Stabilization Arrangement For Communication Buoys

Abstract

In association with a communications buoy of the type launched from a submerged vessel, an automatically deployable surface stabilization arrangement for preventing inundation of the buoy even under severe environmental conditions. A collar of continuous and flexible material such as mylar film is arranged around the buoy proximate to the water line, and is attached to the buoy via the top portion thereof in a substantially leak-proof manner with the bottom portion open in a conical or umbrella-like fashion. The collar is rapidly deployed by a series of spring-loaded or bowed arms fabricated of a resilient material and spaced from one another around the buoy. Release of the force constraining the arms against the buoy, such as occurs upon launch of the buoy from the submerged vessel, permits the collar to automatically deploy, thus forming around the buoy at the water line a pocket to trap air. The collar may be compartmentalized to better maintain the air pocket and insure stability. A plurality of spring-loaded fins may also be provided on a submerged portion of the buoy remote from the collar to provide broad surfaces for further damping of the forces acting on the buoy.

Description

BACKGROUND OF THE INVENTION

This invention relates to stabilization of surface communications buoys launched from submerged vessels and in particular to an automatically deployable stabilization arrangement on a communications buoy for damping the surface forces acting on the buoy and preventing inundation of the buoy and its communications antenna.

Existing submarine operating procedures call for the vessel to remain submerged and moving at most if not all times especially during a communication with the outside world. In most applications this requires that an expendable communications buoy be launched from the submerged vessel which is intended to surface while remaining connected to the submarine by way of an umbilical cord designed for example to transfer command signals and communications information to and from the buoy. The mode envisioned for establishing outside communication while remaining submerged and moving necessarily involves the launching of this communications buoy from the signal gun of the submarine and paying-out the umbilical cord in sufficient length to permit the buoy to rise to the surface and complete the communication assignment before the cord becomes taut and snaps. This requires that the buoy be designed for fast rise time to the surface to preserve for communications as much of the total time available as possible. A necessity arises therefore to eliminate for instance as much weight from the buoy as design and other factors will allow as well as provide the buoy with an exterior which effectively reduces to a minimum the external drag forces, while ensuring at the same time that the buoy will remain stabilized and free from inundation on the surface. Thus, any surface stabilization arrangement accompanying the buoy must not be allowed to adversely effect the rise time due to added weight, such as is the case with existing internally carried stabilization provisions, or by increasing the drag forces through externally arranged stabilizers. Such inadequacies are inherent in systems employing for example gas supplies and gas release control mechanisms which are associated with inflatable floatation collar stabilization arrangements. A most important consideration to be made with regard to externally arranged stabilization provisions is that deployment thereof must occur after launch to prevent considerable damage to the buoy itself as well as the launcher or signal gun.

A further requirement in the establishment of communications in the manner described above is that the buoy's antenna, which may be deployed upon command from the submarine at any time following launch, remain completely out of contact with the water once the buoy has surfaced and communications begun in order to prevent a "shorting" condition which results in the loss of precious communications time. The criticality of time dictates therefore that the surfaced buoy become stabilized and the antenna protected as soon as possible to permit transmission and reception with the minimum of delay following launch.

DESCRIPTION OF THE PRIOR ART

Existing stabilization arrangements used in circumstances as described above comprise various types of inflatable floatation collars which are deployed after launch via command from the submarine either before or after the buoy surfaces. These arrangements, however, require some sort of compressed gas source which, for safety, should be carried inside the buoy during launch. This of course affects weight distribution and takes up badly needed space, and necessitates a recalculation of the buoyancy requirements to enable the buoy to stabilize at all times.

This is compounded by fact that additional means must be employed and stored within the buoy to initiate and control the inflation of the floatation collar; and of course some safety means must be considered to ensure that the command signal to commence the collar's inflation will not occur until after launch. The danger is always present in these prior art arrangements for a premature command signal to be given or the occurrence of a malfunction wherein the collar begins to inflate while the buoy remains in the launcher, which necessarily leads to extensive damage to both the buoy and the launcher. Moreover, with the inflatable arrangements there is required at least one penetration of the buoy or capsule to permit the internally stored gas to reach the externally arranged floatation collar.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a stabilization arrangement for surface communications buoys launched from a submerged vessel which obviates the need for inflatable type stabilizers and associated support and control equipments.

