US2913961A - Gun fire dead area control apparatus - Google Patents

Description

W. H. SCHOFIELD GUN FIRE DEAD AREA CONTROL APPARATUS Nov. 24, 1959 3 Sheets-Sh t 1 Filed y 8, 1958 IN VENTOR.

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GUN FIRE DEAD AREA CONTROL APPARATUS Filed May 8, 1958 3 Sheets-Sheet. 2

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GUN FIRE DEAD AREA CONTROL APPARATUS Filed May 8, 1958 3 Sheets-Sheet 3 m a mm a; M -WM United Sates GUN FIRE DEAD AREA CONTROL APPARATUS Wentworth H. Schofield, Ridgewood, NJ., assignor to the United States of America as represented by the Secretary of the Army Application May 8, 1958, Serial No. 734,063

1 Claim. (CI. 89-41) (Granted under Title 35, US. Code (1952), see. 266) atent O to provide such a method and apparatus which is simple, and easy to control in a more accurate manner and in a short time.

Prior attempts at the control of such a dead area have been tried. An important field of use for such a control has been in connection with the rapid changes in azimuth and elevation of an antiaircraft gun operated automatically by remote control in tracking a rapidly moving aircraft target. Such guns are frequently located near an industrial plant or bridge or other landmark into which a shell should not be fired, yet the gun is moved so rapidly that personnel at the gun cannot be relied on to protect such areas from the fire of the gun. One such prior suggestion has been made in the patent to P. E. Pleusse 2,692,534 dated October 26, 1954, upon which the present invention is an improvement.

According to this invention, such a device has been provided with means for more easily and more quickly changing the outline and location of such an area into which the gun cannot fire, as will be necessary when a gun is moved from one location to another. More specifically, a preferred apparatus consists of a cylinder or a drum rotated in response to changes in azimuth of the gun, and a longitudinally movable contact is responsive to changes in gun elevation. A sheet of paper is removably secured around said drum and the outline of the safe area marked thereon. The area into which the gun may fire is coated with a silver solution to provide a conductive path for the current between the longitudinally shiftable contact and a stationary contact through the electrically conductive coating. When the shiftable contact reaches a dead area representing the area into which the gun should not fire, the current is automatically interrupted and the gun cannot fire, as the primer circuit is interrupted.

Fig. 1 is a diagrammatic view showing the gun and means for transmitting movements in azimuth and elevation from the gun to the apparatus.

Fig. 2 is a longitudinal section through the apparatus to which changes in elevation and azimuth of the gun are connected.

Fig. 3 is a section on the line 3-3 of Fig. 2.

Fig. 4 represents a typical map of the live and dead areas.

Fig. 5 is a less common map showing other areas.

As shown in Fig. 1, an anti-aircraft gun 10 is provided with the usual base or bull ring 11 driving a gear 12 engaged therewith and driving through the flexible connection 13 a portion of the apparatus shown in Fig. 2. A gear is mounted on the trunnion or on the elevation quadrant 15 driving a gear 16 and a flexible connection 17 leading to another part of the apparatus in Fig. 2.

The elevation changes made by the gun are transmitted through the flexible connection 17 to a shaft on which is mounted a gear or wheel 18 and thence motion is transmitted through a pair of universal connections 19 and 20 to a gear 21 meshing with another gear 22 driving the rotatable threaded rod 23 on which is mounted a movable contact member 24. A stationary contact 25 engages a paper removably mounted on the drum 26. The movable contact 24 is moved up and down along the threaded rod 23 with changes in gun elevation. In one embodiment of the present invention the paper was approximately 2% inches in height or along the drum longitudinal axis so that as the gun pointed between 5 and the total movement in elevation in was confined to the 2% inches of the paper or in other words l-=0.278 inch on paper. As shown in Fig. 2, the paper 27 is removably mounted on the drum 26 and an enclosing housing 28 surrounds the drum, the same being provided with a removable cover 29.

