Abstract:
A spool wherein line pay out is limited to a selected length by a pin thats retractable from one or more loops previously formed in the line and extending through a spool flange opening. A detented thumb wheel is eccentrically connected to the pin for retraction thereof.

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 
     This invention relates to line spools or reels, and more particularly a spool or reel device that will permit a selectable, predetermined length of line to be payed out, for example between a float and a suspended, underwater payload. 
     Various devices have been proposed for suspending or tethering a payload of scientific or military equipment at a predetermined water depth. These have included hydrostatic pressure sensing devices that snub a line when a programmed depth is reached, and rotation counting devices that, in effect, measure the amount of line spooled out and actuate a snubber when the predetermined amount of line has been payed out. 
     The foregoing devices are unduly complex, expensive, and subject to malfunction in the harsh enviroment afforded in sea-water use. Accordingly, there exists a need for an inexpensive, reliable, and readily programmed line paying device for the above mentioned purposes. 
     SUMMARY OF THE INVENTION 
     The present invention aims to overcome most or all of the disadvantages of the prior art through the provision of a novel line spool device incorporating a reciprocable pin that is retractable from one or more stop elements, such as knotted loops at one or more locations along the line, by selector means which, in the preferred embodiment, comprises a rotatable dial or thumb-wheel that is calibrated with depth selecting indicia. 
     With the foregoing in mind, it is a principal object of the invention to provide an improved line paying spool device having a line length selecting feature. 
     Another object is to provide a reliable, inexpensive, light weight, and compact device for paying out a predetermined length of line between an underwater payload and a float or anchor so that the payload operating depth can be accurately and quickly selected just prior to deployment, for example by air drop. 
     As another object the invention aims to provide, in an air droppable instrumentation package including a drogue, a float, and and underwater payload, a spool device having a selectively adjustable line arresting means comprising a guide block having a bore in which a pin or rod is reciprocable and having a plurality of grooves or recesses intersecting the bore so that loops, spaced along the line wound on the spool, are each releasably retained in one of the grooves by the rod, and means for withdrawing the rod from one or more of the loops to select a line length that will pay out between the float and the payload. 
     Other objects and many of the attendant advantages will be readily appreciated as the subject invention becomes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIGS. 1a, 1b, and 1c are sequential elevational views of an air droppable instrumentation package including a spool device embodying the invention and shown in succeeding stages of deployment; 
     FIG. 2 is an enlarged view, partly in section, of the spool device portion of FIGS. 1a-1c; and 
     FIG. 3 is a sectional view taken substantially along line 3--3 of FIG. 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1a-1c, there is illustrated a system utilizing the invention. A package 10, dropped from an aircraft, for example, comprises a drogue or parachute section 12, a float section 14, a spool section 16, and a payload section 18. The parachute section 12 deploys a chute 12a to slow the descent of the package 10 to a rate that will prevent injury to the payload section 18 on impact with water W. Upon immersion in the water W, a water activated battery fires a squib means in a well known manner to separate the parachute section 12 from the rest of the package 10, to deploy an inflated float 14a from the float section 14, and to release the payload section 18 from the spool section 16. The state of operation a few seconds after immersion is illustrated in FIG. 2b. 
     Spool section 16, which will later be described in more detail with reference to FIGS. 2 and 3, pays out a predetermined length of line 20, which length is selectable according to this invention from a plurality of available lengths by means which will become apparent as this description proceeds. When the selected length of line 20 has payed out, fall of the payload section 18 will be arrested and maintained at a predetermined depth d as illustrated in FIG. 1c. 
     Referring now to FIGS. 2 and 3, the spool section 16 comprises a cylindrical wall 24 housing a depth selecting spool, indicated generally at 30, which is an exemplary embodiment of the invention. The spool 30 comprises a drum portion in the form of a central tube 32 made of metal or other rigid material, and annular spool end plates 34 and 36 fixed to the opposite ends of the tube, as by welding, to form line confining flanges. Line 20 is wound on the spool 30 and has its outer end portion leading to the payload 18 through a central aperture 38 in a disc 40 retained within wall 24. 
     Mounted in spaced, substantially congruent, relation to annular spool end plate 36 is an annular plate 44, the spacing being determined by tubular spacers 46 through which mounting screws 48 extend into plate 36. Between plates 36 and 44 is mounted the line length selecting means comprising a pin 50 that is reciprocable in a guide member 52. Guide member 52 includes a base 52a, that is fixed by screws 54 to plate 36, and a plurality of spaced portions 52b, 52c, 52d, 52e, and 52f, having aligned bores in which pin 50 is reciprocable. Portions of pin 50 are exposed between spaced guide portions 52b, 52c, 52d, 52e, and 52f. A spring 56 acts between guide portion 52f and a stop washer 58 to resiliently urge pin 50 to its illustrated position. 
     A lanyard 60 is connected from one end of pin 50, around a fair-lead sheave 62, to a link 64 that is eccentrically connected at 66 to a thumb-wheel 68 rotatably mounted between plates 36 and 44. A spring biased detent ball 70 serves to hold wheel 68 in any of a plurality of selectable rotational positions. Suitable line length selecting indicia are conveniently displayed on the side of thumb-wheel 68 to aid in selecting a depth in accordance with the position of that wheel in a manner which will become apparent as the description proceeds. 
     Line 20 is provided with knotted loops 20a, 20b, and 20c at predetermined positions along the length of line 20, which loops extend upwardly through an elongated port 74 in plate 36 and are engaged by those portions of pin 50 that are exposed between the guide portions 52b, 52c, 52d, and 52e. 
     MODE OF OPERATION 
     Prior to use, the spool 30 is programmed to pay out a selected line length by rotating (if necessary) thumb-wheel 68 to bring the desired depth indicia adjacent a suitable reference mark 76. This causes link 64 and lanyard 60 to retract pin 50 from the appropriate loop or loops 20a, 20b, and 20c. Line 20 will, when the package 10 has been dropped and payload 18 separated, pay out until a pin retained loop is reached or, if all loops have been released, to the inner end of line 20 which is attached to the spool 30. 
     It will be appreciated that the invention has provided a spooling device that can be very quickly set to select one of a plurality of predetermined line lengths, and meets the aforementioned objects and advantages in a particularly efficacious manner. Various departures from the example may, of course, be utillized. For example, the spool may be associated with the payload rather than with the float. The payload, may be a floating device, and the spool associated with it or with an anchor. Thus, it will be recognized that either the float or the anchor may be regarded as a positioning reference for the payload. Moreover, operation of the pin actuating wheel may be accomplished by motor means, rather than manually, For example, if rotated by a clockwork mechanism, a time delay feature is achieved. Alternatively, the drive motor may be remotely controlled to provide for line pay-out selection from a distance. 
     Obviously, other embodiments and modifications of the subject invention will readily come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing description and the drawing. It is, therefore, to be understood that this invention is not to be limited thereto and that said modifications and embodiments are intended to be included within the scope of the appended claims.