US 20070075498 A1
This invention is a new-type, full-scale, tank-target silhouette for use in tank gunnery practice with the main gun of a tank. The new target employs lightweight sheet material that is corrugated in the manner of an accordion-door (or pleated) configuration to produce a self-supporting, rigid target silhouette which can be raised and lowered, and which can sustain multiple hits without collapsing. The corrugation configuration, when clamped along the bottom edge of the ridges and grooves, provides the necessary rigidity for the target to stand upright without other vertical structural members which could be hit and destroyed.
9. A full-scale tank target silhouette which is formed from a sheet material that is folded to form corrugations in the horizontal direction with the ridges and grooves of the resulting corrugation running in a vertical direction to give structural strength to the said sheet material which is then securely clamped along the bottom edge using a hinged holding clamp with evenly spaced members that extend into the corrugated material at each groove to provide the clamping force for the free-standing, full-scale, tank-target silhouette image for use in tank gunnery target practice with live ammunition.
The basic method for constructing a large target silhouette for use in tank gunnery practice is to use ½″, or thicker, 4′×8′ sheets of plywood or particle board supported by 2″×4″ or 4″×4″ framing lumber. The 4′×8′ sheets of plywood are cut and assembled downrange near the target lifting mechanism and nailed or screwed to the framing lumber. The vertical supports of 2″×4″ or 4″×4″ lumber are attached to a lifting mechanism, positioned behind a protective berm, that rotates the target silhouette into the exposed upright position above the berm.
A full-scale frontal tank silhouette is approximately 12′ wide and 8′ high and weighs nearly 200 lbs. The actual weight depends on the panel thickness and the length of the vertical supports. The vertical supports are needed to add strength to the plywood panels and to raise the target silhouette above the protective earth mound in front of the target lifting mechanism. With a long lever arm (vertical support length) the torque required to rotate the target becomes very large (200 lbs. ×6′=1200 ft-lb., for example) and a large and powerful lifting mechanism is required.
Examples of heavy rigid targets requiring substantial lifting mechanisms are shown in U.S. Pat. No. 5,403,017 “Target Lifter with Impact Sensing” by Doss, III, et al. and in U.S. Pat. No. 4,330,129 “Light Duty Target Support Apparatus” by Meredith.
A serious limitation of the present technique is the durability of the target and vertical supports. A few well-placed shots from a 120 mm gun can shatter the vertical supports and destroy the target. Another limitation is the excessive fabrication time, as well as the time for the frequent repairs, which require several men to handle the heavy materials involved in the process. The range down-time required to build and repair targets used in gunnery practice reduces the amount and effectiveness of range time available for training.
The following list of patents is given as reference for known prior practices.
The main object of this invention is to provide a large, lightweight, self-supporting, full-scale tank-target silhouette using sheet material which is corrugated along the horizontal direction to form vertical ridges and grooves, similar to the construction of an accordion-folded door.
Another object of the invention is to provide a structurally-rigid target silhouette which is formed by clamping the corrugated target material along the bottom edge of the vertical ridges and grooves with a target holder mechanism that maintains the cross-sectional corrugated shape and that can be rotated backward and forward to lower and raise the target into the firing position.
Another object of the invention is to provide a tank target without structural upright supports which is capable of withstanding multiple hits from the 120 mm large-caliber main gun of the tank during gunnery practice.
Another object of the invention is to provide a lightweight folded target which can be transported easily to the target area, unfolded, and installed in the target holder in a few minutes by one man.
Another object of the invention is to provide a full-scale tank-target silhouette which is lightweight enough to reduce the size and power of the drive mechanism required to raise and lower the target.
The proposed invention is based on the principle that thin-gauge, lightweight materials such as corrugated cardboard or extruded, ribbed-plastic sheet material gain structural strength when folded in a corrugated or accordion shape and are then clamped along one edge defined by the ridges and grooves of the corrugations.
The preferred embodiment of the invention is shown in
Also shown in
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Refer now to
In practice, to replace a target silhouette, a new folded target silhouette 2, which collapses to a bundle approximately 12″W×4″D×96″H in size when folded and which weighs less than 50 lbs., is carried downrange to a target lifting mechanism 4 with clamping and support beam assembly 3 already installed. As described above, the toggle clamps 16 with hook 17 are loosened, the hinged clamping beam assembly 12 is opened, and the old target silhouette 2 is removed. The new collapsed corrugated target silhouette 2 is unfolded and installed into the support beam assembly 11 and then the clamping beam assembly 12 is hinged closed and clamped by the toggle clamps 16.
It is understood that many other methods and materials can be used to form the clamping and support assembly 3 described above. For example, the bottom support assembly could be constructed using an epoxy/fiberglass molding technique with molds designed to match the saw-tooth pattern of the accordion folds of the target silhouette. The hollow fiberglass pieces that would be formed by this technique would then be filled with structural foam to form lightweight rigid clamping members which would be hinged and clamped in a manner similar to the aluminum-channel method described above in the preferred embodiment. It is also envisioned that the bottom of the corrugated target could be held in place by inserting two small tubes, or pipes, through holes in the corrugations across the width of the target silhouette and clamping the tubes to form a rigid dual-rail structure on which the silhouette is held in place.