Abstract:
An apparatus and method for windlocking a curtain over an opening in a building is disclosed and claimed. The windlocking curtain can reside to the exterior or to the interior of the window, door or other opening and protects it from the intrusion of air, water or debris. In its upper position the windlocking curtain permits normal use of the opening and in its lower position it secures the opening. A flexible corrugated curtain has tension rods therethrough and the tension rods run in tracks on each side of the curtain and necessarily on each side of the opening. Interengagement of the tension rods with the tracks is accomplished by deformations in the rods that are referred to as interrupts. In one embodiment the rods are successively longer from top to bottom of the curtain and their interrupts matingly wedge with angled tracks to secure the curtain. In another embodiment the interrupts matingly engage parallel tracks upon the application of force due to wind, fluid (usually water or sea water) or debris. In another embodiment tension rods and interrupts are not used or necessary and a flap on the edges of a flexible curtain engage the side tracks absorbing shocking and sealing the opening. A method for securing the opening utilizing the apparatus is also claimed which provides top, bottom and side securement.

Description:
This application is a continuation-in-part of application Ser. No. 09/520,845, filed Mar. 8, 2000. The invention is in the field of windlocking a building opening to prevent the intrusion of unwanted air, fluid (typically water or sea water) and debris. During hurricanes and other high wind velocity storms, the breach of a building opening can cause great damage to the structure. If the building structure is not breached, then substantial damage can be prevented. 
    
    
     FIELD OF THE INVENTION 
     BACKGROUND OF THE INVENTION 
     Many building codes are now requiring or will soon require hurricane shutters on all new homes built in coastal areas. Similar requirements for buildings other than homes are anticipated as well. The South Florida Building Code, 1994 Edition, requires that storm shutters shall be designed and constructed to insure a minimum of a one inch separation at maximum deflection with components and frames of components they are to protect unless the components and frame are designed to receive the load of storm shutters. 
     The determination of actual wind loading on building surfaces is complex and varies with wind direction, time, height above ground, building shape, terrain, surrounding structures, and other factors. The American Society For Testing And Materials (ASTM) has promulgated a Standard Test Method For Structural Performance of Exterior Windows, Curtain Walls, And Doors By Uniform Static Air Pressure Difference and its designation is E330-97 and was published April 1998. The test method requires that the person specifying the test translate anticipated wind velocities and durations into uniform static air pressure differences and durations. Durations are considered because most materials have strength or deflection characteristics which are time dependent. Testing under this method is performed in a test chamber which measures the pressure difference across the test specimen. 
     Similarly, ASTM has declared a Standard Test Method For Water Penetration Of Exterior Windows, Curtain Walls, And Doors By Uniform Static Air Pressure Difference which includes a water spraying apparatus within the test chamber. See, ASTM designation E331-96. Leakage rate testing can be done under the ASTM Standard Test Method For Determining The Rate Of Air Leakage Through Exterior Windows, Curtain Walls And Doors Under Specified Pressure Differences Across The Specimen. See, ASTM designation E283-91. 
     When a building envelope is breached devastating pressure differentials cause large amounts of damage. Kinetic energy due to the velocity of the fluid is proportional to the square of the velocity. Energy from the wind, therefore, pressurizes the interior of a home or other structure which in combination with the profile of the roof makes the roof, in effect, act like an airplane wing causing it to blow off the remaining structure. Windload and impact resistance requirements depend on the particular community promulgating the requirements. 
     The American Society of Civil Engineers&#39; Standard  7  is being increasingly used by public regulators in formulating requirements. In some areas of high probability for high wind occurrences, such as hurricanes, existing homes are required to upgrade windows and doors or add shutters and other protective devices to building openings to protect them. 
     Conventional storm window protection as shown in U.S. Pat. No. 4,065,900 to Eggert, U.S. Pat. No. 4,069,641 to De Zutter and U.S. Pat. No. 4,478,268 to Palmer are methods of attaching outer coverings to window or door openings. U.S. Pat. No. 4,065,900 to Eggert discloses an apparatus for framing and fastening a secondary glazing pane which utilizes a hinge. U.S. Pat. No. 4,069,641 to De Zutter discloses a storm window frame which utilizes double-faced tape to mount the storm window frame and, hence, the storm window. U.S. Pat. No. 4,478,268 to Palmer discloses a hard flexible curtain door, a tensioned storage or wind-up drum, and channels in which the door resides. The door moves out of the channels under impact and is wound up to open for vehicle passage. 
     U.S. Pat. No. 4,126,174 to Moriarty, et al. discloses a tensioned flexible sheet storage roller, a guide roller and side seal guides. These coverings are normally clear flexible materials that must be installed and removed as needed or can be rolled and stored in a storage area above the window. These materials can be tinted to provide a reduction in sunlight transmission, but tinting would also reduce vision at night. These storm window coverings offer good thermal insulation, but offer minimal protection from high wind velocity pressures and wind borne debris. Further, these coverings are usually made of flexible polyvinyl chloride and will functionally deteriorate with time and must be replaced. The coverings that are of rolling construction must have adequate clearance between the guide rails and the sheet to prevent jamming of the sheet in the guide rails during opening and closing. 
     U.S. Pat. No. 4,294,302 to Ricke, Sr. discloses a security shutter and awning device for covering windows and doors. The device includes slats made from aluminum or other extrudable material of sufficient strength to protect against storms and/or vandalism. The shutter of Ricke, Sr. may be slidably mounted and pivoted so as to act as an awning. 
     U.S. Pat. No. 4,601,320 to Taylor discloses a pressure differential compensating flexible curtain with side edge sections which are sealingly engaged with channels. The first upper end of the curtain is attached to a curtain winding mechanism which includes a spring barrel. Taylor discloses an elastomeric curtain having plastic supports with rubber covers banded thereto. Alternatively the plastic supports may be high molecular weight plastic strips. The purpose behind the design of the supports is to minimize the friction of these supports enabling operation of the door/curtain with a high differential pressure across it. 
     U.S. Pat. No. 4,723,588 to Ruppel discloses a roller shutter slat which interlocks with the adjacent roller sheet slat. U.S. Pat. No. 5,657,805 to Magro discloses a wind-resistant overhead closure with windlocks on the lateral edge portions of the intermediate and bottommost slats of the closure. First means to limit the lateral movement of the lateral edge of the intermediate potions and second means to limit the lateral movement of the endmost door portion are disclosed. Intermediate slats and endmost slats are provided. The &#39;805 patent indicates in col. 2, lines 12 et seq. that it conforms with the South Florida Building Code, 1994 Edition, previously referred to hereinabove. Further, the &#39;805 patent states that its teachings are applicable to both doors and windows. 
     Windlocks can be added at the end of slats which will improve the resistance of multileaf shutters or doors to wind velocity pressures by transmitting the stresses on the continuous hinge area to the ends of the slat, to the guide system and finally to the jambs or building structure. In order for the windlocks to engage the guide track the slat must deflect a considerable amount. Normally clearance is allowed between the guide track and the windlock to keep the door from jamming during operation and the more clearance allowed the more deflection of the slats before the windlocks contact the guide track. Typically, these windlocks are larger in cross section than the slat profile and when the shutter or door deflects from high wind velocity pressures, the windlocks are designed to engage the same space in which the slats are guided. When storing a rolling multileaf shutter or door equipped with windlocks, additional room is needed because the depth of the windlock is larger than the slat profile, the diameter of the storage area increases dramatically. In these designs, clearance between the windlock and the track must be allowed to prevent the windlocks from jamming and care must be taken when operating shutters or doors in a wind because the windlocks will sometimes jam as the product deflects. 
     U.S. Pat. No. 5,445,902 to Lichy discloses a damage minimizing closure door somewhat similar to U.S. Pat. No.4,478,268 to Palmer. The Lichy &#39;209 patent discloses a flexible curtain and a guide for receiving and guiding the side edges of the flexible door during vertical movement. A counterbalancing power spring is associated with the door to assist in raising and lowering the curtain. Side edges of the curtain separate from the guide assembly upon being impacted by an externally applied force such as a vehicle. 
     U.S. Pat. No. 5,482,104 to Lichy discloses in FIG. 17 thereof, a flexible curtain and double windlocks which breakaway from the channel upon the application of excessive force to the curtain. See, col. 7, lines 33 et seq. U.S. Pat. No. 5,131,450 to Lichy discloses in FIG. 6 thereof a double edged guide and a curtain edge with two loose portions sewn to the transverse curtain. See, col. 6, lines 21, et seq. U.S. Pat. No. 5,232,408 to Brown discloses a flexible tape drive system wherein the tape is relatively rigid and it is driven by a toothed cog to provide both push and pull capabilities. U.S. Pat. No. 5,048,739 to Unoma, et al. illustrates a conical toothed drive paper feeder. 
