US 2741177 A
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Description (OCR text may contain errors)
April 10, 1956 H A RlCARDs, JR" ETAL 2,741,177
CHEMICAL BOMB 2 Sheets-Sheet l Filed Nov. '7, 1944 ma. Tm AN M K LT@ EM Gm RLS mmm GW R m m A R RRF AE m@ R .0 AC D mw M m Hw April 10, 1956 H. A. RICARDS, JR., EIAL 2,74%177 CHEMICAL BOMB 2 Sheets-Shen 2 Filed Nov. '7, 1944 MLU? Patented Apr. 10, 1956 criar/ucar. norm Harold A. Ricards, fr., Cranford, George L. Matheson, Union, Lyle M. Cooper, Railway, William T. Knox, Jr., Roselle, and Francis R. Russell, Scotch Plains, hl. assignors to the United States of America as represented by the Secretary of War Application November 7, 1944, Serial No. 562,368
1 Claim. (Cl. 162--6) The invention described herein may be manufactured and used by or for the Government, for governmental purposes, without the payment to us of any royalty thereon.
'i'his invention relates to a type of aerial drop bomb designed to eject from its tail a chemical agent, such as incendiary material, and throw such materials against surrounding objects after impact. Y
Prior to the present invention it was well recognized that dissemination of chemical agents from aircraft could constitute a serious threat in warfare, but the tactical ernployment of chemical bombs was largely handicapped by lack of a suitably designed bomb. In general there were two types of bombs, the intensive'and scatter types. The intensive type was designed to penetrate a building by a direct hit and remain as a unit while functioning in a very restricted area if the bomby lands on combustible material. This type is represented by the thermit-lled incendiary bomb. The scatter type requires the use of a high explosive burster suiciently powerful to rupture the entire bomb body on impact and diffuses or scatters very small particles of the chemical charge in all directions over an area surrounding the ruptured bomb body. Both of these types have a number of limitations. The intensive type necessitates a thick body wall and is not effective unless it lands exactly on a spot where the incendiary action can be started. It is known that only a small percentage of intensive type incendiary bombs land where they can initiate destructive action. The scatter 'type bomb fails to function effectively in that the charge becomes too widely spread out in small particles. A large proportion of small scattered particles from a scatter type incendiary bomb fail to ignite, and those that are ignited have too little heat and flame action to initiate burning of a structure they Contact except in a few favorable circumstances. A large part of the diffused charge from the scatter type bomb is uselessly directed upwardly and downwardly.
An object of the present invention is to provide a type of bomb which has an advantageous loading eiciency by virtue of its high active agent capacity relative to the weight of the bomb, good security qualities for handling, clustering adaptability for area pattern bombing, and desirable distribution characteristics.
Another object is to provide a type of bomb simple and economical for manufacture, assembly, and use. Further objects and advantages will become apparent from the following description.
Broadly, for accomplishing the objects of the present invention, a bomb has been designed to eject forcefully from the tail end of the bomb body a chemical charge to be distributed. More particularly, the bomb used for incendiary action is provided with a combination percussion and time fuze which permits the bomb to fall to rest on its side after penetration into a target so that a mass of viscid incendiary material can be thrown out horizontally like a single projectile from a mortar to strike an object where a concentrated incendiary action can be started in the path of its trajectory. While ejection of the charge as a single projectile is desirable when the bomb is used with an incendiary agent, the bomb is adapted also for discharging other types of agents, such as a vesicant liquid in a thick spray, powdered material in a dense cloud, or the like, when spreading of such agents over an area is desired in the form of a concentrated mass travelling rapidly over the ground.
Various features of the bomb will be described in further detail with reference to illustrations of embodiments in the accompanying drawings which form part of this specification.
in the drawings:
Figure l shows a vertical sectional view of a standardized tail ejection incendiary bomb;
Figure 2 shows an elevational View 0f the tail end of the bomb;
Figure 3 shows a nose end view of the bomb in elevational view and partly in section;
Figure 4 shows an elevational full view of the bomb assembled and with nose end at bottom;
`Figure 5 shows an enlarged longitudinal cross-section of a safety plunger assembly used in the type of fuze shown in Figs. l and 6;
Figure 6 shows a cut away view in a fragmentary section of the nose end of the bomb modified to contain an anti-personnel fragmentation unit;
In the drawings, similar parts are given the same reference characters.
