GB2146295A

GB2146295A - Underwater vessel

Info

Publication number: GB2146295A
Application number: GB08422597A
Authority: GB
Inventors: Egidius Arens
Original assignee: Fried Krupp AG
Current assignee: Fried Krupp AG
Priority date: 1983-09-10
Filing date: 1984-09-07
Publication date: 1985-04-17
Also published as: AU3272784A; GB8422597D0; DK155362B; NO843497L; AU564071B2; DK420784D0; DE3332754C2; GB2146295B; DK420784A; NO155045B; DK155362C; NO155045C; DE3332754A1

Abstract

A submarine carries at the bow of the hull and on the section of the conning tower facing the hull sound absorbers 14, 15 provided with covers shaped to the contours of the hull and the tower, to reduce the chance of the submarine being detected by sonar. <IMAGE>

Description

SPECIFICATION Underwater vessel The invention relates to an underwater vessel, in particular a strategic submarine, of the kind stated in the introduction to claim 1.

The presently available highly efficient ultrasonic location equipment operating at low transmission frequencies - so-called low frequency active soner - permits of reliable location of such submarines over very great distances. The range of this low frequency active sonar is much greater than the maximum fighting range of the submarine at which torpedoes can be launched with a sufficient probability of hitting a target. The submarine must therefore when going into action enter the observation range of the target ship and is therefore gravely endangered.

The object of the invention is to improve an underwater vessel of the above kind in such manner that it can go into action with less risk of detection at fighting range by a target vessel equipped with low frequency active sonar.

This object is fulfilled in an underwater vessel of the kind set out in the introduction to claim 1 having the features set out in the characterising portion of claim 1.

By providing a sound absorber on the stated parts of the underwater vessel, the target mass of the underwater vessel approaching the target vessel is significantly reduced. By suitable disposition of the sound absorber the target mass can be reduced by about 10 to 1 5 dB so that the target mass offered during an attack by the underwater vessel according to the invention to the active sonar of a target vessel is only about 0 to - 5 dB. Accordingly the range of the active sonar for location of the underwater vessel according to the invention, with limitation of the range due to echo to 1/10 to 1/30 and by noise is reduced to about half the location range of existing submarines with a target mass of about 10 dB.The underwater vessel according to the invention can therefore approach nearer without danger to the target vessel and the chance of destroying the target is increased with reduction in the likelihood of self-betrayal.

The covers provided in accordance with the invention at the bow and tower sections serve for attachment of the sound absorber and also due to their shape avoid increase as the resuit of the sound absorber of the drag of the hull and the tower.

An advantageous embodiment of the invention is set out in claim 2. Due to the wide band characteristic of the wedge absorber a wider range of possible transmission frequencies from the low frequency active sonar of the target vessel is covered, so that the underwater vessel according to the invention cannot be located at long range by changes in transmission frequency.

Another advantageous embodiment of the invention is set out in claim 3. Polyurethane has already been used as the material for covers of sonar bases, both in view of its mechanical strength and its acoustic properties. With similar advantage polyurethane can be used as the material for the hull and tower covering of the underwater vessel.

The invention will now be further described with reference to the embodiment shown in the accompanying schematic drawings, in which: Figure 1 is a perspective view of a submarine, Figure 2 is a longitudinal section of the bow of the submarine of Fig. 1, and Figure 3 is a longitudinal section of the front section of the tower of the submarine in Fig. 1.

The submarine shown in Fig. 1 has an elongate hull 10 carrying an upstanding conning tower 11. The bow 12 of the hull 10 and the section 1 3 of the tower 11 facing the bow 1 2 carry respective covers 1 4 and 1 5. The covers 14, 1 5 which are shaped to the contours of the hull 10 and the tower 11 cover sound absorbers 16, 1 7 attached respectively to the hull 10 and the portion 1 3 of the tower.The spaces 18, 1 9 between the sound absorbers 16, 1 7 and the covers 14, 1 5 are filled with water, which is conveniently admitted through channels, not shown, in the covers 14, 1 5 when the submarine dives.

The sound absorbers 16, 1 7 are wide band wedge absorbers. The covers 14, 1 5 are made of synthetic material having approximately the same acoustic properties as water.

The preferred synthetic material is polyurethane.

As shown schematically in Fig. 2, the cover 14 at the bow 1 2 of the hull has an aperture 20. The torpedo tube of the submarine, which is not shown for clarity, extends through this aperture. A similar aperture can be provided for the receiver of a front sonar provided on the submarine.