The flexible shaft 13 from the gun for moving the paper in rotation is shown as being transmitted to a gear driving a larger gear 30 on the shaft 30a. A gear 31 drives another gear, not shown, and eventulaly drives the gear 32 which engages a shaft on which is mounted a gear 33 driving a gear 34 on the shaft of the drum, thus driving the drum. 360 of rotation in azimuth by the gun and bull ring efifect a movement of 360 rotation in the drum and the paper. In Fig. 3, the drum contains a paper retainer in the form of a small cylinder having a slot and mounted beneath the surface of a slot in the large drum. The paper retainer contains a clamping pin or arm at one end by means of which this retainer may be rotated with respect to the cylinder and clamp the paper in place. Any type of means for quickly attaching and removing the paper from the drum may be used.

To install a new sheet of paper as is necessary when the gun is moved to a new location, the drum is removed through the top cover 29 being removed, and then a new piece of paper is put in position on the drum. A sheet of carbon paper is placed around the drum over the drum paper and may be fastened with cellophane tape to assist in marking the safe and unsafe areas. With the paper in position, the gun travels through its full 360 in azimuth. The azimuth and elevation limits of distant friendly areas from the gun are determined from firing tables and maps and the boundaries of these areas are marked. For example, if a friendly area is located between azimuth readings of 2350 mils and 2550 mils at elevation readings of 910 mils and 980 mils, the following procedure is used to track this area:

(1) Traverse the gun, at its minimum elevation to an azimuth heading of 2350 mils (2) Elevate the gun to 980 mils (3) Traverse the gun to 2550 mils (4) Depress the gun to 910 mils (S) Traverse the gun back to 2350 mils at the elevation of 910 mils (6) Depress the gun to minimum elevation.

minutes the paint will have dried, when the drum may be replaced and the cover 29 put back. Friendly or safe areas are not coated with the silver whereby the live areas representing the majority of field of fire will be fired into tion of the paper.

the paper as shown.

as current passes between the two contacts 24 and 25 in tracking a target.

One typical type of map or marked paper is shown in Fig. 4 in which the live areas containing the silver coat are represented by the numeral 35 and the dead or safe areas by the numeral 36. In Fig. 4, as the stationary contact engages the paper at the point 37, the movable contact will allow firing of the gun whenever the movable contact is anywhere on a silver or conductive coated por- In Fig. 5 is represented an unusual type of map in which the silver or conductive area 35a is of the shape indicated surrounding the dead area 36a.

In this case, if the stationary contact reaches the position 37a in Fig. 5, then in order to allow the gun to be fired by the movable contact being in the conductive area below the point 37a, it will be desirable to add a small border to the paper in order that conductive material may be added along a strip extending around at least two sides of This will be equivalent to moving the stationary contact up into the narrow conductive border above the safe area in Fig. 5 in order that the gun may be fired when the movable contact is in the conductive area below.

It may be mentioned that this invention enables more than one safe or dead area to be possible with a live area at the same azimuth setting yet such was not possible with the apparatus of Pleusse, 2,692,534 referred to above since in that construction it was possible to have only one live or safe area at a given azimuth setting. The present invention enables a sharper line to be drawn between live and dead areas than was the case with Pleusse. For exconductive and abrasive resistance properties.

ample, if the object to be protected were near one edge of the dead area it would be necessary in Pleuss to have not only the inevitable 64 mils of safe area but substantially twice that amount or 128 mils. The apparatus of the present invention is easier and quicker to make ready for firing. The maps of Figs. 4 and 5 do not take a great deal of time to prepare. Any quick drying conductive paint can be used, although the silver coating 4817 described in Du Pont Bulletin CP-Z-S 51 is preferred for its In contrast to the simplicity of the conductive map of this invention Pleusse had 64 contacts to be adjusted.

I claim In a system for defining a live area into which a gun may be fired, the combination of a first mentioned means for moving said gun in azimuth, a second mentioned means for moving said gun in elevation, a drum, a sheet of paper removably secured around said. drum and having a conductively coated area representative of said live area means for rotating said drum with said first means, a fixed electrical contact engaging said sheet, a movable electrical contact engaging said sheet, and means for moving said movable contact with said second means.

References Cited in the file of this patent UNITED STATES PATENTS 2,542,483 Fonseca Feb. 20, 1951 2,692,534 Pluess Oct. 26, 1954 FOREIGN PATENTS 583,078 Great Britain Dec. 6, 1946

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