The Reaction Motors LR99 engine was the first large, throttleable , restartable liquid-propellant rocket engine. Development began in the 1950s by the Reaction Motors Division of Thiokol Chemical Company to power the North American X-15 hypersonic research aircraft. It could deliver up to 57,000 lbf (250 kN) of thrust with a specific impulse of 279 s (2.74 km/s) or 239 s (2.34 km/s) at sea level. Thrust was variable from 50 to 100 percent , and the restart capability allowed it to be shut down and restarted during flight when necessary.
20-467: The engine is propelled by liquid oxygen and anhydrous ammonia , pumped into the engine by turbopumps at a mass flow rate of over 10,000 lb (4,500 kg) per minute . After one hour of operation, the XLR99 required an overhaul. Operating times nearly twice that were recorded in tests, but declared largely unsafe. The basic X-15 aircraft carried fuel for about 83 seconds of full-powered flight, while
40-471: A good efficiency and all the energy for refrigeration is provided by the compression of the air at the inlet of the unit. To achieve the low distillation temperatures, an air separation unit requires a refrigeration cycle that operates by means of the Joule–Thomson effect , and the cold equipment has to be kept within an insulated enclosure (commonly called a "cold box"). The cooling of the gases requires
60-442: A large amount of energy to make this refrigeration cycle work and is delivered by an air compressor . Modern ASUs use expansion turbines for cooling; the output of the expander helps drive the air compressor, for improved efficiency. The process consists of the following main steps: The separated products are sometimes supplied by pipeline to large industrial users near the production plant. Long distance transportation of products
80-416: Is cryogenic with a freezing point of 54.36 K (−218.79 °C; −361.82 °F) and a boiling point of 90.19 K (−182.96 °C; −297.33 °F) at 1 bar (15 psi). Liquid oxygen has an expansion ratio of 1:861 and because of this, it is used in some commercial and military aircraft as a transportable source of breathing oxygen. Because of its cryogenic nature, liquid oxygen can cause
100-454: Is fractional distillation . Cryogenic air separation units (ASUs) are built to provide nitrogen or oxygen and often co-produce argon. Other methods such as membrane, pressure swing adsorption (PSA) and vacuum pressure swing adsorption (VPSA) are commercially used to separate a single component from ordinary air. High purity oxygen , nitrogen , and argon , used for semiconductor device fabrication , require cryogenic distillation. Similarly,
120-429: Is by shipping liquid product for large quantities or as dewar flasks or gas cylinders for small quantities. Pressure swing adsorption provides separation of oxygen or nitrogen from air without liquefaction. The process operates around ambient temperature; a zeolite (molecular sponge) is exposed to high pressure air, then the air is released and an adsorbed film of the desired gas is released. The size of compressor
140-432: Is classified as an industrial gas and is widely used for industrial and medical purposes. Liquid oxygen is obtained from the oxygen found naturally in air by fractional distillation in a cryogenic air separation plant . Air forces have long recognized the strategic importance of liquid oxygen, both as an oxidizer and as a supply of gaseous oxygen for breathing in hospitals and high-altitude aircraft flights. In 1985,
160-432: Is energy-intensive. This process was pioneered by Carl von Linde in the early 20th century and is still used today to produce high purity gases. He developed it in the year 1895; the process remained purely academic for seven years before it was used in industrial applications for the first time (1902). The cryogenic separation process requires a very tight integration of heat exchangers and separation columns to obtain
180-416: Is more soluble than nitrogen in water, so if air is degassed from water, a stream of 35% oxygen can be obtained. Liquid oxygen for companies such as SpaceX . Pure oxygen is delivered to large hospitals for use with patients. In steelmaking , oxygen is required for the basic oxygen steelmaking process. Modern basic oxygen steelmaking uses almost two tons of oxygen per ton of steel. Nitrogen used in
200-924: Is much reduced over a liquefaction plant, and portable oxygen concentrators are made in this manner to provide oxygen-enriched air for medical purposes. Vacuum swing adsorption is a similar process; the product gas is evolved from the zeolite at sub-atmospheric pressure. Membrane technologies can provide alternate, lower-energy approaches to air separation. For example, a number of approaches are being explored for oxygen generation. Polymeric membranes operating at ambient or warm temperatures, for example, may be able to produce oxygen-enriched air (25-50% oxygen). Ceramic membranes can provide high-purity oxygen (90% or more) but require higher temperatures (800-900 deg C) to operate. These ceramic membranes include ion transport membranes (ITM) and oxygen transport membranes (OTM). Air Products and Chemicals Inc and Praxair are developing flat ITM and tubular OTM systems. Membrane gas separation
