![Hypergolic Fuel for MESSENGER](https://upload.wikimedia.org/wikipedia/commons/2/2a/Hypergolic_Fuel_for_MESSENGER.jpg)
A hypergolic propellant is a
rocket propellant
Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propuls ...
combination used in a
rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordanc ...
, whose components
spontaneously ignite when they come into contact with each other.
The two propellant components usually consist of a
fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
and an
oxidizer
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...
. The main advantages of hypergolic propellants are that they can be stored as liquids at room temperature and that engines which are powered by them are easy to ignite reliably and repeatedly. Common hypergolic propellants are difficult to handle due to their extreme
toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
and/or
corrosiveness.
In contemporary usage, the terms "hypergol" and "hypergolic propellant" usually mean the most common such propellant combination:
dinitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
plus
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
and/or its relatives
monomethylhydrazine
Monomethylhydrazine (mono-methyl hydrazine, MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as ...
(MMH) and
unsymmetrical dimethylhydrazine
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
(UDMH).
History
In 1935,
Hellmuth Walter
Hellmuth Walter (26 August 1900 – 16 December 1980) was a German engineer who pioneered research into rocket engines and gas turbines. His most noteworthy contributions were rocket motors for the Messerschmitt Me 163 and Bachem Ba 349 intercept ...
discovered that
hydrazine hydrate
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine h ...
was hypergolic with
high-test peroxide
High-test peroxide (HTP) is a highly concentrated (85 to 98%) solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with n ...
of 80-83%. He was probably the first to discover this phenomenon, and set to work developing a fuel. Prof. Otto Lutz assisted the
Walter Company with the development of ''
C-Stoff
C-Stoff (; "substance C") was a reductant used in bipropellant rocket fuels (as a fuel itself) developed by Hellmuth Walter Kommanditgesellschaft in Germany during World War II. It was developed for use with T-Stoff (a high-test peroxide) as an oxi ...
'' which contained 30% hydrazine hydrate, 57%
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
, and 13% water, and spontaneously ignited with high strength
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
.
BMW developed engines burning a hypergolic mix of nitric acid with various combinations of amines, xylidines and
aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine
In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...
s.
Hypergolic propellants were discovered independently, for the second time, in the U.S. by
GALCIT and Navy Annapolis researchers in 1940. They developed engines powered by aniline and
red fuming nitric acid
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
(RFNA).
Robert Goddard
Robert Hutchings Goddard (October 5, 1882 – August 10, 1945) was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket. Goddard successfully laun ...
,
Reaction Motors
Reaction Motors, Inc. (RMI) was an early American maker of liquid-fueled rocket engines, located in New Jersey. RMI engines with thrust powered the Bell X-1 rocket aircraft that first broke the sound barrier in 1947, and later aircraft such ...
, and
Curtiss-Wright
The Curtiss-Wright Corporation is a manufacturer and services provider headquartered in Davidson, North Carolina, with factories and operations in and outside the United States. Created in 1929 from the consolidation of Curtiss, Wright, and v ...
worked on aniline/nitric acid engines in the early 1940s, for small missiles and jet assisted take-off (
JATO
JATO (acronym for jet-assisted take-off) is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term ''JATO'' is used interchangeably with the (more specific ...
).The project resulted in the successful assisted take off of several
Martin PBM and PBY bombers, but the project was disliked because of the toxic properties of both fuel and oxidizer, as well as the high
freezing point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
of aniline. The second problem was eventually solved by the addition of small quantities of
furfuryl alcohol
Furfuryl alcohol is an organic compound containing a furan substituted with a hydroxymethyl group. It is a colorless liquid, but aged samples appear amber. It possesses a faint odor of burning and a bitter taste. It is miscible with but unstable ...
to the aniline.
![Walter Triebwerk HWK109-509 A Luftwaffenmuseum Berlin-Gatow Denis Apel](https://upload.wikimedia.org/wikipedia/commons/f/f9/Walter_Triebwerk_HWK109-509_A_Luftwaffenmuseum_Berlin-Gatow_Denis_Apel.JPG)
In Germany from the mid-1930s through
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, rocket propellants were broadly classed as
monergol
Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...
s, hypergols,
non-hypergols and
lithergols. The ending ''ergol'' is a combination of
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''ergon'' or work, and Latin ''oleum'' or oil, later influenced by the chemical suffix ''-ol'' from
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
.
