US 2436305 A
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Description (OCR text may contain errors)
Feb. 17, 1948;
T. B. JOHNSON AMMUNITION Filed Feb. 3, 1944 j A M/ 22 z zfax /7 /6 0 5 /9 INVENTOR.
\ 77/15000fi5 5. Jam/sow A GENT Patented Feb. 17, 1948 AIMMUNITION Theodore B. Johnson, Bridgeport, Conn., assignor to Remington Arms Company, Inc., Bridgeport, Y Conn., a corporation of Delaware Application February a, 1944, Serial No. 520360 1 Claim. (01.10249) The present invention relates, in general, to I In generaL. primer compositions comprise a percussion, sensitive combustion initiator, an oxidizer and a fuel, the flame and heat of their combustion being adapted to ignite the propellant ofqa cartridge. The primer flame generates much heat and pressure but is of short duration. This characteristic behavior of primer compositions is wholly satisfactory and indeed desirable for those types of cartridges embodying projectiles which are to be propelled by the combustion of the propellant. There are, however, other uses for primer compositions as ignition initiators in which it is desirable that combustion of the primer composition shall proceed more slowly and without such violent and sudden generation of pressure as may scatter the charge to be ignited or damage contiguous objects which maybedelicately balanced and of a frangible nature. In these instances, it is a requisite of the primer that it ignite and develop a flame having sufficient heat to ignite apropellant or other charge, but that the primer reaction shall not be so violent as to disperse such charge and/or displace or break the adjacent mechanisms. A further instance is that wherein it is desired to ignite a fuse by means of a primer cap without producing the noise which characterizes the violent reaction of known types of primers.
The present invention relates to the discovery of an improved deflagrating composition which reacts immediately when subjected to a sharp blow developing a hot flame *but having a relatively noiseless or nonviolent reaction. This result has been achieved by adding certain combustion retarding or violence reducing ingredients to the other constituents of the composition, whereby combustion is retarded without substantial reduction in the total heat developed. That is to say, the heat of combustion remains substantially equal to that of existing primer composition whereas the rate of combustion is appreciably reduced.
a defiagrating composition which is sensitive and retains its sensitivity during storage. A still further object is to provide a primer composition for a pyrotechnic cartridge of the type especially suited for igniting inflammable materials. A still further object is to provide an improved pyrotechnic cartridge which, when ignited, will produce a relatively long flame and one which will burn steadily for fifteen to twenty seconds.
These and other objects, features and advantages of the invention will be more fully described in the following specification.
In the drawings: 7
Fig. 1 shows schematically a suitable flame throwing device with which the pyrotechnic cartridge of this invention may be used.
Fig. 2 is a side elevation in section of a pyrotechnic cartridge embodying the improved primer composition of this invention.
According to the invention, a suitable defiagrating composition sensitive to percussion of the intensity commonly provided by the firing pin of a firearm and adapted especially to produce a hot flame, although by a relatively slow. nonviolent reaction comprises the admixture with a combustion initiator, a suitable fuel and an oxidizer, of a finely divided inert material. The preferred inert material or combustion retarding diluent comprises titanium dioxide, but other inert materials having similar characteristics may be used. For example, barium sulphate and calcium oxalate have been found to have somewhat the same effect in the primer composition. The precise physical or chemical effect of the inert material in the mixture is not known, but it is thought that the reduction in noise and violence of the reaction is due in part to the adherence of the minute particles of inert material to the other ingredients of the composition so that the rate of combustion is slightly retarded without causing a corresponding reduction in the heat developed by the reaction.
The amount of titanium dioxide or other simiiar inertmaterial incorporated in the deflagrating composition varies with the nature of the combustion initiator and the percentages of oxidizer and fuel used, but, for the purposes of thisinvention, is generally from five to twenty percent.
The defiagrating mixture may and preferably does include a suitable abrasive such as glass which is adapted to retain the sensitivity of the mixture.
