NZ209269A - Stabilised buoy for supporting radio antenna in ocean - Google Patents

Description

2092 69 Priority Date(s): . 15. 1 Complete Specification Filed: Class: .{&• 6afiA?4l8 0JUN'M.,...

Publication Date: P.O. Journal, No: (v.-.. i-ATENT OFf!OE 17 AUG 1984 RECEIVED N.Z.No.

NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION "FLOTATION BAG ASSEMBLY" We, HAZELTINE CORPORATION, a corporation organized and existing • » under the laws of the State of Delaware, United States of America 500 Commack Road, Commack, New York 1172 5, United States of America, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : - - 1 - (followed by 1A) 209289 FLOTATION BAG ASSEMBLY ■Th-e Government hoc rlghtc in this inygg^flta. pursuant to rnntrnrt NnnrHP ■ n I' ill 'I nwiiiili ii by the the Navy.

BACKGROUND OF THE INVENTION 1. FIELD OF INVENTION This invention relates generally to a stable support for structures at or above the surface of a fluid medium and in particular to a communications buoy for use in the ocean. 2. DESCRIPTION OF THE PRIOR ART Many types of flotation devices exist with differing characterisitcs.

Damper plates and toroid shaped flotation devices have been used to create buoys which are wave followers. For example, see Buoy Engineering, H.0. Berteaux, John and Sons, 1976 Pg. 212-213. These surface following buoys are subject to strong heave and pitch due to the motion of the ocean.

A more stable buoy can be built by decreasing the cross section of the buoy at the water level. Such devices experience less heavffiggw The mass 2<>9269 O 1 of the buoy can also be distributed to create a 2 righting moment. This will'decrease the pitch. 3 Further stability can be obtained by 4 surface decoupling. A buoyant cylinder with a counterweight suspended from its bottom is a typical 6 example, Berteaux, supra. Such spar buoys cannot have 7 much reserve buoyancy and usually have a large draft. 8 These factors mitigate the usefulness of these types 9 of buoys in deep water. 3. SUMMARY OF THE INVENTION 11 It is an object of this invention to 12 provide a communications buoy having an antenna which 13 uses the surface of the ocean as a ground plane; such 14 buoy having structure which limits the antenna's motion with respect to the surface of the ocean to 16 within 4 inches heave and 25° pitch. 17 It is another object of this invention to 18 provide a stable buoy that can withstand ocean 19 conditions up to and including state 5.

The buoy according to the invention may be 21 used as part of a search and rescue system for 22 locating downed aircraft and ships- in -dlstress..._ Such | t SAPRt987Zi! « 7J ■ I m 209269 1 buoys would be carried by vehicles and be deployed 2 when needed. Their distress signal could be received 3 by satellites and their position located. 4 The according to the invention could carry various other types of payloads or support 6 various antenna structures as well. Other possible 7 uses include oceanographic monitoring buoys and 8 satellite linked sonobuoys. 9 It is an object of this invention to provide an apparatus for the stable support of a £) 11 structure, such as an antenna, in a fluid medium, such 12 as water. 13 It is a futher object of this invention to 14 limit the motion of an antenna supported above the surface of the ocean, within the operational limits of 16 the transmitting system. 17 It is a further object of this invention 18 to support an electronics payload near the surface of 19 the ocean such that the power loss between the electronics payload and an antenna supported on the 21 surface is within operational limits and, C 22 specifically, less than 3db. 23 The invention is an apparatus for the 24 stable support of a structure, such as an antenna, in O h-i cvj -3- if 11 FEB 1987*} e ijyi ( 209269 1 a fluid medium, such as water. The apparatus bu o4" 2 comprises a tojj ^ant first member and first means for 3 engaging the structure. The first means is associated 4 with the member. Second means are provided for channeling the fluid which encroaches upon the tso'uffan't 6 member due to any motion of the member with respect to 7 the surface of the fluid medium, the encroaching fluid 8 being channeled back into the fluid medium such that 9 the kinetic energy of the felffyant first member is dissipated as the fluid is channeled back into the O 11 fluid medium. 12 Alternatively, the apparatus according to buoy<M(f* 13 the invention may comprise a fe-ouyarrt first member for 14 supporting the structure, a payload and decoupling means for supporting the payload below the tttutyartt 16 member such that any motion of the payload is 17 decoupled from the member and any motion of the member 18 is decoupled from the payload. 19 Alternatively, the apparatus according to *- jk the invention may comprise a -oogyafcfe member with an 21 inwardly arched bottom portion, and means, associated ^ J ^ ^ 1 22 with the baffiant member, for engaging the structure. 23 Alternatively, an apparatus according to 24 the Invention may comprise an antenna, a bouffant ^ 25 member, first means for generating an r.f. signal, 1 2 3 4 6 7 6 9 11 12 13 14 16 17 18 19 21 22 23 209269 second means interconnecting the first means and the antenna, and decoupling means for supporting the first means below the tiotyyon-t member such that any motion of the member is decoupled from the first means and the motion of the first means is decoupled from the member.

