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33-415: The Quicklaunch proposed firing apparatus was a light-gas gun using hydrogen as the working gas and natural gas as the explosive heat source. Heating and pre-pressurizing the hydrogen working gas takes 10 minutes before the shot and most of the hydrogen is recovered by a muzzle muffler at the end of the launch tube to be reused for subsequent launches. The 1,100-metre-long (3,600 ft) gun would be, for

66-437: A propellant depot in orbit. Projected costs to orbit were $ 500 per pound ($ 1,100/kg). In a 2016 article, Hunter remarked that the work had been put in stasis due in part to Elon Musk 's company, SpaceX , taking up the challenge of reducing costs to orbit. Hunter however invited someone with a similar level of money and motivation, to take a fresh look at the approach. Later, Hunter ran a new start-up called Green Launch that

99-443: A bore diameter of 3.3 inches (84 mm) to 8.0 inches (200 mm) with a 14.0-inch (360 mm) piston weighing up to 2,300 pounds (1,000 kg). Projectile velocities can reach 4.5 kilometres per second (16,000 km/h) for the 8.0-inch (200 mm) configuration and 7 kilometres per second (25,000 km/h) for the 3.3-inch (84 mm) launcher configuration. The primary use of the range facilities at Arnold Air Force Base

132-568: A function of length. Since the projectiles travel at a known velocity, changes in density as a function of length have a predictable relationship to the impact pressure applied as a function of time. With materials in a wide range of densities (from tungsten powder to glass microspheres ) applied in thin layers, carefully made projectiles can be used in constant-pressure experiments, or even controlled compression–expansion–compression sequences. High-density polyethylene High-density polyethylene ( HDPE ) or polyethylene high-density ( PEHD )

165-433: A malfunction instead of shattering and becoming shrapnel like the other materials. Milk bottles, jugs, and other hollow goods manufactured through blow molding are the most important application area for HDPE, accounting for one-third of worldwide production, or more than 8 million tonnes. Above all, China, where beverage bottles made from HDPE were first imported in 2005, is a growing market for rigid HDPE packaging, as

198-411: A metallic state . A light-gas gun works on the same principle as a spring piston airgun . A large-diameter piston is used to force a gaseous working fluid through a smaller-diameter barrel containing the projectile to be accelerated. This reduction in diameter acts as a lever, increasing the speed while decreasing the pressure. In an airgun, the large piston is powered by a spring or compressed air, and

231-404: A pressure wave cannot propagate any faster than the speed of sound in the medium, thermodynamic analysis suggests that the muzzle velocity is limited to the speed of sound. However, beyond the speed of sound, the kinetic theory of gases , which determines the speed of sound, provides a more detailed analysis in terms of the gas particles that comprise the working fluid. Kinetic theory indicates that

264-518: A result of its improving standard of living . In India and other highly populated, emerging nations, infrastructure expansion includes the deployment of pipes and cable insulation made from HDPE. The material has benefited from discussions about possible health and environmental problems caused by PVC and polycarbonate associated bisphenol A (BPA), as well as its advantages over glass, metal, and cardboard. Industrial production of HDPE from ethylene happens through either Ziegler-Natta polymerization or

297-406: Is 10,000 psi which allows for a 200 g projectile to be launched up to 1,200 m/s. The target tank is generally configured for planar and inclined impact experiments. Soft catch systems are often used to recover materials for post-shot analysis. One particular light-gas gun used by NASA uses a modified 40mm cannon for power. The cannon uses gunpowder to propel a plastic (usually HDPE ) piston down

330-403: Is a thermoplastic polymer produced from the monomer ethylene . It is sometimes called "alkathene" or " polythene " when used for HDPE pipes . With a high strength-to-density ratio, HDPE is used in the production of plastic bottles , corrosion-resistant piping, geomembranes and plastic lumber . HDPE is commonly recycled, and has the number "2" as its resin identification code . In 2008,

363-476: Is a disk (usually metal) of carefully calibrated thickness designed to act as a valve. When the pressure builds up to the desired level behind the disk, the disk tears open, allowing the high-pressure, light gas to pass into the barrel. This ensures that the maximum amount of energy is available when the projectile begins moving. The light-gas guns are typically divided into categories of single-stage and two-stage light gas gun. One such single-stage light gas gun

