US 3294605 A
Description (OCR text may contain errors)
3,294,605 FABRIC FOR AND METHOD OF MAKING PREFABRI'CATED v 5 Sheets-Sheet 1 W. H. FISCHER INFLATABLE STRUCTURES 36 Zfi Dec. 27, 1966 Filed Feb. 8, 1963 INVENTOR. Mu MM flaw/1? ww w A 77'0/f/VEY5 Dec. 27, 1966 w, F 5cH 7 3,294,605
FABRIC FOR AND METHOD OF MAKING PREFABRICATED INFLATABLE STRUCTURES Filed Feb. 8, 1963 3 Sheets-$heet 2 INVENTOR W/L L MM hf 550/56 ATTOR/VfYS Dec. 27, 1966 w. H. FISCHER FABRIC FOR AND METHOD OF MAKING PREFABRICATED INFLATABLE STRUCTURES Filed Feb. 8, 1963 5 Sheets-Sheet 5 United States Patent Oflice 3,294,505 Patented Dec. 27, 1966 ware Filed Feb. 8, I963, Ser. No. 257,314
7 Claims. e1. 15665) This invention relates to inflatable transportable structures, and more particularly to prefabricated enclosures which may be quickly erected by inflation at the site.
Temporary prefabricated structures such as inflatable radome enclosures for radar or communication antennas present serious problems of weakness under wind loading, erection difliculties, and the need for constant pressurizing of the entire interior of the structure, requiring double-door air-1ocks or the like to maintain internal pressure. Inflatable single-skin balloon-like radomes possess the structural strength to support their own weight when inflated, but extreme loading conditions presented by high Wind loads often cause the failure of such structures, since they possess very little structural stiflness and rigidity.
Prior art inflated radomes require considerable sealing and caulking around the juncture of the tower and radome base and around the air-lock and air-lock doors, in order to maintain their inflated shape.
Single-skin prior art radomes are also subject to tearing or ripping on the radar or communications antennas during high winds. This is a particularly serious problem if there is dimpling of the radome skin so that it catches on a rotating radar reflector, for example. When such a tear occurs the radome skin generally splits from top to bottom as air pressure rushes through the break. The ripped radome skin then clings to the radar reflector and acts as a large sail. In high winds the radar may be swept from the radar tower and destroyed.
The prefabricated structures of the present invention provide unusually high strength coupled with unexpected convenience during handling and erection of the structures. They incorporate a unique construction taking ad vantage of a double walled inflatable cellular panel arrangement. The'panels may be conveniently fabricated and transported to the erection site, where their handling and inflation is greatly simplified by their unusual construction. In the event of a tear in a cellular panel, there is no great rush of air through the break. This is due to the battling structure between each cellular chamber in the panels. The break can be easily patched over the low velocity air issuing from the disrupted cellular chamber. Thus a break in a panel wall doe not endanger the whole structure and the equipment it houses, since there is ample time to patch the break.
Accordingly it is a principal object of this invention to provide li htweight structures which may be fabricated, transported and erected with maximum convenience.
Another object of the invention is to provide prefabricated enclosures of the above character affording high strength and stiff rigidity in the completed structure.
A further object of the invention is to provide inflatable structures of the above character which present minimum risk of fast deflation upon being punctured or torn.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of part which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:
FIGURE 1 is a perspective elevation view of a pre I fabricated enclosure incorporating the present invention.
FIGURE 2 is an enlarged fragmentary view of the interpanel locked seam construction of the enclosure illustrated in FIGURE 1.
FIGURE 3' is a further "enlarged fragmentary elevation view of the sector panel locking elements shown in FIGURE 2.
FIGURES 4 and 5 are top and plan views respectively showing the elements of FIGURE 3 in their unlocked and locked juxtapositions.
FIGURES 6 and 7 are enlarged sectional and elevation views showing the woven fabric forming the internal and external skins of the structures of the invention in successive stages of their fabrication. I
FIGURE 8 is an enlarged fragmentary perspective view showing a cross-section of the wall of the enclosure illustrated in FIGURE 1.
