Patent Grant
7775148
1. Field of the Invention
This invention relates to a mean for propelling payloads along a barrel utilizing compressed gas or combustion products.
2. Description of Prior Art
Conventional guns hurl projectiles along the gun barrel by means of chemical propellants which, when ignited in the breech, create high-pressure gases which expand behind the projectile, accelerating it along the barrel. This method, used in forms of weaponry, from cannons, to rifles and handguns, has a fundamental limitation. Once the projectile reaches a high velocity, its speed approaches a limit corresponding to the velocity of the shock wave of the expanding gas.
In practice, the pressure in a gun barrel typically spikes early in the discharge of the gun so that the projectile experiences a very high acceleration at the beginning of discharge. However, as the projectile proceeds down the barrel of the gun, the pressure head behind the projectile begins to decrease, and thus decreases the force of acceleration. In order to increase range, base bleed projectiles have been developed. Additional propellant contained in the projectile is ignited after exiting the barrel to increase the velocity.
Many schemes have been invented to compensate for the velocity limitations of the conventional gun. In light gas guns, for example, helium or hydrogen is used as the propelling gas, where the shock wave travels much faster than that associated with the combustion product gases of the conventional gun. Thus, theoretically and practically, a light gas gun can achieve higher exit velocities from the same length of barrel than can conventional chemical propellant guns. Light gas guns, however, are somewhat limited in the weight of projectiles that can be launched. In a one-stage light gas gun, the gas is contained in a high-pressure vessel near the breech of the gun, and is injected behind the projectile upon discharge by bursting a pressure diaphragm between the pressure vessel and the barrel.
In an alternate version of the light gas gun, pressure storage tanks are located along the barrel with the release of gas triggered to correspond with the passage of the projectile.
In a two-stage light gas gun, there are two chambers or barrels, a larger one containing un-pressured helium or hydrogen, separated from another small caliber barrel containing the projectile by a frangible disk. A chemical charge is ignited in the aft end of the larger chamber forces a piston along the barrel compressing the light gas to the point where the frangible disk breaks and subjects the breech end of the projectile containing barrel to extremely high pressure.
In another novel means of propulsion, a supersonic ramjet or scramjet principle is used to propel the projectile down a barrel that contains an explosive mixture of gas (e.g., oxygen and hydrogen or methane). The projectile is first accelerated by ignition of the gas mixture behind the projectile and giving it an initial impulse. As the projectile travels down the barrel, the un-ignited gases flow around the projectile and are ignited by pressure waves at the base of the projectile, and thus continue the acceleration of the projectile down the barrel. The projectile literally flies supersonically down the barrel of the gun. Although this method overcomes, in principal, the limitation of an expanding gas, as described above, is has practical limitations which to date has limited its application beyond that of laboratory curiosity.
Other non-chemical or compressed gas means of propulsion include electrical or electromagnetic launch schemes. In the so-called rail gun, the barrel consists of two or more rails that are capable of supporting very high current electrical discharge. The projectile essentially shorts out the rails when high voltage is applied, creating a conductive plasma behind the projectile, resulting in an accelerating electromagnetic force that drives the projectile down the barrel. This method of launch suffers from a number of technical challenges. It requires a very large electrical pulse network to feed the rails. Furthermore, erosion of the rails during the launch of the projectile limits the life of the system to a small number of “shots” before the rails need refurbishment.
In an alternate approach, strong magnetic coils are activated along the barrel creating an accelerating magnetic force that propels the payload down the barrel. This coil gun approach also suffers from practical problems associated with the large and costly electrical pulse networks required to fire the projectile, large power switching, as well as, inefficiencies in the transfer of energy from magnetic to linear motion.
In a hybrid chemical/electromagnetic gun, a chemical charge is first ignited in the breech of the gun, with electrodes in the breech simultaneously conducting a heavy electrical discharge that further energizes the plasma driving the projectile down the barrel. This system extends the accelerating force by continuing to feed the plasma energetically. It is, however, limited by the same principals that limit the conventional gun, that is, the projectile velocity is limited by velocity of the shock front of the propelling gas or plasma.
Needs exist for improved accelerating of projectiles through the barrels.
The new multivalve hypervelocity launcher (MHL) utilizes the same basic principal of sequential introduction of high-pressure gas behind the projectile, but with a different design architecture that is more efficient, potentially much lower cost, transportable, and suitable for launching larger projectiles. The MHL system contains attributes of some of the above-mentioned systems, such as the storage of high-pressure light gas, combustion of hydrogen/oxygen to produce the high pressure gas, venting of the gas at intervals along the barrel, and the use of base-bleed projects. But the MHL differs significantly in how the compressed gas/or ignition products are stored and injected into the barrel behind the projectile at the multiple ports. The MHL launcher invention overcomes many of the limitations described above, by injecting high-pressure gas in a continuous manner through many ports behind the projectile all along the path of its travel down the barrel. The projectile experiences a more constant, albeit higher, accelerating force throughout the length of the barrel, because the pressure head behind the projectile is constantly refreshed by the opening of valves sequentially along the barrel, and the release of high pressure gas behind and at the base of the projectile, as the projectile traverses the barrel. This avoids the high-G pressure spikes normally associated with conventional chemical guns, and avoids the phenomenon of the projectile being limited by the velocity limits of the shock wave of the expanding gas.