It is another object of this invention to provide a buoy stabilization arrangement which is automatically deployable upon launch from the submarine without the need for command signals or control mechanisms and which cannot be prematurely deployed.

It is a further object of this invention to provide a light-weight buoy stabilization arrangement for minimizing adverse surface forces acting on the buoy via utilization of the existing atmosphere as an air cushion.

It is yet another object of this invention to provide a buoy stabilization arrangement which aids in reducing the buoy's rise time to the surface after launch from a submerged vessel.

According to the broader aspects of the invention, an automatically deployable buoy stabilization arrangement is provided comprising a collar of continuous and flexible material arranged around the floating buoy or capsule in conical or umbrella-like fashion proximate the buoy's natural water line, with the collar secured via the top portion thereof to the capsule body in a substantially leak-proof manner and opening at the bottom to form in conjunction with the capsule body a pocket, which may be compartmentalized, for trapping air. The collar is aided in deployment by a plurality of resilient arms coupled to the collar and the capsule body wherein the arms are in a spring-loaded or unstable position when the collar is undeployed.

A feature of this invention is that a low-cost arrangement is provided which insures surface stability and helps to reduce the buoy rise time while requiring no penetration of the capsule body.

A further feature is that the stabilization arrangement according to the invention does not hinder in any way the launch of the buoy even though it is externally arranged thereon.

Yet another feature of the invention is that while the stabilization arrangement has a primary responsibility to control heaving forces and prevent inundation of the communications antenna, there is additionally provided a substantial tempering of the roll, surge and other rotational and rectilinear forces acting on a buoy.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other objects and features of the invention will become more apparent and the invention itself will be best understood by referring to the following description when taken in conjunction with the accompanying drawings in which:

FIGS. 1A-1E illustrate in a pictorial time sequence a method of launching a surface communications buoy from a submerged vessel;

FIGS. 2A and 2B illustrate a buoy arrangement according to the prior art; and

FIGS. 3A and 3b illustrate the buoy stabilization arrangement according to the invention in respectively a side elevation with a partial sectional water-line stabilizer and a top view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reliable communications involving a buoy depend on several factors, not the least of which is the stability of the buoy at the surface of the water. Reliability is of course impossible if the buoy's antenna may possibly become inundated or located in a trough between two waves which block the path of radio signals. It is known that a cylindrical configuration is perhaps the most appropriate shape available to submarine communications buoys, both from a launching point of view, and from rise time and surface stability considerations; and it can generally be stated that success in optimizing buoy performance may be accomplished by making the natural period along the vertical axis of a cylindrical configuration short (i.e., maintaining a high buoy natural frequency) and the natural period along the roll axis long, in order for instance to maintain a high heave stability, ie., maintaining a near constant water mark, in spite of the wave forces acting on the buoy. It is required therefore that the buoy natural frequency be considerably above the forcing wave frequencies, which of course enables the buoy to react quickly to the changes in water level.

The natural frequency of the buoy is given approximately by

f.sub.M = 1/2.pi. .sqroot.K/M,

where K is the spring constant of the buoy on the water and M is the buoy's mass. Since stability, and in particular buoy heave stability, is in a direct relationship with the natural frequency of the buoy, a high natural frequency according to the above formula requires that the buoy mass be minimized and/or the spring-constant thereof be maximized. Due to limitations upon the buoy or capsule system and the design thereof, and in further view of the fact that some added mass is desirable for high roll stability, it is therefore desirable to achieve high heave stability through an increase in the buoy spring constant. Since the spring constant is determined largely by the cross-sectional area of the buoy at the water line, this fact must be considered in the design of any worthwhile stabilization arrangement. Thus, it is most advantageous and necessary to increase the buoy size at this point; in fact, the buoy dispacement cross-section should be largest at the water line for optimum results. However, due to the limitations imposed by the diameter of the launcher (signal gun of the submarine) it becomes necessary to provide stabilization means which increase in size only after the buoy is launched.

