Abstract: A countermeasure device which is supplied with air in order to actively compensate for external water pressure at any depth, is disclosed. The countermeasure includes an air bag hover system and one or more acoustic projectors, both of which are connected by an air line to a high pressure air source. A sensor is provided which measures the external water pressure and transmits the measurements to a microprocessor. Upon sensing an increased external water pressure, a pressure regulator valve is opened and air is supplied to both the acoustic projectors and the air bag in order to compensate for the increased water pressure. Similarly, if the external water pressure decreases, then air is released from both the air bag and the acoustic projectors through a pressure vent valve connected to the air bag. The microprocessor can also be programmed to vary the deployment depth of the device by varying the internal pressure within the device relative to the external water pressure.

Abstract: A system and method for operating a cylindrical acoustic projector is provided which allows efficient operation of the projector over a wide bandwidth. The system and method use multiple power amplifiers each tuned to operate over separate and narrow bandwidths, the number of seperate bandwidths corresponding to the number of amplifiers such that the total bandwidth is covered. Each tuning network assembly includes the power amplifier, a transformer and a tuning inductor, with the tuning inductor selected for proper tuning over the frequency bands the amplifier is to operate at. The narrow bandwidths for each power amplifier result in a substantial reduction in the reactive power dissipated in the amplifiers and also the total power consumption of the acoustic projector.

Abstract: A deflection snubber assembly for preventing damage to a propeller which is subjected to instances of high force is disclosed. The propeller includes a hub for mounting the propeller on a shaft and a number of blades exteng radially outward from the hub. Outer tips of the number of blades are interconnected by a continuous, circular band. The propeller is constructed to accommodate a predetermined amount of deflection upon instances of high force before being permanently damaged. The deflection snubber assembly includes a housing circumferentially surrounding the propeller, the housing having a number of deflection limiting members, each of the deflection limiting members limiting deflection of the propeller to within the predetermined amount of deflection upon occurrences of the instances of high force.

Abstract: A countermeasure buoy for use in an underwater environment includes a main ody portion, a propulsion portion, a hull section, and an acoustical array. The main body portion includes a first end and a second end longitudinally opposed from the first end. The propulsion portion includes a main body end connected to the first end of the main body portion and a propelling end opposite the main body end. The hull section includes a rearward end connected to the second end of the main body portion and an open end opposite to the rearward end. The acoustical array is housed within said hull section and includes a base end connected to an interior of the hull section and a free terminal end opposite to the base end. A cap member is removably attached to the open end of said hull section and a vertical alignment of the propulsion portion, the main body portion and the hull portion enables gravitational displacement of the cap member and release of the acoustical array from the hull section.

Abstract: In an underwater device adapted to sink in water, the device having a proler disposed in a tail cone portion thereof and operable to rotate in a first direction to move the device toward a surface of the water, an assembly for preventing the propeller from rotating in a second direction during the sinking of the device in the water. The assembly includes a circular shroud fixed to outboard tips of blades of the propeller and encircling the propeller. A ramp is disposed on an outside surface of the shroud. A tail cone ring is fixed to the tail cone portion and surrounds the shroud. A pivotally movable flap is mounted on an inside surface of the tail cone ring. The ramp and the flap are engageable and configured to prevent rotation of the shroud, and thereby the propeller, in the second direction, and to permit rotation of the shroud, and thereby the propeller, in the first direction.

Abstract: An underwater acoustical projector has its barrel staves located radially tward of a piezoelectric ceramic driver. The barrel staves are in an hour glass arrangement. The cross-sectional arrangement of the barrel staves is circular at both the top and bottom of the hour glass forming elliptical cross-sections of varying eccentricity between said top and bottom of said staves. The cross-section of greatest eccentricity is located midway between the top and bottom of said staves. The cross-section of greatest eccentricity is located midway between the top and bottom of the barrel staves. This forms a projector with a varying radius of curvature in each of the four 90.degree. quadrants around the axis of the projector. This yields large changes in the resonant frequency.