Air-launched buoy

Details Air-launched buoy Air-launched buoy

1997-04-18

1998-08-18

Avila, Stephen

Buoys, rafts, and aquatic devices

Buoy

441 30, B63B 2200

Patent

active

057952035

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to air-launched buoys which are intended to be launched from an aircraft so that they float on the surface of the sea while supporting, immersed at a variable depth, measurement sensors the signals from which are generally sent back to the carrier aircraft by radio link. It is applicable, among other things, to undersea detection.
U.S. patent application Ser. No. 78 21 276 filed on 18 Jul. 1978 by the Applicant Company and granted on 15 Feb. 1980 with U.S. Pat. No. 2,431,419 discloses a buoy of this type which includes, as represented in FIG. 1, an elongate body 101 suspended from a balloon 102 of double-frustoconical shape. As it falls through the air in the direction 103, the air streams 104 slip along the body 101, which is relatively long. Most of this air is ducted by two lateral flaps 105 situated at the top end of the body. These flaps open at the moment of launch and their main function is to actuate an internal mechanism which, among other things, releases the protective cap in which the balloon 102 is contained, as described in U.S. patent application Ser. No. 79 05 002 filed by the Applicant Company on 27 Feb. 1979 and granted with the U.S. Pat. No. 2,450,193 on 26 Sept. 1980. These flaps furthermore allow the air streams to be ducted so that they are directed towards openings 106 situated at the upper part of the body below the flaps and which communicate with the inside of the balloon 102 via a non-return diaphragm 107. Thus after launch, the flaps open, which causes the cap protecting the balloon to be ejected and frees the openings 106. The air streams therefore enter through these openings, raise the diaphragm 107 and start to inflate the balloon 102. When the latter is completely inflated it slows the fall of the buoy like a parachute so that the impact on the surface of the water will not be too hard.
The balloon furthermore includes, on the flanks of its upper half, pockets 108 which allow the movement of the buoy to be stabilized as it falls so as to avoid, or at least greatly limit oscillation. For that, these pockets have a triangular shape truncated at the top and they extend over substantially the entire length of the upper frustoconical part of the balloon. They are fixed to the sides and open at top and bottom. Air thus rushes into them, inflates them and escapes through the upper part which therefore acts in the same way as the hole at the centre of a parachute.
When the buoy enters the water, the flow of air stops and the non-return diaphragm 107 closes, which keeps the balloon inflated. This balloon therefore acts as a float which prevents the body from sinking and keeps it close to the water surface. Under the effect of hydrostatic pressure, a small amount of water nevertheless enters the balloon via the openings by lifting the diaphragm 107, but as this balloon is closed at the top, the air pressure increases and prevents water from continuing to enter. The water level inside the balloon therefore stabilizes at a height slightly below the water level outside this balloon.
French Patent Application No. 2,654,065 also discloses a buoy equipped with a balloon.
However, in this patent application, the balloon has no stabilizing pockets situated at its upper part. On the contrary, these pockets are situated on the lower part of the balloon. Also, the air inlets although they are indeed made in the wall of the balloon, are clearly situated at the connection between the body and the balloon and at the base of the pockets.
In these conditions, the air is prevented from reaching the air inlets by the pockets where air builds up on the one hand pushing the air streams beyond the level of the openings and on the other hand pushing the wall of the balloon inwards. In these conditions, the balloon tends initially to slowly, the balloon then looking like a mushroom which acts as a parachute.
As a result of this, on the one hand, the buoy falls very slowly, which is contrary to the desired goal, where although the descent does indeed need to be slowed down enou

REFERENCES:
patent: 3890591 (1975-06-01), Bocquillon et al.
patent: 4029141 (1977-06-01), Ferrari et al.
patent: 4279025 (1981-07-01), Suppa
patent: 4295211 (1981-10-01), Suppa et al.
patent: 4379534 (1983-04-01), Miller et al.
patent: 4380440 (1983-04-01), Suppa

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