Referring to the drawings, and particularly to Figs. l to 5, casing l, made conveniently of about 18 to 20 gage pressed sheet steel, extends substantially the entire length of the bomb and forms a leakproof container for the assembly described hereinafter. A nose cup 2 made of sheet steel, preferably thicker than casing l, is fixed into the nose (bottom) end of casing l, forming a blunt nose and housing a suitable combination percussion and time fuze assembly 3 together with a charge of ignitingpropellant powder 4l. The powder 4 may be inclosed in thin walled cellulose nitrate plastic containers, which fit into the nose cup adjacent fuze assembly 3.
The fuze assembly 3 is screwed at its threaded head end into a threaded hole 5 in the casing ll and nose cup 2. rThe fuze shown comprises a firing mechanism assembly c-f a die cast aluminum base alloy 6 having a well for holding a primer cap '7 and supporting a hinged striker 8 of die cast aluminum or steel with a torsion spring 9 for restraining movement of the striker 8 until the movement is caused by sufficient impact force on the bomb. A safety plunger assembly iti is centrally recessed in the head end of the fuze base 6, where, in unarmed position, a spring held plunger is pressed inwardly under the striker to prevent movement thereof. A lead spitter fuse ll leads in a groove through the base 6 from the primer cap well under primer cap 7 to a booster charge l2 contained in a cellulose nitrate plastic cup i3. The tiring mechanism assembly is protectively encased in a steel cylinder i4.
A disc shaped steel impact diaphragm plug 15 is mounted in and above a hole in the impact diaphragm l5, which is securely brazed to the upper edge ofV nose cup 2. Diaphragm 1o and plug' 15 serve as reinforcement for a thin sheet steel diaphragm l? brazed to the casing l to act as a leakproof seal between the explosion chamber in nose cup 2 and the lling i8. v
Gelled or viscid fuel charge 18,' occupying the major part of the bomb, is preferably enclosed in a cheesecloth sock i9, the upper end 20 of which is tied securely by a piece of string 21.
in a standardized 6-lb. incendiary oil bomb of the type shown in Fig. l the casing is about 191/2 inches long, hexagonal in shape, 27/s inches wide across the ats,
.nd weighs complete, filled and fuzed, about 6 lbs. Nearly .1/2 lbs. of this weight is a gelled gasoline charge. A ail cup 22, made of sheet steel, is mounted in the tail upper)V end of the casing 1 andV is crimped thereto to erm a leakproof seal but is releasable when subjected to predetermined pressure from within the casing. v As a simplified stabilizing means, tail streamers 23, vhich are lengths of mildew-proof cloth, are attached it one end to a retainer cup 24 spot-welded at the bottom o the tail cup proper 22. A retainer ring 25 ts over he retainer cup 24 to securely hold the ends of treamers 23. When the bomb falls, the free ends of the :trearners 23 ily out, retarding and stabilizing descent of he bomb, so that the bomb falls in approximately a /ertical position at a regulated terminal velocity, e. g., if about 250 ft. per second.
in operation, when the bomb is separated from a cluster lropped by aircraft, the plunger in the safety plunger' assembly 1@ is retracted by a coiled spring away frorrr mder the striker to arm the fuze, the plunger being no Longer pressed inwardly by an adjacent bomb in the :luster: Upon impact of the bomb at its nose end on a target surface, inertia of the weighted portion at the swinging end of the striker 3 pivotally mounted on the base 6 forces the striker 8 to overcome the restraint of the torsion spring 9 and to swing on hinge pin pivot 9a with its ring pin directed toward the primer material in primer cap 7. The firing pin of striker upon being driven into the primer charge dashes the primer, which in turn ignites an underlying end of the lead spitter fuse 11. The lead spitter fuse 11 formed of black powder and collodion compressed in a lead tube burns to its opposite end in a period of about l to 5 seconds, giving a desired delay action, which permits the bomb to penetrate the target surface fairly heavy roof constructions, including common sheet metal and tile roofs, and if desired, also to penetrate one or more iloorings in a building during the delay in the lead spitter fuse, which permits the bomb to penetrate such structures and fall to rest on its side before functioning.