["-ergol", ''Oxford English Dictionary''] Monergols were
monopropellant
Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...
s, while non-hypergols were
bipropellants
A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Liquids are desirable because they have a reasonably high density and high specific impulse (''I''sp). This allows the volume of the propellant ta ...
which required external ignition, and lithergols were solid/liquid hybrids. Hypergolic propellants (or at least hypergolic ignition) were far less prone to
hard start
A hard start is a rocketry term referring to an overpressure condition during start of a rocket engine at ignition. In the worst cases, this takes the form of an unconfined explosion, resulting in damage, or destruction of the engine.
Rocket igni ...
s than electric or pyrotechnic ignition. The "hypergole" terminology was coined by Dr. Wolfgang Nöggerath, at the Technical University of
Brunswick, Germany.
The only rocket-powered fighter ever deployed was the
Messerschmitt Me 163
The Messerschmitt Me 163 Komet is a rocket-powered interceptor aircraft primarily designed and produced by the German aircraft manufacturer Messerschmitt. It is the only operational rocket-powered fighter aircraft in history as well as th ...
B ''Komet''. The Komet had a
HWK 109-509
The Walter HWK 109-509 was a German liquid-fuel bipropellant rocket engine that powered the Messerschmitt Me 163 Komet and Bachem Ba 349 aircraft. It was produced by Hellmuth Walter Kommanditgesellschaft (HWK) commencing in 1943, with licensed ...
, a rocket motor which consumed methanol/hydrazine as fuel and high test peroxide ''
T-Stoff
T-Stoff (; 'substance T') was a stabilised high test peroxide used in Germany during World War II. T-Stoff was specified to contain 80% (occasionally 85%) hydrogen peroxide (H2O2), remainder water, with traces (<0.1%) of stabilisers. Stabilisers ...
'' as oxidizer. The hypergolic rocket motor had the advantage of fast climb and quick-hitting tactics at the cost of being very volatile and capable of exploding with any degree of inattention. Other proposed combat rocket fighters like the
Heinkel ''Julia'' and reconnaissance aircraft like the
DFS 228
The DFS 228 was a rocket-powered, high-altitude reconnaissance aircraft designed by the ''Deutsche Forschungsanstalt für Segelflug'' (DFS - "German Research Institute for Sailplane Flight") during World War II. By the end of the war, the aircraf ...
were meant to use the Walter 509 series of rocket motors, but besides the Me 163, only the
Bachem Ba 349
The Bachem Ba 349 Natter ( en, Colubrid, grass-snake) was a World War II German point-defence rocket-powered interceptor, which was to be used in a very similar way to a manned surface-to-air missile. After a vertical take-off, which eliminated ...
''Natter'' vertical launch expendable fighter was ever flight-tested with the Walter rocket propulsion system as its primary sustaining thrust system for military-purpose aircraft.
The earliest
ballistic missiles, such as the Soviet
R-7 that launched
Sputnik 1
Sputnik 1 (; see § Etymology) was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the Soviet space program. It sent a radio signal back to Earth for t ...
and the U.S.
Atlas
An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth.
Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geographic ...
and
Titan-1, used
kerosene
Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
and
liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
. Although they are preferred in space launchers, the difficulties of storing a
cryogen
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
like liquid oxygen in a missile that had to be kept launch ready for months or years at a time led to a switch to hypergolic propellants in the U.S.
Titan II
The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space l ...
and in most Soviet ICBMs such as the
R-36. But the difficulties of such corrosive and toxic materials, including leaks and explosions in Titan-II silos, led to their near universal replacement with
solid-fuel boosters, first in Western
submarine-launched ballistic missiles and then in land-based U.S. and Soviet ICBMs.
The
Apollo Lunar Module
The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...
, used in the
Moon landings
A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.
The United S ...
, employed hypergolic fuels in both the descent and ascent rocket engines. The
Apollo spacecraft
The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft ...
used the same combination for the
Service Propulsion System
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship ...
. Those spacecraft and the
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
(among others) used hypergolic propellants for their
reaction control system
A reaction control system (RCS) is a spacecraft system that uses thrusters to provide attitude control and translation. Alternatively, reaction wheels are used for attitude control. Use of diverted engine thrust to provide stable attitude contr ...
s.