The MHL system utilizes a soft launch technique that simplifies the construction of the payload and opens up a spectrum of payloads that can be accommodated by the launcher. The payload projectile, its components, and electronics need not be hardened against the high-G pressure spikes. 10,000 g constant force replaces 50,000 g peaks found in chemical guns. This gives flexibility in the use of the materials and structures that can sustain a constant, but lower G level during the launch process.
In the MHL launcher, the stored compressed gas surrounds the barrel so there is a very short path between the axial gas containment chamber, AGC, between the inner and outer barrels, contiguous to the barrel, and the barrel chamber itself. Thus, the distance of travel of the propelling gas to the base of the projectile is short, such that the pressure head, originally developed in the breech of the barrel is constantly replenished as the projectile travels down the barrel. In the case of the explosive mixture approach, the mixture prior to ignition is stored in the annular chamber that runs the entire length of the barrel.
The MHL system relies on the unique design of the fast acting valves along the barrel that is triggered by the pressure head behind the projectile as it travels down the barrel. In the preferred embodiment, the valves are held shut by the extreme pressure differential between the AGC, and the barrel chamber, BC, either evacuated or not evacuated, prior to the launch sequence. The valve is then opened by pressure differences as the projectile passes the valve, as will be discussed in detail in the description of the system.
During the passage of the projectile down the barrel, the pressure head behind the projectile, and the pressure in the AGC, begin to reach equilibrium as the projectile passes each valve. This lessens the extreme pressure differential, as the projectile reaches the valve, triggering the opening of the valve, just as the projectile is passing the valve. The flow of high-pressure gas from the ACG into the BC directly behind the moving projectile, maintains the pressure head in the barrel throughout the passage of the projectile down the barrel.
The MHL uses an obdurator plate, OP, behind the projectile to provide a seal between the projectile and the high pressure gas in the barrel. The OP is a robust disk made from a polymeric material like polyethylene, with an outer diameter fitting snugly with the inner diameter of the metal barrel. During travel down the barrel, the outer rim of the OP may oblate slightly, due to the heat, and provide a very low friction gas bearing between the barrel and the projectile being pushed along by the OP.
The MHL system can be operated as a stored compressed gas system, including light gases, or as a system that utilizes combustion products, generated in the storage area contiguous to the barrel, or in the barrel itself, from precursor fuels and oxidizers stored outside the barrel, or in the projectile itself. Variants of the system can use a variety of oxidizers and fuels within the AGC and the projectiles. The MHL unique features make it practical and economical to build, transport, assemble, operate and maintain.
The MHL design is modular. Identical sections are serially produced in an off-site facility. Subsections are transportable to the launch site for assembly and integration. To maintain the low cost aspects of the system, it utilizes commercially available materials such a large diameter high pressure steel pipe and fittings commonly used for pipelines or other industrial applications where market forces have already established competitive prices. The concept is scalable, meaning, the length and diameter of the barrel, can be sized to meet the requirements of the specific application.
The MHL design also allows for a wide variety of applications both large and small. The following are examples of historic use of hypervelocity guns for both civilian, as well as, defense research, which are examples of applications for MHL. In general, these applications range from very light projectiles (grams) at extremely high velocities (6-8 km/sec), to larger payloads (hundreds of kilograms) at slower, but still significant velocities (2-3 km/sec).
Hypervelocity research for hypervelocity guns have been used in the past for a variety of scientific studies related to the acceleration and interaction of materials at hypervelocity speeds. These studies have launched small sub-kilogram payloads at incredible speeds approaching 10 km/sec.
Lethality studies of hypervelocity guns have been used to launch sub-scale models of hit-to-kill vehicles, used for ballistic missile defense, into different target types, to assess damage and lethality.
Economic launch of instrumented packages into the upper atmosphere is possible with the new MHL. During Project HARP, High Altitude Research Project, 1960-1970, approximately 175 Martlet 2 atmospheric sounding flights were conducted with large caliber 16 inch guns, able to loft to experimental packages to 180 km altitudes. A much larger number of 5-inch and 7-inch flights were also conducted throughout North America for meteorological research purposes.
The new MHL provides economic launch of rocket-assisted payloads into low earth orbit. The HARP project, support by both the US and Canadian governments, also performed numerous studies and experiments related to firing large bore, high mass fraction solid rocket motors (1000 kg) into space. While not actually achieving orbital or space capability, the time and resource-limited HARP activity did establish the feasibility of such a venture.
The new MHL incorporates many features that make the concept more economically viable as an instrument for research as well a means for orbiting space payloads at a fraction of the cost of current methods. Current commercial launches approach $10,000/lb for very large payloads to tens of thousands of dollars/lb for smaller payloads.
The invention encompasses a compressed gas launch system, and variants of that system, for launching payloads, at high velocity, using high-pressure gas or combustion products as a means of propulsion. An object of the invention is to provide a means of injecting high-pressure gas at specified intervals along the path of, and behind, the payload projectile as it accelerates along the barrel of the launcher.
