US3566791A - Signal cartridge for providing long duration display - Google Patents

Abstract

A signal cartridge for providing a night display of relatively long duration having a plurality of flare pellets within a cartridge case and having means for expelling and igniting the flare pellets to produce a shower display of burning chaff which has been mixed into the flare pellets.

Description

providing a night display plurality of flare pellets g means for expelling and ige a shower display of burning References Cited UNITED STATES PATENTS 1/1967 Cat1in......... 10/1969 Bliss et a1. r, H. H. Losche and Paul S.

gnal cartridge for duration having a pellets to produc been mixed into the flare pellets.

1,947,834 2/1934 Driggs, Jr. et a1. 3,257,801 6/1966 Martinez et al. 3,298,311 3,473,472

Primary Examiner-Robert F. Stahl Att0rneys-- Edgar J. Browe Collignon ABSTRACT: A si of relatively long within a cartridge case and havin niting the flare chaff which has was? epresented OVIDING LONG Carl W. Lohkamp Scotland, Ind. 808,734 Mar. 20, 1969 Mar. 2, 1971 the United States of America as r by the Secretary of the Navy DURATION DISPLAY 3 Claims, 3 Drawing Figs. [52] U.S. 37.6, 37.8, 39, 1M

Patented March 2, 1971 INVEN'IOR CARL W. LOHKAMP SIGNAL CARTRIDGE FOR PROVIDING LONG DURATION DISPLAY STATE OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates to a signalling device and more particularly to a signalling device which can be installed in a practice bomb to provide an indication of bombing accuracy.

Various pyrotechnic devices are used in practice bombs which are launched from aircraft to indicate the point of bomb impact. These pyrotechnic devices provide a flash of light and a puff of smoke to show the point of bomb impact. One widely used device is fitted into a signal cavity of a practice bomb and, when dropped, impact forces a firing pin into a primer to ignite a charge of red phosphorus. The burning of this red phosphorus produces a flash of light and provides a puff of white smoke. I

The above-described device having red phosphorus is a reliable device but has a disadvantage of producing a flash of very short duration, with the total duration being only about 0.08 second. This extremely short duration does not allow sufficient time for ground observers to triangulate on the impact point. Airborne observers frequently miss the impact display unless they are looking directly at the correct spot at the time of impact.

SUMMARY OF THE INVENTION The present invention relates to a signal cartridge which, when ignited, provides a visual display of between 2 and 3 seconds in duration, which is over 25 times as long as the red phosphorus devices heretofore used by the military.

A cartridge case is provided with a plurality of pyrotechnic pellets along with a quantity of pistol powder for expelling these pellets from the case upon ignition. Metallic chaff is dispersed within the pyrotechnic pellets and, upon ignition, these pellets first break up into chunks and these burning chunks then further break up and disperse burning chaff which provide a glowing cloud effect. The durationof the display is about two seconds and as the pieces of burning chaff are relatively heavy the display remains near the bomb impact point.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a sectional view ofa practice bomb having a signal cartridge therein;

FIG. 2 is a side view showing a practice bomb emitting a shower of burning chaff to provide a visual display; and

FIG. 3 is a sectional view of a preferred embodiment of a signal cartridge.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. I of the drawing, there is shown a practice bomb 1] having fins 12 on its aft end, and having a central bore 13 in which a signal cartridge 14 is positioned. A firing pin mechanism 15 is positioned in the forward end of practice bomb 11 and is retained by cotter pin 16. A shear pin 17 prevents firing pin 18 from engaging signal cartridge 14, however, upon impact of the bomb with the ground, pin 17 is sheared and firing pin 18 rams into a primer in signal cartridge 14. FIG. 2 of the drawing shows a shower display 19 which results when signal cartridge 14 is detonated.

Referring now to FIG. 3 of the drawing, there is shown a signal cartridge 14 having a closed end and an open end. A primer 21 is positioned in the closed end of signal cartridge 14 and is provided to ignite a quantity of pistol powder 22. A plurality of pellets 23 of pyrotechnic composition are positioned within cartridge 14, and cartridge 14 is closed by felt packing 24 and cover 25. Pellets 23 are provided with a central aperture 26 which facilitates the disintegration of pellets 23 upon expulsion from cartridge case 14. Pellets 23 are separated by a thin film of polyester film 27 which prevents flame from passing through apertures 26.

Pellets 23 are comprised of granulated magnesium, aluminum or magnesium chaff, Teflon, and a fluorocarbon rubber. Experiments and tests have shown that pellets which provide a relatively long duration of display can be made using the following range of ingredients:

Magnesium (Granulated) 32-40 percent Chaff (Aluminum or Magnesium) 15-25 percent Teflon '2035 percent Fluorocarbon Rubber 10-15 percent The following examples are illustrative of the range of ingredients and the mixing procedure for pellets 23.