Alternatively, the invention may comprise a communication/ which is stable in a fluid medium and includes structures for minimizing the heave and pitch of the Specifically, a flotation bag with a concave bottom formed by pulling in the center of the bottom of the bag with straps secured to the inside walls of the bag supports an antenna. A semi-rigid damper skirt extending around the bp«e of the bag is submerged when the apparatus is floating in the fluid medium. The bag is provided with a ribbon fence comprising containers which have an opening above the fluid level, and an opening below the fluid level, when the apparatus is floating in the medium, allowing the fluid to flow in and out of the containers. The payload is supported in a cylindrical chamber connected to the flotation bag by a flexible cable, enabling the payload to swing. 209269 1 BRIEF DESCRIPTION OF THE DRAWINGS 2 Figure 1 is a side view of a 3 communications &oSy according to the invention 4 deployed in water.

Figure 2 is a side view of the tjoffi of ^ 6 Figure 1 with parts broken away to illustrate internal w 7 structure. 8 Figure 3 is a perspective view of a 9 communications -b«9y- according to the invention in an undeployed state. 11 Figure 4 is a top view of a flotation bag 12 according to the invention. 13 Figures 5a -5g are graphs illustrating the 14 operational transmission requirements and the estimated performance of an antenna system according 16 to the invention under varying conditions of heave and 17 pitch. 18 DETAILED DESCRIPTION OF THE INVENTION ^ 19 Referring to figures 1 and 2, flotation bag 1 is an inflated balloon-like structure having a 21 specific gravity less than the specific gravity of 22 fluid medium W. Bag 1 encloses antenna 2 and supports 23 a payload 3 below the surface of medium W, J/'-V 11FEB198T^ 209269 1 Although this embodiment comprises 2 flotation bag 1 which encloses antenna 2, the 3 invention includes flotation devices of any type which 4 support structures.

Figures 5a-5g compare the estimated 2. 6 performance 102 of an antenna such as antenna & under 7 varying conditions of heave and pitch with the ~' 8 operational performance requirement 101 for successful 2. 9 transmission. Antenna 7 uses the surface of the fluid W as a ground plane. Heave and pitch disturb the 2. 11 relationship between the radiating antenna 2 and the 12 ground plane, changing the radiation pattern of 13 antenna §. As shown by graphs 5a, 5b, and 5f, the, 2 14 estimated performance 102 of antenna t crosses and falls below the operational performance requirements 16 for successful transmission between points 103 and 17 104. In summary, successful transmission is not z. 18 achieved when antenna 2 undergoes more than 4 inches 19 heave or 25° pitch. The apparatus according to the invention limits the motion of the antenna relative to 21 the ground plane to within 4 inches heave and 25° ^ 22 pitch, under ocean conditions up to sea state 5. 23 A damper skirt 4 extends around the base 24 of the flotation bag 1 and is made of a semi-rigid material supported in a horizontal position by ribbo. . 'l ^ 26 fence 5. 1 2 3 4 6 7 8 9 11 12 13 14 16 17 18 19 21 22 23 24 209269 When the apparatus is afloat, damper skirt 4 is below the surface of the medium W. The weight of the payload 3, the shape of the bottom of the flotation bag 1 and the jfouffian^y of bag 1, which will be described in detail below, are configured so that damper skirt 4 is below the water line when the apparatus is stable.