Referring to Fig. 5, the safety plunger assembly lil is of a type which has been manufactured for use in standardized thermit incendiary bombs, but an easily made modification is desirable on account of the relatively small distance of travel of the hinged striker in the fuze illustrated in Figs. 1 and 5. Safety plunger assembly 1t) comprises a thin-walled sleeve 27 formed of brass, guild-V ing metal, or the like, for housing a coil spring 2S under compression and the stem 29 of a plunger pin. The plunger pin has a flange 36 which bears against one end of the coil spring 2S and prevents the plunger pin from being entirely ejected from the sleeve 27. In the unarmed position, the plunger pin has a button end 33t projecting outside the sleeve 27, and in an armed position, the plunger pin is pressed inwardly against the coil spring 28 so that the narrow end of the stern 29 of the plunger pin opposite the button end 31 projects into the fuze underneath the striker 8 to prevent movement thereof. A thin washer 32, itted closely around the plunger pin stern 29 between the spring 28 and the inner end of the sleeve 27 reduces the hole diameter at this end of the sleeve and thereby gives better control of the plunger movement. The fuze is maintained unarmed by pressure of an adjacent bomb in a cluster against the button 31 of the plunger pin.
The ignited first ire charge 12 ignites the ignitingpropellant charge 4 adjacent the fuze unit 3, and explosion of the propellant powder causes an immediateincrease in pressure which lifts the impact diaphragm plug 15, ruptures the sealing diaphragm 17 forces out of the tail cup 22, and violently ejects the mass of thickened fuel charge enclosed in the sock as a single flaming projectile with suicient force to Ysend it 25 to 200 feet or farther, or to where it is generally intercepted by an upright lstructure such as the wallor eaves of a building.
4of the propellant charge.
The ejection mechanism depends on Vthe ability of burning propellant powder in the charge i to create suicient pressure in the explosion chamber confined within the nose cup 2 to shear the sealing diaphragm 17, and shoot out the fuel charge from-the tail end of the bomb so that the bomb acts like a mortar, with the fuel charge being ejected by its own piston action. lt has been found that if the impact diaphragm plug 15 is made wide,
enough to fit so that its periphery is close to the inner wall of casing l to have a piston action, that the plug tends to disrupt the casing when it is lifted by the propellant charge explosion; also, such a closely tted diaphragm would be prevented from moving by small deformations in the casing 1, such as may result from slight buckling upon impact. Accordingly, a substantial clearance is provided between the diaphragm plug 15 and the inner wall ofthe casing 1. Satisfactory performance is obtained by having the impact diaphragm plug 15 in the form of a dished plate about 0.2 inch thick resting Von diaphragm disc 16 over the central hole `about 1.5 inches in diameter in this disc and arched toward the tail. The thin sealing diaphragm 17 Vfits snugly over the impact diaphragm plug 15, the impact diaphragm, and nose cup 2. The sealing diaphragm 17 may not have suicient Y by diaphragm plug 15 and diaphragm 16. The impact diaphragm plug 15 acts somewhat in the fashion of a check valve which is opened by the explosive pressure An asbestos gasket 26 may be placed under the diaphragm plug 15 to keep it from being fused to itsY seat on diaphragm le, and the arrange- Y ment is such thatv the-impact diaphragm plug 1S is held in its proper position. f
f The cloth sock 19 made'of cheesecloth has adequate mechanical strength to remain as an intact enclosure of the entire fuel charge during ejection; moreover, the sock improves ignition and helps to give the desired distribution, since it holds the Vfuel together to start ignition of the entire mass and allows the burning fuel'to spread out as a large gob over. the surface of a structure hit by the sock enclosed charge where the sock is finally broken. j i
From a largenumber of tests it was found that the use of a cloth sock for enclosing a viscid oil incendiary charge in the tail ejection type bomb of the present invention is highly advantageous for obtaining complete ejection, positive ignition, and good distribution of the ejected fuel charge. Although the cloth sock may be made from various fabrics, it is preferably made from a loosely woven material, such as, a netting, gauze,'or cheesecloth. A suitable cheesecloth is covered in Federal Specication CCC-C-271; Type 1 (unbleached) with a warp thread count 36, Vfilling thread count 23; approximate weight of 14 lbs. per yard; width of 36V inches; and known commercially as Grade 50 cheesecloth. The size of the sock depends upon the measurements of the bomb.
