Chemical rifle chemical uses the highest liquid
Video Liquid rocket propellant
Description
Approximately 170 different propellants made from liquid fuels have been tested, excluding minor changes to specific propellants such as propellant additives, corrosion inhibitors, or stabilizers. In the US alone at least 25 different propellant combinations have been flown. No new propellant has been used for nearly 30 years.
Many factors go into choosing propellant for a liquid propellant rocket engine. Major factors include ease of operation, cost, hazard/environment and performance. They can be composed of a single chemical, monopropellant, or two, called bipropellants or other mixtures. Bipropellants may be either hipergolic or nonhypergolic propellants. A hyperololic combination of oxidizing agents and fuels will begin to burn when contact occurs. A nonhypergolic needs an ignition source.
Maps Liquid rocket propellant
History
Initial development, 1926
On March 16, 1926, Robert H. Goddard used liquid oxygen (LOX ) and gasoline as a rocket fuel for the launch of his first partially successful liquid-propellant rocket. Both propellants are available, cheap and very energetic. Oxygen is a moderate cryogen because the air will not melt against the liquid oxygen tank, so it is possible to store the LOX briefly in a rocket without excessive isolation.
World War II era
Germany had a very active rocket development before and during World War II, both for strategic V-2 rockets and other missiles. V-2 uses an alcohol/LOX liquid propellant machine, with hydrogen peroxide to drive the fuel pump. Alcohol is mixed with water for engine cooling. Both Germany and the United States developed a reusable liquid propellant rocket rocket engine that uses liquid oxide which can be stored at a much larger density than LOX and liquid fuel that will ignite spontaneously when in contact with high density oxidizers. The German machine is powered by hydrogen peroxide and a mixture of hydrazine hydrate and methyl alcohol. The US machine is powered by oxidizing nitric acid and aniline. Both engines were used for electric planes, the Comet Me-163B interceptor in the case of German engines and RATO units to help take off aircraft in the case of US engines.
1950s and 1960s
During the 1950s and 1960s there was a huge explosion of activity by propellant chemists to find high-energy liquid and solid propellants that were more suited to the military. Large strategic missiles need to sit in ground-based or underwater silos for years, can be launched on the spot. Propellants that require continuous cooling, which causes their rockets to grow an ice sheet that is thicker, is not practical. Because the military is willing to handle and use hazardous materials, large amounts of hazardous chemicals are vacuumed in large quantities, most of which are ultimately deemed unsuitable for operational systems. In the case of nitric acid, the acid itself ( HNO
3 ) is unstable, and most metals are corroded, making it difficult to store. Added a little nitrogen tetroxide, N
2 O
4 , flip the red mixture and save it from changing the composition , but leaving the problem that the rusty nitric acid the container was placed in, releasing the gas that can build up pressure in the process. The breakthrough is the addition of a small amount of hydrogen fluoride (HF), which forms a self-insertion metal fluoride inside the tank wall that is Banned Red Fuming Nitric Acid. This makes "IRFNA" can be saved. Combination of propellant based on IRFNA or pure N
2 O < span>
4 as oxidizing and kerosene or hypergynic (self-igniting ) aniline, hydrazine or dimethylhydrazine asymmetric (UDMH) as fuel was later adopted in the United States and the Soviet Union for use in strategic and tactical missiles. The self-igniting storeable liquid bi-propellant has a specific impulse that is slightly lower than LOX/kerosene, but has a higher density so that larger propellant masses can be placed in tanks of the same size. Gasoline is replaced with different hydrocarbon fuels, for example RP-1 - a very fine kerosene. This combination is quite practical for rockets that do not need to be stored.
Kerosene
The V-1 and V-2 rockets developed by Nazi Germany use LOX and ethyl alcohol. One of the main advantages of alcohol is its water content which provides cooling in larger rocket engines. Petroleum-based fuels offer more power than alcohol, but standard gasoline and kerosene leave too much sludge and combustion byproducts that can clog the engine pipeline. In addition they do not have the cooling properties of ethyl alcohol.
During the early 1950s, the chemical industry in the US was tasked with formulating an enhanced petroleum-based rocket propellant that would leave no residue behind and also ensure that the engine would remain cool. The result is RP-1, a specification completed in 1954. The very smooth form of jet fuel, RP-1 burns much cleaner than conventional fuel oil and also poses no danger to ground personnel from explosive vapors. This has been a driving force for most early American rocket and missile missiles such as Atlas, Titan I, and Thor. The Soviets quickly adopted the RP-1 for their R-7 missiles, but the majority of Soviet launch vehicles ended up using storable hypergolic propellants. In 2017, this is used in the first stage of many orbital launchers.