The invention provides a high-pressure axial gas storage chamber, AGC, parallel to and contiguous to the barrel and connected to the barrel through periodic structures or bulkheads, that add structural stability to both the storage chamber and the barrel, and with end enclosures to provide high-pressure containment of the stored gas.
The invention provides an inner barrel chamber (IBC) that can be evacuated by means of a pump, by sealing each end of the barrel with an aft breech door, and, at the muzzle end, a frangible cover to be breeched by the projectile upon exit, or a rapid activation cover that opens just prior to exit of the projectile.
The invention provides a means for injecting high pressure gas from the AGC to the IBC, first at the breech end, and the sequentially, along the barrel, but behind the projectile, through numerous valves along the barrel, in a sequence that accelerates as the projectile accelerates down the barrel.
Another object of the invention is to provide a fast-acting valve (FAV), the opening of which is timed with, or triggered by, the passage of the projectile past the valve, allowing high pressure gas in AGC to exit into the IBC through ports in the barrel, providing a near constant pressure head against the aft end of the projectile as it exits the barrel.
Another object of the invention is to provide a valve design, the closing of which is accomplished by, or aided by, the pressure differential between the high pressure AGC prior to launch, and the evacuated or non-evacuated, but lower pressure IBC.
Yet another object of the invention is that the opening of the FAV is accomplished by, or aided by, the lessening of the pressure differential as the projectile passes the value, wherein, the pressure head behind the projectile and the pressure within the storage chamber become equilibrated.
The invention provides the option of using single port FAVs or integrated multi-port FAVs that increase the total area of the apertures ports between the AGC and the IBC.
It is a further object of the invention that the FAVs are “recyclable” that is the can automatically reset to the closed position after the passage of the projectile, thus allowing for a “second shot” without having to replace high pressure frangible disks or other hardware required to operate high pressure gun systems.
It is a further object of the invention, that means of propulsion may be accomplished other than the storage of energy in compressed inert gas, and that the pressurization of the AGC may be accomplished by the ignition of a combustible mixture of hydrogen or oxygen or other chemical species in the AGC.
It is a further object of the invention that the pressurization of the AGC can be accomplished by creation of the high pressure gas in a separate vessel connected to the AGC which is then injected into the AGC just prior to launch, thus minimizing effects of any leakage points in the multiple FAV ports.
It is a further object of the invention that the ACG could be further divided into chambers, each parallel to the barrel, one containing, in gaseous form, an oxidizing agent, the other a reducing agent, each of which is released into the area behind the projectile, by means previously discussed, in order to maintain combustion at the aft end of the projectile, with combustion products maintaining the pressure head. The concept could support the utilization of bipropellant hypergolic substances, the mixture of which at the aft end of the projectile causes exothermic release of energy to maintain the pressure head.
It is a further object of the invention that an alternate means of propulsion is accomplished when an oxidizing (or reducing) agent, in gaseous form, is contained in the AGC, and the complementary agent (oxidizer or reducing agent) is contained in the projectile itself in the form of a solid, liquid, or compressed gas ejected from the aft end of the projectile, thus creating a combustion front behind the projectile as it travels down the barrel.
It is a further object of the invention that the projectile itself could be a solid or liquid propellant rocket with payload that is given an initial boost by means of the MHL, and then ignites after transiting the MHL, to further propels the payload into a ballistic or orbital trajectory.
It is a further object of the invention that the projectile can embody different shapes, forms, and seals to reduce friction in the barrel, and to enhance the quick activation of the valves, including the use of expendable or reusable sabot structures that encloses the projectile payload and provides a means for traversing the barrel, but is detached from the payload as the object exits the barrel.
It is a further object of the invention to use obdurator plates in various configurations to provide a low-friction means of sealing and transferring forces from the high pressure gas in the barrel to the projectile as it moves along the barrel.
It is a further object of the invention to reduce cost and enhance portability that the MHL is made in segments or sub modules that can be built as separate units in the factory then transported and bolted together at the launch site facility. To reduce cost, many of the components are commercially available. Large steel pipes for the AGC are similar to products in the oil and gas industry.
It is a further object of the invention that the double walled axial barrel with internal supports increases the torsional and hoop strength of the compound barrel so that its weight is minimized. This allows very long barrels to be constructed which when augmented with structural supports, can be mounted on gantries that allow the MHL to be aimed in azimuth and elevation to support space launch missions.
The invention provides a new projectile launcher barrel apparatus. An inner barrel has an inner barrel chamber with proximal and distal ends. A projectile is placed in the inner barrel chamber near the proximal end. An outer casing surrounds the inner barrel. An axial gas chamber surrounds the inner barrel between the inner barrel and the outer casing. Plural spaced pressure-activated valves connect the axial gas chamber and the inner barrel chamber. The valves sequentially and automatically open from pressure behind the projectile, admitting pressurized gas from the axial gas chamber to the inner barrel chamber and accelerating the projectile through the inner barrel toward the distal end.
Bulkheads extend radially outward from the proximal and distal ends of the inner barrel to the outer casing. Diagonal stiffening connectors are welded between the inner barrel and the outer casing stiffening the inner barrel. Internal bulkheads radially extend between the inner barrel and the outer casing at spaced intervals between the bulkheads at the proximal and distal ends. The internal bulkheads have openings permitting pressure front travel along the axial gas chamber from near the bulkhead at the proximal end toward the bulkhead at the distal end.
