1. Field of the Invention
This invention relates to a means for propelling a projectile at relatively high muzzle velocities using light gas as the working fluid and increasing range and lethality while minimizing visible and acoustic signatures.
2. Description of the Prior Art
Hypervelocity guns have been used since the late 1940s for impact and strength of materials research. These guns use light gases, primarily hydrogen, as the working fluid to propel projectiles at speed ranging from 5 to 30 thousand feet per second. Much of the development of the guns is centered on improving the light gas propellant delivery to the breech. Single stage, two stage, and three stage pistons schema have been proposed, most with the intention of ever higher muzzle velocities.
Koth, U.S. Pat. No. 7,954,413, proposes an improved two-stage light gas gun for launching projectiles at high speeds. The gun consists of three tubes: the expansion, pump, and launch tubes. The expansion tube contains a close-fitting expansion piston that is propelled by an explosive charge. The expansion piston in turn drives the pump piston housed within the pump tube by means of a rod connecting the two pistons. The action of the pump piston adiabatically compresses and heats a light gas of hydrogen or helium, bursting a diaphragm at a predetermined pressure and expelling the projectile from the launch tube at a very high speed. These combustion products can cause fouling of the pump tube, making it impractical to convert the design to a fieldable weapon system. It also uses a single use diaphragm, making rapid fire difficult.
Guthrie, et al, U.S. Pat. No. 5,303,633, proposes a shock compression jet gun with associated explosive charge assembly. The shock compression jet gun features a breech for storage of the explosive charge assembly, a projectile tube, and an expansion nozzle disposed between the breech and projectile tube. The expansion nozzle includes converging and diverging passageways. The explosive charge assembly includes a shock absorbing outer casing, a detonator, a shaped charge positioned within the casing and a compressible medium retained within a recess formed in the shaped charge. The compressible medium is maintained within the recess by way of a membrane sealing one end of the casing. In a preferred embodiment the compressible medium is a liquid such as ammonia, water or a mixture of liquid ammonia and water which dissociate(s) into a mixture of light gases upon detonation of the shaped charge. The design has elements that would lend itself to large guns such as artillery or naval guns, but would still be difficult to transition to a man-portable weapon. In addition, the corrosive nature of anhydrous ammonia or water would create severe wear within the breech, making the fielded system unreliable and decreasing maintainability.
Mcdermott, U.S. Pat. No. 7,775,148, proposes launching payloads at high velocity uses high-pressure gas or combustion products for propulsion, with injection of high pressure gas at intervals along the path behind the payload projectile as it accelerates along the barrel of the launcher. An inner barrel has an interior diameter equal to the projectile diameter or sabot containing the projectile. An outer casing surrounds the inner barrel. Structures at intervals attach the outer casing and the inner barrel. An axial gas containment chamber (AGC) stores high pressure gas between the inner barrel wall, the outer casing wall, and enclosure bulkheads. Pressure-activated valves along the barrel sequentially release the high pressure gas contained in the AGC in to the barrel to create a continuously refreshed high energy pressure heads behind the projectile as it moves down the barrel. A frangible cover at the exit end of the barrel allows the barrel to be evacuated prior to launch. The launcher is rapidly recyclable. The valves close automatically after the projectile has exited the barrel, allowing a new projectile to be introduced into the breech and the AGC to be recharged with high-pressure gas. The system is designed as a launch system that can be rapidly reconfigured for launch. The complexity of the system and the necessity of evacuating the barrel preclude its use as a fieldable weapon system.
Kremeyer, U.S. Pat. No. 8,141,811; proposes modifying a shock wave in a gas by emitting energy to form an extended path in the gas; heating gas along the path to form a volume of heated gas expanding outwardly from the path; and directing a path. The volume of heated gas passes through the shock wave and modifies the shock wave. This eliminates or reduces a pressure difference between gas on opposite sides of the shock wave. Electromagnetic, microwaves and/or electric discharge can be used to heat the gas along the path. This application has uses in reducing the drag on a body passing through the gas, noise reduction, controlling amount of gas into a propulsion system, and steering a body through the gas. An apparatus is also disclosed. The solution requires considerable hardware be added to the projectile, making it unsuitable for a small caliber round. The energy and resultant energy generation or storage required to drive the emitters also outweighs any benefit derived from the reduction in drag.
