Technical Review Improves Minuteman III Nozzle Builds

WRIGHT-PATTERSON AIR FORCE BASE: A team of scientists and engineers at the Air Force Research Laboratory Materials and Manufacturing Directorate, in collaboration with Ogden Air Logistics Center, Hill AFB, Utah, and industry, have resolved a challenging technical issue confronting the nation's land-based Minuteman III intercontinental ballistic missile force.

Dr. Jeffrey R. Calcaterra of the Directorate's Metals, Ceramics, and Nondestructive Evaluation Division, supported by Dr. Ayman A. Salem, Kevin W. Shiveley, and 2nd Lt. Adrienne J. Hickey, was a key member of the Minuteman Stage 3 Nozzle Molybdenum Technical Review Team (TRT) that investigated molybdenum (Mo) throat-support cracks occurring in new nozzle builds for the Minuteman III missile's third stage.

The year-long study has saved several million dollars and increased the preparedness of the nation's strategic deterrence forces. For their outstanding efforts, the TRT received the 2007 Brent Scowcroft Award for ICBM Acquisitions and Sustainment, honoring retired Air Force Lt. Gen. Brent Scowcroft, who later served as national security advisor to two U.S. presidents.

As a direct result of the study, the Air Force avoided $120 million in cost required for new Stage 3 nozzle redesign, static test firings, and flight tests. The TRT's recommendations have also ensured Mo ring production success and prevented $36 million in production delays.

The TRT was comprised of leading technical experts from the 526th ICBM Systems Group, 508th Aerospace Sustainment Wing at Ogden Air Logistics Center, Northrop Grumman Mission Systems, Alliant Technologies, and AFRL. The team members included Doctor Calcaterra from AFRL, Carol A. Graham, Dr. Michael A. Greenfield, Dr. C. Eugene Hymas, Dr. David M. Kendall, Dr. David E. Richardson, Dr. Myrne R. Riley, and Carolyn D. Smith.

From January through December 2007, the TRT spearheaded the investigation of the Mo throat-support cracks in new nozzle builds. Mo is known to have the sixth-highest melting point of any element and for this reason is often used in high-strength steel alloys. The research team studied the Minuteman III's 42-year old legacy nozzle Mo ring design, structural analysis, and remanufacturing processing. They even constructed a high speed thermal-structural finite element model using current best practices and rocket experts.

The AFRL Materials and Manufacturing Directorate team, led by Doctor Calcaterra, played a crucial role in supporting these efforts. Microscopic testing provided by AFRL laboratories saved approximately $20 million in program costs. The team also conducted Mo sample analysis and metallographic testing, which proved instrumental to the investigation's success.