RS-68 being tested at NASA's Stennis Space Center, note the relatively transparent exhaust, this is due to this engine's use of hydrogen fuel

A rocket engine is a reaction engine that takes all its reaction mass from within tankage and forms it into a high speed jet, thereby obtaining thrust in accordance with Newton's third law. Rocket engines can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. Most rocket engines are internal combustion engines, although non combusting forms also exist. Image File history File links Size of this preview: 480 × 600 pixelsFull resolution‎ (600 × 750 pixels, file size: 67 KB, MIME type: image/jpeg) An RS-68 engine undergoing hot-fire testing at NASAs Stennis Space Center during its developmental phase. ... Image File history File links Size of this preview: 480 × 600 pixelsFull resolution‎ (600 × 750 pixels, file size: 67 KB, MIME type: image/jpeg) An RS-68 engine undergoing hot-fire testing at NASAs Stennis Space Center during its developmental phase. ... The RS-68 (Rocket System 68) is the largest existing liquid hydrogen / liquid oxygen engine, producing a thrust of 650,000 lbf (2. ... A reaction engine is an engine which provides propulsion by expelling reaction mass, in accordance with Newtons third law of motion. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Newtons laws of motion are the three scientific laws which Isaac Newton discovered concerning the behaviour of moving bodies. ... This article is about vehicles powered by rocket engines. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. ... For other uses, see Missile (disambiguation). ... A colorized automobile engine The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ...

Principle of operation

Rocket engines give part of their thrust due to unopposed pressure on the combustion chamber

Most rocket engines produce thrust by the expulsion of a high-temperature, high-speed gaseous exhaust. This is typically created by high pressure (10-200 bar) combustion of solid or liquid propellants, consisting of fuel and oxidiser components, within a combustion chamber. Image File history File links Download high-resolution version (1600x1600, 506 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rocket engine ... Image File history File links Download high-resolution version (1600x1600, 506 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rocket engine ... Rocket propellants undergo exothermic chemical reactions which produce hot gas which is used by a rocket for propulsive purposes. ... For other uses, see Fuel (disambiguation). ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... A combustion chamber is part of an engine in which fuel is burned. ...

Introducing propellant into the combustion chamber

Liquid-fueled rockets typically pump separate fuel and oxidiser components into the combustion chamber, where they mix and burn. Solid rocket propellants are prepared as a mixture of fuel and oxidizing components and the propellant storage chamber becomes the combustion chamber. Hybrid rocket engines use a combination of solid and liquid or gaseous propellants. Alternatively, a chemically inert reaction mass can be heated using a high-energy power source. A liquid rocket engine has fuel and oxidizer in liquid form, as opposed to a solid rocket or hybrid rocket or gaseous propellant. ... The Space Shuttle is initially launched with the help of solid-fuel boosters A Solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer). ... A hybrid rocket propulsion system comprises propellants of two different states of matter, the most common configuration being a rocket engine composed of a solid propellant lining a combustion chamber into which a liquid or gaseous propellant is injected so as to undergo a strong exothermic reaction to produce hot... Working mass is a mass against which a system operates in order to produce acceleration. ...

Rocket nozzles

Main article: rocket nozzles

The hot gas produced escapes through a narrow opening (the "throat"), into a high expansion-ratio 'de Laval nozzle'. The nozzle dramatically accelerates the gas, converting most of the thermal energy into kinetic energy. The large bell or cone shaped expansion nozzle gives a rocket engine its characteristic shape. Exhaust speeds as high as ten times the speed of sound at sea level are not uncommon. Figure 1: A de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow The main type of rocket engine nozzles used in modern rocket engines is the de Laval nozzle which is used to expand and accelerate the combustion gases, from burning propellants... This page is about the physical speed of sound waves in a medium. ...

Rocket thrust is caused by pressures acting in the combustion chamber and nozzle. From Newtons third law, equal and opposite pressures act on the exhaust, and this accelerates it to high speeds.

A portion of the rocket engine's thrust comes from the unbalanced pressures inside the combustion chamber but the majority comes from the pressures against the inside of the nozzle (see diagram). As the gas expands (adiabatically) the pressure against the nozzle's walls forces the rocket engine in one direction while accelerating the gas in the other. Image File history File links RocketThrust. ... Image File history File links RocketThrust. ... In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which no heat is transferred to or from the working fluid. ...

Propellant efficiency

For a rocket engine to be propellant efficient, it is important that the maximum pressures possible be created by a specific amount of propellant acting on the chamber and nozzle. This can be achieved by all of:

• pumping the propellant up to high pressures prior to injection into the chamber
• heating the propellant to as high a temperature as possible (using a high energy fuel, containing hydrogen and carbon and sometimes metals such as aluminium or even nuclear energy)
• using a low specific density gas (as hydrogen rich as possible)
• using propellants which are, or decompose to, simple molecules with few degrees of freedom so as to maximise molecular speeds

Since all of these things minimise the mass of the propellant used, and since pressure is proportional to the amount of propellant present to be accelerated as it pushes on the engine, the speed that the propellant leaves the chamber is constant. Thus the exhaust speed is thus an excellent measure of the engine propellant efficiency.

