US2986072A - Liquid fuel catapult - Google Patents

Description

2 Sheets-Sheet 2 c. M. HUDSON LIQUID FUEL CATAPUL'I' IEF.

V/ a v/ ///7// May 30, 1961 Filed. Nov. 19. 1952 m m M a md W W u 4 1H J 2 6 n 3 3 PM 6N 7/ 5 Guam W W z m n in 2 \3 1 "I; I

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ATTORNEYS 2,986,072 LIQUID FUEL CATAPULT Colin M. Hudson, Arlington, Va., assignor to the United States of America as represented by the Secretary of the Army Filed Nov. 19, 1952, Ser. No. 321,534

1 Claim. 01. 89-7) (Granted under Title as, on. Code (1952), sec. 266) The invention described in the specification and claim may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to guns and in particular to a novel system for propelling projectiles from gun barrels or tubes.

In a gun, when the charge is fired, the gas pressure immediately begins to rise in the powder chamber. The projectile at first remains stationary because of the friction fit with the bore but beyond a certain pressure the friction bond is broken an the projectile begins to move forward in the bore. This movement tends to relieve the pressure by increasing the volume within which the gases may expand. But the burning of the charge is not instantaneous and the powder continues to burn and evolve gases as the projectile moves. As long as the projectile is in the bore it is acted upon by a fairly high pressure which reaches a maximum at some point between its original position and the muzzleand functions as an accelerating force. The point in the bore at which the projectile is driven by maximum pressure is determined by a number of factors and in many of the prior art guns this point is about a foot in advance of the powder chamber. As will later more fully be explained my invention will yield a substantial advance in the art of propellants by providing a controlled rate of pressure generation leading to higher projectile velocities at lower peak pressure.

It is a broad object of my invention to improve on the weapons now in use.

It is a further and more particular object of my invention to provide a system for propelling projectiles in which highly reactive liquid chemicals are used in place of the conventional solid propellants.

It is a still further object of my invention to provide a reactive chemical Weapon which is completely safe to op crate, and is reliable in use.

Other objects of the invention will be evident from the following description and the appended drawings in which:

Figure 1 is a fragmentary longitudinal section view of my novel weapon.

Figure 2 is a section view taken along lines 2-2 of Figure 1 and looking in the direction of the arrows.

Figure 3 is a section view taken along lines 3-3 of Figure 1 and looking in the direction of the arrows.

Figure 4 is a fragmentary longitudinal section view of another species of my novel weapon.

Figure 5 is a section view taken on lines 5-5 of Figure 4 and looking in the direction of the arrows.

Figure 6 is a fragmentary longitudinal section view of still another species of my invention.

Figure 7 is a section view taken on lines 7--7 of Figure 6 and looking in the direction of the arrows.

Described briefly my invention consists of a system whereby self igniting chemicals may be intimately intermixed so that their spontaneous reaction produces the pressures for projectile ejection and flight.

In the specification and in the claim appended thereto the word "hypergolic is intended to be used as defined in the Defense Departments Glossary of Guided Missile Terms, Capable of igniting spontaneously upon contact.

Refening now more particularly to Figure 1, wherein a cartridge is used for the pressure source reference character 1 indicates generally a breech block having at the forward end thereof a barrel or tube 2 threadedly received in a cavity and aligned with a combustion chamber 3. Passages 4 and 5 lead from chamber 3 on opposed sides thereof and hold cylinders 6 therein. The cylinders are each provided with an orifice 9 in the end wall proximate the combustion chamber which orifice is normally covered with a frangible plug, and have a piston 7 for a purpose that will presently appear. The bores 4 and 5 are closed at their distal ends by plugs 12 which may be removed to insert the cylinders in a loading operation. Leading rearwardly from the outer portion of bores 4 and 5 are two arms 13, 14 of a forked cavity terminating in a cartridge chamber having nested therein a cartridge 15; A plug 16 slidable in breech block 1 has a lifting eye 17 thereon and carries a spring biased firing pin 18 so ar-f ranged that when the plug is properly seated in the breech block the firing pin is aligned with the primer in the cartridge.

The several injector cylinders 6 are adapted to receive the hypergolic fluids. In general a reactive fuel 19 is contained in one cylinder and an oxidizer 20 is contained in the other. Specific examples of such combinations that have been successfully used are hydrazine (N H with hydrogen peroxide (H 0 and hydrazine with nitric acid. It will be understood however that the above examples are illustrative only and my invention contem plates the use of any and all substances and compounds that react spontaneously and violently upon contact.

It can be readily seen that upon firing of the cartridge 15 by moving firing pin 18 forward, the gases of combustion create a high pressure in passages. 13 and 14 and transmit same to the outer faces of pistons 7. The pistons will urge inwardly upon the confined hypergolic fuel 19 and oxidizer 20 fracturing the frangible covering over the orifices 9 and the several liquids will empty there through and intermingle within combustion chamber 3 with a resultant spontaneous chemical reaction and the production of a high pressure to force projectile 21 out of the barrel.