FIGS. 1A - 1E in a pictorial sequence illustrate an existing method of launching a communications buoy from below the surface of the water and establishing communications with the outside world while the submarine remains submerged and moving at a more or less constant speed. FIG. 1A illustrates that point in time of the buoy deployment sequence which occurs just after launch of the buoy vehicle from the submarine. The vehicle is shown having two parts coupled together, a main portion constituting the communications buoy 1 and a positive-buoyancy secondary buoy 1a. Attached between the secondary buoy 1a and the submarine is an umbilical cord 12, which is shown paying-out from the submarine. The purpose of the secondary part 1a of the vehicle is to create enough positive buoyancy in the system to keep the umbilical cord 12 and the buoy vehicle away from the submarine's propeller, and also to assist in lowering the rise time of the communication capsule 1 to the surface. FIG. 1B, illustrates the next important step in the launch sequence in which the two portions 1 and 1a of the buoy vehicle separate upon exhausting cord 12 while remaining coupled together via a secondary umbilical cord 12a. The separation will occur after all of cord 12 is expended which ensures that the buoy vehicle and/or the umbilical cord is sufficiently elevated from the submarine that it will not become engaged with or approach the submarine propeller. The positive buoyancy requirements of the secondary buoy 1a become even more important following the separation of the two vehicle parts, inasmuch as there are now two separate sections of umbilical cord (12 and 12a) as well as two buoy portions (1 and 1a) which must remain away from the submarine's propeller. The secondary umbilical cord 12a is payed-out from the secondary buoy 1a rather than the main capsule 1 in order to conserve space in and to better control stabilization of the capsule 1 and improve its rise time.

FIG. 1C illustrates an advanced point in time of the deployment sequence in which the umbilical cord portion 12 is fully payed-out and the communications buoy 1 is approaching the surface of the water. The secondary umbilical cord 12a is indicated as only partially expended with a substantial amount stored within buoy 1a which of course will be taken-up during the course of the impending communication.

FIG. 1D shows the communications buoy 1 having arrived at the surface of the water while considerable cord 12a remains in the buoy 1a. Communication with the outside world begins at this point and continues for as long as the cord 12a remains in buoy 1a. Thus is seen the desirability of a fast rise time for the communications buoy and the establishment of buoy stability as soon as possible after it breaks water.

FIG. 1E illustrates that point in the time sequence by which the communication must be completed, in that all of the umbilical cord (12a) is paid out and it is about to be snapped or purposely separated from the submarine. It is not intended that the umbilical cord (12, 12a) be sufficiently strong to allow the communications buoy 1 to be towed along by the submarine inasmuch as this would require a much greater weight cable as well as giving rise to an undesirable transmitting and receiving mode.

Referring to FIGS. 2A and 2B, there is shown a prior art approach to buoy stabilization employing the use of an inflatable collar 3. As stated hereinbefore, this approach requires that a gas cartridge or other source of gas be contained within the buoy 1. Moreover, consideration must be given as to a timing and firing mechanism to prevent premature firing while the buoy is in the launcher or in the submarine. As shown in FIGS. 2A and 2B, the communications buoy 1 has positioned therearound the inflatable floatation collar 3 just above the water line 4, leaving a protected top portion 1b of the buoy out of the water from which extends the communications antenna 2.

Turning to FIGS. 3A and 3B, there is illustrated the buoy stabilization arrangement according to the invention, in which the intended increase in cross-sectional area of the buoy at the water line 4 is developed by means of a conical or umbrella-like collar 5 which has the lower face 6 thereof open. The collar is secured to the buoy 1 in a substantially leak-proof manner via the top portion 9, and, in cooperation with the body of the buoy, forms an air pocket. The collar provides a protected portion 1b of the buoy which is maintained free from inundation, from which extends the communications antenna 2. The collar 5 is fabricated of a continuous and flexible material such as a mylar film, and is deployed around the capsule 1 from a recessed area 10 in the body thereof, which may be provided for storage of the undeployed collar 5 to prevent interferences with the signal gun during launch. The collar automatically deploys immediately after launch as is illustrated in FIG. 1A. It is to be understood that any continuous, flexible, lightweight and substantially leak-proof material may be utilized for the conical collar 5, and that the collar 5 may be secured to the buoy 1 by any acceptable means such as clamps, glue etc.