The trend among western space launch agencies is away from large hypergolic rocket engines and toward hydrogen/oxygen engines with higher performance.
Ariane 1 through 4, with their hypergolic
first and second stages (and optional hypergolic boosters on the Ariane 3 and 4) have been retired and replaced with the Ariane 5, which uses a first stage fueled by liquid hydrogen and liquid oxygen. The Titan II, III and IV, with their hypergolic first and second stages, have also been retired. Hypergolic propellants are still widely used in upper stages when multiple burn-coast periods are required, and in
Launch escape system
A launch escape system (LES) or launch abort system (LAS) is a crew-safety system connected to a space capsule that can be used to quickly separate the capsule from its launch vehicle in case of an emergency requiring the abort of the launch, suc ...
s.
Characteristics
Advantages
Hypergolically-fueled rocket engines are usually simple and reliable because they need no ignition system. Although larger hypergolic engines in some launch vehicles use
turbopump
A turbopump is a propellant pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The purpos ...
s, most hypergolic engines are pressure-fed. A gas, usually
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
, is fed to the propellant tanks under pressure through a series of
check
Check or cheque, may refer to:
Places
* Check, Virginia
Arts, entertainment, and media
* ''Check'' (film), a 2021 Indian Telugu-language film
* ''The Checks'' (episode), a 1996 TV episode of ''Seinfeld''
Games and sports
* Check (chess), a thr ...
and
safety valve
A safety valve is a valve that acts as a fail-safe. An example of safety valve is a pressure relief valve (PRV), which automatically releases a substance from a boiler, pressure vessel, or other system, when the pressure or temperature exceeds ...
s. The propellants in turn flow through control valves into the combustion chamber; there, their instant contact ignition prevents a mixture of unreacted propellants from accumulating and then igniting in a potentially catastrophic
hard start
A hard start is a rocketry term referring to an overpressure condition during start of a rocket engine at ignition. In the worst cases, this takes the form of an unconfined explosion, resulting in damage, or destruction of the engine.
Rocket igni ...
.
As hypergolic rockets do not need an ignition system, they can fire any number of times by simply opening and closing the propellant valves until the propellants are exhausted and are therefore uniquely suited for spacecraft maneuvering and well suited, though not uniquely so, as upper stages of such space launchers as the
Delta II
Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...
and
Ariane 5
Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads int ...
, which must perform more than one burn. Restartable non-hypergolic rocket engines nevertheless exist, notably the cryogenic (oxygen/hydrogen)
RL-10
The RL10 is a liquid-fuel cryogenic rocket engine built in the United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to of thrust per engine in vacuum. Three RL10 ve ...
on the
Centaur
A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse.
Centaurs are thought of in many Greek myths as being ...
and the
J-2 on the
Saturn V
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with multistage rocket, three stages, and powered with liquid-propellant r ...
. The
RP-1
RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is st ...
/LOX
Merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
on the
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
can also be restarted.
The most common hypergolic fuels,
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
,
monomethylhydrazine
Monomethylhydrazine (mono-methyl hydrazine, MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as ...
and
unsymmetrical dimethylhydrazine
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
, and oxidizer,
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
, are all liquid at ordinary temperatures and pressures. They are therefore sometimes called storable liquid propellants. They are suitable for use in spacecraft missions lasting many years. The
cryogenity of
liquid hydrogen
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully li ...
and
liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
has so far limited their practical use to space launch vehicles where they need to be stored only briefly. As the largest issue with the usage of cryogenic propellants in interplanetary space is boil-off, which is largely dependant on
the scale of spacecraft, for larger craft such as
Starship
A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for interstellar travel, traveling between planetary systems.
The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 188 ...
this is less of an issue.
Another advantage of hypergolic propellants is their high density compared to cryogenic propellants.
LOX
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an appli ...
has a density of 1.14 g/ml, while on the other hand, hypergolic oxidisers such as
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
or
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
have a density of 1.55 g/ml and 1.45 g/ml respectively.
LH2
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully liq ...
fuel offers extremely high performance, yet its density only warrants its usage in the largest of rocket stages, while mixtures of
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
and
UDMH
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
have a density at least ten times higher. This is of great importance in
space probes
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually conside ...
