US2778010A - Reflector target - Google Patents

Description

Jan. 15, 1957 N. N. LEONARD REFLEEETOR TARGET Filed Aug. 10. 1953 3 Sheets-Sheet l N. NELSON Jan. 15, 1957 N N. LEONARD REFLECTOR TARGET Filed Aug. 10, 953

5 Sheets-Sheet 2 I/vvENToIe N NELso/v LEONAPD ATTQENE Y- Jan. 15, 1957 N. N. LEONARD REFLECTOR TARGET 3 Sheets-Sheet 3 Filed Aug. 10, 1953 ZNVENTOIE 4V. NELSON L ONARD REFLECTOR TARGET Nathaniel Nelson Leonard, West Los Angeles, Calif., assignor to (Zlaude C. Slate & Associates, Los Angeles, Calif., a copartnership Application August 10, 1953, Serial No. 373,134

1 Claim. (Cl. 34318) This invention relates to reflector targets of the type employed in the operation of radar equipment such as is used by the Coast Guard in spotting objects at sea (e. g. lifeboats or rafts or other small boats).

The invention has as its general object to provide a reflector target that may be used by a small boat or raft in distress, to facilitate sea rescue operations. More specifically, the invention aims to provide a reflector target that will return a radar signal of higher gain than can be obtained from a lifeboat or raft, thereby greatly increasing the range of radar search equipment.

An improved design for such a target is one that pre sents a multiplicity of plane reflecting surfaces disposed in three planes each at right angles to both of the others, intersecting at a common center and presenting a series of trihedral-angular reflector. cavities, each of equi-lateral, inverted pyramid form. More specifically, in the commonly accepted form of such device, the reflector surfaces of the three respective planes are shaped so that the reflector areas of the three planes are square, and so that their peripheral edges collectively define the edges of a regular or equi-lateral tetra-hedron. In such a device, there are eight of the outwardly flaring, trihedral reflector cavities, with the axes of the cavities radiating, at equal angular displacements one from the other, in all directions from the common center of the device, and because of the relationship between the angles of incidence and reflection of a radar beam intersecting the target at any point within its total volume, there will always be at least one of said beams reflected directly back to the source of the beam.

The primary object of the present invention is to provide a suitable construction and arrangement of the pants of a target of this type, whereby the target may be readily collapsed into a package of minimum bulk. The most difficult problem that has been encountered in attempts to provide a collapsible target, is that of avoiding difficulties that be experienced by a person attempting to assemble or expand the target from a folded or collapsed condition to its functional configuration. As to this problem, tests that have been made upon earlier targets such as those mentioned above, and other previously proposed designs for foldable targets, have indicated complete unsuitability of such devices for use by inexperienced persons or persons not possessing a fairly high degree of mechanical ingenuity. However, a basic requirement of a target for use in cases of distress at sea, is that the person in distress shall be able to assemble or manipulate the target to its expanded, functional form without difficulty, regardless of whether he is possessed of mechanical ingenuity or not.

Targets of the foldable type as previously utilized have been made in three separate panels, notched in such a manner that they will fit together to form the configuration previously described and fastened together by cords tied through each of the six corners. These targets have been found extremely difficult to assemble even by experiited States Patent O enced personnel under favorable conditions. Other reflector targets of a different type are available but they cannot be collapsed into a satisfactorily small compact package.

With the foregoing in mind, a primary object of the present invention is to provide a suitable construction and arrangement of the parts of a target of this type, whereby the target may be collapsed into a package of minimum bulk and yet may be assembled or unfolded by inexperienced persons under adverse conditions.

The problems of folding could of course be avoided by utilizing a non-collapsible target. However, because of the large ratio between total volume and solid bulk, freight rates for such a device would be at a maximum scale. Furthermore, the problems of storage, transportation, handling and protection against damage, would rule out the use of a non-collapsible target. The need for a fully collapsible target will be apparent from the foregoing.

The provision of a construction whereby a target may be readily collapsed into a compact package, engenders other problems in addition to the one mentioned above. To provide a target that can be easily expanded to its functional form, its reflecting panel sections must not only be movable relative one to another, but must be provided with means for connecting them together in a manner to permit of relative movement between them such that they can be folded flatly one against another. Such folding process should preferably be guided by the construction of the target, so that the proper folding of the sections is not left to guess work or the vagaries of individuals who may be handling the target. The connections between the sections should preferably be such as to require minimum of manipulation by the operator. On the other hand, the connections should be such that when the target is expanded to its operative shape, the several sections are securely attached one to another, with the entire assembly being relatively rigid. Furthermore, the connecting means should be such that the several sections are accurately disposed in their respective positions, with a minimum of error in the equi-angular relationship between the reflector surfaces. Not the least in importance is the need for attaining the above mentioned characteristics in a relatively simple and inexpensive yet sturdy construction. This is a primary object of the invention.