Damper skirt 4 increases the surface area in contact with the ocean, offering a surface which resists motion V within medium W. In order to rise or tip in response to a wave, damper skirt 4 must travel upwardly through the fluid. The resistance to upward movement of skirt 4 is caused by the fluid above the skirt 4. The energy that would otherwise cause heave and pitch of the flotation bag 1 is dissipated by this resistance and any resulting movement of skirt 4 within the medium W.

As shown particularly in figure 4, ribbon fence 5 which supports the damper skirt 4 is a series of contiguous compartments, 5a-5g. Damper skirt 4 acts as the base of the compartments 5a-5g of ribbon fence 5 and the side Is of the flotation bag 1 forms the back wall of the compartments. The walls of the compartments in the embodiment illustrated comprise a strip of semi-rigid material connected to the side of 209289 1 the flotation bag 1 at spaced apart points P. The 2 flotation bag 1, -damper skirt 4 and the strip form the 3 contiguous compartments, the combination of which is 4 referred to herein as ribbon fence 5.

Each compartment 5a-5g has an opening 6 in 6 the lower portion thereof, where the strip joins to 7 damper skirt 4. The compartments have an opened top 8 7. When stable in the ocean, the bottom hole 6, which 9 has a cross section less than the opening at the top 7, is beneath the level of the medium W. The water 11 line on the flotation bag when the apparatus is at 12 rest in the ocean is approximately at the midpoint/8 13 of the height of the ribbon fence 5. 14 Compartments 5a-5h act as containers for the fluid medium. Fluid encroaching upon bag 1 can 16 enter the compartments through hole 6 or the opened 17 top 7 and can drain from the compartments through the 18 hole 6. When bag 1 rises due to the motion of the 19 ocean, sea water will drain out of the holes 6, dissipating the kinetic energy of bag 1 created by the ^ 21 rising motion of the ocean. Oscillating of the 22 flotation bag 1 within the medium W are thereby 23 damped. The compartments increase the resistance to 24 motion of damper skirt 4 by partially enclosing the fluid and by requiring the damper skirt to lift the u 1 partially enclosed fluid in the compartments as the 2 flotation bag 1 rises in response to a wave. This 3 acts to further decrease the heave and pitch of the 4 flotation bag.

The damper skirt 4 and ribbon fence 5 are 6 described associated with each other, constructed from 7 semi-rigid materials for the purpose of stabilizing 8 flotation bag 1. However, the damper skirt 4 may be a 9 submerged plate and the means for channeling fluid that encroaches on the device. Such structures may be used separately or in combination to decrease both the 12 heave and pitch of the device. 13 Payload 3 comprises electronics 31 14 enclosed in a cylindrical housing 32. Housing 32 is connected to the bottom of the flotation bag 1 by 16 nylon cord 8. One end of nylon cord 8 connects to a 17 point 8a within the housing, approximately one-quarter 18 from the top of the housing and the other end connects 19 to the center of the bottom of the bag 8b, at bulkhead 9, which is a rigid portion. Electrical wires 311 21 also pass from the electronics 31 into the bulkhead 22 9. Beneath the bulkhead 9 is microphonics bumper 91. 23 Nylon cord 8 and the location of the 24 connection between the housing 32 and the flotation — 25 baa 1, at 8a and 8b, decouple the motion of flotation o 1 2 3 4 6 1 8 9 11 12 13 14 16 17 18 19 21 22 23 24 26 209289 bag 1 from housing 32 such that, over a certain range, the motion of bag 1 does not affect the motion of cylindrical housing 32 and the motion of cylindrical housing 32 does not affect the houoing motion of bag 1. The range of motion depends on the demensions of the decoupling apparatus including the diameter of housing 32 and the distance between the top of housing 32 and microphonic bumper 91.

Housing 32 is free to swing like a pendulum until the top of the housing 32a collides with the microphonic bumper 91. Similarly, the flotation bag 1 can freely pitch until the bumper 91 collides with the top of the housing 32a. of the payload 3, measured from the vertical, before contact between housing 32a and microphonic bumper 91. Bumper 91 absorbs some of the energy of any impact between bag 1 and payload 3, decreasing the effect such impact would have on the heave and pitch of the flotation bag. Bumper 91 also protects the electrical wiring that feed to the antenna, preventing interruption or interference with the transmission of a message due to impacts between the _ 32a and the bulkhead 9 through which wires 311 pass.