     Conventional storm curtains without windlocks to engage into guides will pull out of the guides. This is especially true of wider curtains where they might be partially lowered for shading purposes without attaching storm bars required for storm protection. If, while lowering, or subsequent to lowering, wind forces exist that are significant but in no way threatening, the storm curtains typically escape from the guides due to excessive deflection of the slats. When this occurs, the slats become damaged as well as the facade surrounding the guide area becomes damaged as the ends of the slats typically rake the surrounding area in the process of escaping. The majority of applications for conventional storm curtains do not use windlocks. Rather than using windlocks, the problem of excessive curtain deflection which causes the curtain to escape from the guides is addressed with the use of storm bars. Storm bars, however, have disadvantages. 
     Storm bars create a passive system i.e. in the event of a severe storm they need to be taken out of storage and attached in predetermined locations across the span of the curtain. A wide curtain may require as many as three sets of storm bars. Sets consist of two bars in close proximity to each other in such a way as the curtain passes between the two bars. This addresses deflection that occurs in both positive and negative directions. Positive deflection is in the direction of the building and negative deflection is away from the building. At each storm bar location, brackets must first be attached to the floor, soffit and sills. Depending on the surrounding construction materials, secure locations are often difficult to find. After the brackets are attached to the building, the next step is to attach the storm bars to the brackets. Care must be taken to number and code the brackets to the matching storm bar, otherwise the pre-drilled holes for the bolts will not line up with the holes in the storm bars. Also, care must be taken to match and code the storm bars to their various locations since even a slight variation in the bar length causes the holes in the storm bar to misalign with the pre-drilled holes in the building facade. Also, these pre-drilled holes in the facade are permanent and cause problems aesthetically when the storm bar brackets are removed. Given the problems associated with escaping storm curtains, the building owner faces a dilemma when moderate storms are predicted such as severe summertime thunder storms. The daunting task of attaching the storm bars cannot be justified for every storm. Because the risk of damaging the storm curtains without attaching the storm bars is so great, the curtains are not utilized in moderate storms. Therefore, the building owner has a protection system that is either “on or off,” “on” meaning storm bars and curtains and “off” meaning nothing at all. 
     Conventional storm curtains do not have windlocks to prevent the slats from escaping the guides because windlocks have a larger cross section than that of the slat and using windlocks increases storage coil diameter which is a major limiting factor. With windlocks of the related art, storm curtains have a tendency to bind in the guides/tracks when being lowered because of the deflection of the curtain in moderate wind conditions. Enough friction is created, windlock to the inside edge of the guide, to cause the curtain to become obstructed and create unwanted accumulation of slats in the coil storage area. Additionally, adding windlocks to the ends of slats is very labor intensive and creates many more parts to drill and attach. 
     The instant invention addresses these three issues. The first issue with conventional storm curtains, that being an increase in coil storage requirement, is addressed by utilizing an interrupt formed on the ends of the tension rods of the instant invention which does not increase the requirement for coil storage when the curtain is stored. 
     The second issue regarding binding of the curtain is addressed by the instant invention since the tracks are mounted at a divergent angle with respect to each other and contact with the interrupts in the rod and the “J-shaped” channel does not occur until the guide is in a fully closed position minimizing friction. Further, in the instant invention, unwanted accumulation in the coil storage area does not occur and the drive system is able to generate downward closing forces that overcome minimal friction that may occur between the interrupt and the “J-shaped” channel. 
     Finally, regarding the issue of windlocks being labor intensive, the interrupts formed near the ends of the rods in the instant invention are made with a single stroke of a press after the rods are inserted into the curtain and, as such, do not make the windlock system labor intensive. 
     SUMMARY OF THE INVENTION 
     The instant invention uses light weight materials that have stiffness in the direction of the opening and closing but will bend around a radius as small as 0.5 inches. This strengthens the curtain by uniformly spreading the stresses developed by wind velocity pressure or impact over the width of the curtain and transferring the stresses to the track and to the structure of the building. 
     The invention adds tension to the elements of the curtain in the direction along its width or perpendicular to the force that is created by wind velocity pressure or impact from debris. The tension is directly proportional to the wind velocity pressure or impact from debris. Angled guide tracks may be used that tension the curtain when the curtain is closed without jamming the curtain in the guide tracks. Metallic, non-metallic materials (or a combination of both) may be used and they may be and can be opaque or transparent. 
     The windlock feature of the instant invention is incorporated into the curtain without affecting the thickness of the curtain and therefore does not affect the size of the storage area. The mass of the curtain is low allowing precise control of raising and lowering the curtain with a small power source and can be battery powered. Materials such as aramid fibers may be used thus making the curtain bullet proof 
     An apparatus and method for windlocking a curtain covering and protecting an opening in a building is disclosed and claimed. The windlocking curtain resides to the exterior of the window, door or other opening and protects it from the intrusion of air, water or debris. In its upper position the windlocking curtain permits normal use of the opening and in its lower position it secures the opening. A flexible corrugated curtain has tension rods therethrough and the tension rods run in tracks on each side of the curtain and necessarily on each side of the opening. Interengagement of the tension rods with the tracks is accomplished by deformations in the rods that are referred to as interrupts. In one embodiment the rods are successively longer from top to bottom of the curtain and their interrupts matingly wedge with angled tracks to secure the curtain. In another embodiment the interrupts matingly engage parallel tracks upon the application of force due to wind, fluid (usually water or sea water) or debris. In another embodiment tension rods and interrupts are not used or necessary and a flap on the edges of a three-ply flexible curtain engage the interior of the side tracks absorbing shocking and sealing the opening. A method for securing the opening utilizing the apparatus is also claimed which provides top, bottom and side securement. 
     The flexible curtain comprises part of a curtain system for covering an opening in a building. A frame is affixed to an opening in a building. A flexible, corrugated curtain has a plurality of rods extending through some of the corrugations of the curtain. Preferably the rods, sometimes referred to as the tension rods, are rectangular in cross-section so as to provide maximum strength of the rod. Other cross-sectional sizes may be used. Angled tracks are provided in one embodiment which mate and wedge with angled interrupts when the curtain is in its second, closed position. When the curtain is open, it is in its first position and resides primarily on a counterbalanced windup reel. Each successive tension rod is longer than the prior rod so as to engagingly wedge with the angled tracks. The tracks are angled away from each other when the top point of the tracks are taken as the reference points. In other words, the tracks are at a divergent angle and get farther apart at the bottom. 
     The tension rods include a deformed portion sometimes referred to as an interrupt. The purpose of the interrupt is to matingly engage the tracks. In the embodiment which employs tracks which diverge from the top to bottom, the preferred divergent angle is one-half of one degree. Specifically, each track is diverging with respect to an imaginary vertical line at an angle of one-half degree making the total divergence for two tracks equal to one degree. One-half to one degree divergence from vertical per track (one to two degree divergence for both tracks) has been found to work well. Larger divergence angles require necessarily deeper tracks and larger interrupts particularly if a long building opening is to be protected. Those skilled in the art will readily realize from reading this disclosure that other angles may be used depending on the size of the opening to be covered. 
     Corrugated flexible curtain is used in one embodiment as stated above and slits therein may be employed in the face of the curtain to improve the flexibility for storing on the counterbalanced wind-up reel. In regard to storage of the curtain and tensioning rods, the deformations of the tensioning rods (interrupts) do not increase the space required for storage because the thickness of the tension rod is not increased in the direction of the radii of the wind-up reel. 
     Operation of the flexible curtain is enhanced by using divergently separating track as the occurrence of jamming is minimized. All of the tension rods are designed to engage the angled tracks at approximately the same time creating a wedge effect since the interrupts are deformed at a mating angle which matches the angle of the track. 
     Another embodiment of the invention employs parallel tracks and the tension rods do not engage the tracks except during times when they are loaded. In this embodiment the tension rods are all the same length and when the curtain is closed in its second position the lips of the interrupt do not engage the track. When the wind velocity becomes sufficiently high, the curtain deflects and pulls the mating surfaces of the interrupts into engagement with the track. 
     Another embodiment of the invention employs tension rods having a ninety degree radius at the ends thereof and eliminates the need for interrupts. It is the ninety degree radius which engages the angled/parallel tracks. 
     Rectangular apertures exist in the flexible corrugated curtain for engagement with teeth of a driving gear or gears. The gears, under resistance of a counterbalance spring affixed to the wind-up rod, drive the curtain from a first, open position to a second, closed position. All embodiments disclose rectangular curtains. Standard window dimensions are 30 to 36 inches wide and 30, 38 or 54 inches long. However, longer and wider openings can be secured with the embodiments of the invention disclosed herein. Corrugated curtains can be driven with a single gear or with dual gears. Openings in buildings of all sizes may be protected using the principles of the invention. 
     Alternatively, a driven adapter rack and/or an adapter rack and a gear may be simultaneously used to drive the tension rods. 
