Air Fronts: Air Defense FM 5-20F; Camouflage of Antiaircraft Artillery - 4. Use of Artificial Materials

Artificial camouflage materials most useful to an AAA unit are shrimp nets, twine nets, chicken wire, and the osnaburg or burlap strips with which the latter two are garnished. Shrimp nets and twine nets, because of their portability, are adapted to use by mobile units and in temporary positions. Chicken wire, although heavier and bulkier, holds its form better, is more durable, and is invaluable in concealing positions of a permanent nature. A clear field of fire for AA guns requires camouflage nets which can be opened or removed instantly.

Both twine nets and chicken wire may be garnished with cloth strips or with natural materials or with a combination of both. Natural materials must be replaced at the first sign of wilting, if they are to match living vegetation. Garnishing is arranged to resemble the texture and color of the surroundings and, for reasons of blending when applied to flat-tops, is always thinned out irregularly toward edges of nets. During seasonal changes in stable situations, garnishing of nets must be gradually changed to retain good color match (fig. 31). Whenever possible, edges of nets are sited along natural terrain lines, such as hedges, roads, paths, and ditches. If no terrain lines exist, edges of garnishing must he thinned out extremely irregularly. Objects and activities to be concealed must be kept under the area of denser garnishing.

IGLOO

FIGURE 32 (1).- Igloo, closed over an emplaced machine gun. Recommended only for areas possessing good ground cover. Because of its simplicity and ease of operation, this is a useful means of concealing AA machine guns from aerial observation. The vegetation upon which the halves of an igloo fall when opened must be replaced when damaged or wilted.

(2).—Materials consist of two garnished twine nets, two bows made from saplings, stakes on which bows are hinged, and rope or wire for lashing net to bows and for making hinges. Green-growth saplings are desirable for this purpose because of their long life and resiliency.

(3).—Igloo falls open when catch at top is released. Spoil parapet is covered with leaves to blend with surroundings.

Artificial materials require transportation and their use should be confined principally to positions expected to be occupied for an extended period. They should be supplemented as much as possible by natural materials and should be considered merely as aids to the use of natural materials. Natural materials, when available, are always preferable to artificial materials.

BUGGY-TOP

A buggy-top is easy to open and lies flat on ground when collapsed. Although not as easy to build as an igloo, it is almost without profile, casts little shadow, and offers the advantage of enabling a machine gun to fire ground missions to front and flanks without interference, even while buggy-top is closed. By pushing backward on one of the supporting frames, position can be cleared for AA fire in a few seconds. The vegetation crushed by the falling net must be replaced frequently with fresh growth.

Since net must fold compactly when buggy-top is open, twine net is used instead of chicken wire, which is too stiff.

FIGURE 33.—Diagram of buggy-top construction. Length of legs is governed by size of net required. They should be hinged in such a way that net just clears emplacement when it is open or collapsed.

FIGURE 34 (1).—Buggy-top closed. To complete camouflage of position, small bushes must be placed irregularly around edge of net to break up remaining shadows.  

(2).—Buggy-top open.

SWINGING FLAT-TOP

A swinging flat-top for machine-gun emplacements depends for support on a cantilever. A substantial post or tree at one corner serves as both the sole support and hinge for the entire structure. This construction is preferred by some troops because of the ease with which it can be opened. A slight push swings the structure to one side. Ground fire, however, is restricted on the side from which it is suspended.

Construction details are shown in figure 35. Frame is made of saplings and No. 10 wire. Either garnished twine net or chicken wire serves as covering material. Netting must be stretched tight and kept flat. From the air, a sagging net looks like a round hole.

FIGURE 35.-Diagram of swinging flat-top construction. Correct balance depends on post and stakes, which anchor guy wires, being firmly embedded in ground.

FIGURE 36 (1).—Swinging flat-top closed.

(2).—Open.

DOUBLE BUGGY-TOP

FIGURE 37 (1)—1.-Top view of a double buggy-top, composed of two identical buggy-tops, described on page 32. In the 40-mm installation illustrated here, both nets and surrounding ground are covered with the same natural materials from nearby trees to give area uniform texture and color. This good practice should be followed whenever practicable.

(2).—Side view. Two buggy-tops facing each other are closed toward each other so that front edges join over center of emplacement. Director is close to side of structure, and to conceal it from oblique observation a small sloping net has been added. Although frames of two buggy-tops in these photographs are made of pipe, they can be made of saplings or lumber if position is to be occupied for short time only.

THROW-BACK DRAPE

FIGURE 39 (1) , (2), (3), and (4).—The throw-back drape is a quickly removable camouflage cover used only where its irregular surface matches an equally broken and uneven ground surface. Two 15- by 15-foot garnished twine nets, staked to the ground at opposite outer edges, are supported at least 8 to 12 inches above ground on either of two types of improvised hinged sup-ports (1) and (2). A light sapling is fastened to the inside edge of each net. Nets are closed by resting saplings on two pairs of forked sticks. To clear position, throw saplings clear of emplacement; hinged supports, which vary in height and are set to lean out-ward (3) and (4) , fall automatically.

HINGED FALL-AWAY TREE

This method of concealing a .50-caliber AA position makes use of cut trees which are hinged at their base, as in figure 39 (1). Trees are guyed to lean outward; they fall when inside guys, which are hooked to notched stakes within reach of the emplacement (fig. 40, detail A ), are released. For temporary positions use evergreens, if they are present in the surroundings. For more permanent positions, strip leaves from any type of tree and replace with artificial garnishing to match the color and texture of the surrounding foliage (see FM 5-20G, for construction of false trees and foliage).