FIGURE 9 is a perspective view showing one compound curved panel forming a portion of the enclosure illustrated in FIGURE 1.
FIGURE 10 is a plan view of two web elements shown in FIGURE 8, and
FIGURE 11 is a greatly enlarged fragmentary crosssectional perspective view of the structure shown in FIG- URE 8 broken away to show the construction details more clearly.
Similar reference characters refer to similar parts throughout the several views of the drawings.
FIGURE 1 shows a prefabricated structure incorporating the present invention, in the form of a cylindrical, round-topped, beehive-shaped enclosure generally indicated at 20. This structure is formed of six compoundcurved inflatable panels 28 or 30 having the general appearance of the panel 28'shown in FIGURE 9. All of these doubly-curved panels are formed of two generally parallel walls or skins of substantially air-impervious material, spaced apart as shown in FIGURES 8 and 11 by a number of web elements bridging the intervening space and contributing form and shape to the resulting structure upon inflation. Compressed air under low pressure is introduced into the spaces between the two outer skins, producing inflation of the panels illustrated in FIGURE 9, and these panels are firmly locked together along their juxtaposed edges by the locking element illustrated in FIGURES 2-5.
As indicated in FIGURE 1, the structure 20 is anchored in position at its site by a large plurality of guys 22 securing its lower periphery to embedded stakes 24. The guys 22 are joined to the inflatable enclosure 20 by attachment to the successive'peaks of the scalloped guy flaps 26, integrally joined to the lower periphery of each of the panels 28 and 30 which fit together to form the complete structure 20.
The inflatable sector panel 30 diflers from the panel 28 in the presence of an entrance portal 32 incorporating closable mating flaps 34 spanning the portal 32. Otherwise the entrance panel 30 closely resembles the unapertured panels 28 comprising the remainder of the structure 20.
The separate gore-like panels 28 and 30 are firmly locked together along their juxtaposed curved edges 36 by lock flaps 38 having one edge shaped in scalloped configuration presenting outwardly projecting peaks 40, shown in FIGURE 2, each having a helical lock 42 protruding therefrom and which. may be matingly interleaved with a corresponding helical lock 44 of opposite pitch as indicated in FIGURE 3. The helical wireshaped lock members are firmly anchored to the peaks 40 by clamps- 46 riveted in position flanking a nylon bearing block 48, and a bolt rope 49 integrally joined along the curved or scalloped edge of the flap 38 may pass between the clamp 46 and the bearing block 48 to transmit its tension directly to the helical lock members 42 and 44.
As shown in FIGURES 4 and 5, the lock members 42 and 44 are easily interfitted over a portion of their curved peripheries by interleaving the turns of the facing oppositely pitched helical lock members, and a lock wire 50 is then inserted to retain the interleaved helices in their locked engagement. The lock members 42 and 44 and the riveted clamps 46 are preferably formed of weatherproof stainless steel, extending the useful life of the structure 20.
The successive steps in the fabrication of the panels 28 and 30 are shown in FIGURES 6, 7 and 11,. The first step in the fabrication of the sector panels 28 is the weaving of a double layer sheet of fabric 52 having an upper layer 54 and a lower layer 56, these layers being integrally interwoven at a series of predetermined spaced junction lines extending across the entire loomed width of the double layer fabric, which may extend to 54 inches or more. The length of the interwoven junction lines 58 over which the separate panels 54 and 56 are integrally interwoven may be any desired number of fiber diameters, with preferably 10 or 12 or even more fiber diameters being incorporated in each interwoven junction 58. The space between each of the adjacent interwoven junctions 58 is predetermined, to provide the desired curvature in the panel ultimately fabricated therefrom, as will be more fully explained below.