The automatic pressured operated valves are positioned on sides of the internal bulkheads away from the proximal end and admit pressurized gas to the inner barrel chamber behind the projectile as the projectile passes the valves. A pump is connected to the axial gas chamber, and a source of pressurized gas is connected to the pump for supplying the axial gas chamber with gas at increased pressure. In one embodiment, a pressurized gas storage chamber and a valve are added between the pump and the axial gas chamber for storing pressurized gas in the storage chamber and supplying pressurized gas from the storage chamber to the axial gas chamber. An igniter is position in the storage chamber for igniting, combusting gas, and increasing pressure in the storage chamber prior to supplying the gas to the axial gas chamber. In another embodiment, an igniter is mounted in the inner barrel chamber for igniting, combusting, increasing pressure and expanding gas in the inner barrel chamber and driving the projectile through the inner barrel chamber toward the distal end. In other embodiments, dividers extend axially through the axial gas chamber between the inner barrel and the outer casing, dividing the axial gas chamber into first and second sides. An oxidant gas inlet is connected to the casing on the first side of the axial gas chamber, and a reactant gas inlet is connected to the casing on the second side of the axial gas chamber for separately flowing oxidant, and reactant gases onto the casing and into the inner barrel chamber for oxidizing, combusting, expanding and pressurizing gas in the inner barrel chamber and driving the projectile toward the distal end. In one embodiment, a source of oxidant gas is connected to the axial gas chamber, and a reactant source is connected to the projectile for oxidizing, combusting, expanding and pressurizing gas in the inner barrel chamber and driving the projectile toward the distal end.
The projectile includes a payload, a rocket motor, and an obdurator on the rocket motor for driving the obdurator with the pressurized gas in the inner barrel chamber and driving the rocket motor and the payload through the inner barrel chamber. The automatic pressured activated sequencing valves have sealing seats and sliders on the seats. The sliders have relatively large lifting areas and relatively small opposite retainer areas. As the projectile passes the valves lower pressures within the inner cylinder chamber produce greater forces on the large areas, and higher pressures within the axial gas chamber produce lesser forces on the small retainer areas. The force differential between the greater forces and the smaller forces move the sliders away from the seats, releasing pressure from the axial gas chamber to the inner barrel chamber behind the projectile.
Closed volumes and compression springs are located opposite the larger areas of the sliders. Extensions and seals near the larger areas of the sliders isolate the closed volumes when the extensions engage the seals and the sliders engage the seals. Moving the sliders to open the valves moves the extensions away from the seals for communicating pressure in the axial gas chamber to the closed volumes when the sliders move away from the seats. Equalizing pressures and forces on opposite sides of the sliders with pressure from within the axial gas chamber allows the springs to close the valves after they have been opened.
In one embodiment, the valves have single ports and are arranged radially on the inner barrel. The seats surround the single ports. The sliders are cup or hat-shaped and have rims engaging the seats. Inner volumes of the sliders have with outer walls and tops for receiving pressures from within the inner barrel chamber. The extensions extend outward from the tops. The closed volumes have walls and outer ends for engaging the springs, and the walls have inward extending lips for holding the seals against the extensions.
In another embodiment, the valves have multiple ports and are arranged annularly around the inner barrel. The sliders are annular and dish-shaped and have axially extending cylindrical walls with first and second ends. Radial rims extend from the first ends of the axially extending cylindrical walls. The rims form the small areas. The sliders have radially extending annular tops at the second ends of the walls. The tops are the large areas for receiving the pressure from within the inner barrel chamber. The extensions are annular extensions extending radially from the second ends of radially extending cylindrical walls. The closed volumes are annular chambers formed with axial walls, and annular tops against which the springs bear. Inward extending annular radial lips opposite the closed volume top hold the seals against the annular extensions until the annular dish-shaped sliders are moved by pressure from the inner barrel chamber when the projectile passes the valves.
Multiple inner barrels and outer casings are joined end-to-end, forming an elongated projectile launcher barrel, having breech and muzzle ends. The elongated projectile launcher barrel is supported in one embodiment by a trunion on a proximal end and plural cables along the elongated projectile launcher barrel. The cables are suspended from an A-frame truss. In another embodiment, multiple inner barrels and outer casings are joined end-to-end, forming an elongated projectile launcher barrel. The elongated projectile launcher barrel is supported by flotation collars near breech and muzzle ends and is erected by flooding a flotation collar near the proximal end and submerging the breech end.
A new method of projectile launching includes providing an inner barrel having breech and muzzle ends, providing an inner barrel chamber in the inner barrel, receiving a projectile in the inner barrel chamber near the breech end of the inner barrel, providing an outer casing surrounding the inner barrel, providing an axial gas chamber between the inner barrel and the outer casing, providing supporting interconnections between the inner barrel, and providing series of valves along the inner barrel.
The launching is started by evacuating the inner barrel chamber on the muzzle end side of the projectile, providing pressurized gas in the axial gas chamber, and providing pressure on the breech end side of the projectile.