     Another embodiment employs a flexible curtain comprising three-plies laminated together. The plies may be laminated together under the influence of heat and pressure. Additionally adhesive may be used to secure the plies together. Two outer plies or sheets are polymeric and the inner ply is woven. A living seal is formed on the edges of the curtain by folding the edges of the curtain back on the curtain itself. The folded portion is secured by stitching with thread, or by adhesive, or by heat fusing, or by ultrasonic welding. Only a portion of the folded flap is secured. Preferably two-thirds (⅔) of the folded flap is secured to itself and one-third (⅓) remains free. When the three-ply curtain is tensioned under the influence of wind or debris loading, for instance, the folded portion engages the interior of the track which houses the folded portion preventing its escape therefrom. Further, the folded flap provides a total seal which is sometimes referred to herein as a living seal. The free portion of the flap provides a shock absorber which cushions the frame against time variant forces which may be applied due to fluctuating wind and/or debris. The three ply curtain may also be used with angled track by slitting the outer face of the three ply curtain. The slitting provides a loose flap which engages the track. 
     Cylindrical apertures reside in the folded portion of said three-ply curtain and the drive cog interengages the apertures for raising and lowering the curtain against the force of the counterbalance spring. Preferably, there is a folded portion on each side of the curtain residing in its respective track and being driven by its respective drive cog. Conically shaped cogs fit the apertures well and, additionally, the apertures may be fitted with eyelets. A bowed bottom bar is secured within a folded portion of the curtain and guides the curtain into a slot. In other words, the curtain is slightly longer at its edges than in the middle such that as the curtain is coming down for securement in the second, closed position the sides enter the retaining slot first. If the curtain is being closed during a strong wind event, the middle of the curtain may be deflected slightly inwardly but the side portions are not because they are within the tracks which are directly aligned with (above) the retaining slot. This enables the bottom bar to begin seating in the retaining slot at the side edges and guide the bottom bar into place. Additionally, the weight of the bar assists in positioning it in place in the retaining slot. Additionally, a living seal formed by a flap extending from the stitched or heat sealed bottom bar may be employed in a modified retaining slot sometimes referred to herein as a storage slot. 
     Another embodiment of the bottom bar interengages a sill or bottom member having a seal therein. The bottom bar may be affixed to the bottom of the curtain by any one of several known fastening devices such as rivets, bolts and threads, and the like. The curtain system covers a window, door or other opening a building. The curtain system may reside to the exterior of the window, door or other opening or it may reside to the interior of the window, door or other opening. 
     Accordingly, it is an object of the present invention to provide a low cost and light weight flexible curtain which develops transverse (side to side when viewed from the front) tension each time the curtain closes. 
     It is a further object of the present invention to provide a curtain system which uses a light weight counterbalance because of the lightweight construction of the curtain. 
     It is a further object to provide a curtain having windload and impact resistance which is always active when the curtain is closed and requires no other action by the user in the event of a high velocity wind occurrence. 
     It is a further object to provide a curtain which will not jam and cause damage to the curtain during operation even if operated during high wind occurrences. 
     It is further object to provide a storm curtain which stores within standard wall thickness found in the United States. It can be incorporated into the window frame in such a way that the storm curtain does not require additional framework or cover for protuberances created by the larger storage coil diameters typical of conventional storm curtains. 
     It is a further object of the present invention to provide a curtain system which resides to the exterior or the interior of the window, door or other opening in a building. 
     It is a further object to provide a low maintenance storm curtain. Conventional storm curtains require periodic high pressure washing especially along coastal areas where they are exposed to salt spray and blowing sand. Conventional storm curtains are designed so that the longitudinal edges of the slats telescope into each other approximately three-eighths inch (⅜″) to one-half inch (½″) as shown in U.S. Pat. No. 4,173,247 to Prana and U.S. Pat. No. 5,322,108 to Hoffman. The telescoping portion of the slat is exposed when the storm curtain is partially closed, typically for sun control, and because of the weight of the slat suspended below, the slats will be extended from each other. When salt spray and sand accumulate on this portion of the surface of the slat, abrasion and friction will interfere with slat to slat telescoping. If the slats are not cleaned and pressure washed periodically, the lower slats usually start to malfunction first since they have the least gravitational force to cause separation. If this separation or telescoping does not occur and the slats enter the coil storage area they will be put into a severe bind and as a consequence, become damaged. Telescoping slats develop more beam strength when the longitudinal edges of the slats are telescoped into each other when fully closed. However, the maximum allowable radius requirement for the curtain to coil within the allocated storage area cannot be met unless the slat edges are fully extended from each other as they begin to articulate into the coil storage position. In the instant invention, the outside surface consists of a smooth polymeric material with no requirement to telescope. As such, there is no opportunity for salt spray and sand to accumulate in irregular surfaces. It is a further object of this invention to provide a smaller storage area. 
     Another advantage of the instant invention, unlike conventional storm curtains, is that the instant invention becomes taut from top to bottom when in a closed position. For this reason there is no chatter, banging or rattling that exists with conventional storm curtains in buffeting winds. Further, when the embodiment of the living seal is employed, the loose or free portion of the folded flap or strip absorbs shock and therefore does not transmit it to the surrounding frame. This will make a quieter system with low or no maintenance. 
     Still another advantage of the instant invention is that the storm curtain is directly linked to drive gears and a drive shaft which are engaged into perforations pierced into the curtain and essentially (but not actually) place the gear teeth in contact with the metal tension rods lodged in the corrugated curtain which, when activated, cause the curtain to be raised and lowered. The tension rods are completely sealed with respect to contamination by the corrugated material. In the embodiment of the three ply curtain, it completely seals against the intrusion of wind borne salt and debris. Another advantage of the instant invention is that the storm curtain can be pre-installed into the window frame at the factory as a single unit. The sub-contractor normally involved in the installation of storm curtains is no longer required. Another problem frequently encountered and avoided with the instant invention is related to the typically varied conditions prevalent on job sites. With a wide range of window configurations depending on the manufacturer and varied contractor preferred framing methods and sill details, these variations often complicate the installation of storm curtains. This can greatly increase the cost of installation where additional re-framing may be required or where other modifications need to be made so the storm curtain can be installed correctly. In the instant invention, the storm curtain is pre-installed into the window framework and these problems do not exist. 
     Another advantage of the instant invention is that since the interrupts pressed (deformed) into the metal rods embedded in the curtain are engaged into the “J-shaped” track, the curtain cannot escape or “blow out”. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front plan view of a seventy-two inch flexible curtain having a track at one degree (1°) from vertical. 
     FIG. 2 is an exploded view of a portion of FIG.  1 . 
     FIG. 3 is an exploded view of a portion of FIG.  2 . 
     FIG. 4 is a composite view illustrating a reduced scale view of FIG. 1 together with reduced scale views of FIGS. 4A and 4B. 
     FIG. 4A is a cross-sectional view of the flexible curtain illustrated in FIG. 1 taken along the lines  4 A— 4 A. 
     FIG. 4B is a cross-sectional view of the flexible curtain and window illustrated in FIG. 1 taken along the lines  4 B— 4 B. 
     FIG. 4C is an enlarged cross-sectional view of FIG. 4A illustrating the application of the invention to protect a window opening. 
     FIG. 4D is a cross-sectional view similar to that of FIG. 4A illustrating the wind-up reel in greater detail for use in connection with the three-ply flexible curtain and the cog drive. 
     FIG. 5 is a schematic view of the seventy-two (72″) inch curtain illustrating a one degree (1°) runout of the tracks and tension rods. 
     FIG. 6 is a front view of a seventy-two inch (72″) curtain similar to that illustrated in FIG. 1 except that the left side and right side tracks are parallel to each other and, additionally, illustrates that the tension rods do not have any runout. 
     FIG. 7 is an enlarged portion of FIG.  6 . 
     FIG. 8 is a schematic representation of the flexible curtain, track and tension rods of the embodiment of FIG.  6 . 
     FIG. 9 is a front view of a thirty-eight inch (38″) curtain illustrating a one-half degree (½°) runout of the tension rods. 
     FIG. 9A is a view similar to that of FIG. 1 illustrating a one-half degree (½°) runout of the tracks, interrupts and tension rods. 
     FIG. 9B is an enlarged portion of FIG. 9 illustrating the tension rods, flexible curtain and the drive apertures in the curtain. 
     FIG. 9C is a perspective view of a portion of the curtain having a one-half degree runout further illustrating the corrugated flexible curtain and the interrupts mating with the track restraining movement of the flexible curtain toward the window. 
     FIG. 10 is a schematic of the thirty-eight inch (38 ″) curtain illustrating a one-half degree (½°) runout of the track, interrupts, and tension rods. 
     FIG. 11 is a top view of a left side track like that of FIG. 1 illustrating the top rod in its fully down position engaging the track. FIG. 11 illustrates a cross-sectional view of the top of the track which has a one degree (1°) runout. The runout, however, is not illustrated in this drawing. 
     FIG. 11A is a front view of the left side track and the top rod illustrated in FIG.  11 . 
