Ballistic Curtain Cordon System

Abstract

A ballistic curtain system includes a curtain having cells configured to stop a high-speed projectile and a motor connected to the curtain. The motor is capable of deploying or retracting the curtain.

Description

BACKGROUND

Mass shootings make headlines with regularity. The worst of those shootings often take place in confined areas like schools or offices.

Most solutions aimed at preventing mass shootings by an already-armed assailant are based on firearm detection or denial of entry to the building in the first place. Firearm detection includes installation of metal detectors and similar devices around entry points to a building. The problem with these solutions is that they do not prevent entry or slow an active shooter—they merely provide a potential alarm that a motivated shooter has entered a facility, denying entry to a shooter may involve armed guards, airlock dual entry systems, or use of technology-based credentials to afford entry. But even with these solutions, a motivated shooter can gain entry to a facility. This was the case in the Washington Navy Yard shooting in 2013 and the Fort Hood shooting in 2009. Likewise, in the case of the Sandy Hook Elementary School shooting, the shooter was able to defeat the entry denial system by simply shooting his way through a glass panel.

There may be no foolproof way to deny a determined shooter from entering a building. Some buildings now post active shooter plans, similar to fire escape routes, in an effort to inform occupants the best actions to take in an active shooter scenario. These plans remain often ineffective because channeling people through choke points in halls or stairwells only gathers more potential victims in one place.

A need thus exists to provide building occupants with a way of protecting themselves, exiting a building, and if not fully preventing casualties inflicted by a mass shooter, at least minimizing such casualties.

SUMMARY OF THE EMBODIMENTS

A ballistic curtain system includes a curtain having cells configured to stop a high-speed projectile and a motor connected to the curtain (or other force to deploy the curtain as needed). The curtain should be capable of being deployed and retracted, optionally at selected speeds, based upon the direction of deployment—such as sidewise, upwardly, or downwardly—as well as the area to be protected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show an overview of a before and after situation using the ballistic curtain system described herein.

FIGS. 2A and 2B show an overview of a before and after situation using the ballistic curtain system described herein in an alternate configuration.

FIGS. 3A and 3B show an overview of a before and after situation using the ballistic curtain system described herein in an alternate configuration.

FIG. 4 shows a single deployed ballistic curtain system.

FIG. 5 shows a sample cell layout

FIG. 6 shows use of cell material to envelop each cell to create the louvre arrangement of the curtain FIG. 5).

FIG. 7 shows a graphical depiction of the motor.

FIG. 8 shows a wiring schematic of the motor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

1. Introduction

FIGS. 1A and 1B show an overview of a before and after situation using the ballistic curtain system described herein. FIG. 1A shows an active shooter 90 with a clear view of victims 95 down a corridor. In such a situation without the ballistic curtain system, the shooter may be able to harm not only the visible victims 95, but also those who may enter the corridor hoping to exit the building according to an evacuation plan. The shooter 90 also has the ability to move quickly down the corridor unobstructed.

FIG. 2A shows a similar situation in which an active shooter 90 has entered a confined area with many potential victims 95. In this situation, the shooter 90's victims 95 are clustered in a small area and the shooter 90 need move into the room no further than the doorway to inflict harm.

FIG. 3A shows an alternate situation in an outdoor concert or other open venue 300.

FIGS. 1B, 2B, and 3B show the same corridor, room, and open venue but with the ballistic curtain 100 deployed. The ballistic curtain system 100, described in greater detail below, deploys to prevent the shooter 90 from having free access to harm victims 95. The silhouettes 97 in FIGS. 1B and 2B show potential victims who are safe behind a bullet absorbing/blocking/slowing curtain 100. In the corridor scenario in FIG. 1B, these potential victims 95 can egress down the corridor between alternating extended curtains 100a and 100b, which prevent the shooter 90 from having a command position controlling the corridor. The curtains 100 interrupt the shooter 90's visual and physical continuum without preventing potential victims 95 from freely escaping from the area, preferably without significantly slowing down a potential victim 95 from fleeing the scene.

