Reflector Construction

Abstract

A lightweight reflector construction suitable for use in space, having a thin flexible reflector membrane means stretched flat between the projecting ends of a plurality of arms which extend axially and radially from a central support member about which such arms are distributed. The arms accept the reflector membrane tensioning load in compression along their length and are permitted to be of relatively slender construction by virtue of a rigidizing system of guys that constrain the arms against buckling at spaced apart locations along their length.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

Lightweight structures with plane surfaced reflector means.

2. Description of the Prior Art

It has been proposed that relatively large flat mirrors be placed in orbit about a planet and aimed to reflect energy from the sun toward selected areas of such planet to enhance lighting and/or heating thereof, for example. In the behalf of convenience and effectiveness, flat reflector assemblages hundreds of feet in diameter are envisioned for such use. Weight and compactability become factors of concern in making launching of such reflector assemblages into space feasible, and rigidly of the erected assemblages is a factor concerned with maintaining reflector flatness in behalf of maximizing its effectiveness.

SUMMARY OF THE INVENTION

The present invention, by virtue of comprising a thin flexible reflector membrane means stretched flat between the projecting ends of angulated guyed support arms affords an effective lightweight structure which is readily adaptable for preerection compaction as by hinging of the arms for foldup together with the flexible guys and the flexible reflector membrane means.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view of a reflector construction embodying the invention, shown in its erected state; and

FIG. 2 is an elevation view of the reflector construction of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, the reflector construction 5 of the present invention exemplified therein, in its erected state, comprises a thin flexible reflector membrane means 6 stretched flat at spaced apart intervals by tension springs 7 between the projecting ends of a plurality of equally spaced, alike, elongated tilted tubular support arms 8 extending axially and radially from a central support member 9 which are constrained against buckling under the diaphragm stretching load by pluralities of anchor guys 10, 11 and 12 connected to anchor points 13 at longitudinal intervals along the arms.

The reflector membrane means 6 held taut and flat by the tension forces of the springs 7 at intervals about its perimeter may be of the type described and claimed in copending U.S. Pat. application, (Case 41,155) Ser. No. 883,018, filed concurrently with the present patent application, and which membrane means 6 comprises one or a number of side-by-side coplanar sheets of a light, thin, flexible material, a mil or less in thickness, for example, such as plastic materials sold under the trade names Mylar, Kapton, etc., and having a vapor deposited reflective coating of such as aluminum thereon. The flexiblity of the thin membrane material enables it to be in a folded or rolled up state prior to erection of the reflector construction, and edge reinforcement by a support cable (not shown) provides for connection of the membrance 6 to the springs 7 at discrete points therearound while distributing the localized stretch forces from such springs uniformly along the membrane edges. Curvature of the edges of the reflector membrane means 6, such as shown in FIG. 1, translates the radially directed pull on the edge reinforcing cables (not shown) into bidirectional stretch of the reflector membrane means 6 to obtain its flatness.

The support arms 8 as shown in FIGS. 1 and 2 may be of thin wall tubular construction, for example, having a number of longitudinal sections interconnected by hinge means (not shown) constructed and arranged to permit foldup of such arms accordion fashion to a compacted state around the central hub 9 to accommodate deployment into space, together with means (not shown) for unfolding and locking such arm sections into their aligned positions as shown in the drawing after erection of the assemblage in space; in manner similar to the radial arm foldup arrangement disclosed in copending U.S. Pat. application, Ser. No. 637,419, filed May 10, 1967.

In accordance with the present invention, the tilted arms 8 are permitted to function as pure compression members in reaction to the tension forces of the springs 7 which act in a direction tending to pull the projecting arm ends together, by virtue of a system of pure tension members in the form of guys 10, 11 and 12. At the same time, such guy system establishes anchor points 13 along the arms that enhances the column strength of such arms 8 with respect to the compression load imposed along their length.

The guys 10 extend radially outward and axially downward from the projecting end of a rigid mast 14 on the central support member 9 to the anchor points 13 at different locations along the arms 8. The guys 11 extend laterally between longitudinally corresponding ones of the anchor points 13, and the guys 12 extend diagonally between nonlongitudinally corresponding ones of such anchor points. In the erected state in which the assemblage or construction is shown in the drawing, the guys 10, 11 and 12, while of a flexible type which permits rollup for storage while such assemblage is compacted for launching into space, are in straight, taut attitudes in behalf of precisely defining the anchor points 13 for the arms 8. Such guys are also intended to be relatively strong and relatively nonstretchable, so that a single strand or parallel strand of wires, or piano wire quality, for example, is preferred over a twisted wire cable type which may tend to be more stretch prone.

In the guy system, the radial-axial guys 10 constrain the anchor points 13 on the arms 8 against downward movement relative to support member 9, as viewed in FIG. 2, the lateral guys 11 constrain such anchor points against upward movement relative to such member 9, and the diagonal guys 12 constrain such anchor points against sidewise or circumferential movement relative to member 9. Accordingly, at each anchor point 13 on the arms 8, such arms are constrained against buckling by the guy system and hence their capability to support the membrane tensioning load is greatly enhanced by a relatively lightweight, foldup accommodating means.

Claims

What is claimed is:

1. A reflector construction comprising,

a central support member through which an axis of symmetry of the construction passes,

a plurality of arms attached to said support member at their one end and extending axially and radially therefrom with respect to said axis of circumferentially spaced apart intervals therearound,

a central mast attached to said central support member and extending along said axis in a direction opposite to that in which said arms extend,

a thin flat reflector membrane means supported and held in tension at spaced apart intervals about its periphery by the projecting ends of said arms,

a first plurality of guy wires extending from said mast to respective locations along each of said arms, and

a second plurality of guy wires extending between said arms at locations therealong.

2. The reflector construction of claim 1, wherein certain of said second plurality of guy wires extend between longitudinally corresponding locations on the arms and others extend diagonally between nonlongitudinally corresponding arm locations.

3. The reflector construction of claim 1, wherein each of said arms is of equal length and is maintained in a straight attitude by the several pluralities of guy wires.

4. The reflector construction of claim 1, wherein all of the aforesaid guy wires are prestressed in tension.

5. The reflector construction of claim 1, wherein tension spring means are interposed between said arms and said reflector membrane means.