First SLS umbilical undergoing testing at the LETF

by Chris Bergin

The Orion Service Module Umbilical (OSMU) has been installed on to the Launch Equipment Test Facility (LETF) at the Kennedy Space Center. The milestone marks the first umbilical to undergo testing ahead of being installed on the redesigned Mobile Launcher that will host the Space Launch System (SLS) for her maiden launch in 2018.

Testing At The LETF:

The Launch Equipment Test Facility (LETF) is located just south of the Operations and Checkout (O&C) Building at the famous spaceport.

It has a deep history, ranging back to the shuttle era.

It was the testing site for launch-critical ground support systems and equipment, such as the Orbiter Access Arm (OAA), External Tank Gaseous Oxygen Vent Arm, External Tank vent line, Tail Service Masts and umbilical systems, and Solid Rocket Booster Hold Down Posts.

2015-07-07-144441It has also been involved with Cryo testing for the defunct X-33 technology demonstrator for the VentureStar program and had a role in testing Delta IV ECS umbilicals and Centaur Upper Stage rolling beam tests.

The facility allows for simulated launch vehicle events such as movement from wind, ignition and liftoff, effects of solar heating and cryogenic shrinkage.

The facility is equipped with a control room – allowing engineers to collate data and detect any hazardous conditions with the hardware undergoing testing. It also includes workshops and even its own High Bay – large enough to host the assembly of the large ground support structures.

2015-07-07-141058At the heart of the LETF is the Vehicle Motion Simulator (VMS), utilized to emulate all the movements a rocket makes as it is rolled to the launch pad, and more importantly through the first 30 milliseconds of flight.

This allows exact simulations of the force and conditions umbilicals and other launch equipment must work in to become qualified for use. Procedures and clearances can also be evaluated using the VMS.

The LETF received a number of upgrades ahead of its role with SLS and Orion – while also continuing to offer its services to commercial companies – per KSC’s Multi-User Spaceport initiative.

A team from NASA, ASRC Aerospace and MTS Engineering Consulting Services conducted $35 million worth of upgrades.

“We’re looking forward to supporting multiple customers for NASA in the future,” noted Eric Ernst, LETF’s upgrade project manager. “Whether it’s heavy-lift, horizontal launch systems or commercial providers… we really are a multifaceted facility that can support a broad spectrum of customers.”

2015-07-07-154627It has already hosted test umbilical hardware for SLS, including an arm back in 2012, which had originally been planned for use with Ares 1.

However, the installation of the OSMU is a major milestone, with its design now set and ready to become part of an array of connections that will be vital to SLS and Orion ahead of launch.

The OSMU’s testing marks the first actual SLS umbilical to be hosted on the LETF.

2015-07-07-151308“The Mobile Launcher (ML) Element Integration Team (EIT) received the Orion Service Module
Umbilical (OSMU), which is the first ML tower-mounted umbilical arm to be delivered to KSC for
Launch Equipment Test Facility (LETF) testing,” noted L2 information ahead of testing.

“The OSMU is a tilt-up umbilical arm using portions of the design developed for the Constellation Program (CxP). Prior to T-0, commodities are transferred by the umbilical from the ML to the Orion Service Module.”

The full role of the Orion Service Module Umbilical (OSMU) will be to provide electrical, data, and purging processes to Orion’s Service Module.

Weighing approximately 40,000 lbs, the OSMU is 27 feet long, 17 feet wide, and 42 feet tall – including the OSMU safe house to protect it from the intense, SRB-induced launch environment.

“The OSMU is a T-0 umbilical mechanism providing GSP, Environmental Control System (ECS), GCS, BAIR, LCS, and GN2 to the Orion Service Module (SM),” noted an extensive overview presentation in L2.

The release of the OSMU will be triggered at T-0 (SRB ignition) by a signal to the release mechanism on the ground umbilical plate.

At this point, the OSMU truss boom structure will tilt-up into its safe house on the ML umbilical tower. This truss boom structure (arm) will reach out toward but remain 16 feet shy of the Orion Service Module itself.

2015-07-07-162946The 16-foot gap between the OSMU truss boom structure and Orion Service Module will be bridged by draped umbilicals terminating at a ground umbilical plate that will serve as the actual T-0 umbilical to the Service Module. (Screenshot from a full overview of the SLS Umbilicals Video – L2).

Access to this ground umbilical plate will only be provided inside the VAB – meaning the umbilical plate will be inaccessible once the SLS rocket is rolled out to LC-39B for launch.

An ECS umbilical to the LAS (Launch Abort System) will also extend out from the OSMU to the LAS Ogive (roundly tapered end of any three-dimensional object) cavity.

2015-07-07-151716The OSMU – along with the other connections – will be hosted on the Launch Umbilical Tower (LUT) of the Mobile Launcher, which is nearing the end of modification work to convert it from its initial role with the Ares I, to being able to host SLS.

The OSMU is one of the umbilicals that will have its position raised when SLS evolves from the Block 1 to the Block 1B – with the Exploration Upper Stage (EUS) in the 2020s.

“LETF testing is on the critical path for Mobile Launcher operational readiness,” noted Jeff Crisafulli, manager of the facility.

There are currently nine different umbilicals scheduled for qualification testing at the LETF. Once we complete all the needed simulations, we’ll be ready to have the hardware installed on the mobile launcher tower.

“We’ll be ready when Orion and SLS are ready to go.”

2015-07-07-154943Other LUT umbilical hardware currently being fabricated includes the Crew Access Arm (CAA), which will be 67 feet long, 10 feet wide, and 18 feet tall and will include a lower level for access to the Service Module.

The CAA is currently expected to weigh approximately 74,000lbs and will connect to the ML umbilical tower at the 270-foot level, with access from the 260-foot level.

The Core Stage Forward Skirt Umbilical, or CSFSU, is also being constructed.

2015-07-07-163230The CSFSU will be a T-0 umbilical requiring Vehicle Assembly Building (VAB) access for mating of the umbilical plate to the SLS rocket.

Commodity lines for the CS FS would run through the stabilizer truss of the umbilical arm, with drape commodity lines extending from the arm to CS FS attach location.

The proposed umbilical plate would be 46 inches by 34 inches.

All of these umbilicals will make the journey to the LETF for testing on one of its two available towers.

Images: NASA and L2 which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site.)

(L2 is – as it has been for the past several years – providing full exclusive SLS and Exploration Planning coverage. To join L2, click here:

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