In the confined area scenario shown in FIG. 2B, the shooter 90 will have to move from the doorway into the room, and try to access the space behind the curtain. This will not only take time in which authorities may arrive, but also put the shooter 90 at risk of attack, and both circumstances may result in fewer or no casualties. In this “safe corner” configuration, the curtain may optionally be secured to the floor and/or side tracks, like a garage door, which convert the curtain from a free hanging design to a barrier which would take time and effort to overcome.

In the open venue 300 in FIGS. 3A and 3B, the curtains 100 extend upwards and deploy to provide multiple sheltered zones that allow potential victims to seek shelter and escape. This upwards deployment may be accomplished using a scissor-lift, wherein the curtain 100 is deployed as the lift raises a terminal end of the curtain in order to raise the curtain.

Although it is not shown, the curtain could also be deployed horizontally, so that it provided a “roof” like shelter.

The deployment of the ballistic curtain 100 could be manual or mechanical, gravity driven, or based on systems of counterweights or draw chains like an old-fashioned screen. But more likely, the ballistic curtains would deploy using electrotechnical motors in communication with an alarm system that might be automatically activated in response to sound detection indicative of gunfire or explosions, or someone manually activating the system either from within the building like a fire alarm, or remotely from a central location or by authorities.

The ballistic curtain 100 may contain sensors capable of sending feedback to authorities when it registers an impact indicative of a bullet or high-speed projectile. This may help authorities in quickly locating the active shooter, and could also help building occupants make a safe exit if they know where the shooter is. Technology in the building could direct occupants away from the area where the shooter is active, for example.

While the figures and discussion show and describe a ceiling-mounted ballistic curtain that hangs and rolls, this is not meant to be limiting from ballistic curtains that are wall- or floor-mounted, partially or fully rigid, or that are folded or in sheets. As will be appreciated, the curtain 100 may be deployed in any direction, which can readily be selected based upon the location and geometry of installation. For instance, in some situations it may useful to use curtains that when not deployed are at floor-level and deploy upward (such as in outdoor or temporary venues, including stadiums, arenas and the like) while in other situations it may be preferable to utilize curtains that are along the wall when not deployed and deploy inwardly (such as may be useful when ceiling height or other factors make a downward deployment or ceiling mounting impractical).

2. Design Goals

An embodiment of the ballistic curtain system is a storable, armored partition that can be affixed to a ceiling or ground and be unrolled upon activation. The curtain should be capable of stopping or deflecting rifle bullets commonly used in mass shooting attacks, up to and including the 7.62×51 mm NATO round. In addition to being deployable upon user activation, the system should also be retractable at the discretion of first responders. In order to facilitate this, a motor and electronic control system may be incorporated into the system.

Testing and evaluation have identified certain needs and specifications, which are non-limiting. Table 1 summarizes these as used in one example of a prototype (and therefore the values are meant to inform but not be limiting).

TABLE 1.1
Stakeholder needs
Need	Metric	Specification
Ability to stop	Level (Standard	Level 8 & Shotgun (UL 752)
projectiles	org)	Level III A (NIJ 018.01)
		7.62 NATO/Rifle (ASTM F-
		1233)
		Level D (HPW-TP 0500.02) [9]
Deployment	seconds	3, in a standard 9-10-foot hallway
time	Number of impacts	At least 3 shots in a given target
Toughness		area with the highest rated rifle
		round, from 5 feet away or meet
		NIJ standards listed below
Reusability	—	Unused curtains should be able to
		be to stowed in their housings with
		minimal effort
Replaceability	—	Used curtains should be
		repaired/replaceable with minimum
		downtime
Retractability	yes/no	Yes, can be retracted by authorized
		user (SWAT request)
Systems	Number of systems	Two main electrical systems:
	needed	Motor system and network system
Networking	Should	Arduino Ethernet shield or Wi-Fi
	communicate	shield could be used
Integration	Should work with	Device will integrate to existing
	infrastructure	emergency response technologies
		(Alarm systems, PA, etc.)

3. Design Description

3.1. Specifications

The UL 752 standard is widely used in industry and gauges the requirements for “cover materials, devices, and fixtures used to form bullet-resisting barriers which protect against robbery, holdup, or armed attack such as those by snipers.” The National Institute of Justice (NU) standards for ballistic resistance “establish minimum performance requirements and test methods for the ballistic resistance of personal body armor intended to protect against gunfire.” Other standards may be followed including those related to local, state and federal fire codes, building codes and relevant Department of Defense (DOD) and Homeland Security procedures (all of these are constantly being revised and so we do not seek to summarize them since they are constantly evolving).