220-443: Is used to provide oxygen-poor and nitrogen-rich gases instead of air to fill the fuel tanks of jet liners, thus greatly reducing the chances of accidental fires and explosions. Conversely, membrane gas separation is currently used to provide oxygen-enriched air to pilots flying at great altitudes in aircraft without pressurized cabins. Oxygen-enriched air can be obtained exploiting the different solubility of oxygen and nitrogen. Oxygen
SECTION 10
#1732852526071240-508: The X-15A-2 carried fuel for just over 150 seconds. Therefore, each XLR99 was capable, in theory, of between 20 and 40 flights before an overhaul. Like many other liquid-fuel rocket engines, the XLR99s used regenerative cooling , in that the thrust chamber and nozzle had tubing surrounding it, through which the propellant and oxidizer passed before being burned. This kept the engine cool, and preheated
260-470: The USAF started a program of building its own oxygen-generation facilities at all major consumption bases. Liquid oxygen is the most common cryogenic liquid oxidizer propellant for spacecraft rocket applications, usually in combination with liquid hydrogen , kerosene or methane . Liquid oxygen was used in the first liquid fueled rocket . The World War II V-2 missile also used liquid oxygen under
280-500: The fuel. The basic engine has a mass of 910 lb (410 kg). The LR-99 was used exclusively to power the X-15 research aircraft after initial trials that used a pair of Reaction Motors XLR11s . Data from Aircraft engines of the World 1964/65 Liquid oxygen Liquid oxygen , sometimes abbreviated as LOX or LOXygen , is a clear cyan liquid form of dioxygen O 2 . It
300-493: The materials it touches to become extremely brittle. Liquid oxygen is also a very powerful oxidizing agent: organic materials will burn rapidly and energetically in liquid oxygen. Further, if soaked in liquid oxygen , some materials such as coal briquettes, carbon black , etc., can detonate unpredictably from sources of ignition such as flames, sparks or impact from light blows. Petrochemicals , including asphalt , often exhibit this behavior. The tetraoxygen molecule (O 4 )
320-896: The name A-Stoff and Sauerstoff . In the 1950s, during the Cold War both the United States' Redstone and Atlas rockets, and the Soviet R-7 Semyorka used liquid oxygen. Later, in the 1960s and 1970s, the ascent stages of the Apollo Saturn rockets , and the Space Shuttle main engines used liquid oxygen. As of 2024, many active rockets use liquid oxygen: Air separation An air separation plant separates atmospheric air into its primary components, typically nitrogen and oxygen , and sometimes also argon and other rare inert gases . The most common method for air separation
340-440: The nitrogen has evaporated from such a vessel, there is a risk that liquid oxygen remaining can react violently with organic material. Conversely, liquid nitrogen or liquid air can be oxygen-enriched by letting it stand in open air; atmospheric oxygen dissolves in it, while nitrogen evaporates preferentially. The surface tension of liquid oxygen at its normal pressure boiling point is 13.2 dyn/cm. In commerce, liquid oxygen
360-416: The only viable source of the rare gases neon , krypton , xenon is the distillation of air using at least two distillation columns . Helium is also recovered in advanced air separation processes. Pure gases can be separated from air by first cooling it until it liquefies, then selectively distilling the components at their various boiling temperatures. The process can produce high purity gases but
380-528: Was first predicted in 1924 by Gilbert N. Lewis , who proposed it to explain why liquid oxygen defied Curie's law . Modern computer simulations indicate that, although there are no stable O 4 molecules in liquid oxygen, O 2 molecules do tend to associate in pairs with antiparallel spins , forming transient O 4 units. Liquid nitrogen has a lower boiling point at −196 °C (77 K) than oxygen's −183 °C (90 K), and vessels containing liquid nitrogen can condense oxygen from air: when most of
400-404: Was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard , an application which has continued to the present. Liquid oxygen has a clear cyan color and is strongly paramagnetic : it can be suspended between the poles of a powerful horseshoe magnet . Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and
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