Abstract: A low flow noise sonobuoy suspension system having a surface float, a sussion cable having a compliant portion, a bridle, a hydrophone, a mechanical cable, a terminal weight, and a drogue. The hydrophone is located within the bridle and is attached to the bridle so as to allow the hydrophone to remain roughly vertical if the bridle is tilted. The bridle is located below the surface float and is connected to the surface float by means of the suspension cable. The drogue is located below the bridle and is connected to the bridle by a mechanical cable. The drogue is connected at an attachment point on the mechanical cable such that the relative velocity of the hydrophone is negligible. The terminal weight is also attached to the mechanical cable. By means of this arrangement, both the horizontal motion noise caused by the relative velocity of the hydrophone, and the vertical motion noise caused by the surface waves are reduced.

Abstract: An underwater probe for determining true acoustic intensity by the direct asurement of true acoustic velocity and true acoustic pressure in a neutrally buoyant package, utilizes a moving-coil geophone embedded in a casting of syntactic foam and a pair of hydrophones on the exterior of the casting.

Abstract: An acoustic array having polymer hydrophones is disclosed. The array compes a plastic roll, a plurality of polymer piezoelectric sensors affixed to the roll and electrodes that interconnect the sensors to utilization means such as those found for underwater detection systems or geophysical detection systems such as seismic detectors. The plastic roll has a pliant characteristic so as to readily assume a predetermined shape as well as, preferably, having a strong tendency to unravel and is of a relatively thin material. Similarly, the piezoelectric sensors have a pliant characteristic, are relatively thin, and are affixed to one of the surfaces of the plastic roll. Further, the electrodes have a pliant characteristic, are relatively thin, and are affixed to the same surface of the roll as the sensors.

Abstract: The disclosure shows a multi-store, electrically-operated sonobuoy launcher hat is connected to the sonobuoy launcher power system of the aircraft. The sonobuoys are sequentially stacked inside the launcher and current switching and blocking means regulate and direct pulses from a switch in the aircraft to ensure individual, single sonobuoy launches.

Abstract: This invention comprises a multi-store, gas-fired launcher that fits into, nd is electrically connected with, a transporting vehicle and that contains sequentially-stacked assemblies that generate sufficient gas force to discharge an individual store. An electrical pulse from the transporting vehicle cause a sequencer in the launcher to divert the charge to a burn resistor. At burn-out, a spring-activated striking arm punctures a CO2 bottle which provides sufficient gas pressure to force the store out of the launcher.

Abstract: A floating sensor system is provided to detect very low frequency pressure ignals (down to 0.01 Hz). This system detects pressure fluctuations or pressure signals of interest in the ocean or other body of water in the presence of unwanted pressure signals generated by surface wave induced motion. A drifting sensor surface float follows the surface waves and in turn moves a suspended pressure sensor vertically, such that it detects the wave motion as a change in static pressure which then constitutes a noise source. A correlation circuit and a logic circuit discriminate between a first composite signal, comprised of the pressure signals of interest and wave motion noise, and a second reference signal, comprised only of the wave motion noise to provide an output signal transmitted to a monitoring station.

Abstract: A guideable sonobuoy is disclosed that is ejected from a moving aircraft o the free stream with a ring wing opened to guide the buoy along a predetermined flight path. While the buoy remains packed inside a launch container, the ring wing, made of spring steel, is collapsed around the nose portion thereof. Once launched, the ring wing will fly the buoy to a predetermined destination.

Abstract: An improved system is disclosed for calibrating acoustic pressure-sensitive transducers, particularly hydrophones, down to frequencies in the sub-Hertz range. A transducer under test and a reference transducer, both electrically connected to a voltage measuring device, are mounted in aligned proximity to each other upon a pivotal rocker arm immersed in a water tank. A cam and follower unit driven by a motor oscillates the rocker arm so that the transducers are moved through a vertical displacement equivalent to the desired fluctuation of hydrostatic pressure. As a result, calibrations down to 0.01 Hz are achieved.

Abstract: A system for suspending a gradient hydrophone from a flotation member at the surface of a body of fluid by a single compliant member attached closely above the center of gravity of the hydrophone, in order to minimize the number of principal vibration modes, such as the rocking mode, and group the frequencies of such principal vibration modes in a band far enough below the operational acoustical bands of the hydrophone to allow effective electronic rolloff.