The next successive steps in the fabrication of the panel 28 are illustrated in FIGURE 7, where each span of the lower layer 56 is shown cut away wit-h the central strip '60 being removed to leave integral tabs 62 protruding from the junctions 58 along one side of the woven sheet material 52. A layer of impregnated air-imprevious sheet material 65, which may be neoprene-impregnated Dacron fabric, for example, is cemented to the entire surface of the sheet 52 on the opposite side from the protruding tabs 62. The formation of the double-skinned inflatable panel 28 is illustrated in FIGURES 8 and 11, where the outer wall layer 52 is positioned with its protruding tab 62 facing a similar inner sheet 52:: having similar tabs likewise facing the tabs on the opposed sheet 52.
A series of web panels 64 have their elongated opposite edges sandwiched between and firmly cemented to the tabs 62 protruding from each junction '58 on each of the facing wall sheets 52 and 52a as shown in FIGURE 8. The enlarged fragmentary view of FIGURE 11 shows the successive steps in the construction of the cellular inflatable panel 28, beginning at the upper portion of this figure, where the protruding tabs 62 are shown fanned apart and ready to receive a web panel 64. In the center of FIGURE 11 the web 64 is shown in position, with its elongated edge 66 projecting between the fanned apart protruding tabs 62. The near edge 68 of the web panel 64 has the corresponding tabs 62 of the fabric sheet 52a firmly cemented down on its opposite sides to sandwich and bond the web 64 firmly to the fabric sheet 52a along the junction 58.
A completed sandwiched web construction is illustrated toward the bottom of FIGURE 11 where both elongated edges of another web 64 are shown sandwich-bonded between the respective tabs 62 protruding inwardly from the facing junctions 58 of the respective panels 52 and 52a. The resulting bonded webs 64 define with the facing fabric panels 52 and 52a a series of successive longitudinally elongated air chambers 70. The web 64 may be porous and permeable to air passing between adjacent chambers 70, and these chambers may also be connected by end passages not shown on the drawings for convenient infiation of the completed panel member 28.
The compound curvature of the final fabricated panel 28, best shown in FIGURE 9, is produced by the dimensioning of the respective components of the structure. As indicated in FIGURE 8, the generally vertical or right circular cylindrical lower portion of the panel 28 is produced by spacing the parallel junction lines 58 of the inner fabric panel 52a successive equal distances apart, these distances being the same as the distances between the corresponding junction lines 58 on the facing outer panels 52. Thus both inner and outer walls of the lower chambers 70 are of equal height, and the lower or right circular cylindrical portion 72 of the panel 28 is curved only in a single direction, about a vertical axis. This curvature is determined by the radius of curvature of the curved elongated edges of the webs 64a, shown in top plan view in FIGURE 10.
By contrast the compound curvature of the upper, arched section 74 of the panel 28 is produced by moving the junction lines 58 on the inner panel 52a successively closer together over this upper portion of the panel. By this means the upper chambers 70b have their outer walls slightly taller than their inner walls, providing successive angular displacement of the successive webs 64b over the upper portion of the panel 28, producing the inward leaning configuration of the completed panel. This curvature about a generally horizontal axis is combined with sharper curvature at a diminishing radius about a vertical axis with successive and more sharply curved web 64b, as shown in FIGURE 10, where the curvature and radius of curvature of an upper web 64b may be compared with those of a lower web 640.
The successive and more sharply curved webs combined with the diminished relative height of the inner walls of the chambers 70b produces the arched compound curvature illustrated in FIGURE 9, permitting the successive panels 28 and 30 to be joined along the abutting edges 36 to form the completed structure of FIGURE 1.
If the progressive variations in the curvature of the web 64 and the respective heights of the inner and outer walls of the chambers 70b are generally uniform, the smooth curvature illustrated in FIGURES 1 and 9 will result. Non-uniform rates of variation of these variables will produce non-uniform curved surfaces which may if desired produce a sharp edge contour comparable to the hard chine of fiat-bottomed and V-bottomed boats, as contrasted with the smoothly curving hull surfaces and profiles of an hour-glass shaped, deep-keel sailboat hull.
