Communications – electrical: acoustic wave systems and devices – Echo systems – Distance or direction finding
Patent
1999-01-19
2000-05-30
Pihulic, Daniel T.
Communications, electrical: acoustic wave systems and devices
Echo systems
Distance or direction finding
G01S 1500
Patent
active
06069842&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to helicopter-borne underwater mines countermeasures methods and devices in which the means employed for mine-hunting are suspended beneath a helicopter which allows these means at the end of a power and winching cable to be dunked. This makes it possible, on the one hand, to limit the risks of destroying the mines by explosion merely to the destruction of these means, in protecting the carrier, and on the other hand, to increase the speed with which such a system can be deployed.
SUMMARY OF THE INVENTION
Systems comprising magnetically or acoustically influenced drogues and side-scanning sonars towed by large heavy helicopters, of the MH53 type for example, completely dedicated to this mission, are known. These systems are, however, bulky, heavy and expensive and require the use of a very large helicopter that cannot be carried on a medium-tonnage naval carrier such as a frigate for example. The use of its systems is therefore very limited.
Furthermore, the sonars fitted to these systems are of the side-scanning type and are therefore not suited to the detection of moored mines. What is more, the very principle of side-scanning sonar presupposes that it should operate by continuous advancement of its antennas and therefore of their carrier. This being the case, when a suspect object is located, it is difficult to backtrack and re-locate it and to determine precisely the nature of this object (to classify it).
These difficulties prevent the system from being supplemented by a device for destroying the mines which can be carried on board the spotter helicopter. Now, this need to destroy the mine immediately after spotting it is essential when the helicopters are patrolling in front of a flotilla in order to protect it.
There is also known from another source, especially from a French patent filed by THOMSON-CSF on Nov. 28, 1988 under the Ser. No. 86/13485 and published on Apr. 1, 1988 under the U.S. Pat. No. 2,604,530, an anti-submarine warfare device in which use is made of a sonar in the form of a low weight elongate dome of small bulk suspended at the end of the power and winching cable from a winch, itself installed in a low-tonnage helicopter.
This sonar comprises a set of arms which unfold like an umbrella and which support acoustic sensors at their ends, this making it possible to obtain a very large-sized antenna when the arms are deployed. For raising and lowering the dome, the arms are folded. This sonar allows sources of noise, for example submarines submerged at the bottom of the sea, to be located.
In order to alleviate the abovementioned drawbacks, the invention proposes a helicopter-borne underwater mines countermeasures method, in which use is made of sonar means suspended beneath a helicopter, mainly characterized in that use is made of a lightweight sonar dome equipped with means of detecting and classifying the mines and in that the helicopter is made to pass through a series of successive fixed points during which the sonar dome at the end of a power and winching cable paid out by a winch borne by the helicopter is dunked into the water in order to detect and/or classify the mines in a series of successive sectors forming a route that is to be cleared of mines.
In order to implement this method, the invention also proposes a device, mainly characterized in that it comprises an elongate cylindrical body comprising, at its lower part, two arms deployable into a position perpendicular to the axis of the body to form a sonar receiving antenna and articulated to this body by means allowing these arms to be folded back into two first channels formed in the side face of the body parallel to the axis of this body, and at least one sonar emitting antenna located in a third channel formed in the side face of the body parallel to the axis of this body in a position allowing the emission of a sonar beam of axis perpendicular to the axis of the receiving antenna.
According to another feature, this device further comp
REFERENCES:
patent: 5155706 (1992-10-01), Haley et al.
patent: 5602801 (1997-02-01), Nussbaum et al.
Abomnes Pascal
Lagain Henri
Peynaud Fran.cedilla.ois
Verveur Jean
Pihulic Daniel T.
Thomson Marconi Sonar S.A.S.
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