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🌏 | Virgin founder succeeds in space flight, reaching altitude of 85 km


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Virgin founder succeeds in space flight, reaching altitude of 85 km

 
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The ship will ignite a rocket engine and climb after being separated from a large transport aircraft at an altitude of about 15 km.
 

US space-related company Virgin Galactic succeeded in manned test space flight of rocket ship "Unity" on the 11th ... → Continue reading

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Rocket engine

Rocket engineAndPropellantBy injectingthrustGetengine.Newton's third lawbased on.

synonymAsRocket motorThere is.This isSolid fuel rocketIt is generally used in the case of an engine.

Principle of operation

For example, in the rocket engine of a chemical rocket, the chemical reaction of fuel (and oxidizer, etc.) = combustion.high temperature,High pressureBy injecting the gas of, the propulsion force is obtained by the reaction.Usually refers to both the energy source and the substance to be ejected (sometimes the same for popular chemical rockets).PropellantSay.Combustion chamber OfChemical reactionObtained inpressure TheRocket engine nozzleConverted to speed byhigh speedIs jetted backwards.In the case of electric propulsion, the propellant is applied by the electric effect.accelerateTherefore, some do not have a nozzle.

Jet engineThe difference is that the jet engine sucks and compresses the outside air, mixes it with the fuel and burns it, while the rocket engine is pre-installed.OxidantThere is a point to mix and burn with fuel.Therefore, it is big in a short timePower,Work rateCan be obtainedvacuum OfSpace,Atmospheric pressureAlthough it has the advantages of being able to be used in small high altitudes and underwater, it is not suitable for continuous use for a long time.Severe wear and space flightweaponBecause there are many uses that are difficult to collect, such as usespace shuttleForSSMEExcept for many使 い 捨 てIt is a method. (""Jet Propulsion LaboratoryAs you can see from the fact that "" is a rocket research institute, the rocket engine is also "in terms of meaning.jetIt is still an engine based on.However, at present, in general, "jet engine" refers only to air breathing engines. )

For chemical rockets, the thrust isgasDetermined by the ratio of the ejection speed, combustion pressure, and external pressure[Source required]..In the atmosphereAtmospheric pressureBecause of the existence of, the factor of the pressure term is large, and a relatively high combustion pressure is required.In a vacuum, there is no external pressure, so the pressure term is ignored and instead the ejection velocity (high)Specific thrust) Will be emphasized[Source required].

As an indicator of rocket efficiencySpecific thrustThere is.This is the gas ejection speedAcceleration of gravityDivided bymassIt means how long a 1N thrust can be sustained with 1kg of propellant.Fuel efficiencyUnlike, the larger the value, the better the efficiency.Since electric propulsion emphasizes specific impulse, the specific impulse is much larger than that of a chemical rocket at the cost of extremely small thrust.[Source required].

For chemical rocketsSolid fuel rocket,Liquid fuel rocket,Hybrid rocketAnd so on.Solid fuel rockets have a simple structure and are easy to miniaturize and store, but once they start burning, they are difficult to control, so they are small.missileIt is used for such purposes.Liquid fuel rockets are easier to control than solid fuel rockets, but the fuel storage and launch processes are complex.Hybrid rockets are being studied as having the advantages of both.

cooling

The maximum combustion temperature of a rocket engine reaches 3000 ° C or higher, depending on the fuel and combustion pressure.[Source required]..The combustion temperature of a rocket engine is higher than the melting point of the material in the combustion chamber,Graphite,tungstenAlthough it is lower than the melting point of, those materials are not suitable because they are oxidized.Regenerative cooling,Ablation cooling,Film coolingUse the existing material at a temperature that does not impair the strength.ceramic,Functionally graded materialThe development of materials with excellent heat resistance is also underway.The performance of a chemically propellant rocket is effectively determined by the composition of the propellant.[Source required].

Rocket cooling method[Source required]:

  1. Uncooled (generally used for a short test run)
  2. Ablationcooling
  3. Radiation cooling
  4. Dump cooling
  5. Regenerative cooling(In liquid fuel rockets, fuel or oxidizer is used as a coolant in the combustion chamber orTurbo pumpCirculate the bearings.Turbo pumpWhen circulating the bearing of, it also serves as a lubricant)
  6. Curtain cooling (injecting propellant to adjust the temperature of the gas to cool the wall surface)
  7. Film cooling(Cooling by spraying a liquid propellant to form a protective layer on the surface)

Conventionally, pipes are used for regenerative cooling.BrazingCombustion chambers and nozzles were formed by doing this, but this manufacturing method required skill and it was difficult to maintain quality.Developed in the former Soviet Union in recent years, it is slightly heavier but sturdy, reliable and relatively easy to control quality.Channel wall structureIs increasing.

