- Hypergolic propellant
A hypergolic propellant is either of the two
rocket propellants used in a hypergolic rocket engine, which spontaneously ignite when they come into contact. The two propellants are usually termed the "fuel" and the "oxidizer". Although hypergolic propellants tend to be difficult to handle, a hypergolic engine is easy to control and very reliable.
In common usage, the terms "hypergol" or "hypergolic propellant" are often used to mean the most common such propellant combination,
hydrazineplus nitrogen tetroxide, or their relatives.
Soviet rocket engine researcher,
Valentin Glushkoexperimented with hypergolic fuel as early as 1931. It was initially used for "chemical ignition" of engines, starting kerosene/nitric-acid engines with an initial charge of carbolic acid. German professor Otto Lutz independently discovered the principle in 1935. The Wac Corporalrocket developed by JPL in 1944 used nitric acid with aniline fuel.
In Germany from the mid 1930s through
World War II, rocket propellants were broadly classed as monergols, hypergols, non-hypergols and lithergols. The ending "ergol" is a combination of Greek "ergon" or work, and Latin "oleum" or oil, later influenced by the chemical suffix "-ol" from alcohol. Monergols were monopropellants, while non-hypergols were bipropellants which required external ignition, and Lithergols were solid/liquid hybrids. Hypergolic propellants (or at least hypergolid ignition) were far less prone to hard starts than electric or pyrotechnic ignition. The "hypergole" terminology was coined by Dr. Wolfgang Nöggerath, at the Technical University of Brunswick Germany. [Botho Stüwe, Peene Münde West, Weltbildverlag ISBN 3-8289-0294-4 1998 page 220, German]
A hypergolic engine can be precisely controlled with only two valves, one for each propellant. This simplifies the control system and eliminates points of failure. With no complex starting procedure the thrust is more predictable, i.e., the direction and velocity of the rocket will closely match calculations. Hypergolic propellants are also less likely to accumulate to dangerous quantities, then detonate when starting, a potentially catastrophic condition known as a
In addition, the two common hypergols, various
hydrazinesand certain oxides of nitrogen, can be stored at ordinary temperatures and pressures. This allows their use on spacecraft well after launch.
Use in ICBMs
Hypergolic propellants have been used for
ballistic missiles, such as the Titan II, and most Soviet ICBMs in wide deployment. Switching to hydrazines and oxides of nitrogen eliminated cryogenic propellants, which boiled off during storage and needed constant replenishment. But because of difficulties in storing such corrosive and toxic hypergols, the trend in ICBMs has been to move toward solid-fuel boosters, first with Western submarine-launched ballistic missiles, then the next-generation land-based US ICBMs, then later Soviet ICBMs.Fact|date=September 2007
Common hypergolic propellant combinations
Unsymmetrical dimethylhydrazine(UDMH) + nitrogen tetroxide- frequently used by the Soviets, such as in the Proton rocketand supplied by them to France for the Ariane 1 first and second stages (replaced with UH 25); ISRO PSLVsecond stage
Aerozine 50+ nitrogen tetroxide- large engines, especially US: Titan first and second stages; Apollo Service ModuleService Propulsion System; all Apollo Lunar Moduleengines
UH 25+ nitrogen tetroxide- large engines: Ariane 1through Ariane 4first and second stages
Monomethylhydrazine(MMH) + nitrogen tetroxide- smaller engines and thrusters: Apollo Service Module Reaction Control System(RCS); Space ShuttleOMS and RCS; Ariane 5EPS; ISRO PSLV fourth stage
Less common and obsolete combinations
Hydrazine+ nitric acid(toxic but stable)
Aniline+ nitric acid(unstable, explosive), used in the Wac Corporal
Aniline+ hydrogen peroxide(dust-sensitive, explosive)
*UDMH + IRFNA -
MGM-52 Lancemissile system
T-Stoff+ C-Stoff- Messerschmitt Me 163rocket fighter airplane
Kerosene+ hot hydrogen peroxide- Gamma, with the peroxide first decomposed by a catalyst. Because of the heat from H2O2 decomposition, this is arguably not a true hypergolic combination. Aerozine 50is a mixture of 50% UDMHand 50% straight hydrazine(N2H4). UH 25is a mixture of 25% hydrazinehydrate and 75% UDMH.
The corrosiveness of nitrogen tetroxide can be reduced by adding several percent
nitric oxide(NO), forming MON.
* "-ergol", "Oxford English Dictionary".
* "Modern Engineering for Design of Liquid-Propellant Rocket Engines", Huzel & Huang, pub. AIAA, 1992. ISBN 1-56347-013-6.
* "History of Liquid Propellant Rocket Engines", G. Sutton, pub. AIAA 2005. ISBN 1-56347-649-5.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Propellant — A propellant is a material that is used to move ( propel ) an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid.Common chemical propellants consist of a fuel, like… … Wikipedia
hypergolic — /huy peuhr gaw lik, gol ik/, adj. (esp. of rocket fuel propellant constituents) igniting spontaneously upon contact with a complementary substance. [1945 50; HYP(ER) + ERG + OL2 + IC] * * * … Universalium
hypergolic — adjective /hʌɪpəˈɡɒlɪk/ Of fuel or propellant, igniting spontaneously on contact with an oxidiser … Wiktionary
hypergolic — [ˌhʌɪpə gɒlɪk] adjective (of a rocket propellant) igniting spontaneously on mixing with another substance. Origin 1940s: from Ger. Hypergol, prob. from hyper + Gk ergon work + ol … English new terms dictionary
hypergolic — adj. (of a rocket propellant) igniting spontaneously on contact with an oxidant etc. Etymology: G Hypergol (perh. as HYPO , ERG(1), OL) … Useful english dictionary
Rocket propellant — is mass that is stored, usually in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust.Chemical rocket propellants are most commonly used,… … Wikipedia
launch vehicle — Aerospace. a rocket used to launch a spacecraft or satellite into orbit or a space probe into space. [1955 1960] * * * Rocket system that boosts a spacecraft into Earth orbit or beyond Earth s gravitational pull. A wide variety of launch vehicles … Universalium
White Sands Test Facility — (WSTF) is a rocket engine test facility and a resource for testing and evaluating potentially hazardous materials, space flight components, and rocket propulsion systems. NASA established WSTF on the White Sands Missile Range in 1963. [cite web… … Wikipedia
Dinitrogen tetroxide — IUPAC name Dinitrogen tetraoxide … Wikipedia
Rocket — This article is about vehicles powered by rocket engines. For other uses, see Rocket (disambiguation). A Soyuz U, at Baikonur Site 1/5 A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engi … Wikipedia