3.2. Ballistic Curtain System Design Overview

FIG. 4 shows a single deployed ballistic curtain system 100, in one example of a ceiling-deploy orientation (ceiling mounts are adaptable to the needs of a selected location). That example includes a deployable and retractable partition of a curtain 110 that will stop pistol, rifle and shotgun rounds from penetrating it. The curtain 110 is deployable in any direction as mentioned above and its materials may include a cut-resistant outer fabric 120 surrounding a core 130 that may be made from hardened steel armor. The outer fabric 120 may include 1050D ballistic nylon although other load bearing materials or another substrate material can be used. In use, the fabric 120 may support the steel armor core 130 or not be included. It should be appreciated in FIG. 4 that the fabric 120 is shown cut away to show the core 130, for illustration purposes. An electric motor 140 mounted on a frame 150 or other suitable load-bearing structure, deploys each steel curtain 100 and may be configured to operate multiple steel curtains 100 for deployment at once.

3.2.1. Curtain with Cells

FIG. 5 shows an overview of the core 130. The hardened steel cells 132 that make up the ballistic core 130 serve to stop rifle bullets. Using AR500 steel for the cell 132 material was based on its use in marksmanship training with targets comprised of the same material. AR500 targets may stand up to hundreds of impacts from high powered rifles, even with a thickness of just ¼ inch. Thus, AR500 may meet the requirement of being capable of stopping rifle rounds, while maintaining a slim cell design that could be rolled tightly as a curtain. Although AR500 may be presently preferred, it is not meant to be non-limiting.

The steel cells 132 may be rectangular in shape and measure 8 inches long, by 2 inches wide by ¼ inch thick for most deployment, with this sizing being capable of deployment and manufacture, although it will be appreciated that other cell designs may be used such cells that are as long as the curtain is wide (e.g., a curtain that is 36″ wide would have cells measuring 36×2×¼). The cells 132 may be laser cut to this shape. Specific cell sizes may vary as manufacturing and installation design decisions are made.

The steel cells 132 may be mechanically linked to one another to create a fixed louvered arrangement using welding or other mechanical linkage. But what is shown in FIG. 5 is a way of using the material 120 to envelop each cell 132 to create the louvred overlap of each cell 132. There may be metallic mechanical linkages between cells but this can be varied based upon manufacturing and installation design choices.

FIG. 6 shows the fabric 120 having a front side 122 and rear side 124 (which sides could be reversed or interchangeable, the terms front and rear having no meaning besides in the context of the left side of the figure being arbitrarily called the “front”). The rear side fabric 124 may be generally flat and featureless. The front side fabric 122, however, may include pockets 126 appropriately sized to receive each cell 132, which may rest inside the pockets 126 or be bonded, attached mechanically, or removably attached using hook and loop material on each of the cell 132 and pocket 126. Although this “pocket” configuration is shown, other designs may provide a deployable curtain.

The front side 122 and rear side 124 may be bonded to one another using stitching, adhesives, or other bonding means capable of providing structure for the pockets 126 and bonding the sides together.

Although the rectangular shape of cells 123 has been shown and described other cell shapes such as hexagonal may be preferred as they may permit a smaller radius to the curtain 110 when in a stored or undeployed state, although such shapes may be more expensive to manufacture and more difficult to deploy in a louvered arrangement.

The curtain material may be chosen based upon performance characteristics and manufacturing design decisions, but 1050D ballistic nylon is preferred because of its properties s having sufficient resistance to the forces exerted upon the material during normal operation. With an effective tensile strength of approximately 1,000 lbs and a burst pressure resistance exceeding 1500 psi the material can resist both the weight of the steel hanging on it as well as resting broad tearing and destruction associated with the steel cells being impacted by a bullet.