Toward the attainment of the above stated objects, the invention, in general, contemplates a target having a plurality of reflector panel sections hinged together and connected by a harness of cords adapted, when pulled, to completely effect the movement of the panel sections from folded to expanded positions. In the early attempts to achieve such an arrangement, however, difliculty was experienced with tearing the panel sections apart where too much pull was applied to the harness cords. A further object of the invention is to provide an arrangement such that all forces resulting from the pull of the harness cords, are absorbed by the panel sections without being imposed upon the hinges or between laminations or other parts subject to separation.

Other objects will become apparent in the ensuing specifications and appended drawings in which:

Fig. l is a front elevational view, slightly in perspective, of the target fully expanded and in a normal position for use;

Fig. 2 is a fragmentary side elevational view of the same;

Fig. 3 is a fragmentary horizontal sectional view of a corner portion of the same taken on the line 3-3 of Fig. 2;

Fig. 4 is a side elevational view of the target, illustrat- Patented Jan. 15, 1957 ing an early stage in the folding of the quarter sections thereof;

Fig. 5 is a fragmentary front elevational view of the target in the same position of partial folding;

Fig. :6 is a fragmentary horizontal sectional view of the central portion of the target, taken on the line -66 of Fig. 4;

Fig. 7 is a detail vertical sectional view of the upper corner of the target, taken on the line 'l7 of Fig. 4;

Fig. 8 is a front elevational view, slightly in perspective, illustrating the target in a final stage of folding; and

Fig. 9 is a front elevational view of the fully folded target.

Referring now to the drawings in detail, my improved folded radar target comprises a plurality of panel members, each having reflecting surfaces on both faces thereof, said panel members being arranged, in the fully expanded target, so as to provide three square, equal refiector areas disposed in respective planes intersecting one another at right angles at a common center, the three areas being generally designated A, B and C respectively. The respective reflector areas are provided respectively by:

' A. A single square panel, individually providing one of said square reflector areas. This square panel, which will be hereinafter referred to as the base panel, and which is designated (a), is, in those views (Figs. 1, 4 and 9) which are designated as front elevational views viewed generally edgewise, i. e., as lying generally in the line of sight.

B. A pair of half panel sections of right triangular shape, each providing one half of the square reflector area B, and lying generally at right angles to the line of vision in the above mentioned front views. For convenience in referring to them, these half-area panel sections (left and right respectively, as viewed in Fig. 1) are designated b1 and b2 respectively. Each of the sections b1, b2 is hinged along its hypotenuse to the vertical, medial axis of panel .A, indicated at y. The folding ,of the panel sections [21, b2 therefore takes place with a horizontal movement around the y-axis, .as indicated by the arrow 30 in Fig. 8.

C. Four quarter panel sections, of equilateral, right triangular shape, each providing one quarter of the C area, said quarter sections being designated 01, c2, c3 and 04 respectively, for convenience in further reference thereto (see Fig. 4). These four quarter sections are hinged, in pairs, to the respective half sections b1 and 12,2, along a horizontal hinge axis indicated at z. Thus, as is plainly illustrated in Fig. 4, these quarter sections cl-c4, in folding, are moved vertically about the z axis.

It will be noted that in the case of the quarter sections 01-04, the hinge axis occurs .at one of the equilateral sides of each section, the other equilateral side being arranged closely adjacent and parallel to a respective face of the base panel (a) and, in the fully expanded target, the free sides being arranged along the horizontal axis designated x, at right angles to the z axis.

The above referred to x, y and z axes, in the fully expanded target, are arranged each at right angles to both of the others, and intersect one another at the center of the target.

The marginal edges of the panel members (a), b1, b2, cl-c4 are located as the edges of a regular octahedron, i. e., one having eight sides each having the shape of an equilateral triangle.

Referring now to Figs. 3, 6 and 7, the panel (a) is fabricated, in laminated form, from a body sheet of heavy cardboard, laminated wood, plastic material or other suitably stiif sheet material, indicated at 10, and is faced with reflective facings 11 which consist in thin sheets of alumimm or tin foil adhesively attached to body sheet 10, or may be constituted by coatings of electrical conducting material such as colloidal silver paint or electro deposited metaLsuitably applied in a thin film by known methods.