 
FIGURE 40 (1) and (2).

NET SET NO. 3

FIGURE 41 (1).—Net set No. 3, concealing an emplaced 40-mm gun. This net set, entirely pre-fabricated, is issued to 40-mm units. It can be erected in from 10 to 30 minutes, depending on number of men available and whether by daylight or at night. Adjustable brackets on supportting poles allow height of nets to be varied as required by different ground formations. Erection details are shown on page 42.

(2).—Diagram of net set No. 3 over 40-mm emplacement. Parapet must be covered with natural materials to avoid becoming visible through edges of the net. Embrasure, which is where the two 14- by 29-foot nets are joined by a quick-release device, is placed on line between gun and director to prevent nets fouling on director when they are opened. Quick-release devices are explained on page 40. When opened, nets fall apart, clearing gun and director.

(3).—Net set No. 3, opened.

FIGURE 42.

QUICK-RELEASE DEVICES

The hinge-and-pin device in figure 43 opens nets instantly and is the most efficient of the many quick-release devices tested and in use. It is standard equipment on net sets No. 3 and 4 and is available for net sets issued prior to its development which are equipped with a ring-and-loop device (fig. 45). Method of attachment and details of construction are shown in figure 43 (1) and (2). The hinge-and-pin device is used to join nets. Cables forming the supporting frame for nets are joined at the embrasure by a cable-release device (figs. 46 and 47) using the same principle.

FIGURE 43 (1) and (2).—Hinge and pin. A male and female hinge, crimped to net edges at points opposite each other, are locked together by a pin. When cord which joins them is pulled, all devices open at same time. Details: A. Side elevation of hinges. B. Hinges joined and crimped to edges of nets. C. Distance between hinges. Few inches of slack in cord connecting pins permits device to be locked easily.

FIGURE 44.—Caliber.50 machine-gun clips, an excellent expedient. At each interlocking point a clip is fastened to each net in such a way that a 60d nail, joining them, passes through three rings. Cord is attached to nails as in figure 43.

FIGURE 45.—Ring and loop, an-other expedient. It cannot open as quickly as either a hinge and pin or machine-gun clips, since it depends on progressive action.

CABLE-RE LEASE DEVICES

FIGURE 46 (1) and (2).—Goose neck, formerly issued with net sets, replaced by cable release in figure 47. A useful expedient when new device is not available, it can be made easily by a black-smith.

FIGURE 47 (1) and (2).—New cable release for cable frames which support nets is opened by a pull cord and can be operated from a distance, a great advantage over the goose neck, which must be tripped by hand.

NET SET NO. 4

FIGURE 48.-Net set No. 4 closed over gun emplacement; figure 50 shows same position with set open. Net set No. 4, issued one per 90-mm gun, employs two nets, each 17 by 35 feet. In every other respect, including erection details, net sets No. 3 and 4 are the same.

ERECTION PROCEDURE

FIGURE 49 (a).—Lay out the two sections of cable frame. Connect cable releases. Make frame square and taut by pulling on all corners simultaneously. Mark corners while taut. Tighten adjustable brackets on posts to height desired. Hold post erect at each corner and locate stakes by stretching guy cables from adjustable brackets to ground on line with frame cables. Be sure turnbuckles are open when measuring. Drive stakes.
(b).—Attach guy cables to double-eye connectors in frame, as in detail A, and hook through slots in stakes as in  detail B.
(c).—Spread nets on top of frame so snapless sides adjoin. Attach nets to frame.

(d).—Erect frame with nets attached by first inserting double-eye connectors in slots of adjustable brackets on posts (detail C) then raising posts. Posts should lean outward at top to assist nets to clear position when they are released.

(e).—Tighten guy-cable and diagonal-cable turnbuckles until frame is taut and square. Nets may be tightened, if necessary, by inserting snaps  back under several meshes and resnapping to frame. See that cable releases are properly closed and free of net. Join nets together with quick-release device (page 40).
(f).—To open, pull ropes controlling quick-release de-vice and cable releases. Time for erection can be lowered by leaving nets attached to wire frame at all times.

FIGURE 50.

FIGURE 51 (1).—A cut tree fastened to transmitter. Garnished nets are draped around base of mount and over carriage.

CAMOUFLAGE FOR RADAR

No materials of any kind can be used to camouflage antennae of SCR-268, SCR-545, and SCR-584, and only non-metallic materials can be used in the vicinity of these instruments. This rules out the employment of bracing wire, chicken wire, and the like.

Camouflage of SCR-545 and SCR-584 can be accomplished best by digging in until the roof is even with the ground level, then using twine nets or natural materials to conceal the roof and excavation. When these instruments cannot be dug in they are camouflaged in the same manner as vehicles, according to FM 5-20B. In either case, however, the antenna must be uncovered and left free to rotate.

FIGURE 51 (2) and (3).—Two views of small twine nets attached to instrument housing of SCR-268 and supported by wooden poles.

SIMULATED HOUSE

FIGURE 52 .—A disguise for height finders or comparably smalI elements which must be cleared quickly. It is built in two sections of wooden frames covered with cloth. The four frames required are made of saplings or lumber and are hinged to stakes as in detail A. Hinges are improvised from driftpins or No. 10 wire.
(2).—House is anchored to ground by guy ropes and stakes.
(3).—Two sections collapse when fasteners are released from ridge poles. Detail B shows two types of fasteners, one made of two pieces of No. 10 wire twisted together, the other of rope tied in a bow knot.

(4).—House completely collapsed.