US 3221875 A
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Dec. 7, 1965 E. a. PAQUETTE 3,221,375
PACKAGE COMPRISING RADAR CHAFF Filed July 2, 1965 INVEN TOR.
Lame 6. P49 :77: BY 6% A l;
United States Patent 3,221,875 PACKAGE COMPRISING RADAR CHAFF Elmer G. Paquette, Cambridge, Wis., assignor to the United States of America as represented by the Secretary of the Air Force Filed July 2, 1963, Ser. No. 293,236 3 Claims. (Cl. 206-65) This invention relates to packages of parallel strands and to a method of making such packages. More particularly, this invention relates to bundles of strands which may be dispensed into the atmosphere, as chaff or rope, to provide radar reflective dipoles to confuse enemy radar. Such bundles may be of parallel lengths of metal strands, or of strands made of metalized dielectric fibers.
In addition to solid metal fibers, such fibers may be made from vitreous material such as glass or vitreous silica, and coated with a conductive metal such as aluminum, magnesium or copper. Such fibers may be from one micron to 200 microns in diameter, but are generally about to microns in diameter. The metallic coating, which is to be active as a dipole, is usually applied to be from 2 to 100 microns in thickness.
Electromagnetic radiation of a frequency which is reso nant with the dipole, is reinforced by resonance in the dipole, and the radiation is, in effect, rebroadcast by the dipole. In effect, each dipole acts as a reflector. The radiation emanating from a plurality of dipoles which are resonant with the frequency emitted from an enemys radar apparatus appears on the oscilloscopes of the radar as a bright cloud or a bright object having various characteristics depending on the manner in which the dipole material is dispensed. Such dipole material, having a length of from Mi inch to about 1 /2 inches is referred to as chaff. Material which is longer than about 1 /2 inches, and which may be up to say 500 feet in length, but is preferably from about 3 inches to 100 feet in length, is referred to as rope.
Rope is not intended to be resonant with radar frequencies; but is intended to respond to other frequencies, or to effectively emit radiation at other frequencies in response to frequencies to which it is not resonant. It is generally preferred to dispense a certain amount of rope and a certain amount of chaff of various lengths, more or less simultaneously. This invention provides chaff, packaged in convenient form, for ready dispersion in the atmosphere after being dispensed from an airplane.
It is therefore an object of this invention to provide chaff, in improved bundles, for ready dispersion in the atmosphere.
Another object of this invention is to provide bundles of radar chaff in which the strands or fibers are relatively more parallel than has been possible heretofore.
Yet another object of this invention is to provide such bundles which are more compact and more tightly compressed than has been possible in the past.
Still another object of this invention is to provide such bundles which are not enclosed with a vapor barrier and which therefore may breathe.
A further object of this invention is to provide such bundles in which the parallel strands are retained in the bundle by wrapping the bundle with one or more strands in lieu of sheets or strips as heretofore.
A still further object of this invention is to form a bundle of radar chaff which is Wrapped with one or more strands of the same material forming the chaff itself.
Additional objects, advantages and features of the invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention as will appear from the following description and accompanying drawing wherein:
FIG. 1 is a schematic illustration of a preferred man- 3,221,875 Patented Dec. 7, 1965 ner of making wrapped bundles of strands from which the radar chaff or rope is formed;
FIG. 2 is a perspective of one bundle of radar chaff in accordance with this invention and having fine pitch wrapping, and
FIG. 3 is a perspective of one end of another bundle of strands forming rope, and having coarse pitch wrapping.
Referring now to FIG. 1, it will be presumed that the radar chaff bundles are to be formed of metalized fiber glass strands which have been wrapped by wrapping machine 10. A plurality of individual glass strands 12, which had been drawn from a body of molten glass and coated with metal in any suitable manner, are converged and fed through a collector ring 14 from which they emerge in the compacted bundle form 12a. The circularly compacted strands are then passed longitudinally through the hollow shaft motor 15 and emerge from disk 16. Disk 16 is joined to and is rotated, in the direction indicated, by motor 15.