Sequentially opening the valves with force differentials of inner barrel chamber lower pressures applied to relatively large areas and axial gas chamber higher pressures applied to smaller areas flows pressurized gas from the axial gas chamber through open valves into the inner barrel chamber behind the projectile as the projectile moves from the breech end to the muzzle end, accelerating the projectile from the breech end through the inner barrel chamber and outward through the muzzle end. In one embodiment, oxidizer gas and reactant gas are flowed separately through the valves, and the oxidizer gas and the reactant gas react in the inner barrel chamber. Another embodiment provides a chemical reactant on the projectile. Flowing pressurized oxidizer gas into the inner barrel chamber is followed by reacting the oxidizer gas and the reactant in the inner barrel chamber behind the accelerating projectile.
The invention provides new gas force opening valves. The new valves open with lower pressures operating against higher resistant pressures. The valves have sealing seats and sliders seated on the seats. The sliders have relatively large areas and relatively small opposite retainer areas. Lesser pressures within the valves produce greater forces on large areas, and greater pressures outside of the valves produces lesser forces on the smaller retainer areas. Differential forces between the greater forces and the smaller forces move the sliders away from the seats, releasing greater pressure from outside of the valves to the inside of the valves.
Closed volumes and compression springs are positioned opposite the large areas of the sliders. Extensions and seals opposite the large areas of the sliders isolate the closed volumes when the extensions engage the seals and the sliders engage the seals. Moving the extensions away from the seals communicates pressure outside of the valves to the closed volumes when the sliders move away from the seats. Equalizing pressures and forces on opposite sides of the sliders with pressure from outside of the valves, and allowing the springs to close the valves after the valves have been opened.
The valves are arranged radially on a cylinder. The seats surround single ports in a cylinder wall. The sliders are cup or hat-shaped and have rims engaging the seats. Inner volumes of the sliders have tops for receiving pressures from within the valves. The extensions extend outward from the slider tops. The closed volumes have walls and outer ends for engaging the springs. The walls have inward extending lips for holding the seals against the extensions while the valve sliders are seated. In another embodiment, the valves have multiple ports and are arranged annularly around a cylinder. The sliders are annular and dish-shaped and have axially extending cylindrical walls. Radial rims extend from first ends of the walls forming the smaller areas, and wherein the sliders have radially extending tops at opposite second ends of the walls as the large areas for receiving the pressure from within the valves. The extensions are annular extensions extending radially from the slider walls. The closed volumes are annular chambers formed with axial walls, annular radial tops against which the springs bear, and inward extending annular radial lips holding the seals against the annular extensions until the annual dish-shaped sliders are moved by pressure from within the valves.
These and further and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the claims and the drawings.
a shows the basic structure of the new launcher.
b shows an alternate internal support and end flanges for length augmentation.
a, b and c show launch sequences.
a-g show variants of high pressure gas generating, storing, igniting and injecting.
a-d show different projectiles for launch.
a is an exploded view of a single port valve for use on the launcher.
b-e show sequences of sealing, opening and pressure flowing and increasing through the valve before and after the projectile passes the valve.
a is an exploded view of a multiple port valve.
b-e are cutaway views showing the multiple port valve in sequences of sealing, opening, introducing and increasing pressures as the projectile respectively approaches and passes the multiple port valve.
a shows a land-based launcher.
b and c show towing and erecting a water-based launcher.
a shows this basic structure of the MHL system. This includes the inner barrel 1 which contains the projectile during the launch sequence; the AGC, axial gas chamber 2 formed by the IB, inner barrel 1 and the OC, outer casing 3; with internal bulkheads 4 other structures that align and connect the inner barrel and the outer casing, end closure bulkheads fore 5 and aft 6.
The muzzle end of the barrel can be closed off with a frangible cap 7 or fast acting retractable valve or cover that opens just prior to exit of the projectile and closes after exit of the projectile, to conserve the pressurized Helium or Hydrogen. At the other end is the breech assembly 8 that allows insertion of the projectile, and when closed and sealed, allows the inner barrel chamber IBC to be evacuated. Activation valves 9 shown at each internal bulkhead, when triggered, allow high-pressure gas in the AGC 2 to flow into the IBC 10 behind the projectile.
b shows a variant of the basic unit with fore and aft enclosure bulkheads 5 and 6, with one activation valve at the aft end 9. In this configuration, and a number diagonal rods or pipes 11 welded to the inner barrel 1 and the outer casing 3 take the place of the internal structural bulkheads 4 to reduce cost of manufacturing and provide greater structural integrity and stiffness. When the projectile is moving down the barrel, from left to right, very large reaction forces (recoil) would be induced in the inner barrel, from right to left. The diagonal stiffeners might provide a better means of transferring these forces to the outer casing, than the structural bulkheads shown in
Thus, in a complete system, multiple units of the basic modules in
Principal of Operation
a, 2b, and 2c shows the launch sequence first at the breech end 6 in
a-3g show a variety of mechanisms available to provide the high pressure gases needed for launch.