4 Similarly, half sections b1, b2 are fabricated from body sheets 10b having reflective facings 11b on the respective faces thereof. Similarly, quarter panel sections C1-C4 (Fig. 3) are fabricated from body sheets 10c covered with reflective facings 110. In each case, the margins of the panel members are reinforced and protected by margin bindings 12 of channel shape, adhesively secured to the marginal portions of the facings 11, 11b, 11c and embracing the same. Suitable material for the bindings is book-binding buckram, in tape form. Similar material may be utilized to provide hinges 13b, 130, the hinges 13b connecting panel sections b1, b2 to base panel (a) along axis y, and hinges 13c connecting quarter sections 01-04 to base panel (a) along axis z.

Along the axis x, the inner lateral margins of sections 01-04 are in closely spaced, parallel relation so that each pair of sections (c1 and 02 on one side, and c3 and 04 on the other side) defines a narrow slot in which a respective half panel section b1, b2 is respectively received. Since the other lateral margins of the quarter sections are attached, by hinges 130, to "base section (a), the opposed, slot defining margins of sections 01-04 will be securely held in this parallel, closely spaced relation, and will abut the half sections b1, 122 to firmly support the latter in a common plane constituting the bisector of and normal to areas A and C. This will be true as long as the quarter sections c1c4 are disposed in a plane normal to axis -y. By folding the quarter sections c1c4 flatly against the base panel (a), the half sections b1, b2 are released for folding movement around axis y, to positions folded flatly against the infolded quarter sections 01-04, as illustrated in Fig. 9.

In order to attain maximum compactness in the folded target, the quarter sections are preferably folded in the directions indicated in Fig. 4, one of each pair being folded downwardly and the other of each pair being folded :upwardly, although it is possible to fold the sections of one pair downwardly and the other pair upwardly, ,or even to fold all quarter sections in a common direction, either upwardly or downwardly.

The invention is particularly characterized by a harness comprising an arrangement of pull cords d1, d2, d3, d4 which at their ends are attached to eyelets 14, 14' in the free corners of .the respective quarter sections 01, c2, c3, 04; are passed through eyelets 15, 15 in the lateral corners of half sections; and are thence passed through eyelets 16, 16' in the upper corners of the half sections b1, b2.

The ends of cords a1, a2 are joined by a loop 17 and the ends of cords a3, a4 are joined by a loop 17'. In the fully extended target, the loops 17, 17, attached to a suitable support (e. g. a mast, oar, boat hook etc), will function as a leader for attaching the target to the support and suspending it therefrom.

A pull of adequate intensity against the lower end of the target may be provided for by employing, as a handle, a loop 27 which isattached to eyelets 28 in the lower corners of half sections b1, b2.

The harness 01, c4 is particularly arranged so as to execute the following functions: (1) by simply grasping the tips of loops 17, 17 which, in the fully folded target are relatively close to the apex of the target as shown in Fig. 8, and pulling them upwardly while applying a downward pull to the lower end of the target, a pull will be transmitted to the outer corners of the respective quarter panel sections c1-c4, such as to draw them toward the plane .of area Cof the assembled target of Fig. 1, as indicated by the arrows 26 of Fig. 4. As the quartersections 01-04 thus move toward the plane of area C, they will engage and move the half sections b1, b2 to the plane of area B. (.2) When the quarter sections c 1.- c4 have arrived at the plane of area C, further pull on the harness willfunction to hold them securely in that plane.

The e functions are obtained through the arrangement whereinieach cord is attached atone end to an outer (free) corner of a respective quarter panel section, is thence passed through the respective eyelet 15, or to the opposite side of the adjacent half panel section b1 or b2 from the side on which it is attached to the quarter section, is extended along said opposite side from the respective eyelet 15 or 15 to the respective eyelet 16 or 16, and is thence passed through the latter eyelet on the same side of the respective half panel section b1 or b2 as the side on which it is attached to the quarter panel section, where it becomes a portion of a respective loop 17 or 17. It will now be apparent that the respective portions of loop 17 or 17' are passed in opposite directions through the same eyelet 16 or 16' to become respective cords of a pair of cords d1, d2 (or d3, d4, as the case may be); are then extended in a parallel relation along opposite sides of a respective half panel section b1 or b2, are then extended in opposite directions through a common eyelet 15 or 15', and are then attached to the corners of a respective pair c1, 02 (or c3, c4) of quarter panel sections.

