Spaceflight Now: Breaking News

Delta 4 solid rocket motors qualified for launch
Posted: June 23, 2000

The GEM-60 solid rocket motor is test fired. Photo: Boeing
Alliant Aerospace Propulsion Company, Magna, Utah, yesterday successfully completed the last of three static test firings of a new solid propulsion Graphite Epoxy Motor designated as the GEM-60 for The Boeing Company's Delta 4 Medium-plus family of launch vehicles.

Jeff Foote, president, Alliant Aerospace Propulsion Company, said today's test marks the completion of the new motor's development and qualification program, culminating 29 months of design, fabrication, and testing work by employees from Boeing, ATK, and several critical suppliers, including Moog, which supplies the Thrust Vector Actuation system, Hitco, which manufactures the nozzle, and Marvin Engineering, which fabricates the main metal components.

"The GEM-60 motor performed flawlessly in each of the three qualification static test firings, meeting or exceeding all performance requirements," said Foote. "Thanks to an outstanding team effort by everyone involved, we now have a new and more powerful booster that's ready to fly. This team has demonstrated once again its unmatched ability to develop a new solid rocket motor quickly and affordably. The first production motors will be delivered to the launch site this fall and then to Boeing in early 2001. The maiden launch for the Delta 4 vehicle is planned for 2001."

Alliant Aerospace Propulsion Company is delivering GEM-60 motors to Boeing under a contract that extends through 2008. ATK is also producing Delta 4 structures at its new composite structures manufacturing facility in Iuka, Miss.

The latest derivative of Delta rockets that have been lifting satellites into orbit since 1960, the Delta 4 family of launch vehicles is designed to meet the growing needs of satellite manufacturers and users around the globe for reliable and affordable access to space.

The Delta 4 Medium-plus family has three configurations, which are distinguished by the number of GEM-60 motors attached to the common booster core and the size of the upper stages and payload fairings, which protect satellites during the early ascent phases of flight. The configurations are:

  • Delta 4 Medium-plus (4,2) with two solid rocket motors and a four meter fairing for a geosynchronous transfer orbit (GTO) payload of 12,890 pounds.
  • Delta 4 Medium-plus (5,2) with two solid rocket motors and a five-meter fairing for a GTO payload of 10,230 pounds.
  • Delta 4 Medium-plus (5,4) with four solid rocket motors and a five-meter fairing for a GTO payload of 14,475 pounds.
The solid rocket boosters for the Delta 4 vehicles are the newest addition to the ATK family of Graphite Epoxy Motors (GEM), which are used on each of the three Boeing Delta launch vehicles. Measuring 60 inches in diameter, the Delta 4 vehicle's GEM 60 boosters are the largest in the family. The GEM 46 boosters are used on the Delta 3 vehicle, while the Delta 2 vehicle uses GEM 40 boosters.

"The GEM boosters are built under strict and uncompromising statistical process control disciplines," said Foote. "Manufacturing process control, together with state-of-the-art automated production capabilities, are the key ingredients to ensure rocket motor quality and performance repeatability. It is the reason why the Delta 2 rocket has set the standard throughout the world for launch reliability and predictable performance."

Alliant Aerospace Propulsion Company is part of ATK's Aerospace group, which comprises the company's space and strategic propulsion and Utah- and Mississippi-based composite structures operations. The group employs approximately 1,650 people in California, Florida, Mississippi, New York, and Utah. Sales in fiscal year 2000 were $436 million. The GEM-60 motors are manufactured at the group's Utah Composites Center in Clearfield, Utah, and Utah Propulsion Center in Magna, Utah.