Patent Publication Number: US-6904860-B1

Title: Winglet for the trailing end of towed flexible underwater lines

Description:
STATEMENT OF GOVERNMENT INTEREST 
   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 
   1. Field of the Invention 
   The invention relates to the movement of towed underwater lines and is directed more particularly to a winglet for mounting on a trailing end of such lines and operating to improve stability of the line during towing. 
   2. Description of the Prior Art 
   Underwater vehicles, such as submarines and unmanned underwater vehicles (UUV), may be provided with a somewhat flexible line which can be paid out of the submerged vehicle and towed through the water by the vehicle. Typically, the line extends from a bow portion of the vehicle. The line is often provided with a multiplicity of acoustic sensor elements. While the line is somewhat flexible, it also exhibits some rigidity, such that when the line is being towed through the water, the line tends to bend rearwardly and well outwardly from the vehicle. 
   The vehicle is provided with a stabilizing tether which is paid out from the stern area of the vehicle and at its distal end is fastened to the towed line proximate the distal end thereof. The stabilizing tether is reeled in to bring the trailing end of the towed line in nearer the vehicle. The tether is under tension and provides some measure of stability to the towed line. 
   Nonetheless, the trailing end of the towed line is subject to substantial vibration which is unwanted inasmuch as the acoustic, or other measuring devices or sensors carried in the towed line, may be highly position dependent. That is, to gain the most from the measuring devices or sensors, it is required that the precise positions of the devices be known on a continuing basis. There is thus a need to diminish and limit the vibrational movement of the trailing end of the towed line. 
   SUMMARY OF THE INVENTION 
   An object of the invention is, therefore, to steady and stabilize the towed line so as to improve pin-pointing the positions of instruments carried in the line. 
   With the above and other objects in view, a feature of the invention is the provision of a winglet for mounting on a trailing end of a flexible line to be towed by an underwater vehicle. The winglet comprises an internal collar member for connection to an inside surface of the line at the trailing end thereof, and an outer collar member for connection to an outside surface of the line outboard of the internal collar. Connection means are provided for fixing the internal and outer collar members to the line trailing end, and a plurality of fins are mounted on an outside surface of the outer collar member and extend outwardly from the outer collar member. 
   The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made to the accompanying drawings in which are shown illustrative embodiments of the invention, from which its novel features and advantages will be apparent, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
       FIG. 1  is a diagrammatic representation of an underwater vehicle having a flexible line extending therefrom, with a winglet in accordance with the present invention fixed on a trailing end of the line; 
       FIG. 2  is a sectional enlarged view of the winglet of  FIG. 1 ; and 
       FIG. 3  is a sectional view, similar to  FIG. 2 , but illustrative of an alternative embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , it will be seen that an underwater vehicle  10  is provided with a hollow line  12  extending from a bow area of the vehicle and in which are disposed a series of sensors or measuring devices  14 , typically acoustic devices. A tether  16  extends from the stern area of the vehicle  10  and is connected to a trailing end  18  of the line  12  to stabilize the end  18 , as described hereinabove. 
   To further stabilize the line  12  and the devices  14 , and in accordance with the invention, there is provided a winglet device  20  for attachment to the trailing end  18  of the line  12 . 
   Referring to  FIG. 2 , it will be seen that the winglet  20  includes a cylindrically shaped internal collar member  22  for connection to an inside surface  24  of the line  12  proximate the trailing end  18  thereof. The winglet  20  further includes a cylindrically shaped outer collar member  26  for connection to an outside surface  28  of the line  12  outboard of the internal collar member  22 . 
   Connection means  30 , usually fasteners, such as bolts, are provided for fixing the internal and outer collar members  22 ,  26  to the line trailing and  18 , as shown in  FIG. 2 . Alternatively, the winglet  20  may be adhesively bound to the line  12 , or, depending upon the material from which the winglet is made, may be molded integrally with the line  12 . 
   A plurality of fins  32  are mounted on an outside surface  34  of the outer collar member  26  and extend outwardly, or outboard, from the outer collar member  26 . 
   While the winglet  20  may be molded of the same material as the line  12 , it is presently preferred that the winglet be fabricated from a light-weight, corrosion-resistant metal, such as aluminum. Such a winglet, along with mechanical connection means  30 , facilitate use of the winglet as an “add-on” to lines  12  currently in use. 
   Referring to  FIG. 3 , it will be seen that an alternative embodiment of the outer collar member  26  includes a first component  36  having threads  38  at an after end thereof, and a second component  40  having threads  42  thereon engageable with the first component threads  38 . The fins  32  are fixed to the second component  40 , which may be threadedly attached to and removed from the first component  36  which, in turn, is fixed to the line  12 . 
   The embodiment of  FIG. 3  enables the quick and easy replacement of fins, either because of damage or because of the desirability of a particular fin configuration for a particular task. 
   There is thus provided a winglet which may be affixed to the trailing end of a line to be towed by an underwater vehicle to steady and stabilize the trailing end of the towed line, to improve positional accuracy of instruments carried in the line. 
   It will be understood that many additional changes in the details, materials, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.