     FIG. 11B is a top view of a left side track like that of FIG. 9A illustrating the top rod in its fully down position engaging the track. FIG. 9A illustrates a cross-sectional view of the top of the track which has a one-half degree (½°) runout. The runout, however, is not illustrated in this drawing. 
     FIG. 11C is a front view of the left side track and the top rod illustrated in FIG.  11 B. 
     FIG. 12 is a top view of a left side track like that of FIG. 1 illustrating the bottom rod in its fully up position entering the track. FIG. 12 illustrates a cross-sectional view of the top of the track which has a one degree (1°) runout. The runout, however, is not illustrated in this drawing. 
     FIG. 12A is a front view of the left side track and the top rod illustrated in FIG.  12 . 
     FIG. 12B is a top view of a left side track like that of FIG. 9A illustrating the bottom rod in its fully up position entering the track. FIG. 12B illustrates a cross-sectional view of the top of the track which has a one-half degree (½°) runout. The runout, however, is not illustrated in this drawing. 
     FIG. 12C is a front view of the left side track and the top rod illustrated in FIG.  12 B. 
     FIG. 13 is a cross-sectional view of the bottom bar sealingly engaging the bottom sill which is affixed to the frame of the structure. 
     FIG. 13A is a cross-sectional view of a three-ply flexible curtain affixed to a bottom bar. 
     FIG. 13B is a cross-sectional view of a three-ply curtain with a bottom bar secured therein by adhesive or lamination. 
     FIG. 13C is the same as FIG. 13B except stitching is used to secure the bottom bar. 
     FIG. 13D is a front view of the vertically bowed bottom bar alone. 
     FIG. 14 is a perspective view of a tension rod. 
     FIG. 15 is an enlarged portion of the tension rod illustrated in FIG.  14 . 
     FIG. 16 is another enlarged view of a portion of a tension rod. 
     FIG. 17 is a view of the end portion of a tension rod illustrating a circular in cross-section tension rod. 
     FIG. 18 is a plan view of a tension rod. 
     FIG. 19 is a side view of a tension rod illustrating the interrupts therein. 
     FIG. 20 is a perspective view of the track. 
     FIG. 21 illustrates a plan view of one of the tracks. 
     FIG. 22 is a cross-sectional view of a three-ply curtain and track taken along the lines  22 — 22  of FIG.  28 . 
     FIG. 22A is a cross-sectional view similar to the view of FIG. 22 further illustrating eyelets in the apertures. 
     FIG. 22B is a cross-sectional view identical to FIG. 22 except the cross hatching of the polymeric plies is not illustrated so as to better depict the curtain. 
     FIG. 22C is a cross-sectional view identical to FIG. 22A except the cross hatching of the polymeric plies is not illustrated so as to better depict the curtain. 
     FIG. 23 is a cross-sectional view of a three-ply curtain and track with the curtain taken along the lines  23 — 23  of FIG.  7 . 
     FIG. 23A is a cross-sectional view similar to the view of FIG. 23 except the cross hatching of the polymeric plies is not illustrated so as to better depict the curtain. 
     FIG. 23B is similar to the view shown in FIG. 23 except the curtain is shown under the influence of pressure “P.” 
     FIG. 23C is similar to the view shown in FIG. 23A except the curtain is shown under the influence of pressure “P.” 
     FIG. 24 is a cross-sectional view of a three-ply curtain together with a semi-rigid strip affixed to one edge thereof. 
     FIG. 25 is a cross-sectional view of a three-ply curtain similar to the view of FIG. 23 with the curtain under the influence of a force, for example, a high velocity wind. 
     FIG. 26 is a cross-sectional view of a three-ply curtain having a folded edge and illustrating two polymer sheets and a woven sheet secured together with adhesive. 
     FIG. 26A is a cross-sectional view of a three-ply curtain having a semi-rigid strip affixed to one edge thereof by means of adhesive. 
     FIG. 26B is a cross-sectional view of an embodiment employing two plies of polymeric material secured together with a fiber reinforcement. One ply of the polymeric material has been slit to engage the track when the curtain is under tension. 
     FIG. 27 is a rear view of the three-ply flexible curtain illustrating a semi-rigid strip applied to both edges of the curtain. 
     FIG. 28 is a front view of a three-ply curtain being driven by a gear having conical teeth or cogs. 
     FIG. 28A is a cross-sectional view taken along the lines  28 A— 28 A of FIG. 28 illustrating the drive roller. 
     FIG. 28B is a cross-sectional view taken along the lines  28 B— 28 B of FIG. 28 illustrating counterbalanced springs which tension the curtain between the drive cogs and the storage reel. Further, securement of the springs to a fixed structure is shown in this view but is not shown in FIG.  28 . 
     FIG. 28C is a view similar to FIG. 28 further illustrating a bowed bottom bar. 
     FIG. 28D is a perspective view illustrating the bottom bar being guided by the tracks into the storage slot. 
     FIG. 28E is a front view of a flexible curtain and window in a building illustrating the curtain in its first, open position. 
     FIG. 28F is a front view of a flexible curtain and window in a building illustrating the curtain in its second, closed position. 
     FIG. 29 is a side view of FIG.  28 . 
     FIG. 30 is a perspective view of the chain (drive adapter rack) and gear drive. 
     FIG. 31 is a perspective view of an adapter rack illustrating tensioning rods having a ninety degree (90°) bend at the edges thereof 
     FIG. 32 is a perspective view of an adapter drive. 
     FIG. 33 is a perspective view of the gear drive. 
     FIG. 34 is another embodiment of the invention illustrating pressure from the wind applied to the glass window which resides exteriorly to the flexible curtain. 
     A better understanding of the drawings will be had when taken together with the description of the invention and the claims which follow hereinbelow. 
    
    
     DESCRIPTION OF THE INVENTION 
     The first embodiment is the combination of a curtain composed of corrugated nonmetallic material with metallic rods embedded in the corrugations. Inward from the ends of the metallic rods, also known as the tension rods, interrupts are formed which maintain the cross-sectional area of the rod. This provides for uniform tensile strength of the rod. The rod lengths uniformly increase from rod to rod from the top of the curtain toward the bottom of the curtain. The ends of the rods form an angle with respect to the corrugated nonmetallic material of the curtain. The interrupts in the rods have a matching or corresponding angle to the angle of the tracks. This angle allows the curtain assembly to wedge when the curtain is closed. The tracks have a “J-shaped” portion with one leg angled back from the mouth of the “J” to form a mating interrupt with the interrupt on the rod such that as tension is developed in the rod due to wind velocity pressure or windborne debris, the “J” will close on the rod with a clamping action transferring the stress load to the tracks and then to the opening frame and onto the building structure. The curtain is additionally supported by a counterbalance drive tube that will assist in returning the curtain to a rolled up stored position. 
     The nonmetallic portion of the curtain can also be made from sheets of material laminated together capturing and positioning the metallic rod. These sheets can be fused, glued, stitched, or attached by other fastening means to prevent the rotation of the rod in relationship to the curtain. The metallic rods preferred in this curtain can be round or polygonal in shape. The more polygonal, the more retention needed to hold the rod in position. Conversely, the less polygonal or the fewer number of sides in the polygon, then less retention is required. 
     A version of this embodiment can be used on conventional rolling door systems where the slats are cut in uniformly, progressively longer lengths from the top of the door to the bottom of the door with standard windlocks alternately attached to the slat ends and the guide track deepened to the longest slat and set at a matching angle where the slats are uniformly placed in tension when the door is closed. 
     The second embodiment (“parallel” embodiment) is a combination of a curtain composed of corrugated nonmetallic material with metallic rods embedded in the corrugations. Inward from the ends of the metallic rods, interrupts are formed in the tension rods which maintain the cross-sectional area for uniform tensile strength of the rod. Rod length is uniform from rod to rod, from the top of the curtain toward the bottom of the curtain, so that the ends of the rods are aligned parallel to the corrugated nonmetallic material of the curtain. A guide track system is employed that has vertical guide tracks that are parallel to the edge of the curtain. The guide tracks have a “J-shaped” end portion with one leg angled back from the mouth of the “J” to form a mating interrupt with the tension rods such that as tension is developed in the rod, the “J” will close on the rod with a clamping action. The curtain is supported by a counterbalanced drive tube that will assist in returning the curtain to a rolled up position. Further, the curtain is taut between the drive tube and the wind-up reel. The profile of the corrugated nonmetallic material is such that the front and back faces are in continuous contact allowing the curtain to be driven down without jamming or binding. The stored portion of the curtain has a tensioning device (i.e., a counterbalanced spring) to prevent the curtain from resisting movement as the diameter of the stored curtain reduces. 