Hydrogen
Many early rocket theorists believed that hydrogen would be a remarkable propellant, as it provided the highest specific impulse. It is also considered the cleanest when oxidized with oxygen because the only by-product is water. Hydrogen gas is commercially produced by the combustion of natural gas rich in fuel. Carbon forms a stronger bond with oxygen so that the gaseous hydrogen is left behind.
Hydrogen in any state is huge; this is usually stored as a deep cryogenic liquid, a technique that was mastered in the early 1950s as part of a hydrogen bomb development program at Los Alamos. Liquid hydrogen is stored and transported without a boil, because helium, which has a lower boiling point than hydrogen, acts as a coolant coolant. Only when hydrogen is loaded on the launch vehicle, where there is no cooling, it enters the atmosphere.
In the late 1950s and early 1960s it was adopted for hydrogen-fueled stages such as the Centaur and Saturn stages. Even as a liquid, hydrogen has a low density, requiring large tanks and pumps, and extreme cold requires tank insulation. This extra weight reduces the mass fraction of the stage or requires extraordinary measures such as tank pressure stabilization to reduce weight. Stable pressure tanks support most loads with internal pressure rather than solid structures.
The Soviet rocket program, partly due to lack of technical ability, does not use LH
2 as propellants until the 1980s when used for the Energiya nuclear stage.
Upper use
The combination of liquid propellants of liquid oxygen and hydrogen rocket engines offers the highest specific impulse of conventional rockets in use today. This extra performance largely offsets low density losses. The low density of propellant leads to a larger fuel tank. However, small increases in specific impulses in upper level applications can have significant increases in payload to orbit capabilities.
Comparison with kerosene
The launch pad plate due to kerosene spill is more damaging than hydrogen fires, mainly for two reasons. First, kerosene burns about 20% more heat in absolute temperature than hydrogen. The second reason is the buoyancy. Because hydrogen is cryogenically deep, it boils rapidly and rises because of its very low density as a gas. Even when hydrogen burns, the gas H
2 O that is formed has molecular weight of only 18 u compared to 29.9 u for air, so it rises rapidly as well. Kerosene on the other side falls to the ground and burns for hours when it spills in large quantities, inevitably causing extensive heat damage that takes a lot of time to repair and rebuild. This is the lesson most often experienced by the test crews involved with large unproven fired rocket firing. Hydrogen-fueled engines have special design requirements such as running a propellant line horizontally, so traps do not form on the line and cause rupture due to boiling in confined spaces. This consideration applies to all cryogens, such as liquid oxygen and liquefied natural gas (LNG) as well. The use of liquid hydrogen fuels has an excellent safety record and outstanding performance that is well above all other practical rocket chemical propellants.
Lithium and fluorine
The highest specific impulse chemistry ever tested in a rocket engine is lithium and fluorine, with hydrogen added to improve thermodynamics of flue (all propellants must be stored in their own tank, making it a tripropellant). The combination gives 542 specific impulses in a vacuum, equivalent to a 5320 m/s exhaust rate. This chemical impractice highlights why exotic propellants are not actually used: to make all three fluid components, hydrogen must be kept below -252 ° C (only 21 ° K) and lithium should be stored above 180 ° C (453 ° C ). K). Lithium and fluorine are highly corrosive, lithium ignites when in contact with air, blend with fluorine with lots of fuel, including hydrogen. Fluorine and hydrogen fluoride (HF) in the exhaust is highly toxic, which makes working around a difficult foundation, damaging the environment, and making getting a launching license that much more difficult. Both lithium and fluorine are expensive compared to most rocket propellants. Therefore this combination is never flown.
During the 1950s, the Department of Defense initially proposed lithium/fluorine as a ballistic missile propellant. The 1954 accident at a chemicals worked in which fluorine clouds released into the atmosphere convinced them to use LOX/RP-1.
Metana
In November 2012, SpaceX CEO Elon Musk announced plans to develop a liquid methane/LOX rocket engine. It was previously only using RP-1/LOX in the SpaceX rocket engine. In March 2014, SpaceX developed the Raptor methylox bipropel rocket engine, which in 2016 is expected to generate 3,000 kN (670,000 lbf) thrust. The machine is scheduled for use on future super heavy rockets, MCT launch vehicle.
In July 2014, Firefly Space Systems announced their plans to use methane fuel for their small satellite launch vehicle, the Firefly Alpha with aerospike engine design.