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396-544: Is also developing a space light-gas gun . Light-gas gun The light-gas gun is an apparatus for physics experiments. It is a highly specialized gun designed to generate extremely high velocities. It is usually used to study high-speed impact phenomena ( hypervelocity research), such as the formation of impact craters by meteorites or the erosion of materials by micrometeoroids . Some basic material research relies on projectile impact to create high pressure; such systems are capable of forcing liquid hydrogen into

429-427: Is located at Marquette University , Milwaukee, WI . It had been used for studying polymers and metals in pressure regions up to 20 GPa. The light gas gun at Marquette was manufactured by PAI and delivered in 2015. It has two barrels: a 15 foot, two inch smooth bore and a 13 foot, two inch slotted bore. The slotted bore allows for pressure-shear loading and complex target-flyer interactions. The maximum working pressure

462-442: Is resistant to many different solvents , and is exceptionally challenging to glue; joints are typically made by welding. The physical properties of HDPE can vary depending on the molding process that is used to manufacture a specific sample; to some degree, a determining factor is the international standardized testing methods employed to identify these properties for a specific process. For example, in rotational molding, to identify

495-440: Is the measurement of released kinetic energy upon projectile impact. The muzzle velocity of an airgun , firearm , or light-gas gun is limited by, but not limited to, the speed of sound in the working fluid—the air, burning gunpowder, or a light gas. Up to the speed of sound, thermodynamics provides a simple, approximate calculation approach: the projectile is accelerated by the pressure difference between its ends, and since such

528-568: Is usually economic: HDPE is also used for cell liners in United States subtitle D sanitary landfills , wherein large sheets of HDPE are either extrusion welded or wedge welded to form a homogeneous chemical-resistant barrier, with the intention of preventing the pollution of soil and groundwater by the liquid constituents of solid waste . HDPE is preferred by the pyrotechnics trade for mortars over steel or PVC tubes, being more durable and safer: HDPE tends to rip or tear in

561-460: The 1960s and most recently for high-speed thermal imaging. Velocities ranging from 1 km/s up to 8.5 km/s can be achieved. The largest of these involves a 6.25-inch (159 mm) diameter piston weighing more than 46 pounds (21 kg) to compress the hydrogen. Arnold Air Force Base 's Range-G is the "largest routinely operated two-stage, light-gas gun system in the United States". Range-G utilizes interchangeable launch tubes ranging from

594-535: The HDPE has been synthesized, it is ready to be used in commercial products. Industrial production methods for HDPE products include injection molding for complex shapes such as toys. Extrusion molding is used for constant-profile products such as pipes and films. Blow molding is intended for hollow products, specifically bottles and plastic bags. Rotational molding is used for large, seamless parts such as chemical drums and kayaks. The method used during processing depends on

627-463: The Phillips slurry process. The Ziegler-Natta method uses a combination of catalysts, including titanium tetrachloride, in contact with gaseous ethylene to precipitate high-density polyethylene. In a similar way, the Phillips slurry process uses silica-based catalysts in contact with a fast-moving hydrocarbon and polyethylene slurry to precipitate high density polyethylene. Processing will determine

660-399: The cannon barrel, which is filled with high-pressure hydrogen gas. At the end of the cannon barrel is a conical section, leading down to the 5-mm barrel that fires the projectile. In this conical section is a stainless steel disk, approximately 2 mm thick, with an "x" pattern scored into the surface in the middle. When the hydrogen develops sufficient pressure to burst the scored section of

693-449: The difference in density, giving HDPE a higher specific strength . It is also harder and more opaque and can withstand somewhat higher temperatures (120 °C/248 °F for short periods). High-density polyethylene, unlike polypropylene , cannot withstand normally required autoclaving conditions. The lack of branching is ensured by an appropriate choice of catalyst (e.g., Ziegler–Natta catalysts ) and reaction conditions. HDPE