, as the higher propellant density allows the size of their propellant tank to be reduced significantly, which in turn allows the probe to fit within a smaller
payload fairing
A payload fairing is a nose cone used to protect a spacecraft payload against the impact of dynamic pressure and aerodynamic heating during launch through an atmosphere. An additional function on some flights is to maintain the cleanroom environm ...
.
Disadvantages
Relative to their mass, traditional hypergolic propellants possess a lower
calorific value
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it.
The ''calorific value'' is the total energy rele ...
than cryogenic propellant combinations like
LH2
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully liq ...
/
LOX
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an appli ...
or
LCH4 /
LOX
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an appli ...
.
A launch vehicle that uses hypergolic propellant must therefore carry a greater mass of fuel than one that uses these cryogenic fuels.
The
corrosivity
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engin ...
,
toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
, and
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
icity of traditional hypergolics necessitate expensive safety precautions. Failure to follow adequate safety procedures with an exceptionally dangerous UDMH-nitric acid propellant mixture nicknamed
"Devil's Venom", for example, resulted in the deadliest rocketry accident in history, the
Nedelin catastrophe
The Nedelin catastrophe or Nedelin disaster was a launch pad accident that occurred on 24 October 1960 at Baikonur test range (of which Baikonur Cosmodrome is a part), during the development of the Soviet R-16 (missile), R-16 Intercontinental ...
.
Hypergolic combinations
Common
Common hypergolic propellant combinations include:
*
Aerozine 50
__NOTOC__
Aerozine 50 is a 50:50 mix by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH), originally developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket e ...
+
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
(NTO) – widely used in historical American rockets, including the
Titan II
The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space l ...
; all engines in the
Apollo Lunar Module
The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...
.
Aerozine 50
__NOTOC__
Aerozine 50 is a 50:50 mix by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH), originally developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket e ...
is a mixture of 50%
UDMH
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
and 50% straight
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
(N
2H
4).
*
Monomethylhydrazine
Monomethylhydrazine (mono-methyl hydrazine, MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as ...
(MMH) +
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
(NTO) – smaller engines and reaction control thrusters:
Apollo command and service module
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship ...
RCS
RCS may refer to:
Organisations
*Racing Club de Strasbourg Alsace
* Radio Corporation of Singapore
*Radcliffe Choral Society
* Rawmarsh Community School
*Red Crescent Society
*Red Cross Society
* Representation of Czechs and Slovaks, a football t ...
,
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
OMS and
RCS
RCS may refer to:
Organisations
*Racing Club de Strasbourg Alsace
* Radio Corporation of Singapore
*Radcliffe Choral Society
* Rawmarsh Community School
*Red Crescent Society
*Red Cross Society
* Representation of Czechs and Slovaks, a football t ...
;
Ariane 5
Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads int ...
EPS;
Draco
Draco is the Latin word for serpent or dragon.
Draco or Drako may also refer to:
People
* Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived
* ...
thrusters used by the
SpaceX Dragon
American private space transportation company SpaceX has developed and produced several spacecraft named Dragon. The first family member, now referred to as Dragon 1, flew 23 cargo missions to the ISS between 2010 and 2020 before being retired ...
spacecraft.
*
Triethylborane
Triethylborane (TEB), also called triethylboron, is an organoborane (a compound with a B–C bond). It is a colorless pyrophoric liquid. Its chemical formula is or , abbreviated . It is soluble in organic solvents tetrahydrofuran and hexane.
Pr ...
/
triethylaluminium
Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2( C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a dimer. This colorless liquid is pyrophoric. It is an industrially ...
(TEA-TEB) +
liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
– used during the ignition process of some rocket engines that use liquid oxygen, used by the
SpaceX Merlin Engine Family and
Rocketdyne F-1
The F-1, commonly known as Rocketdyne F1, was a rocket engine developed by Rocketdyne. This engine uses a gas-generator cycle developed in the United States in the late 1950s and was used in the Saturn V rocket in the 1960s and early 1970s. Five ...
.
*
Unsymmetrical dimethylhydrazine
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
(UDMH) +
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
(NTO) – frequently used by
Roscosmos
The State Space Corporation "Roscosmos" (russian: Государственная корпорация по космической деятельности «Роскосмос»), commonly known simply as Roscosmos (russian: Роскосмос) ...