For aerodynamic reasons the flow goes sonic ("chokes") at the narrowest part of the nozzle, the 'throat'. Since the speed of sound in gases increases with the square root of temperature, the use of hot exhaust gas greatly improves performance. By comparison, at room temperature the speed of sound in air is about 340m/s while the speed of sound in the hot gas of a rocket engine can be over 1700m/s; much of this performance is due to the higher temperature, but additionally rocket propellants are chosen to be of low molecular mass, and this also gives a higher velocity compared to air. Choked flow is a hydrodynamic condition caused by the Venturi effect. ... This page is about the physical speed of sound waves in a medium. ...

Expansion in the rocket nozzle then further multiplies the speed, typically between 1.5 and 4 times, giving a highly collimated hypersonic exhaust jet. The speed increase of a rocket nozzle is mostly determined by its area expansion ratio—the ratio of the area of the throat to the area at the exit, but detailed properties of the gas are also important. Larger ratio nozzles are more massive but are able to extract more heat from the combustion gases, increasing the exhaust velocity. Collimated light is light whose rays are parallel. ...

Nozzle efficiency is affected by operation in the atmosphere because atmospheric pressure changes with altitude; but due to the supersonic speeds of the gas exiting from a rocket engine, the pressure of the jet may be either below or above ambient, and equilibrium between the two is not reached.

Atmospheric effects

For optimal performance the pressure of the gas at the end of the nozzle should just equal the ambient pressure; if lower the vehicle will be slowed by the difference in pressure between the top of the engine and the exit, if higher then this represents pressure that the bell has not turned into thrust. To maintain this ideal the diameter of the nozzle would need to increase with altitude, giving the pressure a longer nozzle to act on (and reducing the exit pressure and temperature). This increase is difficult to arrange. A compromise nozzle is generally used and some reduction in performance occurs. To improve on this, various exotic nozzle designs such as the plug nozzle, stepped nozzles, the expanding nozzle and the aerospike have been proposed, each having some way to adapt to changing ambient air pressure and each allowing the gas to expand further against the nozzle, giving extra thrust at higher altitude. The plug nozzle is a type of rocket nozzle that, unlike traditional designs, maintains its efficiency at a wide range of altitudes. ... A stepped nozzle is a de Laval rocket nozzle which has altitude compensating properties. ... The expanding nozzle is a type of rocket nozzle that, unlike traditional designs, maintains its efficiency at a wide range of altitudes. ... XRS-2200 linear aerospike engine for the X-33 program being tested The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes through the use of an aerospike nozzle. ...

Overall rocket engine performance

Rocket technology can combine very high thrust (meganewtons), very high exhaust speeds (around 10 times the speed of sound at sea level) and very high thrust/weight ratios (>100) simultaneously as well as being able to operate outside the atmosphere. In physics, the newton (symbol: N) is the SI unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics. ...

Rockets can be further optimised to even more extreme performance along one or more of these axes at the expense of the others.

Specific impulse

Main article: Specific impulse

The most important metric for the efficiency of a rocket engine is impulse per unit of propellant, this is called specific impulse (usually written I_sp). This is either measured as a speed (V_e in metres/second or ft/s) or as a time (seconds). An engine that gives a large specific impulse is normally highly desirable. Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... For other uses, see Impulse (disambiguation). ... A propellant is a material that is used to move an object by applying a motive force. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ...

Net thrust

Below is an approximate equation for calculating the net thrust of a rocket engine:

^[1]

where:

exhaust gas mass flow

actual jet velocity at nozzle exit plane

flow area at nozzle exit plane

static pressure at nozzle exit plane

ambient (or atmospheric) pressure

Since, unlike a jet engine, a conventional rocket motor lacks an air intake, there is no 'ram drag' to deduct from the gross thrust. Consequently the net thrust of a rocket motor is equal the gross thrust.

The term represents the momentum thrust, which remains constant at a given throttle setting, whereas the term represents the pressure thrust term. At full throttle, the net thrust of a rocket motor improves slightly with increasing altitude, because the reducing atmospheric pressure increases the pressure thrust term.

If the pressure of the exhaust jet varies from atmospheric pressure, nozzles can be said to be underexpanded, ambient or overexpanded. If under or overexpanded then loss of efficiency occurs, grossly overexpanded nozzles lose less efficiency, but the exhaust jet is usually unstable. Rockets become progressively more underexpanded as they gain altitude. Note that almost all rocket engines will be momentarily grossly overexpanded during startup in an atmosphere.^[2]

Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ...