Combustion chamber

High-temperature and high-pressure gas generated by burning propellantnozzleSquirt from thatRecoilProduces thrust.

Solid fuel rocket engine

Solid fuel rocket engines are also called rocket motors.There is a solid propellant inside.The container for storing fuelHigh strength steel,Carbon fiber reinforced plasticEtc.CompositeIt is made of.The combustion type is mainly the end face combustion method in which the fuel gradually burns from the part near the nozzle and the inner surface combustion method in which the fuel has a hole in the center like macaroni and the combustion proceeds from the inside to the outside.In the case of the end face combustion method, since the combustion area is constant, a constant thrust is maintained, but the motor case is exposed to high temperature and high pressure gas, so heat resistance is required.On the other hand, in the inner surface combustion method, if a shape having an ordinary circular hole is formed, the combustion area increases and the thrust changes as the combustion progresses, so the cross-sectional shape is devised to adjust the thrust.Generally, the end face combustion method is used to maintain the thrust, and the inner surface combustion method of the light beam cross section is used to generate high thrust in a short time.

It is difficult to increase the size of solid fuel rockets.If you double the size,Square-cube lawAs a result, the volume and weight are eight times larger, but the surface area of ​​the combustion cross section is only four times larger, so it is necessary to double the combustion rate in order to obtain thrust proportional to the increased weight.[1]..Therefore, if the size is increased, it is necessary to develop a propellant having a composition of high-speed combustion accordingly.Therefore, unless the problem of solid propellant combustion rate is solved, there is an upper limit to the size of a practical solid fuel rocket.

Advantages of solid fuel rocket engine

[Source required]

  1. Can be stored for a long time at room temperature.
  2. Can be fired in a short time when needed.
  3. Large thrust is relatively easy to obtain.
  4. Large density specific impulse. (Easy to miniaturize the structure)

Disadvantages of solid fuel rocket engines

[Source required]

  1. Output control is difficult
  2. Specific thrustIs small (compared to liquid fuel rockets)
  3. Square-cube lawDifficult to increase in size due to combustion speed

Liquid fuel rocket engine

It is a rocket engine that uses liquid fuel as a propellant.It is used for various purposes in combination with propellants.For the combustion methodGas generator cycle,Staged combustion cycle,Expander cycleThere are multiple formats such as.

Advantages of liquid fuel rocket engine

  1. Specific impulse is large
  2. Output control is possible and reignition is possible depending on the model

Disadvantages of liquid fuel rocket engine

  1. Complex structure
  2. Some types of fuel are difficult to store at room temperature.
  3. It takes time to launch.
  4. Density specific impulse is small. (The structure tends to be large)

Classification of liquid fuel rocket engines

Liquid fuel rocket engines are classified as follows according to the method of supplying propellant to the engine.

Gas generator cycleEngine

A method of driving a turbo pump by burning a small amount of propellant.