     A third embodiment employs a flexible curtain comprising three plies laminated together. These plies can be fused, glued, stitched or attached by other fastening methods. Two outer plies or sheets are polymeric. The inner ply is woven. A living seal is formed on the edges of the curtain by folding the edges of the curtain back on the curtain itself. The folded portion is secured by stitching with thread, by adhesive, or by heat fusing or by ultrasonic welding. Only a portion of the folded flap is secured, preferably two-thirds (⅔) of the folded flap is secured to itself and one-third (⅓) remains free. Under tension, this free portion of the folded flap seals and cushions the shock caused by the wind or airborne debris. Under the tension the free portion of the flap engages the guide track. The three ply flexible curtain is driven by a cog wheel having conically shaped cogs which drive apertures located along the edges of the flexible curtain of this embodiment. 
     Another version of this invention is a curtain employing a flat sheet of flexible material. It has grooves cut into one face that serve as an interrupt to a mating edge of the “J-shaped” track or of a track having another shape. Inward from the edges of the sheet, grooves at the same angle as track are cut into the curtain such that the grooves at the top of the curtain are closer together than they are at the bottom of the curtain. The guide tracks are then placed at the same angle to place the curtain in tension when the curtain is in the closed position. The grooves create a loose flap which engages the track when the curtain is all the way down in its second position. 
     FIG. 1 is a front plan view of a 72″ flexible curtain having tracks which are 1° from vertical. The entire curtain is not depicted in FIG. 1 because resolution would decrease. Put another way, the tracks are at a 1° angle from the edges of the corrugated curtain. Reference numeral  100  indicates generally the 72″ flexible curtain. The curtain may be driven by motor  101  or by a pulley  102  as determined by a coupling  103  which may engage either the motor or the pulley as a source of energy for raising and lowering curtain  115 . Curtain  115  is a rectangular corrugated nonmetallic curtain. Apertures  116  reside in the left-hand portion of the corrugated curtain and apertures  117  reside in the right-side portion of the corrugated curtain  115 . 
     Left-side track  111  is affixed to the frame or building structure as is right-side track  112 . Reference numeral  113  is spaced leftwardly of track  111  and reference numeral  113  denotes the bottom portion of the left-side track  111 . Reference numeral  114  illustrates the bottom portion of the right-side track  112  and it too indicates a runout rightwardly with respect to the right side track  112 . 
     It will be noticed that FIG. 1 depicts the first several tension rods and interrupts and the last several tension rods and interrupts. Interrupt  121  is near the top of the curtain. Interrupts  122  and  127  are near the bottom left side of the curtain. Tension rods  123  and  124  are shown entering the left side of the curtain traversing through the curtain in corrugated sections thereof and extending rightwardly through the curtain. It will be observed that tension rod  123  has a left side interrupt  122  and a right side interrupt  125 . A plurality of slits  126  are indicated in FIG. 1 to enhance the flexibility of the curtain. Gears  119  and  120  are viewed in FIG. 1 for driving apertures  116  and  117  in the flexible curtain  115 . A front view of bottom bar  118  which engages a sill/receptacle not shown in FIG. 1 is illustrated therein. 
     Referring still to FIG. 1, shaft  104  is supported by bearings  105  and  106 . Curtain  115  extends onto windup reel  107  which is a counterbalanced windup reel. Supports  108  and  109  support the windup reel  107 . Platform  110  which is interconnected to the opening in the building supports the structure generally. 
     FIG. 2 is an exploded view of a portion of FIG.  1 . Referring to FIG. 2, reference numeral  200  generally represents the enlarged portion of FIG.  1 . Track  111  is shown in a cross-sectional view. The outer edge  201  and the intermediate support  202  of track  111  are shown. Mating surface  203  of the “J-shaped” portion  204  of track  111  are also shown. Mating surface  203  on the “J-shaped” portion  204  of track  111  are shown in better detail in FIG.  3 . FIG. 3 is an exploded view of a portion of FIG.  2 . 
     First interrupt  205  is illustrated in FIGS. 2 and 3 and mating point  206  is also illustrated in both figures. Referring to FIG. 3, interrupt  205  includes a surface which engages the mating surface  203  of track  111 . It must be kept in mind that track  111  is angling downwardly and leftward when viewing FIGS. 2 and 3 such that the track and the interrupts are angled at a 1° angle with respect to the left side portion of the left side  220  of the curtain  115 . The second interrupt  207  is illustrated with mating surface  208  which engages mating surface  203  on the “J-shaped” portion  204  of track  111 . Similarly mating surface  209  of interrupt  210  engages mating surface  203  of track  111 . Reference numeral  211  indicates the end of interrupt  205 . Referring to FIG. 3, reference numeral  212  indicates the beginning of the interrupt of the first tension rod near curtain  115 . Similarly the runout of the rods and interrupts can be viewed when reference is made to reference numeral  213  which is the beginning of the interrupt of the third tension rod of the curtain. Reference numeral  213  “points” to a place further leftwardly. The 1° runout of the track, interrupts and the ends of the rods are illustrated in FIG.  5 . 
     FIG. 4 is a composite view illustrating a reduced scale view of FIG. 1 together with reduced scale views of FIGS. 4A and 4B. FIG. 4A is a cross-sectional view of the flexible curtain illustrated in FIG. 1 taken along the lines  4 A— 4 A. FIG. 4B is a cross-sectional view of the flexible curtain illustrated in FIG. 1 taken along the lines  4 B— 4 B. Support frame  407  is interconnected to the frame of the building opening. FIG. 4 illustrates the environment of the invention. FIG. 4A illustrates window  401  along with interior wall  402  and an exterior sheathing  403  such as plywood. A space  404  between the window  401  and curtain  115  is illustrated. FIG. 4C is a full cross-sectional view of FIG. 4A illustrating the application of the invention to protect a window opening. Referring to FIG. 4C, reference numeral  405  represents a full sized 38″ window taken along the lines  4 A— 4 A without track  112  shown. Reference numeral  406  generally indicates wood framing. Still referring to FIG. 4C, windup reel  107  is indicated and the curtain is shown in both a minimum position indicated by reference numeral  408  (i.e., the curtain in its down, second position) and a maximum position as represented by reference numeral  409  (i.e., the curtain in its up, first position). Reference numeral  404  indicates the space between the curtain  115  and the window to be protected  401 . The curtain may be a flexible three ply curtain or it may be corrugated. Some regulatory authorities have promulgated a standard such that the curtain may not deflect within 1″ of the glass  401  under hurricane strength winds. 
     In FIG. 4C, the wind pressure and/or debris is coming from the rightward side of the drawing figure and is headed leftwardly. In FIG. 4C, the curtain resides exteriorly of the window, door or other building opening. In FIG. 34, the wind, debris and pressure “P” is illustrated as coming from the leftward side of the drawing figure and is headed rightwardly. In FIG. 34, a flexible three ply curtain  2805  is depicted. A single ply or double ply curtain may also be used. In FIG. 34, the curtain  2805  resides interiorly to the window, door or other building opening. In the embodiment of FIG. 34, the window  401  would be smashed by debris in a hurricane, but the building would still be protected. Reference numeral  3402  represents the exterior wall and reference numeral  3403  represents the interior wall in FIG.  34 . Slot  2820  restrains the curtain  2805  at the bottom. 
     FIG. 4D is a cross-sectional view similar to that of FIG. 4A illustrating the wind-up reel  107  (sometimes referred to herein as the storage reel) in greater detail adapted for use in connection with the three-ply flexible curtain and the cog drive. 
     FIG. 5 is a schematic view of the 72″ curtain illustrating a 1° runout of the leftside track, tension rods, and interrupts. Reference numeral  500  generally indicates a schematic representation of a 1° runout for a 72″ long window. The interrupts are actually at a 1° angle which matches the angle of mating surface  203  on the “J-shaped” portion of the track. FIG. 11 illustrates the top of a 72″, 1° track in cross section. The “J-shaped” portion of the track in FIG. 11 is indicated by reference numeral  1101 . Referring again to FIG. 5, the dashed unnumbered lines are at 1° angle with respect to the side  220  of curtain  115 . The outer edge  201 B of the track at the bottom is approximately 1.25″leftwardly of the point marked by reference numeral  201  in the preferred embodiment of the 72″, 1° curtain. The intermediate support  202  at the bottom has a runout of the same magnitude as indicated by reference numeral  202 B. All of the runouts, of the rods, the interrupts, and the tracks are the same. When all of the rods progress to their closed, second position as illustrated in FIGS. 1 and 5, the interrupts engage the mating surface  203  of the track and wedge into place. This secures the curtain in its closed position. Reference numeral  203 B illustrates the runout of the mating surface at the bottom of the 1°, 72″ long building opening. Reference numeral  501  illustrates the runout of the outside of the track. Reference numeral  502  illustrates runout of the tension rods. It will be noted that the tension rod  124  illustrates a runout of approximately 1.25″ from the side of the curtain  220 . Reference numeral  503  illustrates a runout of the interrupt engaging surfaces with the mating surface  203  of track  111 . Reference numeral  504  illustrates the runout of the inside portion of track  111 . Curtain  115  has no runout as illustrated by reference numeral  505 . 