A typical example of a defiagrating composition which has been successfully used for igniting ex;-
plosive and pyrotechnic charges has approximately the following composition:
Per cent Potassium chlorate 35 Lead sulphocyanate 17 Antimony sulphide 12 Titanium dioxide 20 Glass 16 As commonly practised in the ammunition art. the composition may be wetted by the addition of a suitable binding agent comprising a gum solution to prevent the composition from crumbling when dry. The primer composition of this invention is not limited in itsuse toany one specific type of binder and has been used successfully with an aqueous solution of tragacanth and arabic gum, glue, thymol and alcohol. For most satisfactory results, substantially 12 cc. of the gum solution are mixed with each 100 grams of the primer mixture. It will be understood, however, that the proportions given may be varied depending upon the physical and chemical characteristics of the ingredients of the primer composition as Well as any variations in the proportions of these ingredients.
For example, a deflagrating composition which is particularly adapted for use in a relatively confined areain close association with delicately balanced and frangible mechanisms comprises:
Per cent Potassium chlorate 48 Lead sulphocyanate 22 Antimony sulphide 15 Titanium dioxide 15 A further variation offthe deflagrating composition is one comprising:
Per cent Potassium chlorate 53 Lead sulphocyanate 25 Antimony sulphide 17 Titanium dioxide This composition has a relatively noiseless reaction and is ideally suited for igniting fuses.
From the foregoing examples, it will be evident that by making slight variations in the proportions of the ingredients of the deflagrating composition, a composition may be adapted to meet the specific requirements of any ignition problem in which high heat and a hot flame is required but where a violent or'noisy reaction must be avoided.
Moreover, it is characteristic of the defiagrating compositions described above that they will ignite immediately when struck and produce a hot flame throughout a range of temperatures from 120 F. to 40 F.
In accordance with a further object of this invention, the deflagrating compositions described above and more especially the composition containing 20% titanium dioxide is suitable as a primer mixture for igniting pyrotechnic cartridges or cartridges of a similar type.
It is desirable that certain types of pyrotechnic cartridges produce a relatively long hot flame which will burn for fifteen to twenty seconds and throughout this interval ignite inflammable substances such as liquid fuels.
Fig. 1 shows schematically a liquid fuel burning device which, for the purposes of this specification, is termed a flame thrower and which comprises a tube 4 through which a solid stream of fluid fuel or a mixture of fuel and air or oxygen is'fed under extremely high pressure from a suitable container 5. A conically shaped hood 6 is shown at the discharge end of the tube having apertures 1 to admit air into the hood for completing the combustion of the fuel. Supported in the shield or hood 6 beneath the tube 4 is a revolver type of firearm 8 having a barrel portion 9 so shaped as to direct a, hot flame issuing therefrom into the path of the fuel being discharged from the end of the tube 4. The revolver is adapted to be supplied with a pyrotechnic cartridge of the type which will provide a long hot flame capable of burning uninterruptedly for a period of fifteen to twenty seconds. During this'time, the fluid fuel being discharged from the tube is ignited by the cartridge flame and issues from the hood as a substantially solid stream of fire.
It has been found that for optimum performance in flame throwing devices, the powder charge of these pyrotechnic cartridges should be ignited at the forward end of the case and burn uniformly rearwardly. Accordingly, the flame from the ignited primer composition in the rear of the case must be long enough to extend forwardly to the front end of the case and must be hot enough to ignite the charge in this portion of the case. Although earlier types of primers have been used to ignite a powder charge in this manner, the violence of the reaction has been such that the powder charge within the case has been broken up if not actually blown out of the case thereby precluding a uniform rate of burning and resulting in a relatively short flame of momentary duration.
Referring to the drawings, Fig. 2 shows an improved pyrotechnic cartridge for flame throwers comprising a case l0 which may be of any suitable metal such as steel or brass and of any desired caliber. In the drawings, the case ID has the proportions characteristic of a .45 caliber shell adapted for use in a revolver or similar type of firearm. The case In is, however, somewhat longer than the standard .45 caliber case to provide for an unusually large powder charge and is provided with the usual type of grooved head, indicated generally at H, having a primer cap [2 loaded with a charge l3 of the above described defiagrating composition As indicated at M, a waterproofing seal comprising a nitrocellulose lacquer is provided around the outer end of the primer cap to seal the cap in its seat [5 in the head of the case.