H-1
Jupiter rocketSaturn I,Saturn IBWas used for.Propellant is kerosene / liquid oxygen
RS-72
Ariane 5It was developed for the upper stage but was not used.
J-2
Saturn vUsed for the second stage of the rocket.Propellant is liquid hydrogen / liquid oxygen
E-1
US Army Ballistic Missile BureauIt was developed in, but it was canceled in the middle and the result was handed over to F-1.
F-1
Saturn vThe engine used in the first stage of the rocket.Propellant is kerosene / liquid oxygen
M-1
Toward a manned landing on MarsNEWAs a rocket engineAerojetDevelopment proceeded at the company, but the plan was cancelled.
Marlin
Falcon 1,Falcon 9Used for.Propellant is kerosene / liquid oxygen
LE-5
HIUsed for the second stage of the rocket.Propellant is liquid hydrogen / liquid oxygen
LR-87
The first stage engine of the Titan rocket.Propellant from kerosene / liquid oxygenAerozine-50/Nitrogen dioxide,Liquid hydrogen/ Supports up to liquid oxygen.
LR-89
The first stage engine of the Atlas rocket.Propellant is kerosene / liquid oxygen
LR-91
The first stage engine of the Titan rocket.The propellant was initially kerosene / liquid oxygen, but laterUnsymmetrical dimethylhydrazine/Dinitrogen tetroxideBecame.
LR-105
Atlas rocketFirst stage engine.Propellant is kerosene / liquid oxygen
MB-3-3
Delta rocketFirst stage engine.It was also licensed in Japan and used from N1 rockets to H1 rockets.Propellant is kerosene / liquid oxygen
RS-27
RocketdyneThe first stage engine of the Delta rocket developed by.Propellant is kerosene / liquid oxygen
RS-27A
The first stage engine of Delta 2 and Delta 3 developed by Rocketdyne.Propellant is kerosene / liquid oxygen
CE-20
IndianGSLV-IIILiquid hydrogen / liquid oxygen engine used in the upper stage of the rocket
HM7B
Ariane 4And Europe's first liquid hydrogen / liquid oxygen engine used in the upper stage of the Ariane 5 rocket
Vulcan
Ariane 5First stage engine.Propellant is liquid hydrogen / liquid oxygen
RS-68
Liquid hydrogen / liquid oxygen engine
YF-73
Long March 3China's first liquid hydrogen / liquid oxygen engine used in the upper stage of a rocket
YF-75
China's second generation liquid hydrogen / liquid oxygen engine
Bell 8000
The upper engine used for the Agena rocket.Propellant TheUnsymmetrical dimethylhydrazine/nitric acid

Staged combustion cycleEngine

Similar to the gas generator cycle, it burns the propellant to drive the turbopump and return the combustion gas to the main combustion chamber.Thermal efficiency can be increased because there is no waste of propellant.

RD-253
Proton rocketUsed for the first stage engine of.The fuel isUnsymmetrical dimethylhydrazine(UDMH) /Dinitrogen tetroxide
NK-33
N-1The first stage engine fuel of the rocket is kerosene / liquid oxygen
RD-120
Zenit rocketKerosene / liquid oxygen engine used in the upper stage
RD-170
EnergiaRocket booster engine fuel is kerosene / liquid oxygen
RD-180
Atlas VThe first stage engine of the rocket. RD-1 advanced fuel is kerosene / liquid oxygen
RD-191
Angara Rocket1st stage engine fuel is kerosene / liquid oxygen
RD-0120
EnergiaRocket core engine fuel is liquid hydrogen / liquid oxygen
RD-0124
Angara Rocket,Soyuz-2Upper engine fuel is kerosene / liquid oxygen
SSME
space shuttleEngine fuel is liquid hydrogen / liquid oxygen
LE-7
H-II rocket1st stage engine fuel is liquid hydrogen / liquid oxygen
LE-7A
H-IIA rocket,H-IIB rocket1st stage engine fuel is liquid hydrogen / liquid oxygen
CE-7.5
IndianGSLVLiquid hydrogen / liquid oxygen engine used in the upper stage of the rocket
YF-77
ChineseLong March 5Liquid hydrogen / liquid oxygen engine used in the first stage of the rocket

Expander cycleEngine

The turbo pump is driven by the fuel used to cool the combustion chamber.It is suitable for the upper engine, and many have reignition capability.

RL-10
CentaurUsed for rockets.America's first liquid hydrogen / liquid oxygen engine
Vinci
Under developmentAriane 5Upper engine that uses rocket liquid hydrogen / liquid oxygen as a propellant
RD-0146
Engine redesigned and produced in Russia based on Pratt & Whitney's RL-10

Expander bleed cycleEngine

Similar to the expander cycle, the turbo pump is driven by the fuel used for cooling, but the hydrogen gas in the part where the turbo pump is driven is thrown into the nozzle and not used for combustion, which is an open expander cycle.

LE-5A
H-II rocket2nd stage engine using liquid hydrogen / liquid oxygen as propellant
LE-5B
H-IIA rocket,H-IIB rocket2nd stage engine using liquid hydrogen / liquid oxygen as propellant
LE-9
H3 rocket1st stage engine using liquid hydrogen / liquid oxygen as propellant (under development)
MB-35
Mitsubishi Heavy IndustriesとRocketdyneJointly researched engine
MB-60
Mitsubishi Heavy IndustriesとRocketdyneJointly researched engine

Pressure-fed cycleEngine

The propellant is sent to the combustion chamber by pressurizing the inside of the tank with helium gas or nitrogen gas.The structure is simpler and more reliable than the method using a turbo pump.Not suitable for large-scale engines due to its structure.

