Abstract: A control mechanism is provided for tripping a system in a releasable missile. The control transmission which controls tripping of the system comprises an energy store held under stress by a locking member. The locking member is designed to be actuated on completion of unwinding of the storage pulley thereby to release the energy store and so initiate tripping of the system connected to it. The invention has a particular application in releasable missiles such as bombs which are transported by aircraft.