Attention is now directed to Figures 4 and 5 wherein a variant of my novel weapon is revealed. Reference character 22 indicates a breech block having at the forward end thereof a barrel 23 threadedly receivedin a cavity and aligned with passageway 24 which is selectively closed by sliding plate 29. A traverse passage in tersects passage 24 to form a combustion chamber 30. On opposed sides of the chamber are slidable injector pistons 31 and 32 having ports 33 and 34 in the closed ends thereof and constructed to slidably receive bosses 35 and 36 formed on the ends of plugs 37 and 38 respectively. Pipe line 39 having a one way check valve 40 serves to connect with a pressurized source containing one of the hypergolic fluids and to a bore in plug 37; and pipe line 41 having a one way check valve 42 serves to connect a pressurized source of the other reactant to a bore in plug 38.

The weapon is illustrated in condition for firingand a cycle thereof will now be described. A valve (not shown) is triggered which simultaneously admits metered amounts of the hypergolic fluids at a high pressure into pipes 39 and 41 respectively. The reactants will quickly fill the volumes between boss 35 and cylinder 31 and between boss 36 and cylinder 32 and a portion of each will be ejected through ports 33 and 34 into combustion chamber 30 where they will meet and intermingle to create a pressure. This pressure acting upon the exposed face of cylinders 31 and 32 will force them toward bosses 35 and 36 respectively thus emptying the filled volumes into. the combustion chamber with great force and the resulting explosion willsend projectile 28 upon its trajectory. .It.

should be noted that the area of the cylinder face exposed to combustion chamber pressure is greater than the area of the cylinder-face exposed to the fluid pressure. Thus a regenerative piston effect is obtained and the pressure of the fluid can be greater than the initial pressure in the chamber but the resultant force will still move thepistonback forcing the reactant therein into the chamber.

. After .the projectile has leftthe muzzle of the barrel the chamber pressure drops and the cylinders are returned to their forward position by expansion of the trapped air compressed behind the open ends of the cylinders during rearward motion thereof and a projectile feeding mechanism (not shown) lifts sealing block 29 up and forces a new projectile into the barrel ready for the next shot.

It can be readily seen that the amount of propellant is readily controlled by limiting the amounts fed to the pistons or limiting the motion thereof whereby the point of maximum pressure acting on the projectile may be adjusted. Also the rate of propellant injection may be controlled by proper selection of piston face areas.

Another species of my invention is disclosed in Figures 6 and 7. Reference character45 indicates generally a breech block secured to barrel 4.6 which is shaped to form a chamber to receive a novel arrangement of the hypergolic fluids. A metallic casing holding a primer54 at thev rear thereof holds the hypergolic liquids in combustible elongated containers arranged longitudinally within the casing with each liquid sandwiched between two dissimilar ones substantially as shown in Figure 7 wherein, for example, reference characters 47, 49 and 51 indicate a reactive fuel and 48, 50 and 52 indicate an oxidizer. A projectile '53 is frictionally held in the barrel and a firing pin 55 is aligned with the primer 54 in the usual manner. I

' When the firing pin explodes the primer the flame moves down the longitudinal axis of the chamber and destroys the containers. The hypergolic liquids thereupon mix and the resulting reaction ejects the projectile from the barrel.

Among the advantages offhgabove described invention are: (1) higher propellant s by reason of the lowered propellant gas molec';

,l (roo which are obtainable with such reactant combinations as such mixtures, (2) controlled rate of pressure generationby control over propellant injection rates, leading to higher velocities at lower peak pressures, and (3) comparable velocities at lower ratios of propellant to projectile weight by reason of the above, so that less propellant and chamber volume is required resulting in a shorter gun.

An extensive series of firings has been conducted on a gun built in accordance with the principles set out in this invention. A projectile velocity of 6200 ft./sec.' at a propellant'to projectile mass ratio of 3.6 was obtained: For a propellant to projectile mass ratio of 1.5 the maxi mum velocities exceeded nitrocellulose values by'as much as 20% at comparable or lower chamber pressures. Velocities as high as 8700 ft./sec. have been attained at substantially lower peak pressures than published figures for nitrocellulose powder.

In a general manner I have in the above description disclosed what I deem to be practical and efiicient embodiments of the present invention. It should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principles of the present invention as comprehended 'within the scope of the accompanying claim.

I claim:' 4 i A firearm comprising a breech casing, a barrel afiixed to said breech casing, a combustion chamber formed in said casing and communicating with said barrel, at least two opposed bores in said casing one end of which corn-. municates with said combustion chamber, a counterbore at the other end of said bores, hollow injection cylinders fixedly received within said counterbores, said cylinders containing a predetermined volume of hypergolic reactants and having at one end thereof a normally sealed orifice opening into said bores, a piston at the other end of said cylinders, a pressure generating cartridge received within said casing, a series of passages in said casing communicating between said pistons and said cartridge, whereby said pistons are actuated to break said seal and inject said reactants into said combustion chamber in response to firing said cartridge.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,017 Peake Aug. 14, 1934 2,573,471 Malina et 'al. Oct. 30, 1951 FOREIGN PATENTS 164,697 Great Britain June 9, 1921 405,645 Great Britain Jan. 29, 1934 1,003,687 France Nov. 21, 1951 OTHER REFERENCES Journal of the American Rocket Society, No. 72, December 1947, Liquid Propellant Rocket .Power Plants by Dr. M. I. Zucrow, pages 31-932. (Copy in Div. 46.)

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