     Track  111 , at a 1° angle, must have a relatively wide mouth, or opening, for use in protecting a 72″ long building opening. Given that reference numeral  502  defines the runout of the rods and, indeed, the end of tension rod  124 , it must fit within the track as it enters from its stored, open, first position. FIG. 5 illustrates that point  502  will fit within the mouth of track  111  as defined by its outer edge  201 . 
     FIG. 6 is a front view of the 72 inch curtain similar to that illustrated in FIG. 1 except that the left side and right side tracks are parallel to each other and additionally the tension rods do not have any runout. FIG. 6 is one of the illustrations of the second (parallel) embodiment. Reference numeral  600  generally refers to the parallel embodiment. Left side track  602  and right side track  603  are illustrated as being parallel to each other. Drive apertures  616  and  617  are driven by gears as was indicated in connection with the gears  119  and  120  of FIG.  1 . The left side  620  of the curtain is parallel to the right side  630  of the curtain and the interrupt of the first rod  705  (FIG. 7) is in the same position relative to the track  602  as is the last rod  627  (FIG.  6 ). FIG. 7 is an enlarged portion of FIG.  6 . FIG. 7 illustrates first tension rod  701 , second tension rod  702 , and third tension rod  704 . Interrupts  705 ,  707  and  710  include respective mating surfaces  706 ,  708 ,  709 . Those mating surfaces are spaced apart from the conjugate mating surface  703  on the “J-shaped” portion  718  of the track  602 . FIG. 6 illustrates the curtain in its second, fully down position. In this second embodiment the interrupts do not wedge and engage with the mating surface  703  on the guide  602  unless pressure due to wind or debris is applied to the curtain. Rather, at rest, there is a distance of approximately ⅛″ in the preferred embodiment between the mating surface  703  and the mating surfaces  706 ,  708 ,  709 , etc. on the interrupts of the tension rods. Therefore, for engagement to occur between the mating surfaces on the interrupts and the mating surface on the J-shaped channel, the flexible corrugated curtain must be deflected and the rods must bow inwardly to move the mating surfaces ( 703 ,  706 ,  708 ,  709 ) into contact with each other. The interrupts for the parallel arrangement are approximately 0.50 inches in length and the end portions are spaced an additional 0.150 inches away from the mating interrupt surfaces. Reference numeral  711  indicates an end of a tension rod. Reference numerals  712  and  713  indicate the beginnings of the interrupts  705  and  707  in tension rods  701  and  702 . The tension rods extend about 0.250 inches leftwardly and rightwardly of the corrugated curtain before the interrupts begin. The parallel arrangement is driven similarly to the wedging arrangement illustrated in the previous drawing figures and FIG. 7 illustrates teeth  719  on the gear driving the corrugated curtain. 
     The preferred material of the corrugated curtain is polycarbonate and the preferred material of the tension rod is aluminum. As the cross-sectional areas of the tension rods increase, so does the shear strength of the rods. The “J-shaped” portion of the track is at an angle of approximately thirty degrees and the gap between the mating edge  703  of the J-shaped portion  718  and the support  702  is approximately 0.07 inches. 
     FIG. 8 is a schematic representation of the flexible curtain, track and tension rods of the embodiment of FIG.  6 . Reference numeral  800  generally indicates the parallel arrangement. Referring to FIG. 8, reference numeral  801  illustrates no runout of the track  602 , reference numeral  802  indicates no runout of the ends of the tension rods, reference numeral  803  indicates no runout of the mating surface of track  602 , and reference numeral  804  indicates no runout of the curtain. All embodiments employ a curtain having a zero runout. It should be noted in connection with the parallel embodiment that the interrupts are pressed (formed) such that they are parallel to the curtain and/or perpendicular to the longitudinal axes of the tension rods. 
     FIG. 9 is a front view of a 38″ curtain illustrating a ½° runout of the tension rods. Reference numeral  900  indicates the curtain generally, slits  926  add flexibility to the curtain and drive apertures  916  and  917  are indicated as well. 
     FIG. 9A is similar to that of FIG. 1 illustrating a ½° runout of the tracks, interrupts, and tension rods. Reference numeral  900 A illustrates the 38″ long curtain having a ½° runout in its fully extended down or second position. Left side track  911  runs out as indicated by reference numeral  913  which is the lower portion of the left side track. Similarly, reference numeral  914  indicates a small, {fraction (1/2+L )}° runout of the right side track  912 . The last tension rod  924  illustrates a relatively small space between the curtain  915  and the interrupts on that last tension rod  924 . A counterbalanced wind-up reel  907  is employed as illustrated in FIG.  9 A. Bottom bar  918  is illustrated in FIG.  9 A. 
     FIG. 9B illustrates an enlarged portion of FIG. 9. A relatively small runout between the near side interrupts  931  and  932  (first and fifth rods of the curtain) is indicated. In other words, interrupt  932  of the fifth rod down is not much leftwardly relative to the interrupt  931  of the first rod. 
     FIG. 9C is a perspective view of a portion of a curtain having a ½° runout further illustrating the corrugated flexible curtain  915  and interrupts  906 ,  908  and  909  mating with the corresponding mating surface  903  at points  903 A,  903 B and  903 C on the “J-shaped” portion  904  of track  911  when the curtain is in its fully down or second position. 
     In this position movement of the flexible curtain toward the window is restrained and the curtain has been wedged into place. FIG. 9C illustrates the “J-shaped” portion  904  angled back (with respect to the side of the curtain). Mating surface  903  is at the same angle as the mating surfaces on interrupts  906 ,  908  and  909 . Reference numerals  903 A,  903 B and  903 C signify a flush contact between the “J-shaped” portion  904  of the track  911  and the respective interrupts. FIG. 9C also illustrates the outside edge  901  of the track and this figure does a particularly good job in representing the corrugated curtain  915 . Corrugations  936  can be viewed in apertures  916  are indicated as are face slits  926 . Reference numeral  935  illustrates the rectangular in cross-section rod extending through the curtain  915 . It will be noticed that where the rods extend through the curtain that there is no slit at a corresponding point in the face. The rods are sealed within the curtain so that contaminants such as sea salt cannot reach them enabling a low maintenance curtain. 
     FIG. 10 is a schematic representation similar to that of FIG. 5 only it will be noticed that the angle is ½° illustrated over a 38″ length as compared to 1° angle illustrated over a 72″ length in FIG.  1 . It will be apparent when viewing FIG. 10 that a smaller mouth or area is needed to receive the bottom rod of a ½°, 38″ curtain system because the runout is much less. Reference numeral  1000  generally indicates this schematic representation. The side of curtain  1013  does not have any runout. Curtain  1015  includes apertures  1016  and the bottom bar is denoted by reference numeral  1018 . Track  1011  has an outer edge  1012  whose runout is indicated with reference numeral  1001 . Similarly the first tension rod has an end  1020  whose runout is indicated with reference numeral  1002 . The first mating interrupt of the first rod is indicated by reference numeral  1007  and its runout is indicated by reference numeral  1003 . Finally, the inner portion of the guide also has a runout as indicated by reference numeral  1004 . Reference numeral  1009  illustrates the surface of the “J-shaped” portion of the track  1011  which mates with the interrupts. In this ½, 38″ embodiment, the interrupts are also at a ½° angle mating arrangement. The track support  1008  performs the same function that the track support performs in the first embodiment in that it supports and restrains the rods during tensioning. During tensioning, the rods will pivot slightly on mating surface  1009  and the end portions thereof, for example end portion  1020 , will engage support  1008 . 
     The track supports (i.e.,  1008 ) are necessarily close to the mating surface (i.e.,  1009 ) of the “J-shaped” portion of the track in the embodiments employing an angled track as well. Bending moments are thus minimized because the gap is preferably small, on the order of 0.007 inches. 
     The distance between the mating surface  1009  and the track support  1008  is important. If this distance is too large then the rods tend to shear as the bending moment caused by the structure of the curtain with the rods therethrough is too large. It has been found that a preferred distance between the track support  1008  and the mating surface  1009  of the track is approximately 0.07 inches. This distance can, however, be changed as those skilled in the art will appreciate. 
     FIG. 11 is a top view of the leftside track like that of FIG. 1 illustrating the top rod in its fully down position engaging the track. FIG. 11 illustrates a cross-sectional view of the top of the track which has 1° runout. The runout, however, is not illustrated in this drawing. Reference numeral  1100  generally illustrates the rod and the relative spacing arrangements for a 72″ long opening having a 1° runout. Rod  1104  includes a relatively long interrupt  1105 . “J-shaped” portion  1101  of track  1103  is shown engaging the mating surface  1106  of the interrupt  1005  of the rod  1104 . In viewing FIG. 1 it is obvious that there are many rods employed in the curtain and each of those rods will seat against the “J-shaped” portion  1101  of the track  1103 . 
     FIG. 11A is a front view of the leftside track  1103  and the top rod  1104  illustrated in FIG.  11 . Reference  1100 A generally illustrates this front view. Gap  1108  is the space between the J-shaped portion  1101  and the track support  1109  and is preferably small (0.007 inches). 