In the embodiment illustrated, electronics This allows for 10° - 15° of motion 31 is close to antenna 2 in order to minimize the 1 2 3 4 6 7 8 9 11 12 13 14 16 17 18 19 21 22 23 24 209269 power loss due to transmission of a signal from electronics 31 to antenna 2 via cable 311.

Preferably, the power loss is less than 3db.

The upper portion 33, of housing 32, referred to herein as a collar, stores the entire flotation apparatus before it is deployed, as shown in Figure 3. After deployment, the upper portion 33 floods with water, through holes in its sides, as shown in Figures 1 and 2. The flooding reduces the t^ffySr&y of the payload 3 which results in payload 3 pulling the flotation bag 1 into the water, ensuring that the damper skirt 4 and bottom hole 6 of ribbon fence 5 are submerged. This increases the stability of flotation bag 1.

The flooding of upper portion 33 results in the center of mass of housing 32 being lower in the medium W, increasing the period of oscillation of housing 32. This stabilizes the entire structure and decreases the heave and pitch of flotation bag 1.

The center of the bottom of the flotation bag 1 is pulled upward by straps 13 secured at 131, along the inside wall of flotation bag 1. This reduces the JeS^pam^y of bag 1, aiding in maintaining the necessary waterline above damper skirt 4 and at the midpoint of ribbon fence 5. The baselof bag 1/f is % \ IIFEBftSI? ,Oa r V. 209269 1 inwardly arched at its center 15 so that the greatest 2 &o8ffiant forces are located at the outer portions of 3 the bag This decreases the pitch of the flotation 4 bag 1 by creating a longer torque arm which must be overcome for the flotation bag to rotate. This 6 righting moment further aids in stabilizing the 3 7 flotation bag. The adhesion caused by inwardly arched 8 center 15 between the surface of the bottom 16 of the 9 bag and the fluid medium W also decreases the heave of the flotation bag. 11 Although this particular embodiment 12 describes a flotation bag with a concave bottom, the 13 invention is meant to cover flotation devices of any 14 material with a bottom of inwardly arched shape.

The apparatus and payload are ejected in 16 the cylindrical housing 3, as shown in Figure 3. 17 Antenna >?, flotation bag 1, ribbon fence 5 and damper 18 skirt 4 are all stored in upper chamber 33 of the 19 housing 32. Housing 32, which is ^offyomt, floats to the surface of the ocean after being ejected. The 21 flotation bag and antenna are then deployed and the 22 preprogrammed messages are transmitted.

Oil if JtFEBWW' 2"9269 3 1 What we claim is:

Claims (15)

1 Claim 1. An apparatus for the stable

2 support of a structure, such as an antenna, in a

3 fluid medium, such as water, said apparatus

4 comprising:

5 a. a buoyant first member having a side

6 wall, said first member having a buoyancy greater

7 than the buoyancy of the medium so that said

8 member, when located in the medium, will float

9 and a lower portion of said member will be

10 submerged;

