VLS Hatch Actuation System Dynamic Analysis

Martin Marietta has always considered reliability and maintainability to be important aspects of good integrated system design. The work discussed in this paper was undertaken to provide the magnitude of mechanical loads under which the U.S. Navy Vertical Launching System (VLS) batch controller and actuation systems must function reliably within sequence time line constraints. Data discussed here are limited to those associated with VLS operation aboard the U.S. Navy operational test ship AVM-1 (U.S.S. Norton Sound). Two types of hatch systems are involved. The cell hatch provides ballistic protection and a water tight seal to a below-deck canister containing a missile prepared for vertical launch on command. The uptake hatch provides ballistic protection and a water tight seal to an uptake shaft which provides for motor exhaust ventilation of a below-deck plenum at missile launch. As an adjunct to optimization of these mechanical design loads, several actuation switches are positioned to control motor current, brake functioning, and to provide hatch position data to the launch sequencer. Based upon the predicted loads, estimates of the margins of safety are made for evaluation of the fatigue life of the mechanical elements of the systems. Tests were performed as soon as hardware subsystems became available to confirm values of critical parameters and to validate system design and operation.