     FIG. 11B is a top view of a leftside track like that of FIG. 9A illustrating the top rod in its fully down position engaging the track. FIG. 11B illustrates a cross-sectional view of the top of the track which has a ½° runout. The runout, however, is not illustrated in this drawing. Reference numeral  1100 B generally denotes the view. It will be noticed that the track  1103 B is somewhat smaller when compared to the track necessary for a 72″ opening having a 1° runout. Further, it will be noticed that the rod  1104 B includes a smaller interrupt  1105 B as compared to the 72″, 1° runout. “J-shaped” portion  1101 B engages the mating surface  1106 B of interrupt  1105 B. End portion  1107 B of the track is supported by support  1109 B during tensioning as was discussed previously. Gap  1102 B is illustrated between “J-shaped” portion  1101 B and track support  1109 B. FIG. 11C is a front view of the leftside track and top rod illustrated in FIG.  11 B. Reference numeral  1100 C generally. denotes this view. Reference numeral  1200  generally denotes this view. 
     FIG. 12 is a top view of a leftside track like that of FIG. 1 illustrating the bottom rod in its fully up position entering the track. FIG. 12 illustrates a cross-sectional view of the top of the track which has a 1° runout. The runout, however, is not illustrated in this drawing. It will be noticed that the interrupt  1205  is relatively and necessarily large. Because this interrupt is relatively large a relatively large mouthed track  1203  is necessary to in effect swallow or accept the tension rod  1204 . The interrupt must straddle the gap  1202  between the “J-shaped” portion  1201  of the track and the track support  1209 . This is caused by a long or large 72″ opening having tracks at 1° divergence from vertical. Put another way, the tracks have a 2° divergence from track to track. The end  1206  of rod  1204  must have sufficient clearance inwardly from track  1203  to enter it. FIG. 12A is a front view of the leftside track and the bottom rod illustrated in FIG.  12  and reference numeral  1200 A generally denotes this view. 
     FIG. 12B is a top view of a leftside track like that of FIG. 9A illustrating the bottom rod  1204 B in its fully up position entering the track. FIG. 12B illustrates a cross-sectional view of the top of the track which has a ½° runout. The runout, however, is not indicated in this drawing. Reference numeral  1200 B generally denotes this view. A smaller track  1203 B is acceptable because the runout over a 38″ long opening having tracks that diverge ½° from vertical or 1° from each other does not require a lengthy interrupt  1205 B. Additionally, it will be noticed too that there is a small clearance between the “J-shaped” portion  1201 B of the track  1203 B and the interrupt  1205 B. This is necessary so that the rods may progress downwardly without much friction. Clearance is indicated in all of FIGS. 11 and 12. Sufficient clearance between end portion  1206 B of the rod  1204 B and the track  1203 B is indicated. Gap  1202 B is indicated between J-shaped position  1201 B and the support  1209 B. 
     FIG. 12C is a front view of the leftside track and the top rod as illustrated in FIG.  12 B and reference numeral  1200 C generally denotes this view. 
     In all of FIGS. 11 and 12, the J-shaped portion is at an angle of 30° and the gap between the mating surface of the J-shaped portion and the support is 0.07 inches. This geometry provides good securement of the curtain under load. 
     Returning to FIG. 5 the problem associated with a long opening such as the 72″ opening employing a track at 1° to vertical (2° angle divergent from track to track) is that the width of the interrupt must increase so that it may straddle the “J-shaped” mating surface and still be within (short of) the outer edge of the track. Therefore, although this invention is useful over any practical angle of divergence from track to track, it is usually more economical to employ a ½° runout and wedge than a 1° runout and wedge for long openings. The wedge principle works over any practical angle, but it may be more economical for some combinations of angle and length than others. 
     FIG. 13 is a cross-sectional view of the bottom bar  1300  sealingly engaging the bottom sill  1304  which is affixed to the frame  1306 ,  1307  of the structure. FIG. 13 illustrates a curtain  1309  which is corrugated. Corrugated curtain  1309  is affixed to the bottom bar  1300  by means of a fastener  1310 . Magnet  1302  is a part of bottom bar  1301  and is attracted to the sill or other structure. Sill  1304  includes seal  1308  which is restrained in sill  1304  by means of adhesive or epoxy. The wood frame traps sill portion  1305  to assist in holding the sill in place. Catch  1303  engages sill  1304  when curtain  1309  is sufficiently flexed by wind or debris. 
     FIG. 13A is a cross-sectional view of a three-ply flexible curtain  1300 A. Two polymeric sheets or plies  1320 ,  1321  are pressed and fused into engagement with a woven ply  1322  which is affixed by fastener  1310  to bottom bar  1301 . 
     FIG. 13B is a cross-sectional view of a three-ply flexible curtain  1300 A together with a vertically bowed bottom bar  1330  entrapped by adhesive/lamination of the flexible curtain. FIG. 13C illustrates entrapment of bottom bar  1330  by stitching the plies together. The bowed bar  1330  is illustrated in FIG.  13 D and functions to guide the curtain into a retaining slot  2820  as illustrated in FIGS. 28C and 28D. When wind pressure or pressure from debris is applied, the middle portion  2841  of the curtain may bow toward the window. The side portions, however, are guided by the tracks ( 2801 ,  2204 ) and the bottom portion  1340  of the curtain is vertically bowed and is guided into retaining slot  2820  first below the tracks and then in the middle. The bottom portion is restrained by the tracks against the pressure of the wind. This gets the curtain started at the sides of the retaining slot and the middle of the curtain follows. 
     FIG. 14 is a perspective view of a tension rod  1401  having an interrupt  1402  in an end portion  1404  and having an interrupt  1403  in an end portion  1405 . The rod is generally represented by the reference numeral  1400 . The tension rod is rectangular in cross-section and the cross-sectional shape has been found to be the strongest shape. Other shapes, however, may be used. 
     FIG. 15 is an enlarged portion of the tension rod  1401  illustrated in FIG.  14 . Interrupt  1402  is shown having curved radii  1501 ,  1502  and  1503 . Reference numeral  1500  generally denotes the end portion of the rod. Flat portion  1504  shown inwardly from radius  1502  engages the mating surface of the “J-shaped” portion of the track. 
     FIG. 16 is another enlarged view of a portion of a tension rod. Reference numeral  1600  generally indicates the end portion of the tension rod with end  1602  and radius  1601 . Mating surface  1601  is a good representation of an angled surface with respect to the longitudinal axis of the tension rod. It is this mating surface  1601  which engages a similarly angled mating surface on the “J-shaped” portion of the tracks. In other words, surface  1601  is at an angle with respect to the longitudinal axis of the rod. 
     Similarly FIG. 17 is a view of the end portion of a tension rod illustrating a circular in cross-section tension rod. Reference numeral  1700  generally represents this embodiment with end portion  1702  having an interrupt formed therein with mating surface  1701  being angled to match the “J-shaped” portion of the tracks. When the embodiment of FIG. 6, to wit, a parallel arrangement is illustrated, the mating surfaces  1601  and  1701  will necessarily be perpendicular to the longitudinal axes of the tension rods. The tension rods are preferred to be rectangular in cross-section so as to maximize the area filled in the corrugated material which is rectangular in cross-section. The rectangular in cross-section rod has been found to be the strongest because it occupies the largest cross-sectional area. 
     FIG. 18 is a plan view of a tension rod illustrating the interrupts  1402  and  1403 . Reference numeral  1800  is a general designation for this rod. Dashed lines  1801 ,  1802 ,  1803  and  1804  correspond to angled track. FIG. 19 is a side view of a tension rod of FIG. 18 illustrating the interrupts therein. Reference numeral  1900  is a general designation for this view of the rod. 
     FIG. 20 is a perspective view of the track which has been referred to in this figure by reference numeral  2000 . J-shaped portion  2001  is well shown in this illustration. FIG. 21 illustrates a plan view of one of the tracks  2000  with bolt holes or apertures  2101  for fixing to a casing or frame. Reference numeral  2100  generally denotes this drawing figure. 
     FIG. 22 is a cross-sectional view of a three-ply flexible curtain  2200  taken along the lines  22 — 22  of FIG.  28 . FIGS. 22-29 illustrates the third embodiment of the invention. A first polymeric sheet  2201 , a second polymeric sheet  2202 , and a third woven sheet  2203  are heated and pressed together forming the construction of a flexible curtain. Track  2204 , preferably metal, is illustrated in FIG.  22 . The edges of the flexible curtain  2200  are folded upon themselves and are maintained in the folded position by stitching  2205 . Alternatively, the folds may be glued to the curtain. The stitching is preferably placed such that ⅓ of the folded flap will be loose and ⅔ of the folded flap will be secured to the curtain. Drive apertures  2206  are shown and reference numeral  2207  indicates the loose flap. Reference numeral  2208  indicates the folded portion of the curtain. FIG. 22A is identical to FIG. 22 only eyelet  2209  in aperture  2206  is illustrated. Eyelets  2209  add strength for driving the curtain between its first, open and second, closed positions. It may be noticed that the cross-hatching used for the plies  2201  and  2202  appear to cause an optical illusion such that the plies do not appear parallel but, in fact, they are parallel. FIGS. 22B and 22C are identical to FIGS. 22 and 22A, respectively, but FIGS. 22B and 22C do not include the cross-hatching. FIGS. 22B and 22C do not portray any optical illusions. 