The sock is made with simplicity and is preferably oversize relative to the volume of the filling. Preferably the sock should be of such length so that its top can be folded over the top of the bomb casing 1 with the tail cup 22 removed during the lling operation.
For a 5-1b. bomb, 14%/2 inches long and 3 inches in diameter, the cheesecloth is cut into swatches of 18 inches by 121/2 inches. The cloth is folded once lengthwise and machine stitched along the bottom and along one side j to form a long bag having a distance of about 5% inches from fold to seam. The sock need not be turned inside out. After illing withrfuel in the bomb, leaving an out- 'age space of about 5% to 8%, the top of the bag is tied closed by ystring 21.
lMany types of thickened and gelled fuels may be used with the sock enclosure in tail ejection bombs. The fuel should have a 'consistency which is not too thin with a ltendency 'to "excessive flash burning nor too hard with a and type of propellant powder.
tendency to rebound upon striking a hard surface. Brieiiy, among types of viscid fuels which may be used are:
Fuels gelled by soaps;
Fuels gelled or thickened by resins, e. g., rubber, polybutenes, isobutyl methacrylate, etc.;
Fuels thickened by gums or other resnous materials, e. g.,
rosin, asphalt, and the like; and
Fuels thickened by mixtures of soaps and resin.
A preferred type of gelled fuel may be made by admixing with naphtha hydrocarbons about 7 to 14% by weight of coprecipitated aluminum soaps of stearic acid and oleic acid, or mixtures of such soaps with soaps of other acids, such as, cocoanut oil fatty acids, and naphthenic acids. The gelled or thickened fuels may include fuel oils less volatile than gasoline, such as, kerosene and even viscous residual oils. They may contain in suspensionnely divided pyrophoric metals, such as powdered magnesium, oxidizing agents, wood meal, carbon, sodium, or other combustion promoting substances. Such incendiary oils on combustion can develop much more heat than burning thermit mixtures compared on the same weight basis.
Fibrous materials, such as, cotton waste, sisal, excelsior, and the like, to some extent act as binders when added to an incendiary oil fuel, but the use of these binders is not necessary when the fuel is enclosed in a cloth sock and particularly when the fuel is heaved from a tail ejection bomb horizontally.
in demonstration tests and in practical bombs, a number 4 primer cap was used in the fuse 3 with a l to 5 second delay lead spitter fuse. The first fire charge 12 was about l gram of Army Grade A No. 4 glazed black powder. The ignition-ejection charge placed in each bomb was about 4 to 7 e. g. of powdered magnesium coated with about 3% boiled linseed oil and about 4 to 7 g. of Grade A No. 4 Army glazed black powder. The primer cap is covered in U. S. Army Specification (Primer New No. 4), a type of primer commercially manufactured for smokeless powder shot shells. The lead spitter fuse is a commercial type of fuse cut into about 'Ma inch lengths.
From studies of many tests it was found that between about 2 and 21/2 lbs. of incendiary oil charge is an optimum quantity in each bomb for starting fires in typical structures. The incident of effective lire starting decreased rapidly in reducing the quantity of charge below this range, whereas the use of larger quantities was found unnecessary. The casing and the firing mechanism in the bomb can be appropriately designed for efficient clustering, suitable ballistics, and target penetration with an optimum quantity of the fuel charge in the bomb.
