Northrop Grumman has conducted a live, static-fire test of a stage-two solid rocket motor for the LGM-35A Sentinel intercontinental ballistic missile at the Air Force Arnold Engineering Development Complex in Tullahoma, Tenn., the company announced Jan. 16.
Northrop is the Air Force’s Sentinel prime contractor and is responsible for building the solid rocket motor for Sentinel stages one and two, while L3Harris Technologies will build the third stage motor.
“The test was conducted in a vacuum chamber simulating real-world environmental conditions the solid-rocket motor would experience during high-altitude and space flight,” Northrop Grumman said. “Test data will be analyzed to determine how motor performance matched digitally engineered model predictions, critical to maturing the design and lowering risk. Following this development effort, Northrop Grumman will begin a series of rocket motor qualification testing for both stages.”
The first Sentinels to be deployed will carry the W87-0 warhead. Later missiles will have a W87-1.
W87-0 will be a version of the Minuteman missile’s III W87 adapted for flight on Sentinel missiles. W87-1 will be a newly manufactured copy of Minuteman’s other warhead, the W78, but with a fresh plutonium pit cast at the Los Alamos National Laboratory. The lab estimates it will start making pits around 2030.
Sarah Willoughby, Northrop Grumman’s vice president and program manager for Sentinel, said in a statement that the stage-two solid rocket motor test moves the company “forward for qualification testing in partnership with the Air Force.”
“The test’s data gives us an accurate reading of our design’s performance and now informs our modeling and designs,” she said.
Northrop Grumman said in March that it had tested the first stage motor at the company’s Promontory, Utah site.
Sentinel is to achieve initial operational capability in May 2029 to begin replacing the 400 Boeing-built Minuteman IIIs.
The Air Force missed its target date of starting Sentinel flight testing by the end of 2023, and Air Force Secretary Frank Kendall told the House Armed Services Committee in April that it will be a challenge for Sentinel to enter service on time.
A version of this story initially appeared in affiliate publication Defense Daily.