Aj-10
AerojetDevelops and producesSelf-igniting propellantUpper rocket engine that uses.Has reignition ability

Tripropellant rocket

There are multiple types of tripropellant rocket, one is a combination of three types of propellants and the other is a type in which the propellant is switched according to the flight stage.In the former case, there is a method of burning lithium / fluorine / hydrogen at the same time, and in the latter case,Single-stage space transporterA method of switching to a combination of kerosene / liquid oxygen at low altitude and liquid hydrogen / liquid oxygen at high altitude is sought.Combustion of kerosene, which has a high density at low altitudes, makes it possible to reduce the size of the fuel tank and burns hydrogen, which has a large specific impulse, at high altitudes.

Pogo oscillation

Pogo oscillation is a phenomenon in which the engine resonates and vibrates during the flight of a liquid fuel rocket.Such vibrations occur when the fuel flow rate increases (the pressure in the combustion chamber decreases) or when the fuel flow rate decreases (the pressure in the combustion chamber increases), the pressure fluctuations gather in order, and the pressure inside the engine Fluctuations trigger and oscillate.When generated at the resonant vibration frequency of the fuel system, the vibration gradually intensifies and destroys the aircraft.

Pogo Oscillation PogoAcronymNot the English Pogo stick (Japanese name)Hopping).

Not a few rockets from the 1950s to the 60s, whose phenomenon was not fully understood, were lost due to this phenomenon.

Comparison of liquid fuel rocket engines

ModelSSMELE-7ARD-0120VulcanRS-68YF-77
Developing countryThe United States of AmericaJapanSoviet UnionEuropean Space AgencyThe United States of AmericaPeople's Republic of China
形式Staged combustion cycleStaged combustion cycleStaged combustion cycleGas generator cycleGas generator cycleGas generator cycle
Height4.24 m3.7 m4.55 m3 m5.20 m4.20 m
直径1.63 m1.82 m2.42 m1.76 m2.43 m
weight3,177 kg1,832 kg3,449 kg1,686 kg6,696 kg2,700 kg
PropellantLiquid hydrogenとLiquid oxygenLiquid hydrogenとLiquid oxygenLiquid hydrogenとLiquid oxygenLiquid hydrogenとLiquid oxygenLiquid hydrogenとLiquid oxygenLiquid hydrogenとLiquid oxygen
Main fuel chamber pressure18.9 MPa12.0MPa21.8 MPa11 MPa9.7 MPa10.2 MPa
Specific impulse in vacuum453 秒440 秒454 秒433 秒409 秒430 秒
Thrust in vacuum2.278MN1.098MN1.961MN1.120MN3.370MN0.700MN
Thrust on the ground1.817MN1.517MN0.800MN2.949MN0.510MN
powered byspace shuttleH-IIA rocket
H-IIB rocket
EnergiaAriane VDelta IVLong March 5

Comparison of upper engine

List of main specifications
 RL-10HM7BVinciCE-7.5YF-75RD-0146ES-702ES-1001LE-5LE-5ALE-5B
Developing countryUnited States flag The United States of AmericaFrench flag FranceFrench flag FranceIndian flag IndiaFlag of the People's Republic of China People's Republic of ChinaRussian flag ロシアJapanese flag JapanJapanese flag JapanJapanese flag JapanJapanese flag JapanJapanese flag Japan
Combustion cycleExpander cycleGas generator cycleExpander cycleStaged combustion cycleGas generator cycleExpander cycleGas generator cycleGas generator cycleGas generator cycleExpander bleed cycle
(Nozzle expander)
Expander bleed cycle
(Chamber expander)
Thrust in vacuum66.7 kN (6.80 tf)62.7 kN (6.39 tf)180 kN (18 tf)73 kN (7.4 tf)78.45 kN (8.000 tf)98.1 kN (10.00 tf)68.6 kN (7.00 tf)[2]98 kN (10.0 tf)[3]102.9 kN (10.49 tf)121.5 kN (12.39 tf)137.2 kN (13.99 tf)
mixing ratio5.055.26.05.555
Expansion ratio404040140130110
Specific impulse in vacuum (seconds)433444.2465454437463425[4]425[5]450452447
Combustion pressure MPa2.353.56.15.83.687.742.453.513.653.983.58
LH2Turbo pump rotation speed min-1125,00041,00046,31050,00051,00052,000
LOX turbo pump rotation speed min-116,68021,08016,00017,00018,000
Overall length m1.731.82.2 ~ 4.22.141.52.22.682.692.79
Mass kg135165280435550242255.8259.4[6]255248285

Major adoption examples of electric propulsion

Many of them are made-to-order for technology demonstration, but they have been commercialized mainly for ion engines.Many studies are still underway.