b shows a variant where the helium or hydrogen 16 is pumped into an external high pressure vessel 18 through a high pressure pump 17, then released into the AGC 2 just prior to launch (seconds or fraction of a second) via a high pressure valve 19 or frangible disk. The rationale for having a variant with an external tank is as follows. If there are pin-hole leaks in the AGC which has numerous high pressure valves, it may be difficult to maintain an extreme high pressure in the AGC during a lengthy pumping process (shown in
c, 3d, and 3e show variants where the high-pressure gas is generated through the combustion of hydrogen and oxygen which can be stored cryogenically near the MHL site. Other high energy density combustible gases may also be used. In
d shows an external high pressure vessel 18, similar to that found in 3b, but with the high pressure gas generated by combustion of H2 and O2 20 pumped into the vessel with pump 17 and ignited by igniter 22, just prior to launch, (1-2 seconds). The high-pressure gas 15 is then injected into the AGC 2 via valve 19.
e shows the case where the H2/O2 mixture is pumped directly into the AGC 2 through pump 17, then ignited with igniter 22, creating high-pressure gas 15 which is then sequentially injected into the IBC through valves 9.
f and 3g show variants where the pressure head behind the projectile 14 is created by a combustion front 24 generated in the IBC 10. In the case of
In
Projectiles
a-4d show various projectiles that could be “soft launched” by the MHL. Each has a rocket booster motor 30 that ignites after the projectile is launched from the MHL. Each has a payload 31 attached to a 1st or 2nd stage booster motor, and subsequently detached after the burn out of the booster motor. Each has an obdurator plate 32, a very robust disk that acts as a “pusher” plate, transferring the force of the high pressure gas to the projectile, and sealing the system so that the high pressure gas does not bypass the projectile. The obdurator plates are not rigidly attached to the projectiles, and they are discarded after launch by flying away from the projectile as it exits the muzzle. The obdurator plate made of polyethylene or other polymeric composite material can be recovered and reconditioned for subsequent launches.
Each of the figures illustrates a different projectile architecture.
In
c shows also a smaller bore booster rocket motor with another means of lateral support in the barrel. In this case, there are aft fins 34 which provide aerodynamic stability after launch, but also stabilize the aft end of the projectile during launch, with the width of the fins slightly less than the inside diameter of the barrel. The obdurator ring 32 at the fore end, behind the payload 31 provides the seal to the barrel transferring the force of the high pressure gas to the fore end of the booster motor, pulling it along during launch (as opposed to the obdurator plates in
In
The launch sequence of multi-stage rockets In
At the heart of the MHL system is the design of the fast acting valves that can withstand the extreme pressures of the AGC 2, and yet open within milliseconds allowing the high-pressure gas in the AGC to flow into the barrel behind the projectile, each valve being triggered by the pressure head behind the projectile.
Fast Acting Valves
Two embodiments of the fast acting valves are described below: 1) a single port valve (SPV) mounted on the exterior of the inner barrel, within the AGC, that allows gas to flow from the AGC to the IBC though one orifice; 2) a multi-port valve (MPV) also mounted on the exterior of the inner barrel, and also within the AGC, that allows gas to flow from the AGC to the IBC through an annular ring of ports. Although the valves have significantly different geometries, they share common principals that allow them to operate successfully in the MHL.
a shows and exploded view of the single port valve (SPV) attached to the exterior wall of the inner barrel, where the valve seat 37 contains an electrometric O-ring 38 that provides a high-pressure seal when the slider cup 39 is held against the valve seat 37 prior to valve activation. After activation, slider cup 39 is retracted telescopically into the receiver cup 40. The receiver cup is held rigidly to the inner barrel 1 by pedestal mounts 41 that are welded to the receiver and the inner barrel. When the valve activates, high-pressure gas from the AGC flows into the IBC through port 42.
b is a cutaway side view of the SPV showing the valve in a closed position prior to launch. The slider cup 39 is fitting snugly against the valve seat 37 with the electrometric O-ring 38 providing a high-pressure seal. High-pressure gas in the AGC 2 shown as PA is blocked from flowing into the IBC 10 through port 42, where the pre-launch barrel pressure PB extends into the slider cup enclosed volume 43 through port 42, and then into the receiver enclosed volume 44 through pin hole opening 45.
Under pressure equilibrium conditions, the slider 39 is held shut by spring 49. The closing force on the valve, however, is determined primarily by the extreme differential pressure when PA is much greater than PB, (PA>>>PB). The downward force on the slider 39 shown in the figure as black arrow 46, is equal to PA times the area of an annular ring 46 the outside radius of which is R4 and the inside radius R3 which is also the radius of an O-ring 48 shown above at 47 where the there is an interface between the slider cup 39 and the receiver cup 40.
The pressure on the outside radius of the O-ring 38 is PA while the pressure on the inside is PB since there is a gap between the slider 39 and the valve seat 37 on the exterior of the inner barrel 1. This gap has direct access to the interior of the valve core 43 and is therefore in equilibrium with the core pressure PB. The downward pressure on the whole slider cup 39 is transferred mechanically to the interface between the slider cup 39 and the receiver cup 40 shown as seal 47 with O-ring 48. The force 46 on the valve seat O-ring 38 and the force 47 on the interface O-ring 48 are equivalent due to the fact that both are part of the slider cup structure 39 and are therefore mechanically linked. There is an additional force provided by the closer spring 49, but this force is only a fraction of that provided by the differential pressure of PA and PB acting on the slider cup at point 46.