None of the systems described in the prior art is adaptable to a man-carried weapon system. Each has limitations that preclude sustained rates of fire, light weight, and the simplicity and reliability necessary for a weapon system.
The light gas gun of this invention is a compressed gas weapon or launcher that uses helium or hydrogen as the working fluid. The light gas gun described herein provides a unique and potentially devastating weapon that will provide the operator greater range, superior lethality, more stealth, and ultimately greater survivability than any other weapon of its kind. The gun is designed to provide muzzle velocities greater than any conventional firearm of the same caliber currently in use. Two embodiments are capable of firing standard caliber projectiles, but using the unique projectile assembly maintains projectile velocity much farther than conventional rounds, significantly increasing range and lethality.
The gun of this invention consists of five primary elements: the frictionless barrel assembly, the breech assembly, the projectile assembly, the muzzle valve assembly, and the light gas that is used as the propellant. The barrel assembly uses gas bearings to minimize projectile assembly contact with the barrel walls. The gas bearings virtually eliminate friction with the barrel, thus greatly reducing barrel wear. Given the substantially increased muzzle velocities capable with a light gas gun, this is an enabling feature.
The breech assembly includes the trigger valve, a receiver locking bolt 17, used in loading the round, the breech where the projectile is held prior to firing the gun, and a means of providing high pressure light gas propellant. Propellant can be provided by any number of means, including a simple reservoir, or using mechanically, combustion, or gas driven pistons.
The projectile assembly is a center-of-pressure/center-of-gravity (CP/CG) stabilized round, capable of storing light gas and injecting the light gas into the boundary layer as the round travels downrange. The shape of the round and the material of construction enable a ballistically stable projectile superior to standard firearm rounds.
Each of the embodiments of this invention incorporates a means of firing the weapon with the barrel filled with light gas. This creates an environment where the internal ballistics of the gun are governed by the properties of the light gas. Because the speed of sound is substantially higher for light gases, all the internal ballistics are subsonic, greatly increasing efficiency of the gun. This is accomplished by either purging the gun barrel with light gas immediately prior to firing the gun or by continually maintaining a positive light gas pressure in the gun using a muzzle valve assembly. By using the muzzle valve assembly, the majority of propellant gases can be routed through a suppression canister, reducing the acoustic signature of the gun.
All of these elements combined enable a gun that can be adapted to use as a very powerful handgun, a sniper rifle with exceptional performance, artillery with extreme range, a naval gun uniquely adapted to surface warfare, or even an orbital launch system that eliminates the first stage booster.
The fourth embodiment of this invention enables a sniper rifle with a muzzle velocity 30 percent greater than weapons currently in use with no muzzle flash and an acoustic signature of less than 80 db. This would provide stealth to special operations soldiers and snipers. In addition, the projectile assembly would increase the range of the weapon system by more than 50 percent.
When scaled up to artillery or naval guns, the same benefits would apply. Increased muzzle velocity and range would put artillery well behind the forward edge of battle, beyond counterbattery fire. The reach of naval guns would enable longer standoff distances or enable naval guns to reach targets well beyond standard naval guns. The reduced acoustic signature would reduce the acoustic hazard associated with large guns.
The invention can also be used to accelerate a rocket and it's payload, eliminating the first stage booster. Such a scheme would eliminate refurbishment of the launch pad, could be reconstituted in hours, as well as eliminating the expense of the first stage booster.
The first object of this invention is to improve efficiency by using a light gas atmosphere in the barrel in front of the projectile, reducing the energy required to propel the projectile out of the barrel.
