Mulit-barrel automatic weapon centerline aiming laser   

SUMMARY

The multi-barrel automatic weapon centerline aiming laser (MAWCAL) is a direct solution to the problems inherent in the aiming of a standard military multi-barrel automatic weapon, and it specifically improves the utility of the rifle-caliber multi-barrel automatic weapons in counter-terrorism operations.

The MAWCAL consists of three claims which together greatly increase the accuracy of all multi-barrel automatic weapons. 1. The first claim is the mounting of a laser on the centerline of the multi-barrel automatic weapon. 2. The second claim is the process of aligning the beam in the centerline of the multi-barrel automatic weapon. 3. The third claim is the selection of key parameters (laser divergence, manufacturing and assembly tolerances, and adjustment) so that the apparent radius of the laser (while rotating) is closely related to the ballistic drop of the bullet over the effective range of the weapon.

Referencing FIG. 1, the prior art mutt-barrel automatic weapon consists of a clamp or a series of clamps (1) which hold a series of gun barrels (2) in a circular arrangement. Note that FIG. (1) is specifically proportioned to represent rifle-caliber (e.g. 7.62 mm) multi-barrel automatic weapons, which are the style of multi-barrel automatic weapons most often used in counter-terrorism.

The purpose of this arrangement of multiple gun barrels is to allow for a very high rate of sustained fire for one weapon. In counter-terrorism, the use of this sustained rate of fire with a relatively small caliber weapon makes the weapon useful against personnel and vehicles at a short range in confined locations without the collateral damage associated with a larger caliber weapon. As a result, the multi-barrel automatic weapon is often used for counter-terrorism perimeter defense of military and nuclear-related installations in populated areas, on civilian armored vehicles for personal counter-terrorism defense, on HMMVs and similar military vehicles for counter-terrorism urban operations, and on military aircraft for similar counter-terrorism purposes.

Common low-cost installations of the rifle caliber multi-barrel automatic weapons (such as most of those used in counter-terrorism) generally do not have accurate aiming methods. Thus, a common practice in these low-cost installations of rifle caliber multi-barrel automatic weapons (also called miniguns) is for the operator to use the following steps: begin by aiming the minigun in the general direction of the target, initiate the cyclic firing of the weapon, note the stream of shells (typically tracer rounds) with respect to the location of the target, and adjust the position of the weapon until the stream of shells lands on the target. Not only is this wasteful of ammunition and time, this practice seriously threatens civilians in a counter-terrorism environment (such as in populated towns and cities).

The informed reader will note that these multi-barrel automatic weapons have been used for years, and that larger multi-barrel automatic weapons often use sophisticated computer aiming. However, the same reader will note that even the computer-aided larger caliber versions suffer from boresighting difficulties. Thus, while historical uses of these weapons against personnel and vehicles have been successful, those experiences were in prior wars against concentrations of troops, vehicles, or insurgents. In the use of these multi-barrel automatic weapons in the counter-terrorism role, the weapon needs to be able to quickly and accurately eliminate terrorists who will be on foot or only occupy one or two vehicles in an otherwise peaceful town or city; thus any stray round has the possibility of wounding or killing civilians.

Even without the sophisticated computer-controlled aiming which is used on larger caliber multi-barrel automatic weapons, not all low-cost multi-barrel automatic weapon installations are without aiming devices. Some installations of miniguns include an optical or laser-assisted sight; however, those sights are usually mounted on top of the weapon. The sights suffer from a need for repeated boresighting (involving high maintenance) and they are susceptible to damage which would misalign the sight with respect to the barrels. Moreover, in instances where the operator directly fires the weapon (vs. a mechanical aiming and firing), the sight is usually placed a few inches above the weapon and therefore 1-2 feet below the eye of the operator; particularly troublesome given the large number of these weapons which are manually aimed and fired in counter-terrorism. Thus, as stated above, conventional aiming devices only serve to bring the weapon to a general location and therefore require the operator to “walk” the weapon to the target with the gun firing the entire time.

