GEM 63XL solid rocket booster is the longest single-segment motor ever flown

Northrop Grumman‘s 63-inch diameter, extended-length Graphite Epoxy Motor (GEM 63XL) solid rocket booster (SRB) is making its debut on 8 January, supporting the inaugural flight of United Launch Alliance’s (ULA) Vulcan Centaur rocket. The GEM 63XL uses using virtual reality and monolithic designs.

At more than 72 feet long, the GEM 63XL is the longest monolithic SRB ever produced for flight, a designation previously held by its predecessor, the 66-foot long, 63-inch diameter GEM 63.

Manufacturing and casting the GEM 63XL as a single piece makes the motors more reliable and efficient by reducing joints, hardware and overall mass. This is crucial for an SRB of this length that can deliver over over 210,000 kilograms (463,000 pounds) of thrust to enhance the capabilities of rockets launching the US’s most critical payloads.

The fifth-generation GEM 63XL benefits from flight-proven designs and components, advancing the GEM legacy of increasing capabilities.  “You think you see everything in CAD, but there are restrictions when viewing a two-dimensional design,” said Kevin Foster, chief engineer, GEM 63/63XL, propulsion systems, Northrop Grumman. “We are able to identify potential issues and make design adjustments before production starts which saves us vital time and reduces costs.”

The fact that the GEM 63XLs was built monolithically rather than segmented provides several efficiency benefits, including reducing hardware and overall mass, motor handling and assembly operations, field joint interfaces and launch-site assembly support. In addition, other advantages include streamlining booster mating to core vehicle and enabling rapid launch cadence scheduling, therefore reducing joints and potential points of failure.

Up to six GEM 63XL SRBs can be integrated with the Vulcan rocket. Together with the pair of BE-4 engines, powerful liquefied natural gas engines serving as the rocket’s main engine propulsion deliver over 3.3 million pounds of thrust to lift customer payloads to desired orbits.“Larger, more capable rocket motors, including vehicles that support ride-sharing missions are a result of a customer need to place larger, more advanced payloads into space,” said Robert Gonzalez, senior program director, propulsion systems, Northrop Grumman.

The GEM motors have more capabilities, including their design, and building the motors to be shipped directly to the launch pad with little assembly required.