Resistojet

PropellantHeating wire,Ceramic heaterSince it is only warmed by such means, it was installed in many early artificial satellites.

Meteor 3-1
Russian artificial satellite.Equipped with a resist jet that uses ammonia as a propellant, about 10 aircraft were put into orbit.
GlobalStar-3
American artificial satellite.Although he had trouble during the apogee kick, he recovered the orbit with the on-board resistojet and escaped the total loss.

Ion engine

Extremely expensiveSpecific thrustIt has become standard equipment on current commercial satellites.

μ10, μ20, μ10HIsp, μ1
A series of ion engines developed at the Institute of Space and Astronautical Science.In the meaning of the upper rocket engine of the mu rocket, the numerical value indicates the diameter of the ion engine. HIsp means a high specific impulse type of μ10.μ10 TheMUSES-C "Hayabusa"The technology was demonstrated in.In principle, the thrust is lower than other ion engines.
MIPS
Miniature Ion Propulsion System (Small Ion Propulsion System) is an ion engine that utilizes consumer products developed by the Research Center for Advanced Science and Technology of the University of Tokyo and the Next Generation Space System Technology Research Association.
NSTAR
Abbreviation for NASA Solar Electric Propulsion Technology Readiness.
A proven engine installed in the comet probe Deep Space 1 and DAWN.
XIPS
Abbreviation for Xenon Ion Propulsion System.It is a DC discharge type ion engine developed by Boeing, and is a standard option for the company's satellite bus.
RIT-10
A German engine mounted on a European EURECA-1 reusable satellite.Due to trouble, the cumulative operation is limited to about 240 hours.

DC arc jet

Many 1-2kW class arc jets have a track record of being installed in satellite systems.

DRTS "Kodama"
Japanese data relay satellite.The arc jet of US PRIMEX (currently General Dynamics) is used for north-south control in geosynchronous orbit. PRIMEX supplies arc jets to many artificial satellites.
ESEX
An abbreviation for Electric propulsion Space eXperiment, it originally refers to the in-orbit test itself of a high-power arcjet.The US Air Force took the lead in testing a 26kW class arcjet.

Hall thruster

In addition to having a track record mainly in the former Soviet Union and Europe, research is enthusiastically carried out in the United States.

SPT series, TAL series
Both are representative Hall thrusters developed by the former Soviet Union, and have the highest production volume and orbital performance in the world.Technology is being developed in Europe and the United States.
TM-50
50kW class large thrust thruster tested by NASA
PPS-1350
European Hall thruster.It was installed as the main engine on the lunar explorer SMART-1.

MPD thruster, PPT

A thruster that uses electromagnetic force.A simple system and high energy density can be realized.

MS-T4 "Tansei"
An artificial satellite launched at the Institute of Space and Astronautical Science, equipped with an ammonia MPD thruster.
EPEX
Abbreviation for Electric Propulsion EXperiment.In the orbital demonstration test of the Japanese MPD thruster, a 1kW class satellite was mounted on the reusable artificial satellite SFU.
EO-1
A US Navy maritime satellite equipped with PPT for attitude control.
ZOND-2
Former Soviet artificial satellite equipped with Teflon PPT for attitude control.This is the world's first practical example of electric propulsion.

footnote

  1. ^ Looking back on MV rocket propulsion system research and development
  2. ^ The thrust when the nozzle skirt with an opening ratio of 40 is not attached is 48.52 kN (4.9 tf).
  3. ^ The thrust when the nozzle skirt with an opening ratio of 40 is not attached is 66.64 kN (6.8 tf).
  4. ^ Specific impulse when the nozzle skirt with an opening ratio of 40 is not attached is 286.8 seconds.
  5. ^ Specific impulse when the nozzle skirt with an opening ratio of 40 is not attached is 291.6 seconds.
  6. ^ Calculated value

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