The advent of modern compact lasers makes possible a simple solution to this problem, and that simple solution is the subject of this invention. By placing a laser aiming device in the center of the barrel clamping mechanism on a multi-barrel automatic weapon, and by selecting a laser with the appropriate beam divergence, the laser spot can completely and repeatedly illuminate the impact area of the weapon. This patent application identifies and claims the method of mounting the laser in the clamping mechanism, the method of aligning that laser, and the parameters to be varied to appropriately illuminate the target area. The laser may be selected to be a visible laser or a near-infrared laser depending upon the anticipated use—in either case, the inherent advantage of the system is that the operator can use this invention to point the multi-barrel automatic weapon directly at the target, the weapon\'s aim can be confirmed by the operator\'s observation of the laser illumination of that target, and the operator can chose to fire upon the target only after confirming that the weapon is indeed pointed at the target. Thus the error of the initial shots can be reduced by an order of magnitude; for a minigun, this is a reduction from nearly 100 ft using the current method to the order of 6 ft with this new method (the typical apparent diameter of the rotating laser at the target distance).

The first and key element of the claims of this patent application is the mounting of a laser illuminator in the center of the multi-barrel automatic weapon barrel clamping mechanism. An embodiment of that mounting is described herein.

For the ease of understanding the invention, it is instructive to first understand the design of the barrel clamp of a standard multi-barrel automatic weapon. Looking briefly at the muzzle end of the standard multi-barrel automatic weapon as shown in FIG. 1, a circular barrel clamp (1) serves as a housing which holds a pattern of gun barrels so that the muzzles (2) are in a circular arrangement. This circular barrel clamp (1) may be a single piece, a series of round metal plates, a centerline tube connecting two or more plates, or a combination of any of the above. In some variations, a flash suppressor device (3) is integrated with this barrel clamp mechanism. Regardless of the design of the barrel clamp (1) all current housing designs have a hollow or solid center; shown as hollow in FIG. 1 at location (4). No current designs have any use for this volume between the barrels.

The MAWCAL barrel clamp laser mount uses this otherwise unused volume in the center of the barrels to mount a laser, and does so for two important reasons. First, this volume is most closely aligned to the gun barrel, thus reducing any parallax error between the aiming mechanism and the weapon\'s barrels. Second, the location makes use of the inherent high-speed rotation of the weapon to create a natural centering for the aim point, recognizing that even a fraction of a miliradian of misalignment is otherwise noticeable across the typical operational range of most multi-barrel automatic weapons—this range varies from hundreds of yards to thousands of yards, depending upon caliber. Both of these features which are inherent in this centerline mounting of the laser combine to create superior accuracy compared to other laser aiming (or sighting) mechanisms.

Referencing FIG. 1, a typical embodiment of this MAWCAL barrel clamp laser mounting is shown for the sake of explaining the invention. Note that the claim of a centerline laser mount is independent of the actual mechanical or electrical layout of used to employ the centerline laser mount.

The most apparent feature of FIG. 1 is the addition of a laser diode (5) in the center of the otherwise empty void of the barrel clamp. This laser diode (5) is placed so that it projects a laser beam (6) parallel to the centerlines of the barrels (7) in the weapon. As noted above, a primary advantage to this design compared to other laser aiming mechanisms is that the natural tendency (due to manufacturing tolerances, wear, etc.) of this (or any) laser beam (6) to be slightly misaligned with respect to any barrel (7) will be nullified by the constant rotation of the weapon in operation; thus, the result will be (to the human eye) a slightly larger but otherwise constant diameter laser spot projected in the direction that the weapon is pointed.

Further defining this typical embodiment of the invention, the laser diode (5) is mounted in a housing (8) which is mounted in the center tube (9) of the barrel clamp. One or two rows of set screws (10) would typically be used for fine alignment in service, as described in the second claim of the invention. The centerline tube (9) serves a secondary purpose of holding the forward of the two barrel clamps (11) in place, as is often done in other barrel clamp designs for multi-barrel automatic weapons. The reader will note that multi-barrel automatic weapons which do not have the structural rigidity to mount this system toward the muzzle (as shown in the figure) could easily mount the system near the breech end of the barrels; this mounting location is not shown, but understood to be a natural variation of this same claim.

A typical method of providing power to the laser would be to centerline mount a battery pack (12) in the same barrel clamp tube (9). The battery pack (12) would typically be designed to house standard sized batteries (e.g. standard “AA,” “C,” or “D” sized) providing enough current as required for the intended laser intensity. Power would typically be provided between the battery pack (12) and the laser diode housing (8) by a cable (13), although direct rigid contacts may be used to improve the overall ruggedness of the design. In this illustration, a rear battery access cap (14) would allow for change-out of the batteries; in other embodiments of the invention, the battery access may be designed differently as dictated by maintenance needs and manufacturability.