1. An underwater vessel, in particular a strategic submarine, having an elongate hull carrying an upwardly extending conning tower, characterised in that sound absorbers are provided on the bow of the hull and on the section of the tower facing the bow and the sound absorbers are provided with covers shaped to the contours of the hull and the tower.

2. An underwater vessel according to claim 1, characterised in that the sound absorbers are broad band wedge absorbers.

3. An underwater vessel according to claim 1 or claim 2, characterised in that the covers are of synthetic material having sub

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Underwater vessel The invention relates to an underwater vessel, in particular a strategic submarine, of the kind stated in the introduction to claim 1. The presently available highly efficient ultrasonic location equipment operating at low transmission frequencies - so-called low frequency active soner - permits of reliable location of such submarines over very great distances. The range of this low frequency active sonar is much greater than the maximum fighting range of the submarine at which torpedoes can be launched with a sufficient probability of hitting a target. The submarine must therefore when going into action enter the observation range of the target ship and is therefore gravely endangered. The object of the invention is to improve an underwater vessel of the above kind in such manner that it can go into action with less risk of detection at fighting range by a target vessel equipped with low frequency active sonar. This object is fulfilled in an underwater vessel of the kind set out in the introduction to claim 1 having the features set out in the characterising portion of claim 1. By providing a sound absorber on the stated parts of the underwater vessel, the target mass of the underwater vessel approaching the target vessel is significantly reduced. By suitable disposition of the sound absorber the target mass can be reduced by about 10 to 1 5 dB so that the target mass offered during an attack by the underwater vessel according to the invention to the active sonar of a target vessel is only about 0 to - 5 dB. Accordingly the range of the active sonar for location of the underwater vessel according to the invention, with limitation of the range due to echo to 1/10 to 1/30 and by noise is reduced to about half the location range of existing submarines with a target mass of about 10 dB.The underwater vessel according to the invention can therefore approach nearer without danger to the target vessel and the chance of destroying the target is increased with reduction in the likelihood of self-betrayal. The covers provided in accordance with the invention at the bow and tower sections serve for attachment of the sound absorber and also due to their shape avoid increase as the resuit of the sound absorber of the drag of the hull and the tower. An advantageous embodiment of the invention is set out in claim 2. Due to the wide band characteristic of the wedge absorber a wider range of possible transmission frequencies from the low frequency active sonar of the target vessel is covered, so that the underwater vessel according to the invention cannot be located at long range by changes in transmission frequency. Another advantageous embodiment of the invention is set out in claim 3. Polyurethane has already been used as the material for covers of sonar bases, both in view of its mechanical strength and its acoustic properties. With similar advantage polyurethane can be used as the material for the hull and tower covering of the underwater vessel. The invention will now be further described with reference to the embodiment shown in the accompanying schematic drawings, in which: Figure 1 is a perspective view of a submarine, Figure 2 is a longitudinal section of the bow of the submarine of Fig. 1, and Figure 3 is a longitudinal section of the front section of the tower of the submarine in Fig. 1. The submarine shown in Fig. 1 has an elongate hull 10 carrying an upstanding conning tower 11. The bow 12 of the hull 10 and the section 1 3 of the tower 11 facing the bow 1 2 carry respective covers 1 4 and 1 5. The covers 14, 1 5 which are shaped to the contours of the hull 10 and the tower 11 cover sound absorbers 16, 1 7 attached respectively to the hull 10 and the portion 1 3 of the tower.The spaces 18, 1 9 between the sound absorbers 16, 1 7 and the covers 14, 1 5 are filled with water, which is conveniently admitted through channels, not shown, in the covers 14, 1 5 when the submarine dives. The sound absorbers 16, 1 7 are wide band wedge absorbers. The covers 14, 1 5 are made of synthetic material having approximately the same acoustic properties as water. The preferred synthetic material is polyurethane. As shown schematically in Fig. 2, the cover 14 at the bow 1 2 of the hull has an aperture 20. The torpedo tube of the submarine, which is not shown for clarity, extends through this aperture. A similar aperture can be provided for the receiver of a front sonar provided on the submarine. CLAIMS

3. An underwater vessel according to claim 1 or claim 2, characterised in that the covers are of synthetic material having sub stantially the same acoustic properties as water, preferably polyurethane.

4. An underwater vessel according to one of claims 1 to 3, characterised in that the inner spaces of the covers are filled with water.

5. An underwater vessel according to any of claims 1 to 4, characterised in that the bow cover has at least one aperture for reception of a torpedo tube and for the receiver of a sonar.