, such as in the
Proton (rocket family)
Proton (Russian: Протон) (formal designation: UR-500) is an expendable launch system used for both commercial and Russian government space launches. The first Proton rocket was launched in 1965. Modern versions of the launch system are sti ...
, and supplied by them to France for the Ariane 1 first and second stages (replaced with
UH 25 UH 25 is a fuel mixture for rockets. It was developed for the European Ariane 2–4 launch vehicles.
UH 25 was developed after a disaster during flight 2 of the Ariane 1 rocket. During launch, one of the four Viking engines on the first stage deve ...
);
ISRO
The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman ...
rockets using
Vikas engine
The Vikas (a portmanteau from initials of ''VIK''ram ''A''mbalal ''S''arabhai ) is a family of liquid fuelled rocket engines conceptualized and designed by the Liquid Propulsion Systems Centre in the 1970s. The design was based on the licensed ...
.
Less common or obsolete
Less-common or obsolete hypergolic propellants include:
*
Aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine
In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...
+
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
(unstable, explosive), used in the
WAC Corporal
The WAC Corporal was the first sounding rocket developed in the United States and the first vehicle to achieve hypersonic speeds. It was an offshoot of the Corporal program, that was started by a partnership between the United States Army Ordn ...
*
Aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine
In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...
+
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
(dust-sensitive, explosive)
*
Furfuryl alcohol
Furfuryl alcohol is an organic compound containing a furan substituted with a hydroxymethyl group. It is a colorless liquid, but aged samples appear amber. It possesses a faint odor of burning and a bitter taste. It is miscible with but unstable ...
+
IRFNA
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
(or
red fuming nitric acid
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
) –
Copenhagen Suborbitals
Copenhagen Suborbitals is an amateur, crowd-funded, and open-source human space program. Since its beginning in 2008, Copenhagen Suborbitals has flown five home-built rockets and two mock-up space capsules. Their stated goal is to have one of th ...
SPECTRA Engine
*
Furfuryl alcohol
Furfuryl alcohol is an organic compound containing a furan substituted with a hydroxymethyl group. It is a colorless liquid, but aged samples appear amber. It possesses a faint odor of burning and a bitter taste. It is miscible with but unstable ...
+
WFNA (or
white fuming nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nit ...
)
*
Hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
+
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
(toxic but stable), ultimately abandoned due to lack of relieable ignition. No engine with this combination ever went into mass production.
*
Kerosene
Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
+ (
high-test peroxide
High-test peroxide (HTP) is a highly concentrated (85 to 98%) solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with n ...
+ catalyst) –
Gamma
Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...
, with the peroxide first decomposed by a catalyst. Cold
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
and
kerosene
Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
are not hypergolic, but concentrated hydrogen peroxide (referred to as high-test peroxide or HTP) run over a catalyst produces free oxygen and steam at over which is hypergolic with kerosene.
*
Tonka
Tonka is an American producer of toy trucks. The company is known for making steel toy models of construction type trucks and machinery. Maisto International, which makes diecast vehicles, acquired the rights to use the Tonka name in a line of ...
(TG-02, approx. 50%
triethylamine
Triethylamine is the chemical compound with the formula N(CH2CH3)3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine or tetraethylammonium, for which TEA ...
and 50%
xylidine
Xylidine can refer to any of the six isomers of xylene amine, or any mixture of them.
The chemical formula of xylidines is C8H11N or, more descriptively, (CH3)2C6H3NH2. The CAS number for the isomer mixture is . They are colorless solids or liqui ...
) typically oxidised with
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
or its anhydrous
nitric oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
derivatives (AK-2x group in the Soviet Union) e.g.
AK-20F (80% HNO
3 and 20% N
2O
4 with
inhibitor).
*
T-Stoff
T-Stoff (; 'substance T') was a stabilised high test peroxide used in Germany during World War II. T-Stoff was specified to contain 80% (occasionally 85%) hydrogen peroxide (H2O2), remainder water, with traces (<0.1%) of stabilisers. Stabilisers ...
