{"id":39089,"date":"2016-04-14T19:59:57","date_gmt":"2016-04-14T11:59:57","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/delta-iv-h-wdr-as-ula-lines-up-its-immediate-and-long-term-goals\/"},"modified":"2016-04-14T19:59:57","modified_gmt":"2016-04-14T11:59:57","slug":"delta-iv-h-wdr-as-ula-lines-up-its-immediate-and-long-term-goals","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/delta-iv-h-wdr-as-ula-lines-up-its-immediate-and-long-term-goals\/","title":{"rendered":"Delta IV-H WDR as ULA lines up its immediate and long-term goals"},"content":{"rendered":"

United Launch Alliance (ULA) successfully conducted a Wet Dress Rehearsal (WDR) on Thursday for its Delta IV- Heavy tasked with the launch of the NROL-37 spacecraft. Meanwhile, the company is continuing to evaluate the underperformance issue with its most recent Atlas V mission, while agreements were signed for its future rocket, the Vulcan \u2013 specifically related to the payload fairings.
\nNROL-37:<\/p>\n

ULA will be tasked with lofting another secret military payload for the US National Reconnaissance Office, with the launch likely to take place sometime in early June.<\/p>\n

The rocket rolled out to its pad at Space Launch Complex \u2013 37B (SLC-37) earlier this month.<\/p>\n

It is the same pad from which the Saturn rocket made its first orbital launch in January 1964, with a Saturn I carrying the nose of a Jupiter missile into low Earth orbit.<\/p>\n

\"2016-04-14-224332\"The Delta IV-H is the largest and most powerful rocket currently flying and was utilized to loft the first Orion capsule \u2013 during Exploration Flight Test -1 (EFT-1) \u2013 on a successful test flight.<\/p>\n

The Delta IV-H was developed by Boeing as a replacement for the Titan IV which the US Air Force used for its largest payloads throughout the 1990s and early 2000s.<\/p>\n

It is one of five configurations that the Delta IV can fly in, with the smaller Medium, Medium+(4,2), Medium+(5,2) and Medium+(5,4) variants used for the majority of payloads.<\/p>\n

At Launch Complex 37B, the Delta IV uses a combination of off-pad horizontal and on-pad vertical assembly. The liquid boosters, first stage and second stage are mated in the Horizontal Integration Facility (HIF) a kilometer away from the pad.<\/p>\n

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\"2016-04-14-224223\"The rocket is then rolled to the complex and erected inside the Mobile Service Tower (MST). This tower is then used to stack the payload to the rocket, and when the Delta IV is flying in the Medium+ configurations it is also used to attach solid rocket motors at the base of the first stage.<\/p>\n

On Thursday morning, the MST was rolled back to allow the Delta IV-H undergo the WDR, which allows for a full countdown test that includes the fueling of the rocket. Unlike the static fire tests conducted by rockets such as SpaceX\u2019s Falcon 9, the engines on the Delta IV-H aren\u2019t ignited during the WDR.<\/p>\n

ULA note the WDR was concluded nominally on Thursday.<\/p>\n

On launch day, the three Common Booster Cores (CBCs), powered by a single Aerojet Rocketdyne RS-68 engine, will come to life and power the huge rocket uphill. The Delta Cryogenic Second Stage (DCSS) will complete the job, deploying the secret passenger into it desired orbit.<\/p>\n

Atlas V\/OA-6 Investigation:<\/p>\n

ULA\u2019s previous launch involved its Atlas V rocket, launching the Orbital ATK Cygnus on the OA-6 mission to the International Space Station (ISS).<\/p>\n

\"2016-04-14-222516\"The veteran Atlas V rocket launched on its first attempt at the opening of the available window on Tuesday, departing from SLC-41 at Cape Canaveral.<\/p>\n

The Atlas V\u2019s first stage shut down several seconds earlier than planned, as immediately noticed during the webcast coverage.<\/p>\n

\u201cDuring the launch, the system experienced a premature first stage shutdown. The first stage cut-off occurred approximately 6 seconds early,\u201d noted ULA in a statement.<\/p>\n

As pre-planned, a further six seconds after engine shutdown, the spent stage separated, with the Centaur\u2019s RL10C-1 engine entering its prestart phase. Ten seconds after stage separation, the Centaur engine ignited to begin a single burn that was pre-planned for a duration of thirteen minutes and 38 seconds.<\/p>\n

However, this burn lasted over a minute longer than noted in the pre-flight mission documentation.<\/p>\n

\"2016-03-25-145605\"Notably, Centaur\u2019s longer burn allowed it to deliver Cygnus into the correct 230km orbit and into its correct RAAN (Right Ascension of the Ascending Node), which ultimately classed the mission as a success.<\/p>\n

\u201cThe Centaur automatically compensated by burning longer. The robustness of the system achieved mission success, delivering Cygnus to a precise orbit as planned,\u201d added ULA.<\/p>\n

However, the specific reasons for the issue with the Atlas V first stage performance remain under evaluation.<\/p>\n

\u201cThe ULA engineering team is continuing to review the data and has developed initial fault trees with our industry partners. The team has been successful in isolating the anomaly to the first stage fuel system and its associated components,\u201d added the company, pointing to an issue relating to the fuel ratio parameters on the booster.<\/p>\n

See Also<\/h4>\n