To aid in deployment of the collar 5 there is provided a series of arms or spokes 7 coupled to the collar 5. One arrangement envisioned provides for the arms to be constructed of a bowed resilient material, or alternatively a light metal with curved cross-section (not unlike the metallic roll-up tape measures), wherein the arms 7 form ribs within or on the surface of the collar 5 substantially equally spaced around the buoy 1 and run from the open face 6 of the collar 5 to the top portion 9 thereof, at which point the rib-like arms 7 are attached to the capsule body 1. The manner of attachment to the capsule body 1 is such as to place the arms 7 in a spring-loaded or unstable position substantially adjacent to the buoy 1 when the collar 5 is undeployed. The arms may be in continual contact and attachment with the collar 5 substantially along their entire lengths or may be coupled at discrete points, such as at or near the top and bottom portions (9 and 6 respectively) of the collar 5. Also, the arms may be arranged on either or both the underside of the collar 5 and on the outer surface thereof. Another possible arrangement is to have the arms 7 coupled to the collar near the open face 6 and to the capsule body 1 at points remote from the upper portion 9 of the collar 5 such that when the collar 5 is undeployed the arms 7 are elastically buckled in a U-shaped manner. It is to be understood, however, that any manner of connection or any arrangement of the arms 7, in association with the collar 5 and the capsule body 1, falls within the spirit of this invention as long as the arms 7 assist in the deployment of the collar 5 through achieving a stable position when the collar 5 is deployed, as arrived at from an unstable position when the collar 5 is constrained in the undeployed state, such as occurs when the buoy is in the signal gun prior to launch. It is to be noted also that the choice of material and the arrangement of the collar 5 may be such as to permit self-deployment without requiring the assistance of arms 7.

It is clear from the above that, in view of the open lower face 6 and the resultant air pocket formed by the collar 5 cooperating with the capsule body 1, there is no longer required to be a penetration of the capsule body 1 or timing and firing mechanisms for deployment of a buoy stabilization arrangement. This open lower face 6, moreover, continually drains off any water entering, thereby periodically reforming the air pocket. In view of the fact that the inventive collar arrangement also increases the damping constant, there results a corresponding further reduction of the effects of heaving vibrations on the capsule 1.

To further improve the effectiveness of the inventive principle, the conical collar 5 may be compartmentalized in order to minimize spillage of the air trapped by the pocket. The compartmentalization may be achieved by coupling to the conical collar 5 and to the capsule body 1 in a substantially leak-proof manner a plurality of dividers 13 spaced apart from one another around the buoy to form a series of individual compartments 8. In a preferred embodiment the dividers 13 are fabricated of a continuous and flexible material and may be coupled to the capsule body by clamps, glue or any other acceptable and lightweight means. The dividers 13 may be similarly coupled to the collar 5 or, in the alternative, may be homogeneous therewith. One very practical arrangement envisioned combines the functions of the dividers 13 and the deployable arms 7 into one, wherein the combined arms/dividers are fabricated of such a material and arranged in such manner as to automatically provide compartmentalization and assist in deployment of the collar 5 by being arranged in an unstable state when the collar is undeployed. A preferred embodiment which satisfies the above criteria may have the compartment dividers 13 constructed in concertina-like fashion and perhaps made out of a resilient material. Of course, the concertina-like arms/dividers in the undeployed or unstable state could be stored in the recessed area 10 provided for a streamlining of the exterior of the buoy 1 when the collar 5 remains undeployed. One major advantage of compartmentalization is that whenever one or two compartments become punctured, the air pocket would yet remain via the other compartments and thus the effectiveness of the stabilization arrangement would be largely maintained. This is of course not true in general with the inflatable floatation collar arrangements.