11 b. first means attached to the lower

12 portion of said first member, said first means 13 engaging the structure; 14 c. a ribbon fence attached to the side 15 wall, said ribbon fence comprising at least one 16 container with a top opening, a side opening and 17 a closed bottom, said container supported by the 18 side wall of the buoyant first member such that 19 the top opening is above the level of.the fluid 20 medium and the lower opening is below the level 21 of, the fluid medium when the apparatus is floating 22 in the medium; and ~~~~ It 2"9269 23 d. said ribbon fence positioned on the 24 side wall such that fluid which encroaches 25 upon the side wall due to motion between 26 the buoyant member and the fluid medium 27 enters the top opening whereupon it is 28 temporarily stored in the container and KihtHc/ ^ 29 dissipates its k-et*e£ic energy and;30 thereafter exits the container through the;31 side opening.;■\T) 1 Claim 2. An apparatus as in claim 1,;2 wherein said ribbon fence comprises a plurality;3 of adjacent compartments supported by and located;4 about the side wall, each compartment having an;5 open top, a side opening having a cross sectional;6 area less than the cross sectional area of the;7 top opening and a closed bottom.;1 Claim 3. An apparatus as in claim 2,;2 wherein each said compartment comprises the side;3 wall, a substantially vertical wall having sides ^ 4 attached to the side wall and having the side;5 opening therein and wherein all of said closed;6 bottoms form a concave, semi-rigid disk attached;7 to the bottom of the buoyant member and bottom;edges of all of the vertical walls, said diu—■^!v r o\;^\\;f riSAPRIWtf!;-15-;209269;9 being submerged within the medium and impeding;10 the motion of the apparatus with respect to the;11 medium, thereby decreasing the heave and pitch to;12 which the buoyant member is subject due to;13 movement of the medium.;1 Claim 4. An apparatus as(claim 1 ^further;2 comprising a payload and decoupling means;3 attached to the underside of the buoyant member;4 and supporting the payload below the buoyant;5 member such that motion of the payload within a;6 given range is decoupled from the member and;7 motion cf the member within a given range is;8 decoupled from the payload.;1 Claim 5. An apparatus as in claim 4 >;2 wherein the payload includes a housing and said;3 decoupling means is a flexible member;4 interconnecting the housing and the buoyant;5 member.;1 Claim 6. An apparatus as in claim 5f;2 further comprising:;3 a. a collar extending from the housing;4 and surrounding the flexible member;;""1;-16- ■ \ 1 5 APR 1987n?ij;V /;X'. ^ -V"';A;209269;©;r>.;5 b. a rigid portion supported by the;6 underside of the buoyant first member,;7 said flexible memberfcon$ected to said;8 rigid portion;;9 c. a bumper supported by said rigid;10 portion and engaging the collar when the;11 pivotal movement of the housing with;12 respect to the rigid portion is greater;13 than a predetermined angle within the;14 given range.;1 Claim 7. An apparatus as in claim 6>;2 wherein said bumper is a microphonics bumper and;3 the predetermined angle is approximately 10°.;1 Claim 8. An apparatus as in claim 7?;2 wherein said housing includes a chamber within;3 which said buoyant member is stored when the;4 apparatus is in an undeployed state, said chamber;5 being flooded after the apparatus is deployed in;6 the fluid medium.;1 Claim 9. An apparatus as in claim 8,;2 wherein the buoyant member is a flotation bag >2^ 3 having straps connected to the inside walls of;4 the bag and the center of the bottom o1L_±Jbe__bagj;5 pulling the center of the bottom of the bag _;6 inward, forming the concave shape. °h;-17-;!;S:;I;;0 2"9369;1 Claim 10. An apparatus as in claim 9>;2 further comprising an antenna supported by said;3 buoyant member, first means fox generating an;4 r.f. signal included in said payload and means;5 interconnecting said antenna and said first means.;1 Claim 11. An apparatus as in claim 1,;2 wherein said lower portion of said first buoyant;3 member is inwardly arched to form a concave shape.;I Claim 12. An apparatus as in claim 1: O a. further including an antenna;;3 b. wherein said buoyant first member;4 comprises a flotation bag with a concave;5 bottom formed by pulling in the center of;6 the bottom of the bag with straps secured;7 to the inside walls of the bag, said bag;8 supporting said antenna;;9 c. further including a semi-rigid damper;10 skirt extending around the base of the;II bag, which is submerged when the apparatus;12 is floating in the fluid medium;;13 d. wherein said ribbon fence comprises a;14 plurality of compartments each with an;15 opening above the fluid level, and an;16 opening below the fluid l_£\Lelwhen the;17 " f;2*9269 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 1 allowing the fluid to flow in and out of the compartments; e. said damper skirt for impeding the heaving and pitching motion of the flotation bag, said compartments supporting the damper skirt in a substantially horizontal position; f. further including a payload including first means for generating an r.f. signal; and g. further including a longitudinal, cylindrical housing for supporting a payload, said housing having a floodable chamber, said housing being connected to a rigid portion of the flotation bag by a flexible cable surrounded by said chamber, enabling the housing to swing.

Claim 13. The buoy of claim 12 wherein said bag supports said antenna above the surface of the fluid medium such that the surface of the fluid medium functiors as a ground plane with respect to the antenna when the antenna is radiating due to r.f. excitations from the first means. ™ 15 APR 19873) A 19 209269 1

Claim 14. An apparatus as claimed in 2 claim 1>substantially as herein described with 3 reference to the accompanying drawings. 1

Claim 15. A communications buoy in 2 accordance with claim 12,substantially as herein 5 described with reference to the accompanying 4 drawings. HAZELTINE CORPORATION BY Their Attorneys