A typical method of switching the laser on or off would be through an accelerometer mounted to one of the plates of the barrel clamping mechanism; however, many other types of switching mechanisms may be used. In this embodiment, an accelerometer (15) is wired in series to the battery pack (12) via a cable (16) in order to act as an on/off switch; thus, as the barrels are rotating, centrifugal force would actuate the accelerometer, closing the switch, and turning on the laser. In this embodiment, the accelerometer (15) is shown attached to the inside of the rear barrel clamp plate (17) and between two of the barrels (7) so as to allow the maximum possible distance (thus gradient in force) to actuate the accelerometer. It is noted that this embodiment would be most effective if the barrels could be rotated separately from the feeding of ammunition to the gun (thus allowing time for the system to be aimed after the laser is switched on); therefore, the invention recognizes that other switching methods could be used depending upon the overall optimal multi-barrel automatic weapon design intent.

Thus, the centerline laser mount claim of the MAWCAL is shown to be a simple mounting concept for a laser, easily retrofitted to existing multi-barrel weapons, and sufficiently different from the current clamping mechanisms or laser sighting mechanisms. Likewise, the advantages have been shown not only in its low complexity but in its tendency to always remain boresighted with the weapon. The second claim of this invention involves the improvement of the apparent diameter of the aiming point, and is shown in FIG. 2.

Referencing FIG. 2, the laser beam centerline (18) is shown offset from the weapon\'s centerline (20) by some angle (21) which is exaggerated in the figure for the sake of illustration. While the beam divergence creates a more-or-less constant diameter (22) spot at a fixed distance (due to small angle assumptions in practice), the offset angle (21) creates a set distance (23) of the outer edge of that spot from the centerline of the weapon. In most boresighting methods that distance (23) is very difficult to determine, because the true (or intended) projection of the centerline of the weapon over the distance is not known. However, in this device, the distance (23) will be known because the rotation of the weapon\'s barrels by 180 degrees will move this same offset angle by 180 degrees, which will create a distance (24) between the centerline of the weapon and the outer edge of the laser beam. Noting that the distance in each location is the same by symmetry, the actual offset can be easily computed geometrically by comparing the known beam divergence (22) to the apparent spot diameter—the latter being the sum of the distances which were noted above (23 and 24).

For reasonably accurate machining and reasonable amounts of wear, the total distance of the diverged and offset laser beam (23 and 24) will be less than double the diameter of the diverged laser beam (22); thus when the weapon is rotating at typical firing speeds the operator will perceive a single apparent spot at the aiming distance. The reader will note (as is explained further in claim 3) that the summation of these typical manufacturing tolerances and beam divergence angles would create (over most distances) an apparent spot diameter which is consistent with the drop of a typical round fired over that distance. If, however, wear or manufacturing tolerances combine to create a wider-than-desired spot, then the set screws (10) can be adjusted to realign the laser diode housing (8) to create a more desirable laser aiming point spot diameter.

As noted above and alluded to in claim 2, the third claim involves a convenient and desirable summation of geometric tolerances and laser beam divergence; a summation which actually further assists the aiming of the weapon. An individual informed in the fields of gun manufacturing, laser manufacturing, and weapon ballistics will note that the aim point of a truly straight and fully coherent laser would not be the impact point of the round fired. However, these sources of error can be made to easily compensate for each other; that is the subject of the third claim.

The individual informed in the fields of gun manufacturing and laser manufacturing will note that the beam divergence angle and the standard angular error for parallel milled holes are both on the order of fractions of degrees. Likewise, the individual informed in the ballistics of weapons will note that the drop of a bullet over the effective range of the weapon could be divided by the effective range of the weapon, and the inverse tangent of the result would also be on the order of fractions of degrees. The MAWCAL takes advantage of this fact to create a spot at the aim point which can be adjusted to be the same or similar radius as the drop of the bullet over the effective distance. This is especially apparent to an informed individual who is familiar with the rifle caliber multi-barrel weapons used in counter-terrorism; noticing that the drop of the bullet at most target ranges is the radius of the divergence of most standard pocket lasers, and that the drop of the bullet at its maximum effective range is double the divergence of most standard pocket lasers (or about the same as the divergence plus a reasonable manufacturing tolerance).