US3893403A

US3893403A - Ring-shaped hydrofoil

Info

Publication number: US3893403A
Application number: US405358A
Authority: US
Inventors: Jr Shelton M Gay; Jr Frederick C Belen
Original assignee: US Department of Navy
Current assignee: Talon Inc; US Department of Navy
Priority date: 1973-10-11
Filing date: 1973-10-11
Publication date: 1975-07-08
Anticipated expiration: 1992-07-08

Abstract

A hydrofoil in the form of a short tubular ring or annular hydrofoil is disclosed for controlling the position of a connected tow cable below or to the side of a ship or other towing craft. An attached ballast weight and towing bridle are adjusted to maintain the desired attitute to the slip stream.

Description

United States Patent [1 1 Gay, Jr. et al.

[ RING-SHAPED HYDROFOIL [75] Inventors: Shelton M. Gay, Jr., Vienna;

Frederick C. Belen, Jr., Arlington, both of Va.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Oct. ll, 1973 [2]] App]. N0.: 405,358

[52] U.S. Cl 114/235 B [51] Int. Cl. B63B 21/56 [58] Field of Search ll4/235 R, 235 B, 66.5 H,

1l4/l6 F; 244/3, 34 A, l TD 56] References Cited UNITED STATES PATENTS 2,325,616 8/l943 Landweber i. 114/235 B [111 3,893,403 [451 July 8,1975

3,012,534 l2/l96l Thomas ll4/235 R 3,l54,269 10/!964 Musil 244/34 A 3,460,384 8/1969 Fohl r n 114/235 8 3,645,224 2/l972 Haberman ll4/235 B FOREIGN PATENTS OR APPLICATIONS 865,643 5/1940 France u 244/] TD Primary Examiner-Trygve M. Blix Assistant Examiner-Stuart M. Goldstein Attorney, Agent, or Firm-R. S. Sciascia; Q. E. Hodges; D. McGiehan [57] ABSTRACT A hydrofoil in the form of a short tubular ring or annular hydrofoil is disclosed for controiling the position of a connected tow cable below or to the side of a ship or other towing craft. An attached ballast weight and towing bridle are adjusted to maintain the desired atti tute to the slip stream.

2 Claims, 2 Drawing Figures 1 RING-SHAPED HYDROFOIL The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The instant invention relates generally to hydrofoils such as paravanes or fish and more particularly to an annular ring hydrofoil for depressing a towed cable.

Heretofore, typical methods for developing the forces required to maintain a certain separation between a towing craft and the end of a tow cable include conventional winged devices, buoyant floats, weights, and combinations thereof. In many applications it is desirable to tow the cable at some predetermined position below or to the side of the ship or towing craft, and these applications require some dynamic lift beyond mere static forces produced by simple buoyant and weight devices.

The conventional depressors, paravanes, otters or fish used to provide lift are complex rectangular or tapered wing configurations with stabilizer surfaces, and require extensive structure support to sustain the hydrodynamic loads. These complex configurations are highly susceptible to damage during launching from an underway towing craft due to the initial contact with the water and to the severe snatch-up loads. Another problem with these devices is that their behavior becomes erratic if the tow cable slacks during launch and even when the craft is underway. Also initial high cost and the likelihood of damage are disadvantages of the prior art devices.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a new and improved towed cable controlling hydrofoil.

Another object of the instant invention is to provide a simple and reliable cable controlling hydrofoil that is relatively unsusceptible to damage.

Still another object of the present invention is to provide a cable controlling hydrofoil that is easy and safe to launch from a moving towing craft.

A further object of the instant invention is to provide a cable controller that is free of erratic operation during cable slackness at launch and underway.

Briefly, these and other objects of the instant invention are attained by the use of a hydrofoil having an annular ring or short tube configuration which has an adjustable towing bridle and ballasting weight attached thereto. The bridle is adjusted to provide the desired attitude of the ring hydrofoil with the slip stream to fly" down or to the right or left. A ballasting weight is attached to the ring to maintain the desired portion down and also to preclude rotation of the ring.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a pictorial view of towing craft with a towed cable controlled by the ring hydrofoil; and

FIG. 2 is a perspective view of the ring hydrofoil according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference numerals designate corresponding parts throughout the several views, there is shown generally in FIG. I a towing craft 10 on the surface 12 of a body of water, towing cable 14, attached at its distal end to a ring hydrofoil 16. While the towing craft 10 is depicted as an aircraft such as a helicopter l flying in close proximity to the surface, it is to be understood that it may be a surface ship, such as a mine sweeper or a survey ship towing a hydrophone cable, a submarine or other submersible craft. Furthermore, the ring hydrofoil 16 may be placed nearthe towing craft to depress or displace to the right or left the lead end of the cable 14. Also a buoy 18 on a pendant 20 shown attached to the ring hydrofoil I6 may be used to indicate its position.

