Cryogenic rocket engine

Last updated
Vulcain engine of Ariane 5 rocket Moteur-Vulcain.jpg
Vulcain engine of Ariane 5 rocket

A cryogenic rocket engine is a rocket engine that uses a cryogenic fuel and oxidizer; that is, both its fuel and oxidizer are gases which have been liquefied and are stored at very low temperatures. [1] These highly efficient engines were first flown on the US Atlas-Centaur and were one of the main factors of NASA's success in reaching the Moon by the Saturn V rocket. [1]

Contents

Rocket engines burning cryogenic propellants remain in use today on high performance upper stages and boosters. Upper stages are numerous. Boosters include ESA's Ariane 5, JAXA's H-II, ISRO's GSLV, LVM3, United States Delta IV and Space Launch System. The United States, Russia, Japan, India, France and China are the only countries that have operational cryogenic rocket engines.

Cryogenic propellants

RL-10 is an early example of cryogenic rocket engine. RL-10 rocket engine.jpg
RL-10 is an early example of cryogenic rocket engine.

Rocket engines need high mass flow rates of both oxidizer and fuel to generate useful thrust. Oxygen, the simplest and most common oxidizer, is in the gas phase at standard temperature and pressure, as is hydrogen, the simplest fuel. While it is possible to store propellants as pressurized gases, this would require large, heavy tanks that would make achieving orbital spaceflight difficult if not impossible. On the other hand, if the propellants are cooled sufficiently, they exist in the liquid phase at higher density and lower pressure, simplifying tankage. These cryogenic temperatures vary depending on the propellant, with liquid oxygen existing below −183 °C (−297.4 °F; 90.1 K) and liquid hydrogen below −253 °C (−423.4 °F; 20.1 K). Since one or more of the propellants is in the liquid phase, all cryogenic rocket engines are by definition liquid-propellant rocket engines. [2]

Various cryogenic fuel-oxidizer combinations have been tried, but the combination of liquid hydrogen (LH2) fuel and the liquid oxygen (LOX) oxidizer is one of the most widely used. [1] [3] Both components are easily and cheaply available, and when burned have one of the highest enthalpy releases in combustion, [4] producing a specific impulse of up to 450 s at an effective exhaust velocity of 4.4 kilometres per second (2.7 mi/s; Mach 13).

Components and combustion cycles

The major components of a cryogenic rocket engine are the combustion chamber, pyrotechnic initiator, fuel injector, fuel and oxidizer turbopumps, cryo valves, regulators, the fuel tanks, and rocket engine nozzle. In terms of feeding propellants to the combustion chamber, cryogenic rocket engines are almost exclusively pump-fed. Pump-fed engines work in a gas-generator cycle, a staged-combustion cycle, or an expander cycle. Gas-generator engines tend to be used on booster engines due to their lower efficiency, staged-combustion engines can fill both roles at the cost of greater complexity, and expander engines are exclusively used on upper stages due to their low thrust.[ citation needed ]

LOX+LH2 rocket engines by country

Chinese YF-77 engine used by Long March 5 YF-77 at CSTM.jpg
Chinese YF-77 engine used by Long March 5

Currently, six countries have successfully developed and deployed cryogenic rocket engines:

CountryEngineCycleUseStatus
Flag of the United States (23px).png  United States RL-10 Expander Upper stageActive
J-2 Gas-generator lower stageRetired
SSME (aka RS-25) Staged combustion BoosterActive
RS-68 Gas-generator BoosterRetired
BE-3 Combustion tap-off New Shepard Active
BE-7 Dual Expander Blue Moon (spacecraft) Active
J-2X Gas-generator Upper stageDevelopmental
Flag of Russia.svg  Russia RD-0120 Staged combustion BoosterRetired
KVD-1 Staged combustion Upper stageRetired
RD-0146 Expander Upper stageDevelopmental
Flag of France.svg  France Vulcain Gas-generator BoosterActive
HM7B Gas-generator Upper stageActive
Vinci Expander Upper stageDevelopmental
Flag of India.svg  India CE-7.5 Staged combustion Upper stageActive
CE-20 Gas-generator Upper stageActive
Flag of the People's Republic of China.svg  China YF-73 Gas-generator Upper stageRetired
YF-75 Gas-generator Upper stageActive
YF-75D Expander cycle Upper stageActive
YF-77 Gas-generator BoosterActive
Flag of Japan.svg  Japan LE-7 / 7A [5] Staged combustion BoosterActive
LE-5 / 5A / 5B [6] Gas-generator(LE-5)
Expander bleed(5A/5B)
Upper stageActive
LE-9 [7] Expander bleed BoosterActive