A second object of this invention is to improved efficiency by using a gas bearing in the barrel wall to virtually eliminate friction in the barrel, eliminating barrel wear, and reducing the requirement for high peak pressures in the barrel.
A third object of this invention is to increased muzzle velocities by using light gas as a propellant in a gun that can be made man-portable.
A fourth object of this invention is to reduce the acoustic signature of the light gas gun to levels well below those of conventional firearms.
A fifth object of this invention is to increase the range of the gun by significantly increasing the muzzle velocity of the gun as compared to conventional firearms.
A sixth object of this invention is to increase range by reducing the drag on the projectile.
A seventh object of this invention is to increase the energy on target for a given range, as compared to comparable firearms.
An eighth object of this invention is to reduce the acoustic signature of the projectile downrange.
A ninth object of this invention is to improve reliability of the gun by reducing possible outside contaminants such as dirt and sand from entering the gun.
A tenth object of this invention is to increase accuracy of the gun by eliminating second and third order effects that impact standard firearms.
A final object of this invention is to reduce the muzzle flash by using a non-combusted light gas as a propellant.
Aft Projectile Body. The rearward piece of the projectile assembly that contains the spring loaded valve and the projectile spring. The aft projectile body is hollow and threaded into the forward projectile body. Assembled, they make up the projectile assembly.
Barrel Assembly. A two piece barrel made up of an inner tube and an outer tube. The inner tube is press fit into the outer tube and has channels cut into the outer diameter and holes drilled in the channels that allow light gas to flow down the barrel and into the interior of the inner tube, acting as gas bearings to keep the round centered in the barrel.
Breech. The cylindrical cavity where the projectile or projectile assembly rests prior to firing the light gas gun.
Breech Assembly. Made up of the breech body, the receiver locking bolt, the trigger valve, and the receiver safety. The breech assembly is mechanically connected to the barrel assembly on the front or muzzle end and to the light gas source.
Breech Assembly Body. The part to which the receiver locking bolt, trigger valve, receiver safety, and barrel assembly are connected. The breech is bored into the breech assembly body and aligned with the barrel assembly.
Channel. Rectangular grooves milled into the outside wall of the inner tube to allow light gas to flow the length of the barrel, supplying gas to the gas bearing ports drilled into the bottom of the channels. Channels are milled at angles in embodiment one and three in order to create a vortex to spin stabilize the round, but normal to the outside wall for embodiments two and four where spin stabilization is not required.
CO2 Piston. The driving piston in the dual piston assembly shown in embodiment four, and part of the best mode. Larger in diameter than the light gas piston so as to multiply the force on the light gas piston. In addition to using high pressure CO2, it is assisted by a pressure boosting spring.
Dual Piston Assembly. The mechanism that provides the light gas propellant to the breech assembly in embodiment four. It consists of a CO2 piston, a light gas piston, mechanisms for actuating the assembly, and the necessary gas connections and vents to prepare the assembly for firing.
Forward Projectile Body. The forward piece of the projectile assembly, threaded to accept the aft projectile body, and bored down the centerline to provide a path for light gas to the meplat of the round.
Gas Bearings. Holes in the inner tube, aligned the length of the barrel, equally spaced around the circumference of the inner tube, and connected by channels running from the breech end of the inner tube to just shy of the muzzle end of the inner tube. The gas bearings direct high pressure light gas axially inward, toward the round, keeping it centered in the inner tube.
Gas Bearing Port. One of the holes drilled in the inner tube that directs light gas toward the projectile.
Gas Directing Tube. The hole bored into the forward projectile body to direct light gas to the meplat of the round, ensuring sufficient light gas flow into the boundary layer at the front of the round.
Inner Tube. The interior cylinder of the barrel assembly, press fit into the outer tube, with channels milled the length of the tube and gas bearing ports drilled at specified distances, centered in the channels.
Leaf Bore. A hole bored in the muzzle valve leaf that allows the round to exit the light gas gun when aligned with the barrel assembly bore and the other muzzle valve leaves.