In the folded target, each of the cords d1d4 extends from a respective loop 17 or 17' through a respective eyelet 16 or 16, is thence extended downwardly along one side of a respective half section b1 or b2, -is thence extended through an eyelet 15 or 15' and thence extends upwardly (or downwardly) to the free corner of the respective quarter section as indicated in Fig. 8. In opening the target to fully extended condition, the last mentioned portions of the cords, extending upwardly (or downwardly) from the eyelets 15, 15 to the free corners of the folded quarter panel sections, are drawn through the eyelets 15, 15 until the point of attachment of the cord to the corner of the respective quarter section is directly opposite the respective eyelet 15, 15. At this point, no more cord can be drawn through the eyelets 15, 15, and accordingly the pull on the cords firmly holds the free corners of the quarter panel sections directly opposite the respective eyelets 15, 15, i. e., in registration with the lateral corners of the respective half panel sections b1, b2.

In folding the target, the harness is released so that the various cords are free to draw through the eyelets 15, 15, 16, 16'; the base panel (a) is suitably held; and the four quarter panel sections c1c4 are then folded against their respective sides of main panel (a), in. directions opposite to those indicated by arrows 26, until they are flatly folded against panel (a). In this folding operation, the cords d1d4 will be drawn through eyelets 15, 15', 16, 16 and only the short loops 17, 17' will remain projecting beyond the apex of the target. The half sections b1 and b2 are then folded in opposite directions against the respective sides of the base panel (a), as indicated by arrow in Fig. 8, to bring the target to the flatly folded, compact package form shown in Fig. 9. The folded target may then be placed in a suitable pouch or envelope, until ready for use.

It will now be apparent that the folded target can be expanded to operative form simply by grasping the cords d1-d4 in one hand and the loop 27 in the other hand and moving the hands apart to impose a pull between the cords and the loop. This can be executed by any person of limited mechanical ingenuity, and in only a second or a few seconds of time.

An important characteristic of the invention is the arrangement of the harness so that the tension forces in cords d1-d4 are transmitted through eyelets directly into half panel sections b1, b2, and thence longitudinally through half panel sections b1, b2 to loop 27 without being imposed upon hinges 13b, 130 or set up between laminated parts 10, 11, 12 etc.

I find that with the construction shown, wherein loop 27 is attached to the lower corners of half sections b1, 122 through eyelets 28, wherein cords dl-d4 are threaded through eyelets 15, 15', 16, 16' in sections b1, b2 and are attached to quarter sections c1-c4 through eyelets 14, 14, that loads of several hundred pounds can be transmitted through the target between the cords and the loop 27 without de-laminating, tearing out the eyelets, pulling apart the hinges, or otherwise damaging the target.

I claim:

In a collapsible reflector target: a plurality of panel members each having reflector surfaces on both faces thereof, said panel members, in the expanded target, occupying three equal areas of square form disposed in planes each intersecting both of the others at right angles along axes of intersection each constituting a common median diagonal axis of two of the areas; said panel members comprising a single square base panel coextensive with one of said areas, a pair of isoceles right triangular half panel sections having hypotenuse margins hinged to opposite sides of said base panel along a first one of said median diagonal axes thereof and together constituting another of said areas, and four isosceles right triangular quarter panels arranged in pairs each having respective side margins hinged to opposite sides of a respective half panel section along a second one of said median diagonal axes and having free side margins arranged to abut respective faces of said base panel along the third one of said median diagonal axes and to thereby brace said half panel sections to maintain their respective plane normal to the plane of said base section, said quarter panel sections being adapted for hinging movement around said second axis to positions folded in face-to-face engagement with the respective half sections to which they are hinged, with said free side margins substantially registering with said first axis, whereby to allow said half panel sections to be folded about said first axis to positions in substantially face-to-face relation to said base panel, whereby the target becomes fully collapsed; and means for expanding the target from said fully collapsed condition to a fully open condition, comprising means to anchor one corner of said base panel at one end of said first median diagonal axis means defining a pair of apertures in the opposite corner of the base panel on opposite sides of said first axis, means defining a lateral aperture in each of the other two corners of said base panel, and a harness comprising a plurality of cords each attached to the free corner of a quarter section, passing through a respective one of said lateral apertures thence extended to said opposite corner of the base panel and passing through one of the apertures therein, the cords of opposed quarter panel sections on opposite sides of the base panel being passed in opposite through a common lateral aperture and again through a common one of said pair of apertures, with all of said cords extending away from the target along an extension of said first axis, whereby all quarter sections may be simultaneously moved toward their open positions by exerting a common pull against all cords simultaneously in opposition to said anchor means.

References Cited in the file of this patent UNITED STATES PATENTS 2,419,549 Griesinger Apr. 29, 1947 2,475,633 Morris July 12, 1949 2,498,660 Dunmore Feb. 28, 1950 FOREIGN PATENTS 466,670 Canada July 18, 1950 658,915 Great Britain Oct. 17, 1951

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