     FIG. 23 is a cross-sectional view taken along the lines  23 — 23  of FIG.  28 . FIG. 23A is identical to FIG. 23 without cross-hatching of the polymeric plies illustrated. FIGS. 23 and 23A illustrate the curtain without any pressure applied. FIGS. 23B and 23C correspond to FIGS. 23 and 23A, respectively, only they are illustrated with pressure applied. 
     FIGS. 23B and 23C are cross-sectional views of the three-ply curtain and tracks with the curtain under the influence of a force, for example, a high velocity wind indicated by the letter “P.” The force of the wind causes the curtain to attempt to extract itself from the tracks  2204  and  2801 . The folded edge which have loose flaps are deformed and seal the interior of the tracks  2204  and  2801 . There are at least four sealed points  2302 ,  2303  on the right side and  2304 ,  2305  on the left side when viewing FIGS. 23B and 23C. Gaps  2306  and  2307  are created between the flaps  2207  and  2209  the three-ply flexible curtain when the curtain is under pressure “P.” Gap  2308  between track  2204  and the folded edge is created as the curtain attempts to exit the track. Similarly, gap  2309  between track  2801  and the other folded edge is created as the curtain attempts to exit the track. As force is applied, flaps  2207  and  2209  are no longer loose and act as shock absorbers which take up energy imparted to the curtain by the wind. The elastic properties of the flexible curtain absorb the energy of the wind. Hook portions  2210  and  2811  of tracks  2204  and  2801  are spaced from the curtain at rest such that the aforementioned seals will be made when the curtain is subjected to pressure. 
     FIG. 24 is a cross-sectional view of a three-ply curtain together with a semi-rigid polymeric strip  2401  affixed to one edge thereof. The polymeric rigid strip  2401  includes a flap  2402  which is not securely fastened to the three-ply curtain  2400 . Stitching  2405  or other means may be used to affix the strip to the curtain  2500 . 
     FIG. 25 is a cross-sectional view of a three-ply curtain similar to the view of FIG. 23 with the curtain under the influence of a force, “P,” for example a high velocity wind. A seal is made at points referred to by reference numerals  2503  and  2507 . Gap  2504  exists between the rigid strip  2402  and the main three-ply curtain. 
     FIG. 26 is a cross-sectional view of a three-ply curtain having a folded edge and illustrating two polymeric plies  2201  and  2202  and a woven sheet  2203  secured together with adhesive  2601 . Reference numeral  2602  indicates a ⅓ flap length as the preferred free distance of the flap. Similarly, reference numeral  2603  illustrates that ⅔ of the flap is secured by stitching  2205 . Those skilled in the art will readily recognize that different lengths may be chosen for securement with attendant different results. In the preferred embodiment the track has an approximate inner length of one inch meaning that ⅓ of an inch would be the free distance for the flap and ⅔ of an inch would be the secured distance for the flap. These distances represent the preferred embodiment and in no way limit the invention. 
     FIG. 26A illustrates adhesive  2609  affixing a portion of the semirigid strips  2401  to the main three-ply curtain. Alternatively, a strip of the three-ply curtain may be used in place of the semirigid strip. 
     FIG. 26B is a cross-sectional view of an embodiment employing two plies of polymeric material  2615 ,  2616  secured together with a fiber reinforcement  2617 . This material is high-tear vinyl polyester and is commercially available from BONDCOAT MANUFACTURING COMPANY. A loose flap  2620  has been slit such that it engages truck  2204  at lip  2210  when the curtain is under the influence of pressure. The slit may be used in either the horizontal or the divergent angle embodiments. 
     FIG. 27 is a rear view of the three-ply flexible curtain  2700  illustrating a semi-rigid strip applied to both edges of the curtain. Semi-rigid strip  2702  is applied to the left side of the curtain and semi-rigid strip  2701  is applied to the right side of the right edge of the curtain. Apertures  2703  are placed in a repeating fashion along the left and right side edges of the curtain for interengagement with conical cogs to raise and lower the curtain. 
     FIG. 28 is a front view of a three-ply curtain  2805  driven by a cog/pin drive  2802  (sometimes referred to herein as the drive roller  2802 ) having cogs/pins  2803 . Leftside track  2801  is illustrated in FIG. 28 as is rightside track  2204 . These tracks are secured to the building structure as indicated in FIG.  4 . Wind-up reel  2804  sometimes referred to herein as a storage reel is illustrated and it is also counterbalanced. See, FIG.  28 B. FIG. 28 illustrates the curtain in its second, down position. 
     FIG. 28A is a cross-sectional view taken along the lines  28 A— 28 A of FIG. 28 illustrating the drive roller  2802 . The drive roller  2802  is driven by a motor or by a hand operated pulley. See, FIG. 1 illustrating an arrangement for accomplishing operation of the drive roller  2802 . The drive roller  2802  and the storage reel are supported as illustrated in FIG.  1 . The drive roller  2802  supports the curtain which is under constant tension between the cogs/pins  2803  and the storage reel  2804 . In practice, the three-ply curtain is less than {fraction (1/16)} of an inch thick and, where folded, less than ⅛ of an inch thick. It is important to keep the flexible curtain taut between the storage reel  2804  and the drive roller  2802  so as to ensure an even accumulation of the curtain on the storage roller. By even, it is meant a smooth continuous winding without folds or creases. 
     FIG. 28B is a cross-sectional view taken along the lines  28 B— 28 B of FIG. 28 illustrating counterbalanced springs  2820 ′,  2821  which tension the curtain between the drive cogs  2803  and the storage reel  2804 . The springs are grounded by pegs  2850  which are coupled to the building  2840 . Spring holders  2822 ,  2833  secure the spring to the storage reel  2804 . FIG. 28C is a view similar to FIG. 28 further illustrating a bowed bottom bar  1340  approaching a retaining slot  2820  as illustrated in FIG. 28D as previously described above. Tracks  2801  and  2204  keep the edges of the curtain aligned with the retaining slot. The edges  1341 ,  1342  of the bottom portion  1340  of the curtain enter the retaining slot  2820  first followed by the middle portion. 
     FIG. 28E is a front view of flexible curtain  2805  and window  2870  in a building illustrating the curtain in a first, open position. Bottom bar  1340  is shown in phantom behind siding  2860 . Reference numeral  2880  indicates travel of the curtain upwardly and downwardly. FIG. 28F is a front view of a flexible curtain  2805  illustrated in the second, closed position. Window  2870 , side tracks  2801  and  2204 , and retaining slots  2820  are illustrated in FIG. 28F in phantom. The side tracks and retaining slots are affixed to the frame of the building in a manner understood by those skilled in the art. Alternatively, the window  2870  and curtain may be preinstalled as illustrated in FIGS. 4B and 4D, for example. Frame  407  in FIG. 4B represents an embodiment which may be used to preinstall the window and curtain. 
     FIG. 29 is a side view of FIG.  28  and reference numeral  2900  generally indicates the assembly. Track  2204  is also shown in FIG.  29 . 
     FIG. 30 is a perspective view of the chain drive (drive adaptor rack) and gear drive. In this embodiment the tension rods  3006  pass through the flexible curtain  3007  and are tensioned and rolled up upon counterbalanced wind-up reel  3009 . Adaptor rack  3001  includes notched holes  3002  that are vertically spaced between slots  3003  with rods  3006  at a spacing equal to the circular pitch of the drive gear  3005  as the curtain is moved from the opened, first position to the closed, second position. The drive system of FIG. 30 is preferably used with the parallel embodiment but with certain modifications it may be used with the divergent track. 
     FIG. 31 is a perspective view of an adaptor rack  3104  illustrating tensioning rods  3101  having a 90° bend  3102  at the edges thereof. This embodiment of the drive system may be used with the divergently angled tracks or it may be used with the parallel tracks. Rods  3101  pass through corrugated curtain  3106 . Track  3105  is the same track described previously. 
     FIG. 32 is a perspective view of an adaptor drive illustrating engagement of tensioning rods  3203  with the adaptor drive  3201 . 
     FIG. 33 is a perspective view of a gear drive such as the one illustrated in FIG.  1  and is generally represented by reference numeral  3300 . Gear  3303  includes teeth  3301  which drive the flexible curtain  3302 . FIG. 33 illustrates the curtain in the down, second position. 
     It will be understood by those skilled in the art that several changes may be made to the instant invention without departing from the spirit and scope of the claims which follow hereinbelow.