The present invention relates to a closure for a missile launching tube and more particularly to a frangible missile tube closure.
Launch tube closures may be used as a sealing means in conjunction with an outer hatch for the launching of missiles from a submerged or underground missile launcher. The closures may also be used as an environmental closure on launch tubes of surface, ground or air launched missiles. In either case, the closure is designed to be removed prior to launching of the missile.
Prior art launch tube closures include flat plastic diaphragms with explosive cord arranged along a predetermined pattern, Mechlin, Jr. et al, U.S. Pat. No. 3,135,163. The explosive cord is detonated to rupture the diaphragm into several pieces prior to missile launch. A similar type of launch closure employs a thin frangible plastic diaphgram placed over the launch tube so as to be ruptured by the missile as the missile exits the launch tube, Kroh, U.S. Pat. No. 3,742,814. One drawback of these types of closure is that the thin nature of the diaphragm prevents the closure from being used with submerged or underground launch tubes due to the high differential pressures encountered.
Another launch tube closure, Schenk, U.S. Pat. No. 3,962,951, is a dome shaped closure formed of asbestoes reinforced phenolic plastic with plastic foam or other strengthening material between the phenolic plastic dome and the missile. A linear shaped charge is again provided to cut the plastic dome. The disadvantage of this type closure is that the missile must cam back the reinforced phenolic plastic and strengthening material as the missile exits the launch tube. The camming action places a front end load on the missile which may later affect the missile trajectory.