Comparison of first stage cryogenic rocket engines

model SSME/RS-25 LE-7A RD-0120 Vulcain 2 RS-68 YF-77
Country of originFlag of the United States (23px).png  United States Flag of Japan.svg  Japan Flag of the Soviet Union.svg  Soviet Union Flag of France.svg  France Flag of the United States (23px).png  United States Flag of the People's Republic of China.svg  China
Cycle Staged combustion Staged combustion Staged combustion Gas-generator Gas-generator Gas-generator
Length4.24 m3.7 m4.55 m3.00 m5.20 m2.6 m
Diameter1.63 m1.82 m2.42 m1.76 m2.43 m1.5 m
Dry weight3,177 kg1,832 kg3,449 kg1,686 kg6,696 kg1,054 kg
Propellant LOX/LH2 LOX/LH2 LOX/LH2 LOX/LH2 LOX/LH2 LOX/LH2
Chamber pressure18.9 MPa12.0MPa21.8 MPa11.7 MPa9.7 MPa10.1 MPa
Isp (vac.)453 sec440 sec454 sec433 sec409 sec428 sec
Thrust (vac.)2.278MN1.098MN1.961MN1.120MN3.37MN0.7MN
Thrust (SL)1.817MN0.87MN1.517MN0.800MN2.949MN0.518MN
Used in Space Shuttle
Space Launch System
H-IIA
H-IIB
Energia Ariane 5 Delta IV Long March 5

Comparison of upper stage cryogenic rocket engines

Specifications
  RL-10 HM7B Vinci KVD-1 CE-7.5 CE-20 YF-73 YF-75 YF-75D RD-0146 ES-702ES-1001 LE-5 LE-5A LE-5B
Country of originFlag of the United States (23px).png  United States Flag of France.svg  France Flag of France.svg  France Flag of the Soviet Union.svg  Soviet Union Flag of India.svg  India Flag of India.svg  India Flag of the People's Republic of China.svg  China Flag of the People's Republic of China.svg  China Flag of the People's Republic of China.svg  China Flag of Russia.svg  Russia Flag of Japan.svg  Japan Flag of Japan.svg  Japan Flag of Japan.svg  Japan Flag of Japan.svg  Japan Flag of Japan.svg  Japan
Cycle Expander Gas-generator Expander Staged combustion Staged combustion Gas-generator Gas-generator Gas-generator Expander Expander Gas-generator Gas-generator Gas-generator Expander bleed cycle
(Nozzle Expander)
Expander bleed cycle
(Chamber Expander)
Thrust (vac.)66.7 kN (15,000 lbf)62.7 kN180 kN69.6 kN73 kN186.36 kN44.15 kN83.585 kN88.36 kN98.1 kN (22,054 lbf)68.6 kN (7.0 tf) [8] 98 kN (10.0 tf) [9] 102.9 kN (10.5 tf)r121.5 kN (12.4 tf)137.2 kN (14 tf)
Mixture ratio5.5:1 or 5.88:15.05.85.055.05.26.05.26.05.555
Nozzle ratio4083.11004080804040140130110
Isp (vac.)433444.2465462454442420438442.6463425 [10] 425 [11] 450452447
Chamber pressure :MPa2.353.56.15.65.86.02.593.684.15.92.453.513.653.983.58
LH2 TP rpm90,00042,00065,000125,00041,00046,31050,00051,00052,000
LOX TP rpm18,00016,68021,08016,00017,00018,000
Length m1.731.82.2~4.22.142.141.442.82.22.682.692.79
Dry weight kg135165550282435558236245265242255.8259.4255248285

Related Research Articles

A tripropellant rocket is a rocket that uses three propellants, as opposed to the more common bipropellant rocket or monopropellant rocket designs, which use two or one propellants, respectively. Tripropellant systems can be designed to have high specific impulse and have been investigated for single-stage-to-orbit designs. While tripropellant engines have been tested by Rocketdyne and NPO Energomash, no tripropellant rocket has been flown.