In furtherance of weight savings, the entire length of the curtain 110 may be limited in its inclusion of cells 132, meaning that as shown in FIG. 4, the curtain may include a fabric only portion 115 and a fabric and cell portion 117 (the fabric and cell portion shown in FIG. 4 has the material cutaway, but FIG. 6 shows the fabric and cell portion 117 more clearly). The material and cell portion 117 may be expanded or contracted based on the need and placement in order to provide vital coverage of human dimensions. In a normal hallway or one level room environment, in one option the fabric and cell portion 117 may not extend higher than 6′ from the floor and 6″ from the floor. This bifurcated form of construction allows for visual interruption throughout the entire length of the partition as well as optimal weight, pliability and energy dissipation.

3.2.2. Material Details

• • AR500 Steel

AR500 (Abrasion resistant, Brinell hardness of 500) steel-AR500 is an abrasion resistant high carbon steel. Its hardness and abrasion resistant qualities make it an excellent ballistic material.

Tables 2 and 3 summarize its composition and properties.

TABLE 2
Composition of AR500 Steel
Element    % composition
Carbon     0.31
Manganese  1.50
Phosphorus 0.025
Silicon    0.50
Chromium   0.87
Nickel     0.70
Molybdenum 0.35
Boron      0.003
Sulfur     0.015

TABLE 3
Material Properties
Property         Value
Yield Strength   200 ksi
Tensile Strength 225 ksi
Brinell Hardness 477-550 (500)-Core 450 min.
Elongation       12% (in 2″)
Impact Strength  CVNL ~20 ft @−40 F.

• • Anti Spall Coating

One of the greatest threats from a ballistic attack comes from spalling or explosion of metal fragments. Anti-spall coatings may be sprayed over the cells 132, which will encapsulate bullets and other ballistic objects, remaining intact, without posing further secondary damage resulting from spalling and fragmentation.

• • Kevlar

The fabric material may be made from Kevlar, a synthetic fiber made by DuPont having the chemical formula: [—CO-C6H4-CO—NH-C6H4-NH-] n

3.3. Motor System

When ascertaining the specification for a motor 140 to deploy and store the curtain 110, torque is a parameter that is usually measured in oz-in. An as-tested, ceiling-deployed model yielded the following results.

TABLE 4
Parameters converted to motor specification units
	Metric	Lighter	Heavier
	Weight (lbs) → Mass (oz-in/	2.0704	4.141
	sec{circumflex over ( )}2)
	Target Speed (Curtain going	1	1
	up) (ft/sec)
	Motor Gear ratio	6	6
	Curtain Roll Radius (inches)	3.72	3.72

Assuming correct units, the inertia of the curtain (Jr), motor (Jm) and total inertia (Jeq) were calculated using a MATLAB script. The first step in calculating the torque was to calculate inertia pertaining to two main systems: the curtain roller (Jr) and the motor (Jm). After the two results of inertia were found, the total inertia of the system was calculated and translated through the gear ratio. This final inertia (Jeq) was the inertia used in order to determine the final torque calculation.

Subsequent to determining the inertia of the system, angular acceleration was to be ascertained. In order to calculate this specification, a benchmark test speed for raising the curtain was selected. Since the input voltage pattern was known, the angular acceleration could be calculated in rads/sec.

Utilizing angular acceleration and total inertia, both known at this point, the torque at the rotor (Tr) could be calculated. Translating this torque through the gear ratio gave the final torque measurement of the motor (Tm). However, this is the peak torque seen by the motor during normal operation and only occurs for a small amount of operating time. Since the motor may be operating for at least 10 secs during a lift, the continuous torque, or RMS torque of the motor, was required (Trms). Table 5 depicts the final values of RMS torque, speed, and inertia that the motor had to meet.

TABLE 5
Final motor parameters based on torque calculations and updated weight
	RMS torque or rated torque
Weight of curtain (Ibs)	(oz-in)	Total inertia
100	307.1	59.17

These calculations provided a reliable estimate regarding the size of the motor needed. A brush DC motor may be used to allow for easier speed and position control. Additionally, DC motors are markedly less expensive than DC brushless motors and stepper motors. A tertiary reason for selecting a brushed DC motor was lacking any need for precision control pertaining to the position of the rotor. This is simply because the only positions that were relevant were fully lowered or fully retracted.