Efficient ejection is obtained generally with the following relationship of diaphragm strength, tail cup release pressure, powder charge and fuel viscosity:
Diaphragm (sealing) thickness, about 0.008 inch (about 400 to 500 lb./ sq. in. rupture pressure resistance).
Tail cup release pressure, about 100 to 150 lb./sq. in.
Black powder charge, about 4 to 14 g.
Magnesium powder charge, about 4 to 7 g.
Fuel viscosity for sock inclosed charge, about 300 to 2000 g. Gardner.
Volume ratio of powder chamber to propellant powder charge, less than :1.
The kind of ejection may be varied with the amount A typical composition of black powder is about 75 weight percent potassium nitrate, 15% charcoal, and about 10% sulfur. Differences in granulation and surface characteristics of the powder affect changes in the speed of burning and rate of pressure development.
in practical tail ejection bombs designed to hold optimum quantities of an incendiary oil charge, too low an amount of propellant powder, less than about 4 g.,
develops insufficient pressure to properly eject the incendiary charge; whereas amounts of propellant powder larger than about 14 g. tend to develop excessive pressures. Various igniting materials may be added to the propellant powder charge to act as a source of hot particles for ignitng the incendiary oil charge as it is being ejected. Powdered magnesium was found to be a very satisfactory igniting material, particularly when coated with boiled linseed oil and to give close to ignition over a complete temperature range from minus 40 F. to about 150 F. Other igniting materials may be used such as powdered aluminum with an admixture of oxidizing and promoting substances, such as barium nitrate and sulfur.
With the thin-walled casing having a substantially uniform polygonal, preferably hexagonal, cross-section from its nose to its tail, except for a slight crimping with a single seam at the tail end, the bomb has a high loading and ejection ehciency. With this shape, an extensible flight stabilizer, and suitably disposed fuse having a safety plunger, the' bomb is adapted for efficient clustering with standardized aimable clustering means.
The tail ejection bomb may be provided with a delayed action anti-personnel element or burster to discourage approach by firefighters and increase damage in the vicinity of the bomb. A suitable burster or fragmentation unit is illustrated in Fig. 6.
Referring to Fig. 6, fixed into the casing 1 under the nose cup 2, which holds the fuse and powder charge, is a delay fuse cup 32 for holding. a helically wound delay fuse 33 in varying lengths. The delay fuse 33 may be of a standard type, such as, the .7Crescent fuse manu-v factured by the Ensign Bickford Co., Simsbury, Connecticut, otherwise known as Miners safety fuse, which gives time delays of 30 to 90 seconds per foot. l This type of fuse gives more satisfactory performance if dried to reduce its moisture contents to less than about 2% and preferably to less than 1.7%, although ordinarily it has on an average 3.5% moisture. The moisture resistance of the delay fuse may be further improved by replacing the'usual fibrous jute covering of the powder train by a material, such as, glass, wool, asbestos, nylon, or the like, which does not absorb moisture. At the initial igniting end, the fuse is in firm contact with a quick match composition 35, such as formed of Army black powder, Grade A No. 6, and collodion. This composition in turn is in iirm contact with a short iength of Navy quickmatch which is readily ignited by the flame generated by the explosion in the nose cup 2 and transmitted to the Navy quick-match by a flash hole %2" in diameter. The delay fuse and Navy quick-match junction is maintained by a suitable crimp. At the other end, the delay fuse is secured in contact with a detonator 36 e. g., a tube containing lead azide, by crimping to a detonator holder sleeve 37 fixed by crimping to the bottom of the delay fuse cup 32. The lower part of the detonator 36 is surrounded by a high explosive filling 35i, such as tetryl or TNT, contained in the end cup 39. The end cup 39 is forced with a press fit snugly into an adapted sleeve 40, which is brazed to the end of the casing l. A rubber gasket 41 may be placed betweenvthe upper edge of the cup 39 and the bottom of the powder chamber cup 2. A strip of'metal 42 fitted into the top of the delay fuse holder cup 32. serves to keep the coiled delay fuse 33 in place and to position the Navy quick-match end under a vent hole in the bottom of nose cup 2.