<span class="mw-page-title-main">Hypergolic propellant</span> Type of rocket engine fuel

A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other.

A liquid air cycle engine (LACE) is a type of spacecraft propulsion engine that attempts to increase its efficiency by gathering part of its oxidizer from the atmosphere. A liquid air cycle engine uses liquid hydrogen (LH2) fuel to liquefy the air.

A propellant is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine. Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts.

<span class="mw-page-title-main">Liquid oxygen</span> One of the physical forms of elemental oxygen

Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear light sky-blue liquid form of dioxygen O2. It 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.

<span class="mw-page-title-main">RP-1</span> Highly refined form of kerosene used as rocket fuel

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 (H2), but is cheaper, is stable at room temperature, and presents a lower explosion hazard. RP-1 is far denser than H2, giving it a higher energy density (though its specific energy is lower). RP-1 also has a fraction of the toxicity and carcinogenic hazards of hydrazine, another room-temperature liquid fuel.

<span class="mw-page-title-main">Liquid-propellant rocket</span> Rocket engine that uses liquid fuels and oxidizers

A liquid-propellant rocket or liquid rocket utilizes a rocket engine burning liquid propellants. (Alternate approaches use gaseous or solid propellants.) Liquids are desirable propellants because they have reasonably high density and their combustion products have high specific impulse (Isp). This allows the volume of the propellant tanks to be relatively low.

<span class="mw-page-title-main">Space Shuttle external tank</span> Component of the Space Shuttle launch vehicle

The Space Shuttle external tank (ET) was the component of the Space Shuttle launch vehicle that contained the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplied the fuel and oxidizer under pressure to the three RS-25 main engines in the orbiter. The ET was jettisoned just over 10 seconds after main engine cut-off (MECO) and it re-entered the Earth's atmosphere. Unlike the Solid Rocket Boosters, external tanks were not re-used. They broke up before impact in the Indian Ocean, away from shipping lanes and were not recovered.

<span class="mw-page-title-main">Rocketdyne F-1</span> Rocket engine used on the Saturn V rocket

The F-1 is a rocket engine developed by Rocketdyne. The 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 F-1 engines were used in the S-IC first stage of each Saturn V, which served as the main launch vehicle of the Apollo program. The F-1 remains the most powerful single combustion chamber liquid-propellant rocket engine ever developed.

<span class="mw-page-title-main">Rocketdyne J-2</span> Rocket engine

The J-2, commonly known as Rocketdyne J-2, was a liquid-fuel cryogenic rocket engine used on NASA's Saturn IB and Saturn V launch vehicles. Built in the United States by Rocketdyne, the J-2 burned cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) propellants, with each engine producing 1,033.1 kN (232,250 lbf) of thrust in vacuum. The engine's preliminary design dates back to recommendations of the 1959 Silverstein Committee. Rocketdyne won approval to develop the J-2 in June 1960 and the first flight, AS-201, occurred on 26 February 1966. The J-2 underwent several minor upgrades over its operational history to improve the engine's performance, with two major upgrade programs, the de Laval nozzle-type J-2S and aerospike-type J-2T, which were cancelled after the conclusion of the Apollo program.

The highest specific impulse chemical rockets use liquid propellants. They can consist of a single chemical or a mix of two chemicals, called bipropellants. Bipropellants can further be divided into two categories; hypergolic propellants, which ignite when the fuel and oxidizer make contact, and non-hypergolic propellants which require an ignition source.

<span class="mw-page-title-main">Staged combustion cycle</span> Rocket engine operation method

The staged combustion cycle is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is thus combusted in stages. The main advantage relative to other rocket engine power cycles is high fuel efficiency, measured through specific impulse, while its main disadvantage is engineering complexity.

<span class="mw-page-title-main">Gas-generator cycle</span> Rocket engine operation method

The gas-generator cycle, also called open cycle, is one of the most commonly used power cycles in bipropellant liquid rocket engines.

<span class="mw-page-title-main">Aerojet M-1</span> One of the largest rocket engines to be designed

The Aerojet M-1 was one of the largest and most powerful liquid-hydrogen-fueled liquid-fuel rocket engines to be designed and component-tested. It was originally developed during the 1950s by the US Air Force. The M-1 offered a baseline thrust of 6.67 MN and an immediate growth target of 8 MN. If built, the M-1 would have been larger and more efficient than the famed F-1 that powered the first stage of the Saturn V rocket to the Moon.