Note there is also a force exerted downward on the slider cup 39 equivalent to PA times the area subtended by an annular ring formed by the inner radius of the valve seal O-ring 38 with radius R3 and the outer radius R2 of the slider cup cylindrical structure. This downward force however is counteracted by an equal and upward force on the slider cup 39 by PA times an annular ring of equal area bounded by the inner radius of O-ring 48 that is, R3, and the outer radius R2 of the slider cup cylindrical structure. Thus the total net downward force on the slider cup is 46, equal to PA times the annular area 46.
c shows the change in pressures due to the passage of the projectile 14 past the SPV port 42. The pressure outside of the port changes rapidly (milliseconds) from a vacuum or near-vacuum PB to the pressure head PH behind the projectile, which is approximately equal to the pressure PA in the AGC. The pressure change in the valve core 43 now exerts an extreme upward force on the slider cup 39 equivalent to PH times the area of the top of the slider cup, with radius R1. The downward force on the top of the cup provided by the pressure PB in the core of the receiver cup 44 is negligible (vacuum or near vacuum). The amount of hot gas leaking back into 44 from 43 through pin-hole 45 is negligible since the valve opening occurs in milliseconds, not enough time for substantial amounts of gas to pass from 43 into 44. The slider cup 39 will begin to move upward when the upward force on the slider cup, (PH×π(R1)2) is equal to the downward force (PA×(π(R4)2−π(R3)2). For geometries illustrated in
d shows the movement of the slider cup upward, with the valve seal O-ring 38 remaining affixed to the valve seat 37 on the inner barrel 1, and the interface O-ring 48 remains attached to receiver body 40. Spring 49 is shown undergoing compression while the slider cup 39 moves upward and admits high pressure gas from the AGC 2, into cavity 43 subsequently into the IBC 10 via port 42. The base of the slider cup has upward turning fluted edges 50 to aid the upward movement of the slider cup as high pressure gas impinges from the right and left sides of the slider cup, as shown in the illustration.
e shows the value in the full open position, with the top of the slider cup 39 reaching the base of the receiver cup 40, and the return spring 49 fully compressed. Once all of the gasses have reached pressure equilibrium in the AGC 2 and the IBC 10, there will be no net force opposing the closer spring 49 which will then return the slider ring to the original closed position as shown in
Multi-Port Valve
a shows and exploded view of the Multi-Port Valve (MPV) attached to the exterior wall of the inner barrel, where the valve seat ring 51 contains an elastomeric valve seat O-ring 52 that provides a high-pressure seal when the slider ring 53 is held against the valve seat ring 51 prior to valve activation. After activation, slider ring 53 is retracted telescopically into the receiver ring 54.
The valve seat ring 51 is supported by multiple stiffeners 55 welded to the exterior of the valve seat ring 51 and inner barrel 1. In like manner, the receiver ring 54 is supported by multiple stiffeners 56. When the valve activates, high-pressure gas from the AGC flows into the IBC through multiple ports 57 arranged around the circumference of the inner barrel 1. Guide plates 59 welded to the interior of the valve seat ring 51 and to the exterior of the inner barrel 1 between each of the ports 57 provides additional support to the valve seat ring, but also acts as a stiffener for the inner barrel structure adding to its structural integrity locally around the ports.
Under pressure equilibrium conditions, the slider ring 53 is held shut by springs 58 distributed around the receiver ring. In analogous fashion with respect to the SPV, the closing force on the MPV valve is determined primarily by the extreme differential pressure when PA is much greater than PB (PA>>>PB). The closing force on the slider ring 53 shown in the figure as black arrow 63, is equal to PA times the area of an annular ring 63 the outside radius of which is R8 and the inside radius R7 which is also the radius of an O-ring 65 where there is an interface between the slider ring 53 and receiver ring 54.
The pressure on the outside radius of the valve seal O-ring 52 is PA while the pressure on the inside is PB since there is a gap between the slider ring 54 and the valve seat 51 below ring 52. This gap has direct access to the interior of the valve core 60 and is therefore in equilibrium with the core pressure PB. The closing pressure on the whole slider ring 53 is transferred mechanically to the interface between the slider ring 53 and the receiver cup 54 shown as seal 64 with O-ring 65. The force 63 on the valve seat O-ring 52 and the force 64 on the interface O-ring 65 are equivalent due to the fact that both are part of the slider ring structure 53 and are therefore mechanically linked. There is an additional force provided by the closer spring 49, but this force is only a fraction of that provided by the differential pressure of PA and PB acting on the slider ring at point 63.
The closing pressure on the whole slider ring 53 is transferred mechanically to the interface between the slider ring 53 and the receiver ring 54, which is shown as seal 64 with O-ring 65. The force 63 on the annular ring 52 and the force 64 on the O-ring 65 are equivalent due to the fact that both are part of the slider ring structure 53 and are therefore mechanically linked. There is an additional force provided by the closer spring 58, but this force is only a fraction of that provided by the differential pressure of PA and PB acting on the slider ring at point 63.