One or more rotatable spools 18, carrying nonadhesive wrapping thread 20 are supported by and rotate with disk 16. The thread is spirally wrapped onto the strands as they are longitudinally drawn, without rotation, by roller 22 and roller 24 which is driven by motor 26 through belt 28. It is well understood that the pitch of the thread encompassing the strands will be a function of the linear travel of the strands and the rate at which disk 16 is caused to rotate.
Thread 20 may conveniently be of glass, either fine or coarse, and may consist of twisted and plied glass yarn or of strands of roving. Whether closely or widely spaced, the spiral wrapping does not form a vapor barrier. The weight of the thread forming the wrapping can be substantially less than that of the paper used on an equivalent roll.
The product leaving wrapping machine 10 may be cut to any suitable length chaff or rope in various manners well known to the art. FIG. 2 depicts a typical bundle of relatively short length strands to be used as chaff. FIG. 3 depicts a broken end portion of the same strands cut to proper length for use as rope. When used as chaff, the thread 20 is wrapped to have a fine pitch, as shown in FIG. 2, and when used as rope the thread is wrapped to have a coarse pitch as shown on FIG. 3.
The glass thread is obviously as temperature resistant as the fibers themselves, and assumes no set whatever. For making transverse cuts, the wrapping has the same cutting characteristics as the material which it confines and shows no tendency to snag and tear. For longitudinal slitting, the wrapping is much easier parted than a felted or woven covering. It may be slit with almost any kind of cutting edge or even with a heated wire loop; and when slit at one point along the circumference of the roll, it fully releases the contents. Metalized fiber may be used as thread for the wrapping instead of bare glass. The gain in efficiency of the chaff, if any, is insignificant, and it appears that for most purposes a rather fine strand of glass textile stock is most desirable.
The strands 12 may be of glass, metal, metalized, glass, synthetic fiber, or natural fiber including paper, twisted or untwisted, plied or unplied, and formed of staple or monofilamentary fibers. Likewise, the thread forming the wrapping may be made of any material suitable for the strands, or may be tapes of woven or unwoven fabric, metal, paper, plastic film or other material. By varying the passage through the collector ring to suit, in addition to the substantially cylindrical bundle shown, bundles may be produced having oval, square, triangular, or any other cross-sectional configuration.
It is to be understood that the embodiment of the present invention as shown and described is to be regarded as illustrative only and that the invention is susceptible to variations, modifications and changes within the scope of the appended claim.
1. A package of radar chalf comp-rising: a plurality of metallic coated dielectric strands having a selected length of from A inch to 1 /2 inches formed into a longitudinal bundle and a wrapping of adhesion-free thread spirally wound and longitudinally encompassing said bundle of strands, said thread being of a dielectric material.
2. A package of radar chaff comprising: a plurality of metallic coated fiber glass strands having a selected length of from /1 inch to 1 /2 inches formed into a longitudinal bundle and a wrapping of thread spirally wound and longitudinally encompassing said bundle of strands, said thread being a fiber glass strand.
3. A package of radar chafi' comprising: a plurality of metallic coated fiber glass strands having a selected length of from 4 inch to 1 /2 inches formed into a longitudinal bundle and a wrapping of thread spirally wound and longitudinally encompassing said bundle of strands, said thread being a metallic coated fiber glass strand.
References Cited by the Examiner UNITED STATES PATENTS 2,238,727 4/1941 Glassford 57-18 2,430,358 11/1947 Merwin et al. 57-18 2,516,212 7/1950 Hoffmann et al. 573 2,572,052 10/1951 Pheazey 57--3 3,029,586 4/1962 Walsh et a1 57--3 3,049,080 8/1962 Schermuly 102-37.6
LOUIS G. MANCENE, Primary Examiner.
SAMUEL FEINBERG, Examiner.
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