<span class="mw-page-title-main">YF-73</span>

The YF-73 was China's first successful cryogenic liquid hydrogen fuel and liquid oxygen oxidizer gimballed engine. It was used on the Long March 3 H8 third stage, running on the simple gas generator cycle and with a thrust of 44.15 kilonewtons (9,930 lbf). It had four hinge mounted nozzles that gimbaled each on one axis to supply thrust vector control and was restart capable. It used cavitating flow venturis to regulate propellant flows. The gas generator also incorporated dual heat exchangers that heated hydrogen gas, and supplied helium from separate systems to pressurize the hydrogen and oxygen tanks. The engine was relatively underpowered for its task and the start up and restart procedures were unreliable. Thus, it was quickly replaced by the YF-75.

The YF-75 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in a gas generator cycle. It is China's second generation of cryogenic propellant engine, after the YF-73, which it replaced. It is used in a dual engine mount in the H-18 third stage of the Long March 3A, Long March 3B and Long March 3C launch vehicles. Within the mount, each engine can gimbal individually to enable thrust vectoring control. The engine also heats hydrogen and helium to pressurize the stage tanks and can control the mixture ratio to optimize propellant consumption.

<span class="mw-page-title-main">YF-77</span> Chinese rocket engine

The YF-77 is China's first cryogenic rocket engine developed for booster applications. It burns liquid hydrogen fuel and liquid oxygen oxidizer using a gas generator cycle. A pair of these engines powers the LM-5 core stage. Each engine can independently gimbal in two planes. Although the YF-77 is ignited prior to liftoff, the LM-5's four strap-on boosters provide most of the initial thrust in an arrangement similar to the European Vulcain on the Ariane 5 or the Japanese LE-7 on the H-II.

The RD-701 is a liquid-fuel rocket engine developed by Energomash, Russia. It was briefly proposed to propel the reusable MAKS space plane, but the project was cancelled shortly before the end of USSR. The RD-701 is a tripropellant engine that uses a staged combustion cycle with afterburning of oxidizer-rich hot turbine gas. The RD-701 has two modes. Mode 1 uses three components: LOX as an oxidizer and a fuel mixture of RP-1 / LH2 which is used in the lower atmosphere. Mode 2 also uses LOX, with LH2 as fuel in vacuum where atmospheric influence is negligible.

<span class="mw-page-title-main">Aerojet LR87</span> American rocket engine family used on Titan missile first stages

The LR87 was an American liquid-propellant rocket engine used on the first stages of Titan intercontinental ballistic missiles and launch vehicles. Composed of twin motors with separate combustion chambers and turbopump machinery, it is considered a single unit and was never flown as a single combustion chamber engine or designed for this. The LR87 first flew in 1959.

<span class="mw-page-title-main">Rocket propellant</span> Chemical or mixture used as fuel for a rocket engine

Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines.

References

  1. 1 2 3 Bilstein, Roger E. (1995). Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles (NASA SP-4206) (The NASA History Series). NASA History Office. pp.  89–91. ISBN   0-7881-8186-6.
  2. Biblarz, Oscar; Sutton, George H. (2009). Rocket Propulsion Elements. New York: Wiley. p.  597. ISBN   978-0-470-08024-5.
  3. The liquefaction temperature of oxygen is 89 kelvins, and at this temperature it has a density of 1.14 kg/L. For hydrogen it is 20 K, just above absolute zero, and has a density of 0.07 kg/L.
  4. Biswas, S. (2000). Cosmic perspectives in space physics. Bruxelles: Kluwer. p. 23. ISBN   0-7923-5813-9. "... [LH2+LOX] has almost the highest specific impulse."
  5. https://www.rocket.jaxa.jp/rocket/engine/le7/ [ bare URL ]
  6. https://www.rocket.jaxa.jp/rocket/engine/le5b/ [ bare URL ]
  7. https://www.rocket.jaxa.jp/rocket/engine/le9/ [ bare URL ]
  8. without nozzle 48.52kN (4.9 tf)
  9. without nozzle 66.64kN (6.8 tf)
  10. without nozzle 286.8
  11. without nozzle 291.6