In September 2014, Blue Origin and United Launch Alliance announced joint development of the BE-4 LOX/LNG engine. BE-4 will provide 2,400 kN (550,000 lbf) thrust.
Monopropellants
- Hydrogen peroxide
- breaks down into vapor and oxygen.
- Hydrazine
- decomposes energetically to nitrogen, hydrogen, and ammonia (2N 2 H 4 -> N 2 H 2 2NH 3 ) and is the most widely used in space vehicles. (Unoxidized ammonia decomposition is endothermic and will degrade performance).
- Nitrous oxide
- breaks down into nitrogen and oxygen.
- Steam
- when heated externally provides a fairly simple substrate of sp up to 190 seconds, depending on material corrosion and thermal boundaries.
Current use
In 2018, the commonly used liquid fuel combination:
- Kerosene (RP-1)/Liquid Oxygen (LOX)
- Used for the lower stage of the Soyuz amplifier, and the first stage of the Saturn V, Atlas, and Falcon 9 AS amplifiers. Very similar to Robert Goddard's first rocket.
- Liquid hydrogen (LH)/LOX
- Used in the Space Shuttle stage, Space Launch System, Ariane 5, Delta IV, New Shepherd, H-IIB, GSLV and Centaur.
- Dimethylhydrazine is not symmetrical (UDMH or MMH)/Dinitrogen tetroxide (NTO or N
2 O
4 ) - Used in the first three phases of the Proton propulators of Russia, the Indian Vikas engine for PSLV and GSLV rockets, mostly Chinese boosters, a number of military rockets, orbital and deep rockets, because the combination of these fuels is hypergynic and can be stored for long periods of time at temperatures and reasonable pressure.
- Hydrazine ( N
2 H
4 ) - Used in space missions as they can be stored and hypergolized, and can be used as monopropellants with catalysts.
- Aerozine-50 (50/50 hydrazine and UDMH)
- Used in space missions as they can be stored and hypergolized, and can be used as monopropellants with catalysts.
Table
This table uses data from the JANAF (JANNAF) Interagency Propagation JANAF (JANNAF) table, with the best specific impulses calculated by Rocketdyne under the assumptions of adiabatic combustion, isentropic expansion, one dimensional Expansion and some balance shift unit has been converted to metric, but no pressure.
Definition
- V e
- Average exhaust speed, m/s. Same size with specific impulses in different units, numerically the same as the specific impulses in NÃ, Â · s/kg.
- r
- Mixed ratio: mass/mass fuel oxidizer
- T c
- Room temperature, Ã, Â ° C
- d
- Bulk density of fuel and oxidizer, g/cmÃ,³
- C *
- Characteristic speed, m/s. The pressure in the same space is multiplied by the throat region, divided by the mass flow rate. Used to check the efficiency of combustion of experimental rockets.
Bipropellants
Definisi dari beberapa campuran:
- IRFNA IIIa
- 83,4% HNO 3 , 14% TIDAK 2 , 2% H 2 O, 0,6% HF
- IRFNA IV HDA
- 54,3% HNO 3 , 44% TIDAK 2 , 1% H 2 O, 0,7% HF
- RP-1
- Lihat MIL-P-25576C, pada dasarnya kerosene (kira-kira C
10 H
18 ) - MMH monomethylhydrazine
- CH
3 NHNH
2
Not all data for CO/O 2 , is intended for NASA for Mars-based rockets, only a specific boost of around 250s.
- r
- Mixed ratio: mass/mass fuel oxidizer
- V e
- Average exhaust speed, m/s. Same size with specific impulses in different units, numerically the same as the specific impulses in NÃ, Â · s/kg.
- C *
- Characteristic speed, m/s. The pressure in the same space is multiplied by the throat region, divided by the mass flow rate. Used to check the efficiency of combustion of experimental rockets.
- T c
- Room temperature, Ã, Â ° C
- d
- Bulk density of fuel and oxidizer, g/cmÃ,³
Monopropellants
References
External links
- Cpropep-Web online computer program to calculate the propellant performance in a rocket engine The Liquid Thermodynamic Analysis Analysis Tool is a computer program to predict the performance of a liquid propellant rocket engine. Clark, John D. (1972). Ignition! Informal History of Liquid Rocket Propellant (PDF) . Rutgers Press University. p.Ã, 214. ISBNÃ, 0-8135-0725-1. for the history of liquid rocket propellants in the US by pioneering rocket rellione developers.
Source of the article : Wikipedia
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