FIG. 7 shows a graphical depiction of the motor 140 described herein, showing a driveshaft 142 and winding drum 144, which is attached to the curtain 110 and about which the curtain 110 winds and unwinds. An electromechanical brake system may be activated during lowering the curtain to allow for rapid and safe deployment. This system may work using an active low principle; meaning that the brake's force is applied to the motor's driveshaft when no voltage is applied. Once voltage is applied to the brake, it releases and the curtain drops. Reiteratively, torque calculations were done to size the brake in probable terms. Since the brake is the only device restraining the descent of the curtain, a peak torque estimation was used instead of an RMS torque. This was to allow for error approximation as well as a safety factor.

FIG. 8 shows a wiring diagram of the control system for the motor having a as components the motor 140, motor relay 145, motor controller 146, Arduino 147, brake 148, brake relay 149 and voltage source 143. The brake 148 may have an operating voltage of 24 volts and the motor 140 may have a max voltage of 24 volts. A single 24-volt supply 143 may be split and fed into the brake relay 149 and motor controller 146. Relays may be used to ensure that voltage is applied only when requested and also to prevent back EMF from the motor 140 causing over voltage issues in the rest of the circuit when the curtain 100 is deployed. An Arduino 147 may be used to control the speed and direction of motor 140 as well as when the brake 148 is applied.

In a networked or connected ballistic curtain system, a control system may ensure that only authorized users can deploy the curtain 110. The control system may be accessed by only authorized users, who may gain access using a credential such as passwords, fobs, retinal scans or other secure access, and those users may access the control system to deploy or retract the curtain(s) in total, one at a time, or in only some areas. The access may also allow a user to see what curtains have been or are being damaged.

4. Testing

4.1. Analytical Testing

A prototype testing plan encompassed two phases. The first phase entailed analytical testing of models using multi-physics simulation software like ANSYS workbench and FEA methods similar to those available in Creo. This allowed the tester to analyze the model as much as possible in a virtual setting before completing a design. Emphasis was centered on the analysis of forces exerted on the structural components of the BCCS in order to ensure that they could withstand the force of gravity while in free hanging mode, as well as the dispersed energy of ballistic impacts.

An ANSYS “Explicit Dynamics” project was generated in order to reflect a single projectile impact and simulate realistic material behavior of the system. Within the ANSYS environment the model was refined to reflect explicit materials. The ANSYS library did not have an AR-500 steel offering as an available material. Therefore, another steel compound (Steel-4340) was modified to reflect the proper material values in order to emulate AR-500 steel. The simulated bullet represented a pure copper round due to computational limitations.

Two bullet impacts were separately simulated. Each simulation conformed to the NIJ standards for armor testing. The initial impact, representing the “low” end of the standards scale, was a 9 mm parabellum Luger Full Metal Jacket (FMJ). The secondary impact, representing the “high” end of the standard scale, was a 7.62 mm (.308 caliber) FMJ NATO round. Both rounds were fired from several centimeters away from the plate at 373 and 847 m/s respectively [11] per NIJ standards. From these impacts, the acceleration of the front face and back face of the plate was probed. The data from the acceleration probes was plotted in ANYS. Through analysis, the relevant acceleration and time steps were extracted.

A simplified model of the curtain was produced in MSC ADAMS, a multibody dynamics simulation software, in order to simulate the effect of an impact over the entire curtain. The acceleration data from the ANSYS tests was incorporated in the ADAMS model test by using a step function to supply a force. This produced calculated acceleration results over its time step interval, as evidenced from the acceleration graphical data. This force was applied at the center of the curtain allowing the dynamic simulation to exhibit the force reactions within the curtain. Throughout the ADAMS simulation, the top, middle and bottom plates were probed in order to analyze the dynamic response of the curtain to impact. This data is relevant for the addition of a possible added feature of the BCCS, which can help locate the shooter, as the data is characteristic to which side of the curtain the gunshots are originating.

4.2. Physical Testing

The second phase entailed physical testing. This process involved subjecting a functional prototype to ballistic impact tests, as well as subjecting a non-ballistic prototype to deployment and roll-ability tests.

4.2.1. Ballistic Testing

The ballistic tests were conducted on the prototype. For this testing, a ballistic curtain measuring 2 ft×2 ft was suspended from wooden frame allowing feasible replication of full deployment. Approximately 1 ft behind the curtain, a backdrop of contractor's paper was spanned across the area of the curtain. Ballistic penetration, residual debris or fragmentation would be evidenced upon the backdrop. Cameras were positioned forward of, and adjacent to, the target area in order to film the terminal ballistic effects upon the curtain.

