Abstract: Improved double-stage air filter of modular construction for attachment been aligned openings of a spaced double wall structure in order to supply filtered air flow to a controlled area. The filter is generally made up of casing means and combined plate and sleeve means. Both the casing means and plate means are provided with a flange means. The sleeve means is provided with a series of perforations and the plate means flange means is provided with a plurality of relatively spaced slots. The casing means flange means is affixed to the outer wall so that the casing means extends between the walls. The plate means includes retainer means that is affixed to the inner wall so that the sleeve means is inserted in the casing means. Inner and outer filter means for cleaning and purifying an air flow are disposed about the sleeve means. Retainer means are connected to the casing means flange means so as to hold the filter means in sealing engagement between the last mentioned retainer means and the plate means.

Abstract: The tail section of a fin-stabilized, guided projectile having centrifuga deployed fins is disclosed. A fin retainer and release mechanism engages the projectile fins and holds the fins within the projectile diameter during normal stowage, handling and travel of the projectile down the gun tube. The fin retainer and release mechanism is designed to operate from the forces of gun launch to enable centrifugal deployment of the fins due to projectile rotation after the projectile leaves the gun tube.

Abstract: Disclosed is an air supply system that provides filtered ventilation to a protected zone which is maintained at a positive pressure so as to prevent contaminants from infiltrating therein. The system further discloses a three-stage air filter apparatus that provides all the necessary filtering to remove contaminants from the air that may be created by chemical, biological and radiological conditions.