U.S. Air Force and Northrop Grumman Complete Major Test of Sentinel Missile's Second-Stage Rocket Motor

The U.S. Air Force, working with Northrop Grumman, has successfully completed a full-scale qualification test of the stage-two solid rocket motor for the LGM-35A Sentinel intercontinental ballistic missile (ICBM). The test was carried out on July 20 by the 717th Test Squadron at the Arnold Engineering Development Complex in Tennessee. It marks a critical step in the U.S. military’s efforts to modernize its land-based nuclear missile force.

To simulate high-altitude launch conditions, the test was conducted inside a vacuum chamber. This allowed engineers to gather detailed information on how the motor performs — including thrust output, burn rate, and how well it can be steered using its thrust vector control system.

This second-stage motor is one of three booster stages that power the Sentinel missile. The recent test is part of a broader campaign to verify how well the missile components align with digital models created through a model-based engineering approach. These models are designed to reduce the need for physical prototypes and speed up development.

Brigadier General William S. Rogers, the Air Force’s program executive officer for ICBMs, said the test shows steady progress:

“We’re not just testing hardware — we’re proving that our models are accurate, our development timeline is achievable, and the system will be ready to deliver when called upon.”

The data collected will help engineers fine-tune the design of the second-stage motor and minimize technical risks before entering mass production. It also plays a key role in verifying the accuracy of digital simulations used throughout the missile’s development.

This successful test comes after a stage-one motor test in March at Northrop Grumman’s facility in Promontory, Utah, which also met expectations and matched performance predictions based on simulations.

The Sentinel program represents a major overhaul of the U.S. nuclear arsenal. It is replacing the aging Minuteman III missiles that have been in service for decades. Northrop Grumman is the lead contractor on the project, and the Air Force has emphasized the use of digital engineering tools to make development faster, more efficient, and more cost-effective.

More stage-two tests are scheduled later this year to evaluate how the motor performs in different environmental conditions, further ensuring that the Sentinel system will be ready to operate under real-world launch scenarios.

General Rogers added,

“This isn’t just about one motor test. It’s about building confidence — in our engineering; in our program schedule; and, most importantly, in our ability to deter aggression and defend the nation.”

The Sentinel missile is expected to become the cornerstone of America’s land-based nuclear deterrent well into the 21st century.