The Pentagon has slowed down its purchases of the new AIM-120D version of the Advanced Medium Range Air-to-Air Missile (AMRAAM) because of problems with producing its rocket motors, the U.S. Air Force’s top acquisition official said.
“They’re behind on the delivery of the missile,” David Van Buren said Feb. 14 of the Raytheon-produced system. “There are problems with the motor.”
As I’ve written about various US tactical missile systems over the years, one thing that has been a constant thread, if not a prominently mentioned one, is the vast increase in the capability of solid rocket motors. At the beginning of the missile age, many early missiles such as Bullpup used liquid fuel motors because solid rocket motors just couldn’t provide either the required thrust, or had such short burn times as to be impractical.
But very quickly, improvements in fuels and production of solid rocket motors meant that for a given size, the specific impulse of a motor increased dramatically. Techniques such as dual mode motors (an initial high thrust burn to accelerate, and a longer lower thrust burn to sustain that speed, all in one stage) led to much greater range and speed for a missile.
The AIM-120D looks to build on this progress to greatly improve the range of the current US long range air-to-air missile. But apparently, there is still a steep learning curve. Let’s hope they figure out a way to improve the production rate.