Light Gas. Elemental helium or molecular hydrogen.
Light Gas Piston. The piston that compresses the light gas used as the propellant in embodiment four. Driven by the CO2 piston. It is also used to reset the CO2 piston after firing by venting the gas in the CO2 piston and driving both pistons and compressing the pressure boosting spring back to their firing position with light gas from the supply source.
Muzzle Valve. The valve that opens to allow the round to exit the light gas gun and closes to retain unused light gas. The muzzle valve and opposing multi-leaf valve are used interchangeably in embodiment four. The opposing multi-leaf valve is a specific type of muzzle valve.
Muzzle Valve Assembly. Consists of a muzzle valve body, a muzzle valve, a plurality of muzzle vent valves, hydraulic actuators to drive the muzzle valve, and a suppression canister. The assembly seals the light gas gun in order to hold a positive pressure in the breech and barrel. Opens the muzzle valve to allow the round to exit and to vent propellant gases to the atmosphere through the suppression canister. The muzzle valve assembly is mechanically connected to the barrel assembly on the muzzle end.
Muzzle Valve Body. The structure to which all other muzzle valve components are attached.
Muzzle Valve Chamber. The space between the end of the barrel assembly and the muzzle valve where propellant light gas is directed to the muzzle vent valves.
Muzzle Valve Leaf. A component of the specific opposing multi-leaf valve used in embodiments three and four. A plurality of the leaves are used to allow the round to leave the light gas gun when they are hydraulically driven together to align the holes bored in the individual leaves with the bore of the barrel. When hydraulic pressure is released, the leaves are then reset by springs that drive them back into their pre-fire positions, sealing the muzzle.
Muzzle Vent Valve. A small pressure relief valve that opens whenever pressure in the muzzle chamber rises above a predetermined level. The muzzle vent valve vents to the atmosphere through the suppression chamber.
Opposing Multi-Leaf Valve. The specific type of muzzle valve used in the third and fourth embodiments, designed to minimize the impulse imparted to the light gas gun while opening and closing. May be used interchangeably with muzzle valve.
Outer Tube. The exterior cylinder of the barrel assembly. Attached to the breech assembly and, in embodiments three and four, the muzzle valve assembly. The inner tube is press fit into the outer tube.
Projectile. A standard caliber bullet or artillery round
Projectile Assembly. A specialized bullet that stores high pressure light gas that it injects into the boundary layer as the bullet travels downrange.
Projectile Spring. The spring in the projectile assembly that keeps the spring loaded valve seated. The spring is compressed when external pressure exceeds the projectile assembly internal pressure plus the compression strength of the spring, opening the spring loaded valve. When the pressures are equalized the spring loaded valve closes.
Purge Valve. A valve that is triggered in the firing sequence to put medium pressure light gas into the front of the breech. The light gas flows long enough to ensure the barrel is clear of air and filled with light gas. The valve closes as the trigger valve opens.
Receiver Locking Bolt. The mechanism that allows a round to be loaded into the breech. It unlocks, moves toward the rear sufficiently far to allow loading of the round, then moves forward after the round is loaded, locks, and seals the breech in preparation for firing.
Receiver Safety. A spring-loaded mechanism that holds the round in place in the breech. It includes a mechanical lock that prevents the round from moving until the firing safety is turned to the fire position. This prevents accidental firing of the round.
Round. Used interchangeably to denote either the projectile or the projectile assembly
Suppression Canister. A hollow cylinder connected to the muzzle valve assembly that surrounds the barrel assembly and is connected to the breech assembly. The cylinder contains baffles and flame retardant foam that allows the light gas entering from the muzzle valve assembly to exit to the atmosphere through vent holes in the side of the cylinder, directing the light gas away from the operator. The baffles and the foam reduce the acoustic signature of the light gas gun and help to prevent contaminants from reaching light gas gun mechanisms.
Suppression Vent. The holes drilled into the side of the suppression canister that direct light gases away from the operator.
