December 15, 1977: Extendable Nozzle Exit Cone for M-X ICBM Tested

An extendable nozzle exit cone (ENEC) for an upper stage of the M-X ICBM was successfully tested over a rocket motor at the Rocket Propulsion Laboratory on Leuhman Ridge. The collapsible nozzle was designed to extend after stage firing, greatly extending the range of the missile. The M-X was designated Peacekeeper in October 1982.

The Missile X (MX) system is an advanced. highly accurate. mobile intercontinental ballistic missile system the Air Force is starting to develop. Its increased survivability. as compared to the fixed-in-place Minuteman stem. is intended to be gained by having a number of possible missile launch points. In this way, an enemy would be unable to identify the exact location of the missile before launch. Compared to Minuteman III, Missile X is also intended to be more accurate and capable of delivering a larger number of nuclear warheads.

Air Force officials are generally satisfied with results in missile risk areas. However, for one area--directional rocket motor nozzle technology--test results have not been totally successful. Although two experimental nozzles failed during testing, program officials expressed confidence that technical risk for the directional nozzle area has been reduced. Tests conducted were more severe than tests planned for the MX nozzles.