Referring now to FIG. 2, the ring hydrofoil I6 is depicted in detail. The essential part is a short tubular ring or band 22 which may be of any diameter necessary to produce the desired dynamic lift forces to depress or displace a towed cable, and made of steel, aluminum, plastics or other suitable materials. The cross-section of the ring foil per se is shaped like an airfoil, having a blunt rounded leading edge 24 and a tapered afterbody 26 ending in a sharp trailing edge 27, conducive to smooth flow and dynamic lift. Attached to the hydrofoil ring near the leading edge thereof and generally diametrically opposed are a pair of links 28. Links 28 are attached to the ring for rotation at one end by conventional fasteners such as rivets or bolts. Connected between the other ends of the link is a bridle 30 of flexible cable material such as rope, wire rope, chain, or the like, depending on the strength required. At the center of the bridle 30 is a clamp-type connector 32 which may be slid along and clamped to the bridle for adjustment purposes, to be described hereinafter. At the center of the connector 32 is an eye 34 for attachment of the main tow cable 14. As shown and in operation, a ballast weight 36 is secured to the lower portion of the ring by fasteners such as bolts, screws. rivets or the like. And although not always necessary, a pair of trimming fins 38 may be affixed to the outer periphery of the ring hydrofoil near the bridle links 28.

While the advantages and operation of the ringfoil may be obvious from the above description it will be further explained below. Obviously, a primary advantage of the ringfoil lies in its simplicity of design making it singularly immune to damage as a result of striking object or during launch. Depending on whether the device is to be used merely as a cable depressor or to displace the cable to the left or right, the bridle links 28 may be placed near the leading edge 24 and at such positions around the ringfoil shown by experimentation and calculation to produce the desired result. Further, the bridle connector 32 may be adjusted along the bridle 30 to produce left or right lift, to displace the cable to the side of the towing vessel. The tow cable 14 is attached to the eye 34, and the rig launched in the usual manner.

The trimming fins 38 may be used to adjust the towing attitude in pitch, but are not required for stability as another feature of the ring hydrofoil is its inherent stability without these appendages. Typically, stability is defined in terms of various modes: pitch, roll, and yaw, and stabilization occurs when an excursion in a particular mode causes a restoring force to be generated. Therefore, perturbations from a path result in forces which restore the device to the path. If the ringfoil 16 rolls, the low center of gravity produced by the ballast weight 36, and the relatively high bridle attachment results in a restoring moment. For pitch stability, a nose-up perturbation are restored by hydrodynamic gravity moments, by the ballast weight while a nosedown perturbation is restored by hydrodynamic forces acting on the upper and lower surfaces of the foil 16. A perturbation in yaw is restored both by hydrodynamic forces on the ringfoil 16 as well as by the bridle 30. The bridle attachment is near the leading edge 24 of the foil to produce proper clamping during operation.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A hydrofoil for controlling the depth and lateral displacement of a cable being towed by a craft, comprising:

an annular ring having a thin radial cross section conducive to smooth flow and hydrodynamic lift presented edgewise to the slip stream having a blunt rounded leading edge, a tapered afterbody, and a sharp trailing edge;

a bridle attached adjacent to the leading edge of said annular ring at substantially diametrically opposed positions;

a tow cable attached to said bridle intermediate the ends thereof; and

a ballast weight affixed to said annular ring.

2. The hydrofoil of claim 1 further comprising:

a ballast weight affixed to said annular ring at a lower and forward position concentrating the weight forward of said bridle attachment.

i i l

Claims

1. A HYDROFOIL FOR CONTROLLING THE DEPTH AND LATERAL DISPLACEMENT OF A CABLE BEING TOWED BY A CRAFT, COMPRISING: AN ANNULAR RING HAVING A THIN RADIAL CROSS SECTION CONDUCIVE TO SMOOTH FLOW AND HYDRODYNAMIC LIFT PRESENTED EDGEWISE TO THE SLIP STREAM HAVING A BLUNT ROUNDED LEADING EDGE, A TAPERED AFTERBODY, AND A SHARP TRAILING EDGE; A BRIDLE ATTACHED ADJACENT TO THE LEADING EDGE OF SAID ANNULAR RING AT SUBSTANTIALLY DIAMETRICALLY OPPOSED POSITIONS; A TOW CABLE ATTACHED TO SAID BRIDLE INTERMEDIATE THE ENDS THEREOF; AND A BALLAST WEIGHT AFFIXED TO SAID ANNULAR RING.

2. The hydrofoil of claim 1 further comprising: a ballast weight affixed to said annular ring at a lower and forward position concentrating the weight forward of said bridle attachment.