to the lunar surface. The Astrobotic lander, called Peregrine, is part of NASA’s Commercial Lunar Payload Services program, which buys trips to the moon for agency payloads on commercially owned spacecraft.

Also aboard the first Vulcan launch will be two prototype satellites for Amazon’s Kuiper broadband network.

ULA’s Vulcan rocket has been selected by the US Space Force to launch the majority of large military satellites for national security over the next five years. The military requires the Vulcan rocket to be certified for flights before it is approved for homeland security launch missions.

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Follow Stephen Clark on Twitter: @StephenClark1.


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