Note, analogous to the situation described for
c shows the change in pressures due to the passage of the projectile 14 past the MPV ports 57. The pressure outside of the port changes rapidly (milliseconds) from a vacuum or near-vacuum Pg to the pressure head PH behind the projectile, which is approximately equal to the pressure PA in the AGC. The pressure change in the valve core 60, with very little of the high pressure gas PH entering the receiver core 61 through pin hole 62 since the pin hole is small and the time of activation short. Likewise, these could be minor leakage at point 66 where the inner radius of the slider ring 53 meets the outer radius R10 of the barrel 1. As with the pin-hole, this leakage is small and the time of activation short, therefore there is minimal impact on the pressure mechanism for opening the valve. If, in practice, this leakage is deemed undesirable, an O-Ring arrangement similar to 65 could be implemented at point 66.
With the passage of the projectile 14, the pressure differential between the slider core 60 and the receiver core 61 is very large (PH>>>PB). This creates a large opening force on the slider ring 53 equivalent to PH times the area of the base of the slider ring, The area of the base of the slider ring is equivalent to the annular ring defined by R9 at its outer edge, and R10 at the inner edge. The slider ring 53 will begin to move from left to right in the figure when the opening force on the slider ring, (PH×(π(R9)2−π(R10)2) is greater than the closing force which is created by pressure PA on annular ring area 63. For geometries illustrated in
d shows the movement of the slider ring from left to right in the figure, with the valve seat O-ring 52 remaining affixed to the valve seat 51, and the O-ring 65 remaining attached to receiver ring body 54. Spring 58 is shown undergoing compression while the slider ring 54 moves toward the right and admits high pressure gas from the AGC 2, into cavity 60 subsequently into the IBC 10 via ports 57. The tops of the valve seat ring 51 and the slider ring 53 are fluted outward to aid the opening force on the slider ring as high pressure gas impinges from the top with a great deal of momentum, adding force to the opening of valve.
The guide plate 59 serves two purposes in the MHL. When the value is closed, the guide plates spaced evenly around the inner barrel provide support to the closefitting cylindrical part of the slider ring 53 which is under great pressure PA from the top, (see area marked 53 in
e shows the value in the full open position, with the base of the slider ring 53 reaching the base of the receiver ring 54, and the return spring 58 fully compressed. Once all of the gasses have reached pressure equilibrium in the AGC 2 and the IBC 10, there will be no net force opposing the closer spring 58 which will then return the slider ring to the original closed position as shown in
a shows a ground deployment of a large MHL where the outer casing 3 appears as a long tube (high length over diameter-L/D) in the center of a grid or network of cabling and cross members that provide a support structure 67 for the MHL tube, keeping it aligned in the axial direction. The MHL muzzle 7 appears in the upper right and the breech 6 in lower left. Two steel girder structures 68 provide support to the MHL from the top through multiple cables 69 running from the apex 70 to hard points 71 on the MHL support grid 67. The elevation of the MHL can be controlled by adjusting these cable lengths through pulleys and machinery at the apex 70. Motorized wheeled carts 72 at the base of the support girders 68 and at the breech 6 are capable of rotating the whole structure in the azimuth direction by movement along a circular track 73.
b and 7c show a marine deployment of the MHL. In
The parameters of an MHL system are show at the bottom and right side of the figure, for a system that could launch a comparable sized, sabot projectile from an MHL barrel that is 200 foot long, with a 5 ft diameter to the outer casing. The figure shows MHL breech pressure, base pressure, and acceleration throughout the length of the barrel, as flat, modestly decreasing curves that are significantly lower than those of the HARP projectile over most of the HARP launch, and are only comparable to HARP parameters at the end HARP launch as the projectile exits the muzzle (1200 inches).
What is noteworthy is the ramp up in the velocity of the MHL projectile to a comparable level as that achieved by the HARP gun, but with relatively low pressures (max 12,000 psi for MHL versus a max 60,000 psi for the HARP gun). Even though the MHL launcher is longer, the overall weight could be considerably less than that of the HARP gun, because of the much lower pressure requirements.
The moderate decrease in the breech or base pressure for the MHL as the projectile moves down the barrel is due to the following. At the beginning of launch, the AGC is fully pressurized, and the IBC is in vacuum or at atmospheric pressure. As the projectile moves down the barrel, the valves open and high pressure gas from the AGC as it flows into the IBC is in effect “diluting” the high pressure gas from the AGC since it is now occupying a larger volume, that is the AGC volume plus the IBC volume. In a nominal architecture, the IBC volume is ¼ of that of the AGC, so there should be a 25% larger volume in which the high-pressure gas resides at the end of launch. This results in a 25% lower pressure in the AGC after equilibrium has been reached when the projectile exits the barrel. This translates to a constant reduction in the MHL projectile base pressure over the length of the barrel to 75% of the original base pressure at the beginning of launch.
While the invention has been described with reference to specific embodiments, modification and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.
This application claims the benefit of U.S. Provisional Application No. 60/642,125 filed Jan. 10, 1005, which is hereby incorporated by reference in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 60642125 | Jan 2005 | US |
