UNDERWATER CRAFT LESS LIKELY TO BE DETECTED ACROSS GREAT DISTANCES

Abstract

An underwater craft is considerably less likely to be detected by sonar if the underwater craft includes an outer hull as disclosed herein, which outer hull may extend in a longitudinal direction through a stern section, through a midship section, and through a bow section. The outer hull in the midship section may have a polygonal cross section. The outer hull of the midship section may also have curvature along the longitudinal direction throughout the midship section. A ratio of a radius of curvature to a total length of the underwater craft in the longitudinal direction may be between 5 and 1000. Further, a cylindrical pressure vessel may be disposed under the outer hull.

Claims

1.-15. (canceled)

16. An underwater craft comprising: an outer hull that extends in a longitudinal direction through a stern section, a midship section, and a bow section, wherein with respect to a plane that is transverse to the longitudinal direction the outer hull in the midship section has a polygonal cross section, wherein the midship section has a length extending in the longitudinal direction, wherein the outer hull has curvature along the longitudinal direction over the length of the midship section; and a substantially cylindrical pressure vessel disposed under the outer hull.

17. The underwater craft of claim 16 wherein the polygonal cross section comprises rounded corner regions.

18. The underwater craft of claim 16 wherein the polygonal cross section is symmetric about a line that is perpendicular to the longitudinal direction.

19. The underwater craft of claim 16 wherein the outer hull is curved along the longitudinal direction over the length of the midship section over a cross section transverse to the longitudinal direction.

20. The underwater craft of claim 19 wherein the outer hull forms a conical section in the longitudinal direction or the outer hull is comprised of two or more conical sections.

21. The underwater craft of claim 16 comprising a tower in the midship section.

22. The underwater craft of claim 16 wherein the curvature comprises a radius of curvature, wherein a ratio of the radius of curvature to a total length of the underwater craft in the longitudinal direction is between 5 and 1000.

23. The underwater craft of claim 16 wherein a center of the polygonal cross section is half of a height of the polygonal cross section, wherein a widest point of the polygonal cross section is disposed below or above the center, wherein the widest point of the polygonal cross section is at least 10% of half of the height of the polygonal cross section below or above the center.

24. The underwater craft of claim 16 wherein all planes of the polygonal cross section comprise an inclination of at least 10? relative to a perpendicular.

25. The underwater craft of claim 16 wherein all planes of the polygonal cross section comprise an inclination of 10? to 40? or 50? to 80? relative to a perpendicular.

26. The underwater craft of claim 16 wherein the outer hull has a sound-absorbing property.

27. The underwater craft of claim 16 wherein the outer hull is substantially reflecting and/or absorbing for soundwaves in a frequency range of 100 Hz to 100 kHz.

28. The underwater craft of claim 16 comprising sensors and/or fuel stores disposed between the outer hull and the substantially cylindrical pressure vessel.

29. An underwater craft comprising: an outer hull that extends in a longitudinal direction through a stern section, a midship section having a length in the longitudinal direction, and a bow section, wherein a cross section of the outer hull in the midship section is polygonal-shaped, wherein the outer hull has curvature along the longitudinal direction throughout the length of the midship section; and a cylindrical pressure vessel disposed under the outer hull.

30. The underwater craft of claim 29 wherein the polygonal-shaped cross section comprises rounded corner regions.

31. The underwater craft of claim 29 wherein the polygonal-shaped cross section is symmetrical.

32. The underwater craft of claim 29 wherein the cross section of the outer hull is curved along the longitudinal direction over the length of the midship.

33. The underwater craft of claim 32 wherein the outer hull comprises a conical section in the longitudinal direction.

34. The underwater craft of claim 29 wherein the curvature of the outer hull along the longitudinal direction throughout the length of the midship section has a radius of curvature, wherein a ratio of the radius of curvature to a total length of the underwater craft in the longitudinal direction is between 10 and 250.

35. The underwater craft of claim 29 comprising sensors and fuel stores disposed between the outer hull and the cylindrical pressure vessel.

Description

[0047] The underwater craft according to the invention is explained in more detail below with reference to exemplary embodiments which are illustrated in the drawings, in which

[0048] FIG. 1 shows a top view of an underwater craft according to the invention,

[0049] FIG. 2 shows a cross section of a first exemplary underwater craft,

[0050] FIG. 3 shows a cross section of a second exemplary underwater craft,

[0051] FIG. 4 shows a cross section of a third exemplary underwater craft,

[0052] FIG. 5 shows a cross section of a fourth exemplary underwater craft.

[0053] FIG. 1 illustrates a top view of an underwater craft 10 having a bow section 20, a midship section 30 and a stern section 40, wherein the underwater craft comprises a rudder 60, here in the form of a cross rudder, and a propeller 70, in the stern section 40. The underwater craft 10 comprises an outer hull 50 which comprises a curvature of the midship section in the longitudinal direction of the underwater craft 10, as can be seen in comparison to a pressure vessel 80 illustrated in simplified form as a cylinder. In practice, the pressure vessel 80 will also comprise rounded ends, preferably hemispherical ends, at the bow and at the stern, which has been left out here for simplification purposes. The pressure vessel 80 also does not have to take up the full length. In particular, weapon tubes can be arranged in the bow.

[0054] FIG. 2 shows a first exemplary cross section. The outer hull 80 has a hexagonal cross section, the widest point 100 lies precisely level with the center 90 which is formed by the center point of the cylindrical pressure vessel 80. This point is correspondingly used here and below as the center in accordance with half the height of the polygonal cross section since they virtually coincide, but the center point can be illustrated more easily visually. All of the surfaces of the outer hull 50 are at an angle of 30? or 90? in relation to the perpendicular.

[0055] FIG. 3 shows a second exemplary cross section. The outer hull 80 comprises an irregular hexagonal cross section, wherein the widest point 100 is arranged significantly above the center 90. By this means, a large portion of the incident waves is reflected to the sea bed, which results in a further minimization of the likelihood of detection.

[0056] FIG. 4 shows a third exemplary cross section. The outer hull 80 comprises an irregular hexagonal cross section, wherein the widest point 100 is arranged significantly below the center 90. Although a large portion of the incident waves is thereby reflected to the water surface, the center of gravity of the underwater craft 10 can, however, be arranged lower. This is advantageous for the stability of the underwater craft 10.

[0057] In contrast to FIG. 2 to FIG. 4, FIG. 5 shows a cross section having rounded corners which otherwise is basically identical to the second exemplary cross section from FIG. 3. In addition, fuel stores 110 and sonar sensors 120 are arranged between the outer hull 50 and the pressure vessel 80.

[0058] All of the cross sections shown in FIG. 2 to FIG. 5 are of mirror-symmetrical design. This is not necessary, but is preferred.

REFERENCE SIGNS

[0059] 10 Underwater craft

[0060] 20 Bow section

[0061] 30 Midship section

[0062] 40 Stern section

[0063] 50 Outer hull

[0064] 60 Rudder

[0065] 70 Propeller

[0066] 80 Pressure vessel

[0067] 90 Center

[0068] 100 Widest point

[0069] 110 Fuel store

[0070] 120 Sonar sensors