In view of the severe rotational and rectilinear forces experienced from time to time which act on the buoy or capsule 1 at the surface, it is perhaps desirable to incorporate further stabilization means in the form of a plurality of vanes or fins 11 added to the buoy 1 on a submerged portion thereof remote from the collar 5. These fins 11, with respect to the cylindrical capsule illustrated in FIG. 3A, are arranged at the submerged end thereof, and are triangularly shaped and substantially equally spaced from one another around the capsule body. Application of the fins according to the invention is particularly effective in maintaining roll stabilization, which is most desirable for minimizing signal fading. The fins or vanes 11 may be constructed of a continuous film plastic or other suitable material and may be deployed in the same manner as the conical collar 5, i.e, by securing thereto deployable or hinged arms. Alternatively, a sliding ballast may be used which will force out rigid vanes as the buoy initially rights itself at the surface; or a separate cable could be used, one end thereof being attached to the interior of the launcher and the other end to the rigid vanes. When the buoy is enjected, the cable will force out the fins prior to breaking. It is of course possible and entirely within the scope of this invention to have fin shapes and arrangements other than as illustrated in FIG. 3A or described above, the important consideration being that the fins offer substantially broad surfaces to increase the buoy damping constant. Moreover, the stabilization arrangement according to the invention has application to floating bodies other than communications buoys, which bodies may have for instance rectangular, spherical or other non-cylindrical shapes. Additionally, the invention has application to non-geometrical shapes, particularly the human body.

While the principles of this invention have been described above in connection with specific apparatus, it is to be understood that this description is made only by way of example and not as a limitation to the scope of the invention as set forth in the objects and features thereof and in the accompanying claims.

Claims

What is claimed is:

1. A stabilization arrangement for a floatable body comprising a collar composed of a continuous and flexible material arranged via the top portion thereof around the body in a substantially leak-proof manner, with the bottom portion open to the atmosphere substantially at the water line to permit deployment in an umbrella-like fashion to form in cooperation with the body a pocket for trapping air.

2. The arrangement according to claim 1 further including a plurality of arms coupled to said collar and the body for aiding in deployment of said collar.

3. The arrangement according to claim 2 wherein said arms are spaced from one another around the body and coupled thereto proximate said top portion of said collar.

4. The arrangement according to claim 2 wherein said arms are spaced from one another around the body and coupled thereto remote from said top portion of said collar.

5. The arrangement according to claim 2 wherein said arms are arranged on the underside of said collar.

6. The arrangement according to claim 2 wherein said arms are arranged on the outer surface of said collar.

7. The arrangement according to claim 2 wherein said arms are fabricated of a resilient material having a curved cross-section.

8. The arrangement according to claim 2 wherein said arms are in a spring-loaded position when said collar is undeployed.

9. The arrangement according to claim 8 wherein said arms in said spring-loaded position are arranged substantially adjacent to the surface of the body.

10. The arrangement according to claim 1 further including plurality of dividers composed of a flexible and continuous material coupled to said collar and to the body to compartmentalize the pocket formed by said collar.

11. The arrangement according to claim 10 wherein said dividers are homogeneous with said collar.

12. A stabilization arrangement for a communications buoy such as is launched from a submerged vessel comprising a body portion of said buoy which is located proximate to the water line and a collar composed of a continuous and flexible material arranged around said body portion and attached by way of the top portion thereof to said body portion in a substantially leak-proof manner, with the bottom portion of said collar opening to the atmosphere to be deployable in an umbrella-like fashion and form in cooperation with said body portion a pocket for trapping air, whereby the buoy is protected from inundation.

13. The arrangement according to claim 12 further including a plurality of dividers composed of a flexible and continuous material coupled to said collar and to said body portion in a substantially leakproof manner to compartmentalize said pocket formed by said collar and said body portions.

14. The arrangement according to claim 12 further including a plurality of arms coupled to said collar and to the buoy for assisting in deployment of said collar.

15. The arrangement according to claim 12 further including a plurality of fins arranged on a submerged portion of the buoy remote from said collar, said fins being spaced from one another around the buoy and providing broad surfaces for additional buoy stability.