Safety was a vital consideration for the ballistic testing phase. Primary concerns included ricochet and fragmentation. Secondary concerns related to hearing protection and collateral property damage.

From a range of 25 meters, various rifle calibers were fired at specific points on the curtain. The first cartridge to be tested was the 7.62×51 mm NATO round as this was the largest anticipated ammunition round within our design parameters. At the conclusion of two test fires, the first round made impact at the convergence of two plate edges. The bullet damaged both plates and was able to pass through. However, the bullet had fragmented upon impact, as evidenced from the paper backdrop. The second round struck a plate center mass and cleanly penetrated through the armor. A thicker armor could stop this round in theory but this was not evaluated.

The second phase of testing entailed a 5.56 mm, 55 grain, “green tip” NATO round. This commonly used and acquired caliber within the U.S. It is utilized within a diverse range of firearm platforms to include the widely popular semi-automatic AR-15 rifle and variants. Despite several rounds of test fire, this load and caliber bullet was unable to penetrate the steel plate. Residual evidence of bullet strikes included impact craters and scarring, but lacked complete perforation. Impacts upon the convergence of plates did not evidence bullet puncture, although there was trace evidence of spall passing through.

Finally, pistol rounds of 9 mm and .45 caliber were fired at the curtain from a range of 10 meters. As expected, these rounds had essentially no effect on the steel and were unable to pass through the curtain. Damage to the hook and loop material that holds the cells in place did occur on the impact side of the curtain. However, as the cells are held in place from both sides with hook and loop, the non-impacted side remained undamaged, thus the steel cells remained securely in place. This remained true even for cells that experienced 3 direct hits.

While the invention has been described with reference to the embodiments above, a person of ordinary skill in the art would understand that various changes or modifications may be made thereto without departing from the scope of the claims.

Claims

1. A ballistic curtain system comprising:

a curtain comprising cells configured to stop a high-speed projectile; and

a motor connected to the curtain capable of deploying or retracting the curtain.

2. The ballistic curtain system of claim 1, wherein the cells are plates.

3. The ballistic curtain system of claim 2, wherein the cells are contained within a fabric.

4. The ballistic curtain system of claim 3, wherein the fabric comprises pockets, wherein each pocket comprises a plate.

5. The ballistic curtain system of claim 4, wherein the cells overlap.

6. The ballistic curtain system of claim 4, wherein the cells overlap to form a louvered arrangement.

7. The ballistic curtain system of claim 3, wherein the fabric comprises a front side and a rear side.

8. The ballistic curtain system of claim 7, wherein the front side and the rear side are attached to one another.

9. The ballistic curtain system of claim 3, wherein the curtain comprises a fabric only portion and a fabric and cell portion, wherein the fabric only portion comprises no cells.

10. The ballistic curtain system of claim 9 wherein the fabric only portion is nearer to the motor than the fabric and cell portion.

11. The ballistic curtain system of claim 1, wherein the motor turns a driveshaft.

12. The ballistic curtain system of claim 11, wherein the driveshaft turns a drum about which the curtain can wind and unwind.

13. The ballistic curtain system of claim 1, wherein the system comprises multiple curtains deployed in alternating arrangement.

14. The ballistic curtain system of claim 1, further comprising a controller that can be activated to control the motor.

15. The ballistic curtain system of claim 14, wherein the controller can only be accessed by a user with a credential.

16. The ballistic curtain system of claim 1, wherein the curtain is configured to deploy in an upward direction.

17. The ballistic curtain system of claim 1, wherein the curtain is configured to deploy in a downward direction.

18. The ballistic curtain system of claim 1, wherein the curtain is configured to deploy in a sidewise direction.

19. The ballistic curtain system of claim 1, wherein the deployment of the curtain is done by allowing gravity to act on the curtain.

20. A method of protecting an area comprising deploying a ballistic curtain system comprising:

a curtain comprising cells configured to stop a high-speed projectile; and

a motor connected to the curtain capable of deploying or retracting the curtain, wherein the area protected would be on an opposite side of the curtain from a threat.