Northrop Grumman’s GEM 63 undergoes 1st test fire

Jason Rhian

PROMONTORY, Utah — An array of new launch vehicles have either already entered into service or are set to do so soon. Two United Launch Alliance rockets are slated to use members of the new GEM 63 solid rocket motor family. This new booster wasn’t developed in a vacuum, however, and can trace its lineage back several decades.

Northrop Grumman is placing the Graphite Epoxy Motor (GEM) 63 family of motors, which includes the GEM 63XL, under an extensive training regime. These solid-fueled motors are being readied to serve on ULA’s Atlas V and Vulcan rockets.

During a test that took place at 1 p.m. MDT (19:00 GMT) Sept. 20, 2018, an estimated 373,000 pounds (1,660 kilonewtons) of thrust was unleashed in just 15 seconds. The test itself lasted an estimated 110 seconds.

“The test regimen is designed to mimic what these boosters would experience during an actual flight,” Eric Gross, Northrop Grumman’s GEM program manager, told SpaceFlight Insider. “During this test the motor will go through a max Q bucket, so that we can qualify this motor for the conditions we will see during an actual flight.”

This first firing was a “cold-condition” test to gather data on a wide range of tolerances the booster might encounter. Some of these include insulation performance, ablative nozzle erosion, nozzle plug and igniter insulator performance.

The GEM 63 is designed for intermediate-to-large-classes of launch vehicles and was selected over Aerojet Rocketdyne’s AJ-60A solid rocket booster in 2015 for United Launch Alliance’s Atlas V rocket. The reason for switching from the AJ-60A to the GEM 63 series is one of simple economics. The GEM 63 offers a higher rate of performance at half the cost of the AJ-60A.

Meanwhile, the GEM 63XL is expected to be used on variants of the Vulcan rocket, which ULA is currently developing, and is about 5 feet (1.5 meters) longer than the GEM 63.

“Today is not the end of development,” Mark Peller, ULA’s vice president of Major Development told SpaceFlight Insider. “There’s a second static fire planned, which will be the QM-2 test, which is currently scheduled for December of this year (2018). It’s the culmination of years of developing the solid rocket motor. Obviously the experts in that are those with Northrop Grumman.”

ULA’s Atlas V rocket is regularly selected to send a wide variety of payloads toward their assorted destinations. NASA exploratory missions, national defense satellites as well as commercial payloads all use the venerable rocket. Now these missions will now also depend on the GEM 63.

“The Atlas V can use anywhere between zero to five of these motors,” Katie Qian the senior manager, business development with Northrop Grumman told SpaceFlight Insider. “We saw how powerful just one of these motor is, try to imagine the amount of thrust five of them would produce when they were all fired at once.”

Development and production of these new boosters build upon other SRBs, which include the GEM 40, 46 and 60 motors. This history provides the booster with a rather impressive legacy to live up to. However, the new booster appears to have the chops to get the job done.

Capable of providing up to 450,000 pounds (2,000 kilonewtons) of thrust, the GEM 63 measures about 63 inches (160 centimeters) in diameter. All total, the motor measures about 56 feet (17 meters) in length. With its nose cone attached, the motor stands about 65 feet (20 meters) and will be used in varying numbers dependent on the mission it is flying.

The GEM 63 should first take to the skies affixed to an Atlas V as part of the Space Test Program-3 mission, which is currently slated to be launched late next summer (2019). During this mission five GEM 63 motors will be attached to the rocket’s first stage.

The next steps in the rocket motor’s production include more casting of test articles, more static test firings as well as qualification testing.

This series will not require the amount of start up funding that similar systems require. This is due to the fact that the GEM 63 utilizes technologies that have already been flight proven. Northrop Grumman has produced some 1,000 solid rocket motors in the last 20 years alone.

Then there’s the GEM 63XL, a larger variant of the motor. Northrop Grumman is working alongside ULA to develop the GEM 63XL in preparation for the first flights of the Vulcan rocket (currently slated to conduct its first mission in mid-2020).

“Northrop Grumman has been supplying solid propulsion motors for a variety of launch vehicles since 1964,” said Scott Lehr, president, flight systems, Northrop Grumman. “As ULA’s largest legacy supplier of solid propulsion, we’re pleased that our most recent product has reached this important milestone. The successful completion of this test enables full production to begin.”

Video courtesy of SpaceFlight Insider