The panels 28 are preferably made of weather resistant impregnated Dacron fabrics, woven in the double layers shown in FIGURE 6 and subjected to a heat setting treatment for cleaning and preshrinking the fabric prior to the fabrication steps described above. The layer 65 may be formed of closely woven nylon or Dacron fabric, preferably coated on both sides with one or more thinly doctored layers of neoprene or vinyl material, thus impregnating this outer layer 65 to enhance air retention, strength and abrasion resistance of the resulting structure. These impregnating materials are generally applied in solvent solutions from which the solvent is evaporated by heat during the coating process to leave the dry impregnated fabric ready for the fabrication of the panels 28.
After the removal of the central strip 60 to leave the protruding tabs 62, these tabs 62 and if desired the adjacent surface of the fabric sheet 52 is covered with a thin coating of neoprene-solvent solution to fill the intertices of the tabs 62, stiffening or sizing these tabs for subsequent use and priming the tabs to produce a firmer 22nd sandwiching the panel 64 between the mating tabs Automatic processing equipment is easily adapted to produce the desired radius of curvature for each of the web panels 64 and the loom on which the double layer fabric panels 52 are woven can be adjusted to space the junctions 58 successively closer together at the precise predetermined distances required to produce the desired curvature of the resulting panels 28.
To maintain the position orientation of the components, a match mark system of successive marks spaced at small intervals, such as 3 inches or 6 inches, along the mating edges of the fabric will facilitate the desired registration of the component elements.
The successively piled, horizontal orientation of the chambers 70, producing the beehive appearance shown in FIGURE 1, provides a unique construction advantage during the erection operation. The panels 28 may be laid out in a generally radial direction from the center of the area which the structure 20 is to occupy, and as inflation proceeds the chamber 70 will inflate and elongate to provide lightweight tubular cell structures which will roll and move freely about their elongated axes to facilitate the successive inflation orientations of the panel 28, while resisting endwise distortion which might throw the inflating panel out of alignment and cause twisting or knotting of the panel as it inflates to its erect position.
The inflatable enclosures of the present invention are well adapted for convenient erection in as short a period as three hours by a practiced team of erectors, and they may be dismantled with equal ease. These structures require low pressures of less than one pound per square inch to raise them to their erect position, and an internal inflation pressure less than 2 p.s.i. will stiffen the resulting structure to withstand wind loadings. produced by hurricane force winds of 100 miles per hour.
The extremely lightweight structure illustrated in FIG- URE l, 43 feet high and 43 feet in diameter, is formed of 6 panels each weighing less than 300 pounds and producing a total structure weight of only 1,700 pounds. This flexible enclosure, with its panels inflated and locked together in the manner shown in FIGURES 1 and 2, is capable of supporting a 2,000 pound weight suspended inside the center of its dome.
While a more airtight wall can be made by adding additional layers 65 to one or both walls of the panels 28, the addition of this extra weight is preferably eliminated by providing an air compressor 76 connected to supply additional compressed air to the panels whenever required, at the command of pressure sensitive limit switches 78, as shown in FIGURE 9.
The desired objectives of convenience in fabrication, transportation and erection are thus combined with extremely lightweight, structural rigidity and stiffness to provide temporary or semi-permanent prefabricated structures and enclosures which are well adapted to provide shelter for men and equipment under severe adverse conditions of wind and weather. The absorption or reflection of external radiation may be controlled by the incorporation of metallized or vapor-deposited layers of aluminum in one or both of the surface walls of the panels 28 to produce Thermos bottle or greenhouse? effects as desired. While the interior of the resulting structures need not be pressurized to provide structural rigidity, breathable atmospheres may be maintained at the desired pressures, higher than any rarified atmospheres outside the structure if desired.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.