EXAMPLE I A 5 pound mix was made using the following parts, by weight, of ingredients:

Magnesium (Gran l6 36 Aluminum Chaff(.OO2 X .008 X .25)

Fluorocarbon Rubber (Viton A) 15 Three-fourths of a pound of fluorocarbon rubber, was mixed with 3.95 pounds of acetone. The mixture was agitated for sufficient time to insure that the fluorocarbon was completely dissolved. This solution was then put into a mixer and L8 pounds of magnesium (gran l6) and 0.90 pounds of aluminum chaff were added and mixed for 10 minutes. Next the Teflon was added and the mixture was again mixed for 10 minutes. Hexane was then added to drive out acetone from the composition and was mixed for 10 minutes. When mixing was finished, the liquid was removed from the mix and discarded. Hexane was again added to the mix in sufficient quantity so that the hexane covered the mixture and the ingredients were mixed for 10 minutes. The hexane was then removed and the composition was placed in drying trays. The mixture was hand worked every 15 minutes for a period of 3 hours to insure a uniform composition. The mixture was then pressed into pellets at 800 pounds dead load.

The pellets were put into a signal cartridge, as shown in FIG. 3 of the drawing, and upon firing, a showering display was produced which lasted approximately 3 seconds.

EXAMPLE II A5 pound mix was made using the following parts, by weight, of ingredients:

Magnesium (Gran 16) 42 Chaff(Magnesium turnings) Fluorocarbon rubber (Viton A) 16 The ingredients were mixed and pressed into pellets as described in EXAMPLE I and then placed into a signal cartridge. Upon firing, a showering display was produced which lasted approximately 2 seconds.

EXAMPLE III pany under the trade name Viton A. Viton A has the formula (C H F and is comprised of about 32.1 percent of carbon, about 1.8 percent of hydrogen, and about 66.1 percent of florine. Viton A is used as a binder and a source of Florine. Teflon, which has the chemical name of polytetrafluoroethylene, was procured under the designation of Teflon 01 and is a needle-shaped powder which was used as a source of florine.

OPERATION Assuming the signal cartridge shown in FIG. 3 of the drawing is to be used in a practice bomb for help in locating the point of bomb impact, the cartridge is loaded into practice bomb 11, as shown in FIG. 1 of the drawing. Upon dropping 5' practice bomb l1, dirt, water, or debris will enter into the central bore 13 and move firing pin mechanism 15 in an aft direction thereby causing pin 17 to shear. Firing pin 18 will then engage and detonate primer 21, which in turn will ignite pistol powder 22. The force created by the ignition of pistol powder 22 causes packing 24 and cover 25 to be ejected. Pellets 23 are ignited and ejected and the combination of the pressure on the interior of the pellets produced by the pistol powder and by the gaseous by-products of the flare, causes the flare to break into multiple chunks. These burning chunks then further break up and disperse burning chaff which gives a glowing cloud effect. The effect of this multiple breakup is to keep the visual display in the near vicinity of the bomb impact point. I

While the operation of cartridge is described in conjunction with a practice bomb, it should be understood that other devices could be used to detonate the signal cartridge of the present invention. For example, a hand-held pyrotechnic pistol might be used to fire the signal cartridge.

Iclaim: l. A signal cartridge comprising: a cartridge case having a closed end and an open end; an expelling powder charge within said cartridge case adjacent said closed end; a plurality of flare pellets within said cartridge case consisting, by weight, of between 32 and 40 percent of granulated magnesium, between 15 and 25 percent of a metal-.

lic chaff selected from the group consisting of aluminum and magnesium, between 10 and 15 percent of fluorocarbon rubber and between 20 and 35 percent of polytetrafluoroethylene; and

a cover closing the open end of said cartridge case.

2. A signal cartridge as set forth in claim 1 wherein said expelling powder charge is pistol powder and wherein a primer is positioned in said closed end for igniting said pistol powder.

3. A signal cartridge as set forth in claim 1 wherein said metallic chaff is aluminum.

Claims (3)

1. A signal cartridge comprising: a cartridge case having a closed end and an open end; an expelling powder charge within said cartridge case adjacent said closed end; a plurality of flare pellets within said cartridge case consisting, by weight, of between 32 and 40 percent of granulated magnesium, between 15 and 25 percent of a metallic chaff selected from the group consisting of aluminum and magnesium, between 10 and 15 percent of fluorocarbon rubber and between 20 and 35 percent of polytetrafluoroethylene; and a cover closing the open end of said cartridge case.

2. A signal cartridge as set forth in claim 1 wherein said expelling powder charge is pistol powder and wherein a primer is positioned in said closed end for igniting said pistol powder.

3. A signal cartridge as set forth in claim 1 wherein said metallic chaff is aluminum.

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