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726-482: The disk, the hydrogen flows through the hole and accelerates the projectile to a velocity of 6 km/s (22,000 km/h) in a distance of about a meter. NASA also operates light-gas guns with launch tube sizes ranging from 0.170 inches (4.3 mm) to 1.5 in (38 mm) at Ames Research Center . Hazardous testing is conducted at White Sands Test Facility . These guns have been used in support of various missions beginning with Apollo program reentry studies in

759-403: The environmental stress crack resistance of a sample, the notched constant tensile load test (NCTL) is put to use. Owing to these desirable properties, pipes constructed out of HDPE are ideally applicable for drinking water and waste water (storm and sewage). HDPE has a wide variety of applications; for applications that fall within the properties of other polymers, the choice to use HDPE

792-444: The global HDPE market reached a volume of more than 30 million tons. HDPE is known for its high strength-to-density ratio. The density of HDPE ranges from 930 to 970 kg/m . Although the density of HDPE is only marginally higher than that of low-density polyethylene , HDPE has little branching , giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. The difference in strength exceeds

825-592: The most part, submerged in the ocean. Its horizontal and vertical direction ( azimuth and elevation ) could be adjusted based on customer launch requirements. The proposed launcher was designed to give projectiles an initial speed of 6 km/s (3.7 mi/s) while the Earth orbital speed is 6.9 to 7.8 km/s (4.3 to 4.8 mi/s). The projectile design therefore included a one-stage rocket which ignites some time after launch. The designed payloads could include spacecraft, satellites, consumable, water or fuel to supply

858-451: The polyethylene chains, and helps determine properties such as flexibility, yield strength, and melt temperature. After the precipitate is formed, the temperature, pressure, and cooling time during processing will dictate the degree of crystallinity, with a higher degree of crystallinity resulting in greater rigidity and chemical resistance. Depending on the application, the method and processing steps can be adjusted for an ideal result. Once

891-404: The propellant behind the piston, which is perforated to allow ignition. The resulting combination of electrical heating and piston compression provide higher pressures and temperatures, resulting in more power and a higher potential speed than a standard light-gas gun. When the projectile fired by a light-gas gun impacts its target, the pressure applied depends upon the mass of the projectile and

924-457: The properties of the HDPE. The method used to synthesize the HDPE is crucial because the micro structure of the HDPE will vary. The Phillips Slurry process results in HDPE with less branching and more precise molecular weights than the Ziegler process, but the Ziegler process provides greater flexibility in the type of polyethylene produced. The molecular weight of HDPE refers to the length of

957-419: The speed of sound in the ambient conditions. The hybrid electrothermal light-gas gun works on similar principles of the standard light-gas gun, but adds an electric arc to heat the light gas to a higher temperature and pressure than the piston alone. The arc is applied in the chamber containing the light gas, raising the temperature and pressure to the point where the gas both breaks the bursting disk and ignites

990-523: The surface area, or cross-section, over which the impact force is distributed. Because air-launched projectiles experience friction with air molecules, drag increases proportionally to increased projectile surface area, which results in slower velocities the larger the surface area of a projectile is. As such, a dense and narrow projectile will apply more pressure overall than a light and wide one. Looking at constant cross-sectional projectiles, researchers have recently begun to vary their projectiles' density as

1023-403: The temperature of the fluid (but is independent of the pressure), so the heat formed by the compression of the working fluid serves to increase the maximum possible speed. Spring piston airguns increase the temperature of the air in the chamber by adiabatic heating ; this raises the local speed of sound enough to overcome frictional and other efficiency losses and propel the projectile at more than

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1056-493: The velocity of the gas particles is Maxwell-Boltzmann distributed , with the velocity of a large fraction of the particles exceeding the speed of sound in the gas. That fraction of the gas can continue to apply pressure to and therefore accelerate the projectile beyond the speed of sound in diminishing amounts as the projectile's speed increases. The speed of sound in helium is about three times that in air, and in hydrogen 3.8 times that in air. The speed of sound also increases with

1089-417: The working fluid is atmospheric air. In a light-gas gun, the piston is powered by a chemical reaction (usually gunpowder ), and the working fluid is a lighter gas, such as helium or hydrogen (though helium is much safer to work with, hydrogen offers the best performance [as explained below] and causes less launch-tube erosion). One addition that a light-gas gun adds to the airgun is a rupture disk , which

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