1. A process for forming a curved inflatable cellular panel comprising in combination the steps of (A) arraying two sheets of double layer fabric having a first layer and a second layer integrally interwoven with said first layer along a plurality of transverse junction lines spaced apart at predetermined distances;
(B) removing the central strip portions of the second layer between said junction lines to leave integrally interwoven pairs of tabs protruding from said junction lines along one face of each sheet of said fabric;
(C) arraying the two sheets of fabric with corresponding interwoven junction lines juxtaposed and protruding tabs in facing relationship;
(D) and, joining said tab pairs together to form cellular chambers between the two sheets of fabric.
2. A process for forming a curved inflatable cellular panel comprising in combination the steps of (A) arraying two sheets of double layer fabric having a first layer and a second layer integrally interwoven with said first layer along a plurality of transverse junction lines spaced apart at predetermined distances;
(B) removing the central strip portions of the second layer between said junction lines to leave integrally interwoven pairs of tabs protruding from said junction lines along One face of each sheet of said fabric;
(C) arraying the two sheets of fabric with corresponding interwoven junction lines juxtaposed and protruding tabs in facing relationship;
(D) positoning a plurality of flat web panels having curved longitudinal edges adjacent said tabbed wall panels with one longitudinal curved edge of each said web panel fitted between the protruding tabs along one junction line of each said wall panel,
(E) and, joining the mating tabs together sandwiching the interleaved longitudinal web edges to form integr-ally bonded sandwich constructions joining said web panels to said wall panels along said junction lines.
lines are spaced more closely together on said inner wall panel than they are spaced on said outer wall panel whereby the resulting infiatable double-walled cellular panel assumes compound curvature upon inflation.
4. A double layer fabric suitable for constructing cellular inflatable structures comp-rising in combination (A) a first woven fabric layer and (B) a second woven fabric layer integrally interwoven with said first layer along a plurality of elongated tr-anverse junction lines spaced apart at predetermined distances (C) the central strip portions of the second layer between said junction lines being removed to leave integrally interwoven pairs of tabs protruding from said junction lines along one face of said fabric.
5. The method of forming an inflatable cellular panel comprising the steps of (A) arraying two sheets of fabric (1) having integrally interwoven tabs protruding along junction lines from one face of each of said sheets,
(2) said sheets being arrayed with said tab junction lines on each sheet being substantially juxtaposed to the tab junction lines of the other sheet,
(B) joining the juxtaposed tabs together to form cellular chambers between said sheets, and
(C) sealing the ends of said cellular chambers for inflation.
6. A fabric for inflatable structures comprising:
(A) a layer of woven fabric for forming a wall of an inflatable structure,
(B) a plurality of substantially elongated parallel fabric tab pairs (1) each tab pair being interwoven with said wall forming fabric (2) and protruding from a common side thereof.
7 8 (3) the tabs of each pair being adjacent one 7 References Cited by the Examiner another, whereby said tab pairs may be joined to like tab pairs of a UNITED STATES PATENTS facing wall forming fabric to form the double wall of an 2 117,954 5/1938 Gr o d 139- 391 inflatable S u I 5 2,250,261 7/ 1941 Goldsmith 139407 7. A double layer fabric for inflatable multicellular 2,515,806 7/1950 Spanel 156--65 structures comprising in combination 2,990,837 7/19611 Cushman 135-1 (A) a first woven fabric layer and 3,009,232 11/ 1961 Martin 28-72 (B) a second fabric layer integrally interwoven with 3,055,379 9/1962 Fink 135-1 said first layer along a plurality of transverse junction 10 3 066 330 12/1962 M N 11 t 1 28.42
lines spaced apart at predetermined distances,
(C) said second layer being cut between and substantially parallel to said transverse junction lines, EARL BERGERT P'lmary Examiner (1) each of said cuts being spaced from said junc- HARRISON R. MOSELEY, D. J. DRUMMOND. C. S.
tion lines to form protruding tab pairs at each 15 KAIMAN, Assistant Examiners. junction line.