With the added feature of a fragmentation unit, the bomb functions efliciently to first eject its incendiary or chemical charge.
The tail ejection bomb, based on the principles set forth by this invention, may be modified in various respects, as for example, in the construction of the fuze for setting off a propellant charge, the housing of the fuse and propellant powder charge, the design of the ight stabilizing 7 sembly'at the tail end of the bomb and the nature of the arge. The described tail ejection bomb, also, is adapted for .arging with various other chemical agents, such as, white xosphorus, liquid vesicants, or solid agents in powdered rm. The action of the tail ejection bombs in penetrating a rget has been described. In landing on earth instead of 1 unyielding structure, the bombs tend to sink into the 'ou'nd to the extent of several inches, depending on the lrdness of the ground, since the fuze action is not inantancous; and, in general, they tend to be tilted to some :tent from a vertical position when they discharge their lemical contents to set up a high concentration of the ected charge.
In contrast to the scatter type of chemical bombs, there a far reaching distribution of the charge from the tail ection bomb over the surrounding area instead of'a crasring and excessive discharge within a limited area just round the place where bomb lands. Also, in contrast to :atter type bombs hitherto known, the tail ejection type omb of the present invention gives the more desirable rojection of the chemical r'illing Without the need of a omplicated fuze or high explosive burster that requires large amount of critical high explosive, and is more uitable for clustering'to obtain pattern bombing.
While this invention pertains to an assembly of co- `perative components for accomplishing the objects set orth, it is not concerned specifically with any particular ype of fuze mechanism, fuze housing construction, tail asembly construction, or manner of loading with a chemical 111er. hat each of these component parts of the tail ejection )omb is subject to modications.
The fuze construction illustrated in Figs. 1 and 6 forms ubject matter claimed in an application by Lyle M.
It has been indicated in the foregoing description Y ooper, Serial No. 562,370, led November 7, 1944, now l' ?atent 2,666,389, granted January 19. 1945. The cloth sock loading of incendiary oil is subject matter claimed n an application filed November 7, 1944, by Francis R. Russell and William T. Knox, Ir., Serial No. 562,369. tt is to be understood that other modifications and variaions may be carried out without departing from the spirit and scope ofthe invention as dened by the appended claim.
We claim: Y A tailejection bomb; comprising a thin-walled elongated casing hexagonal incrossfsection with a length Yto width as a propellant charge adjacent the fuze in the nose cup,V
a rupturablesealing diaphragm closure for space conned surrounding the fuze and propellant powder container so that the volume of Vthis space is no greater than 10 times the volume of the propellant powder, a thin-walled cup hexagonal in cross-section crimped at the edge of its side walls to the tail end of the casing to be released by development of up to about 150 lbs. per sq. inch pres# sure inside the casing by explosion ofV the propellant powder, an extensible flight stabilizing means attached to the tail cup and normally compressed therein, and a chemical agent lling in the casing between said sealing diaphragm and the tail cup.
Referencescited in the le of this patent UNITED STATES PATENTS 1,005,578 Schneider Oct. 10, 1911 1,276,635 Foxworth Aug. 20, 1918 1,305,751 Stearns V June 3, 1919 1,326,258 Graumann Dec. 30, 1919 1,484,190 Ray Feb. 19, 1924 2,119,697 Anderson June 7, 1938 2,217,645 De Wilde etal. Oct. 8, 1940 2,247,111 Batchelor et al. June 24, 1941 FOREIGN PATENTS 18,569 Great Britain of 1899 121,045 Great Britain Dec. 5, 1918 307,149 Germany Feb. 6, 1920 616,917 France Nov. 6, 1926 711,463 France June 30, 1931