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Launch Abort Engines for Boeing’s CST-100 Starliner undergo testing

Boeing CST-100 Starliner Launch Abort Engine test in Mojave, California. Photo Credit: Aerojet Rocketdyne posted on SpaceFlight Insider

Archive Photo Credit: Aerojet Rocketdyne

The Launch Abort Engines (LAE) that are planned for use on Boeing’s new CST-100 Starliner spacecraft have completed a series of hot-fire tests in the Mojave Desert in California. Two of the engines were tested by their manufacturer Aerojet Rocketdyne.

The engines tested used new propellant valves which will be employed on the propulsion system for the Starliner service module. The tests were carried out to validate that these new valves can adjust the propellant flow and control peak thrust.

Boeing CST-100 Starliner image credit Boeing posted on SpaceFlight Insider

The CST-100 Starliner crew module. Image Credit: Boeing

This system would only be used in the event of an emergency during launch. The LAE has both a fuel valve as well as an oxidizer valve. These were both checked out under NASA’s Commercial Crew Transportation Capability (CCtCap) subcontract. There are four 40,000-pound (177.9-kilonewton) thrust launch abort engines incorporated into the Starliner service module.

“These innovative valves successfully enabled the engine to demonstrate precise timing, peak thrust control and steady-state thrust necessary during a mission abort. This testing culminates a year of dedicated hard work by the LAE Integrated Product Team at Aerojet Rocketdyne,” said Aerojet Rocketdyne CEO and President Eileen Drake via a release issued by the company. “This is another important step forward as our nation prepares to safely and reliably send humans back to the space station from American soil.”

The LAE was developed under a CCtCap contract, one designed to produce propulsion systems. Besides the LAE, also included in this agreement is Reaction Control System (RCS) thrusters as well as Orbital Maneuvering and Attitude Control (OMAC) thrusters.

The OMAC thrusters are 1,500-pound (6,672-newton) thrust class and are used for low-altitude launch abort attitude control, maneuvering, and stage-separation functions, along with high-altitude direct abort capability and large orbital maneuvers.

The spacecraft’s RCS engines are 100-pound (445-newton) thrust class and provide high-altitude abort attitude control and on-orbit maneuvering. Moreover, these engines can also provide the ability to reboost the space station when required.

At its Commercial Crew and Cargo Processing Facility (a.k.a. “C3PF”) at NASA’s Kennedy Space Center (KSC) in Florida, Boeing will incorporate prefabricated propulsion hardware into the Starliner service module segment. This section provides the capsule-based design with many of the propulsion capabilities required to have the Starliner spacecraft travel to and from the International Space Station, which orbits at an average altitude of some 250 miles (402 kilometers).

Boeing CST-100 Starliner Launch Abort Engine test in October of 2016 in Mojave, California. Photo Credit: Boeing / NASA

Photo Credit: Boeing / NASA

As noted, the Starliner service module also provides the ability to conduct an abort during launch if required. The Starliner service module also contains the systems which allow the spacecraft to dock and undock from the orbiting lab.

Completion of the Starliner service module’s task occurs soon after it leaves the ISS. At this point, monopropellant thrusters (also being produced by Aerojet Rocketdyne) on the crew module portion of the spacecraft provide the vehicle with control during its re-entry into Earth’s atmosphere.

The C3PF, where Boeing is manufacturing the Starliner spacecraft, was previously one of KSC’s former Orbiter Processing Facilities (OPFs). The hangars there, now renamed, were once used to service NASA’s now-retired fleet of space shuttle orbiters.

NASA has rather stringent requirements when it comes to any hardware which will eventually carry astronauts. More tests await the engines which will be used on the Starliner. These include pad abort and system qualification tests (which are scheduled to take place at NASA’s White Sands Test Facility in New Mexico) and an orbital flight test (which will start from Cape Canaveral’s Space Launch Complex 41 in Florida atop a United Launch Alliance Atlas V 422 rocket).

The LAE is a “pusher” system. While the word “pusher” might not have a positive connotation in that word, the Starliner pusher-type abort system is designed to save the lives of those who will ride the spacecraft to and from low-Earth orbit. If needed, it will “push” the Starliner capsule away from the launch vehicle in the event of an anomaly.

Statistically, it is very unlikely that this system will be used for its intended purpose. As such, the LAE’s propellant would be tasked to complete a Starliner’s mission.

The first flight of Starliner will likely take place no-earlier-than late 2018. It was hoped that spacecraft produced under the Commercial Crew Program would begin test flights as early as 2015. Budgetary and technical issues have pushed these missions back.

Video courtesy of Boeing



Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

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