The pressure-fed engine is a class of rocket engine designs. A separate gas supply, usually helium , pressurizes the propellant tanks to force fuel and oxidizer to the combustion chamber. To maintain adequate flow, the tank pressures must exceed the combustion chamber pressure.
16-517: The KDU-414 ( Russian Корректирующая Двигательная Установка , Corrective Propulsion Unit), is a pressure-fed liquid rocket Propulsion Unit developed and produced by the Isayev Design Bureau (today known as KhimMash). From 1960 onward, it powered several unmanned Soviet Spacecraft, including the first series of Molniya satellites , several Kosmos satellites as well as the space probes Mars 1 , Venera 1 , Zond 2 and Zond 3 , featured as
32-402: A $ 1,000 research grant for a pilot study. Truax was looking for volunteers with enough money to help fund the effort and who wished to fly aboard his rocket. He got thousands of volunteers, but few of them had the financial resources. One person selected to fly in the rocket was engineer Jeana Yeager , who worked for Truax Engineering. Peruvian-born Daniel J. Correa was at one point announced as
48-671: A February 1939 report in Astronautics . In 1938, he showed a thrust chamber that he had constructed to the British Interplanetary Society and wrote technical reports published by the American Rocket Society . Following two years' sea duty, first on USS Enterprise (CV-6) and then a destroyer, then-Lieutenant Commander Truax worked at the Engineering Experiment Station at Annapolis in
64-415: A part of standardized spacecraft buses known as KAUR-2 , 2MV and 3MV . The Corrective Propulsion Unit consists of a single chamber 'S5.19' liquid rocket engine and a conical thermal protection cowl containing the spherical propellant tank. A barrier splits the tank into two separate compartments, filled with the propellant, UDMH , and the oxidizer, IRFNA , respectively. This combination of propellants
80-403: Is hypergolic , igniting on contact. The rocket motor is supplied with fuel by pressurizing the tank using gaseous nitrogen , which doubles as a source of RCS propellant . Elastic barriers within the tank prevent the nitrogen gas and propellant/oxidiser from mixing with each other. A gimbal mount allows the engine to swivel along two axes. In 1974, it was replaced with its derived successor,
96-543: The Bureau of Aeronautics Ship Installations Division under Commander C. A. Bolster. Truax headed the Navy Development Project (ensigns R. C. Stiff, J. F. Patton, W. Schubert and MIT civilian Robertson Youngquist), where hypergolic propellant was discovered—fuel that burst into flame spontaneously when brought into contact with nitric acid, leading to the use of aniline plus 20% furfuryl alcohol for
112-961: The PGM-17 Thor missile. Truax subsequently worked on the Navy's Viking rocket and UGM-27 Polaris missile. Truax studied the sea launching of rockets, such as the Sea Bee and Sea Horse projects . After serving as 1957 American Rocket Society president, Truax retired from the United States Navy in 1959 and headed the Aerojet-General Advanced Development Division and Aerojet's Sea Dragon project. Truax died from prostate cancer at his home in Valley Center, California on September 17, 2010. In 1966 Robert Truax founded Truax Engineering, which studied sea launch concepts similar to
128-556: The 1945 WAC Corporal (the first free-flight rocket to use the fuel). By early 1943, the Truax group had developed a 1,500 lbf (6.7 kN) thrust JATO using hypergolic fuel before the introduction of solid fuel JATO units. From 1955 to 1958, Truax was assigned to the United States Air Force under General Bernard A. Schriever , where Truax and Dr. Adolf Thiel headed the initial design studies and IRBM specifications for
144-619: The Aerojet AJ10 and TRW TR-201 used in the second stage of Delta II launch vehicle, and the Kestrel engine of the Falcon 1 by SpaceX. The 1960s Sea Dragon concept by Robert Truax for a big dumb booster would have used pressure-fed engines. Pressure-fed engines have practical limits on propellant pressure, which in turn limits combustion chamber pressure. High pressure propellant tanks require thicker walls and stronger materials which make
160-520: The KDU-414A with the S5.114 engine. Pressure-fed engine Pressure fed engines have simple plumbing and have no need for complex and occasionally unreliable turbopumps . A typical startup procedure begins with opening a valve, often a one-shot pyrotechnic device, to allow the pressurizing gas to flow through check valves into the propellant tanks. Then the propellant valves in the engine itself are opened. If
176-888: The Reaction Control (RCS) and the Orbital Maneuvering (OMS) engines of the Space Shuttle orbiter; the RCS and Service Propulsion System (SPS) engines on the Apollo Command/Service Module ; the SuperDraco (in-flight abort) and Draco (RCS) engines on the SpaceX Dragon 2 ; and the RCS, ascent and descent engines on the Apollo Lunar Module . Some launcher upper stages also use pressure-fed engines. These include
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#1732869104670192-635: The earlier Sea Dragon —the Excalibur, the SEALAR, and the Excalibur S. Truax also designed the Skycycle X-2 , which he unsuccessfully tested on April 15, 1972 and June 24, 1973, and which Evel Knievel unsuccessfully used at the Snake River Canyon in 1974. The X-3 Volksrocket (other names: Arriba One, Skycycle X-3) was a reusable space tourism rocket planned by Robert Truax after Evel Knievel provided
208-442: The fuel and oxidizer are hypergolic , they burn on contact; non-hypergolic fuels require an igniter. Multiple burns can be conducted by merely opening and closing the propellant valves as needed. If the pressurization system also has activating valves, they can be operated electrically, or by gas pressure controlled by smaller electrically operated valves. Care must be taken, especially during long burns, to avoid excessive cooling of
224-550: The pressurizing gas due to adiabatic expansion . Cold helium won't liquify, but it could freeze a propellant, decrease tank pressures, or damage components not designed for low temperatures. The Apollo Lunar Module Descent Propulsion System was unusual in storing its helium in a supercritical but very cold state. It was warmed as it was withdrawn through a heat exchanger from the ambient temperature fuel. Spacecraft attitude control and orbital maneuvering thrusters are almost universally pressure-fed designs. Examples include
240-454: The vehicle tanks heavier, thereby reducing performance and payload capacity. The lower stages of launch vehicles often use either solid fuel or pump-fed liquid fuel engines instead, where high pressure ratio nozzles are considered desirable. Other vehicles or companies using pressure-fed engine: Robert Truax Captain Robert C. Truax ( USN ) (September 3, 1917 – September 17, 2010)
256-627: Was an American rocket engineer in the United States Navy , and companies such as Aerojet and Truax Engineering , which he founded. Truax was a proponent of low-cost rocket engine and vehicle designs. As a teenager, Truax was inspired by Robert Goddard articles in Popular Mechanics magazine to build his own rockets while residing in Alameda, California . From 1936 to 1939, midshipman Truax tested liquid-fuel rocket motors and published
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