Trigger Valve. The valve that controls the light gas flow to the rear of the breech. The trigger valve is actuated with the pull of the trigger to allow high pressure light gas to flow for sufficient time to propel the round out of the barrel.
This system description describes four different embodiments of the invention. Each embodiment is representative of different potential applications and will have different means of providing the necessary light gas to be used as the propellant.
The light gas gun of this invention
The first embodiment
The second embodiment,
The second embodiment would also typically use a simple reservoir to provide the light gas propellant. By adding a heater to the reservoir, the light gas could be heated prior to use to increase the speed of sound in the light gas. The hotter light gas would mostly impact the projectile assembly 20 performance by injecting the hotter gas into the boundary layer.
The second embodiment contains the other elements from the first embodiment, the breech assembly
The third embodiment introduces the muzzle valve assembly
The fourth embodiment is the best mode, and includes the projectile assembly 20, the frictionless barrel assembly
There are numerous applications for the different embodiments described herein, including handguns, rifles, ground artillery, naval guns, industrial processes, research, and even orbital launch systems. These different applications might use substantially different methodologies for providing the necessary light gas propellant at the pressures, temperatures, and quantities required, but they all contain the respective elements of the four embodiments. A relatively simple reservoir of light gas large enough to ensure a constant pressure at the firing valve after it is opened might be sufficient for some applications. Others would likely need a two stage piston that could be powered by other pressurized gas, steam, hydraulics or combustive propellants.
The projectile 10 is loaded into the breech assembly
The second embodiment is identical to the first with two exceptions. The projectile assembly 20 is substituted for the known projectile 10. The channels 12 and gas bearing ports 13 are cut and drilled normal to outside wall of the inner tube 15, as it is no longer necessary to impart spin on the projectile assembly 20.
The projectile assembly 20 is loaded in the same fashion as in the first embodiment. When the light gas gun is fired, the pressure behind the projectile assembly 20 increases rapidly. The spring loaded valve 40 in the aft projectile body 41 of the projectile assembly 20 opens as the pressure external to the projectile assembly 20 is greater than the internal pressure plus the compression strength of the projectile spring 43. The spring loaded valve 40 closes as the internal and external pressures equalize. The forward and aft projectile bodies 42/41, as well as the spring loaded valve 40, are constructed of sintered metal. With high pressure light gas stored in the projectile assembly 20, the light gas starts to flow through the walls of the projectile into the boundary layer as the projectile assembly 20 travels down range. A gas directing tube 44, bored along the centerline of the forward projectile body 42 of the projectile assembly 20, ensures there is sufficient gas flow to the meplat of the projectile assembly. The flow rate through the sintered metal of the projectile assembly will ensure that there will be light gas flowing into the boundary layer for the entire flight of the projectile assembly 20.
The projectile assembly shape, center of gravity, and center of pressure provide for stable flight through all regimes of the projectile assembly 20 flight, from supersonic, through transonic, to subsonic. Using a center of gravity significantly forward of the center of pressure eliminates spin drift. Because the projectile assembly 20 has no striations from lands and grooves, the body of the round remains smooth and is subject to fewer air flow disturbances, which also improves accuracy.
The light gas gun's other mechanisms, the frictionless barrel
In the third embodiment, the necessity to purge the barrel assembly
The muzzle valve 23 as shown in
As the pressure wave in the barrel assembly
In the third embodiment, the light gas is provided by a piston assembly (not shown) powered by steam, hydraulics, or electrical power. The piston chamber is filled with sufficient light gas that when compressed will produce the desired muzzle velocity. When the trigger signal is received, the motive force moves the piston in the piston chamber, compressing the light gas to the necessary pressure and temperature. When this pressure is reached, the trigger valve 14 opens, providing high pressure light gas to the aft end of the breech 38.
