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.
11-471: 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
22-416: 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
33-432: 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,
44-517: 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
55-474: 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
66-508: 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
77-493: 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 )
88-759: 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 Too Many Requests If you report this error to
99-440: 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
110-528: 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
121-404: 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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