(stabilised >80% peroxide) +
C-Stoff
C-Stoff (; "substance C") was a reductant used in bipropellant rocket fuels (as a fuel itself) developed by Hellmuth Walter Kommanditgesellschaft in Germany during World War II. It was developed for use with T-Stoff (a high-test peroxide) as an oxi ...
(methanol, hydrazine, water, catalyst) –
Messerschmitt Me 163
The Messerschmitt Me 163 Komet is a rocket-powered interceptor aircraft primarily designed and produced by the German aircraft manufacturer Messerschmitt. It is the only operational rocket-powered fighter aircraft in history as well as th ...
World War II German rocket fighter aircraft, for its
Walter 109-509A engine.
*
Turpentine
Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthene, terebinthine and (colloquially) turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a special ...
+
IRFNA
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
(flown in French Diamant A first-stage)
*
UDMH
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...
+
IRFNA
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
–
MGM-52 Lance
The MGM-52 Lance was a mobile field artillery tactical surface-to-surface missile (tactical ballistic missile) system used to provide both nuclear and conventional fire support to the United States Army. The missile's warhead was developed at La ...
missile system,
Agena and
Able Upper Stages, Isayev-built maneuvering engines.
Proposed, remain unflown
*
Chlorine trifluoride
Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temp ...
(ClF
3) + all known fuels – Briefly considered as an oxidizer given its high hypergolicity with all standard fuels, but ultimately abandoned in the 70s due to the difficulty of handling the substance safely.
Chlorine trifluoride
Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temp ...
can only be extinguished by flooding the burning area with
Nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
or
noble gases
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemi ...
. The substance is known to burn concrete and gravel.
Chlorine pentafluoride
Chlorine pentafluoride is an interhalogen compound with formula ClF5. This colourless gas is a strong oxidant that was once a candidate oxidizer for rockets. The molecule adopts a square pyramidal structure with C4v symmetry, as confirmed by ...
(ClF
5) presents the same hazards, but offers higher
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse i ...
than ClF
3.
*
Pentaborane(9)
Pentaborane(9) is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fue ...
and diborane +
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
–
Pentaborane(9)
Pentaborane(9) is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fue ...
, a so-called
Zip fuel
Zip fuel, also known as high energy fuel (HEF), is any member of a family of jet fuels containing additives in the form of hydro-boron compounds, or ''boranes''. Zip fuels offer higher energy density than conventional fuels, helping extend the rang ...
, was studied by Soviet Rocket Scientist
V. P. Glushko for usage in combination with
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
in the
RD-270M rocket engine. This propellant combination would have yielded a significant increase in performance, but was ultimately given up due to toxicity concerns.
[Astronautix: RD-270]
.
*
Tetramethylethylenediamine
Tetramethylethylenediamine (TMEDA or TEMED) is a chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylenediamine by replacement of the four amine hydrogens with four methyl groups. It is a colorless liquid, ...
+
IRFNA
Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks ...
– A sightly less toxic alternative to
Hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
and its derivatives.
Related technology
Pyrophoric
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolith ...
substances, which ignites spontaneously in the presence of air, are also sometimes used as rocket fuels themselves or to ignite other fuels. For example a mixture of
triethylborane
Triethylborane (TEB), also called triethylboron, is an organoborane (a compound with a B–C bond). It is a colorless pyrophoric liquid. Its chemical formula is or , abbreviated . It is soluble in organic solvents tetrahydrofuran and hexane.
Pr ...
and
triethylaluminium
Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2( C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a dimer. This colorless liquid is pyrophoric. It is an industrially ...
(which are both separately and even more so together pyrophoric), was used for engine starts in the
SR-71 Blackbird
The Lockheed SR-71 "Blackbird" is a long-range, high-altitude, Mach 3+ strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporation. It was operated by the United States Air Force ...
and in the
F-1 engines on the
Saturn V
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with multistage rocket, three stages, and powered with liquid-propellant r ...
rocket and is used in the
Merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
engines on the
SpaceX
Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal of ...
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
rockets.
Notes
References
;Citations
;Bibliography
*
* ''Modern Engineering for Design of Liquid-Propellant Rocket Engines'', Huzel & Huang, pub. AIAA, 1992. .
* ''History of Liquid Propellant Rocket Engines'', G. Sutton, pub. AIAA 2005. .
External links
*
{{spacecraft propulsion
Rocket fuels
Soviet inventions