The fourth embodiment, also offered as the best mode, includes the projectile assembly 20, the frictionless barrel assembly
The projectile assembly 20 is loaded into the breech assembly
When the light gas gun is fired, the pressure behind the projectile assembly 20 increases rapidly. The spring loaded valve 40 in the aft projectile body 41 of the projectile assembly 20, opens as the pressure external to the projectile assembly 20 is greater than the internal pressure plus the compression strength of the projectile spring 43. The valve 40 closes as the internal and external pressures equalize. With high pressure light gas stored in the projectile assembly 20, and because the forward and aft projectile bodies 42/41 and the spring loaded valve 40 are constructed from sintered metal, the light gas starts to flow through the walls of the projectile assembly 20 into the boundary layer as the projectile assembly 20 travels down range. A gas directing tube 44, bored along the centerline of the forward projectile body 42, in the projectile assembly 20 ensures there is sufficient light gas flow to the meplat of the projectile assembly 20. The flow rate through the sintered metal of the projectile assembly 20, will ensure that there will be light gas flowing into the boundary layer for the entire flight of the projectile assembly 20.
The projectile assembly's shape, center of gravity, and center of pressure provide for stable flight through all regimes of the projectile assembly 20 flight, from supersonic, through transonic, to subsonic. Using a center of gravity significantly forward of the center of pressure eliminates spin drift resulting from a spin stabilized round. Because the projectile assembly has no striations from lands and grooves, the body of the projectile assembly 20 remains smooth and is subject to fewer air flow disturbances, which also improves accuracy.
The muzzle valve assembly
The muzzle valve 23 is an opposing multi-leaf valve 28, as shown in
In the fourth embodiment, the light gas is provided by a dual piston assembly
The barrel assembly
Channels 12 that allow high pressure gas to travel down the barrel are milled on the outside of the inner tube 16. These channels 12 are small compared to the caliber. The interior tube 16 is press fit into the outer tube 15.
There are two different type valves in the muzzle valve assembly
The suppression canister 25 is a cylindrical canister partially filled with porous, non-flammable, acoustic deadening foam. The canister 25 releases the high pressure light gas into the atmosphere through suppression canister vents 26, while minimizing the acoustic signature caused by the escaping gas. The gas must travel through a series of foam baffles to exit the canister 25. The foam also inhibits dust, dirt, and other particulates from entering the rifle barrel and fouling the valves in the muzzle valve assembly
The muzzle valve assembly
The breech assembly
The operator loads the projectile assembly 20 into the breech 38, using compressed CO2 gas to open the receiver locking bolt 17 and push the round into a loading ramp, then closes and locks the receiver locking bolt 17. The round is held in place by the receiver safety 53, which is a mechanical lock in the breech 38, to keep the round in the correct position in the chamber. This is necessary because the round has a non-cylindrical shape and smaller diameter than the barrel bore. It also provides spacing to let gas escape should there be a leak in trigger valve 14.
High pressure light gas is compressed to the working pressure by the pressure boosting spring 45 and CO2-driven piston 46. CO2 is used as the actuating gas because it can be stored at room temperature as a liquid. When the dual piston assembly
The breech assembly
The breech assembly
The projectile assembly 20 is manufactured using standard machining processes. The forward projectile body 42 and aft projectile body 41 are compression molded using sintered metal. Boring and threading are accomplished by standard CNC lathes, as is lapping of the spring loaded valve 40 and seat in the aft projectile body 41. The forward projectile body is bored to a predetermined depth, and then threaded. A second boring operation drills a gas delivery tube 44 to the front of the forward projectile body, just shy of the meplat. This tube helps to distribute light gas to the forward end of the projectile assembly. Assembly starts by installing the valve spring 43 onto the spring loaded valve seat 40 and inserting the spring loaded valve seat 40 into the aft projectile body 41. This assembly is then screwed into the forward projectile body 42. The milling and boring processes tend to close surface pores, but the small hydrogen molecule and elemental helium will still have acceptable flow. Electric discharge machining can be used if the flow is insufficient, instead of using standard milling operations.