As pointed out above, the improvedcartridge is one which is adapted to supply along hot flame for a period of fifteen to twenty seconds, and, to this end, comprises a main powder charge l6 which fills a major portion of the body of the case. One type of main powder charge which provides a long hot flame is a modification of the so-called red flare composition commonly used Pyrotechnic compositions having the above formulas not only provide a not sustained flame but areas I have satisfactory charging and ignition characteristics as well as good storage stability.
For optimum performance, the main charge 18 is provided with an axial aperture I! to enable the primer flash or flame to travel uninterruptedly from the rear of the main charge forward to the front end of the case where ignition of the main charge is initiated.
Ignition of the main charge is accomplished by a secondary powder charge l8 which is loaded into the case on top of the main charge and is selected for its immediate response to the balanced heat-violence characteristics of v the primer composition and concurrent ignition of the main charge. Typical secondary charges having no appreciable time lag and having' satisfactory storage stability characteristics comprise the following compositions: V
In keeping with an ultimate purpose of the invention these secondary charges have a relatively nonviolent reaction. Although each secondary charge will be ignited immediately by the flame from the primer, the rate of burning of the charge is relatively moderate to avoid blowing out the cartridge top wad prior to ignition of the main charge,
Any suitable method may be used in making the cartridges and one method which has had considerable success is as follows: The hollow cylindrical main charge It is pelleted directly intothe case in two orthree increments under one thousand pounds dead load, the second charge l8 being pressed into place with the final increment f the main charge and having the form of a ring or annulus. A felt top wad l9 is'then placed on top of the secondary charge and securely held in position by crimping over the rim of the case. F
To insure immediate and certain ignition of the secondary charge l8, a coating 20 of a'. highly inflammable material such as a paste comprising one-third part pitrocellulose lacquer and twothirds parts of the secondary charge, as for example the lead dioxide, calcium silicide composition, is spread on the inside surface of the wad I9 so as to be in immediatecontact with the secondary charge l8 and in direct line with the primer flame. Thus, when the primer is ignited, its flame passes through the main and secondary charges l6 and 3 respectively and strikes directly against the nitrocellulose paste 20. The latter is instantaneously ignited and in turn assists in igniting the secondary charge It, which in turn ignites the main charge [6, the latter burning from its forward end rearwardly in the case. The top wad I9 is quite regularly burned'out of the mouth of the case or a clean round hole is burned through the wad by the hot flame issuing from the mouth of the case. Due to the nonviolent reaction of the primer composition and secondary charge I8, the powder charges I6 and I8 are undisturbed in the case and burn uniformly sustaining 9, flame of maximum length and duration.
To insure consistent performance under adverse climatic conditions, the cartridges are sealed, as indicated at 22, with a suitable waterproofing agent such as an oil modified nitrocellulose lacquer or a cement of adequate waterproofing properties.
What is laimed is:
A cartridge for producing a sustained flame comprising a case having a hollow main charge, a hollow secondary charge in front of the said main charge to ignite the latter, the rate of combustion of said main charge being substantially equal to the rate of combustion of said secondary charge, a wad held in said case on top of said secondary charge, a, coating of a nitrocellulose paste on said wad in contact with said secondary charge, and a percussion responsive primer in said cartridge in proximity to said main charge and arranged to project a flame through said hollow main charge and said hollow secondary charge to ignite a small area only of said paste,
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,495,350 Olin May 27, 1924 1,503,530 Henning Aug. 5, 1924 1,917,998 Snelling July 11, 1933 1,989,729 Alexander Feb. 5, 1935 1,991,731 Burns Feb. 19, 1935 2,072,719 Pearsall Mar. 2, 1937 r 2,072,720 Pearsall Mar. 2, 1937 2,132,996 Palmieri Oct. 11, 1938 2,195,965 Holm Apr. 2, 1940 2,299,466 Coflfman Oct, 20, 1942 2,362,927 Pratt Nov. 14, 1944 FOREIGN PATENTS Number Country Date 26,909 Great Britain 1907 288,482 Germany July 24, 1919 288,483 Germany July 24, 1919 346,092 Great Britain Apr. 9, 1931