Throttling

Rockets can be throttled by controlling the propellant rate (usually measured in kg/s or lb/s).

Note that because rockets choke at the throat, and due to the supersonic exhaust the pressure at the exit is ideally exactly proportional to the propellant flow , provided the mixture ratios and combustion efficiencies are maintained. It is thus quite usual to rearrange the above equation slightly: Look up choke in Wiktionary, the free dictionary. ...

Where:

effective exhaust velocity (I_sp) in vacuum

In principle rockets can be throttled down to an exit pressure of about one-third of ambient pressure (due to flow separation in nozzles) and up to a maximum limit determined only be the mechanical strength of the engine.

In practice, the degree to which rockets can be throttled varies greatly, but most rockets may be throttled by a factor of 2 without great difficulty; the typical limitation is combustion stability, as for example, injectors need a minimum pressure to avoid triggering damaging oscillations (chugging or combustion instabilities); but injectors can often be optimised and tested for wider ranges.

Energy efficiency

Rocket energy efficiency as a function of vehicle speed divided by effective exhaust speed

Rocket engine nozzles are surprisingly efficient heat engines for generating a high speed jet, as a consequence of the high combustion temperature and high compression ratio in accordance with the carnot cycle. For a vehicle employing a rocket engine the energetic efficiency is very good if the vehicle speed approaches or somewhat exceeds the exhaust velocity (relative to launch); but at low speeds the efficiency asymptotically approaches 0% at zero speed (as with all jet propulsion.) See Rocket energy efficiency for more details. Image File history File links PropulsiveEfficiency. ... Image File history File links PropulsiveEfficiency. ... A heat engine performs the conversion of heat energy to work by exploiting the temperature gradient between a hot source and a cold sink. Heat is transferred to the sink from the source, and in this process some of the heat is converted into work. ... Bold text The compression ratio is a single number that can be used to predict the performance of any engine (such as an internal-combustion engine or a Stirling Engine). ... The Carnot cycle is a particular thermodynamic cycle, modeled on the Carnot heat engine, studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s. ... This article should be split into multiple articles accessible from a disambiguation page. ... This article is about vehicles powered by rocket engines. ...

Cooling

The reaction mass's combustion temperatures can fairly typically reach ~3500 K (~5800 °F) which is often far higher than the melting point of the nozzle and combustion chamber materials, two exceptions are graphite and tungsten (~1200 K for copper). Indeed many construction materials can make perfectly acceptable propellants in their own right. It is important that these materials be prevented from combusting, melting or vapourising to the point of failure. Materials technology could potentially place an upper limit on the exhaust temperature of chemical rockets. For other uses, see Graphite (disambiguation). ... For other uses, see Tungsten (disambiguation). ...

Alternatively, rockets may use more common construction materials such as aluminum, steel, nickel or copper alloys and employ cooling systems that prevent the construction material itself becoming too hot. Regenerative cooling, where the propellant is passed through tubes around the combustion chamber or nozzle, and other techniques, such as curtain cooling or film cooling, are employed to give longer nozzle and chamber life. These techniques ensure that a gaseous thermal boundary layer touching the material is kept below the temperature which would cause the material to catastrophically fail. Regenerative cooling in rockets is where the propellant is passed through tubes around the combustion chamber or nozzle as the fuel is a good conductor of heat. ... In physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. ...

The coolant methods include:

1. uncooled (used for short runs mainly during testing)
2. ablative walls (walls are lined with a material that is continuously vapourised and carried away).
3. radiative cooling (the chamber becomes almost white hot and radiates the heat away)
4. dump cooling (a propellant, usually hydrogen, is passed around the chamber and dumped)
5. regenerative cooling (uses the propellant to cool the chamber via a cooling jacket before being injected)
6. curtain cooling (propellant injection is arranged so the temperature of the gases is cooler at the walls)
7. film cooling (surfaces are wetted with liquid propellant, which cools as it evaporates)

In all cases the cooling effect that prevents the wall from being destroyed is caused by a thin layer of insulating fluid (a boundary layer) that is in contact with the walls that is far cooler than the combustion temperature. Provided this boundary layer is intact the wall will not be damaged. Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. ... Radiative cooling is the condition in which a body loses more energy by radiation than it gains from its surroundings. ... This article is about the chemistry of hydrogen. ... Regenerative cooling in rockets is where the propellant is passed through tubes around the combustion chamber or nozzle as the fuel is a good conductor of heat. ... In physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. ...

Disruption of the boundary layer may occur during cooling failures or combustion instabilities, and wall failure typically occurs soon after.

With regenerative cooling a second boundary layer is found in the coolant channels around the chamber. This boundary layer thickness needs to be as small as possible, since the boundary layer acts as an insulator between the wall and the coolant. This may be achieved by making the coolant velocity in the channels as high as possible. This article is about velocity in physics. ...

Mechanical issues

The combustion chamber is often under substantial pressure, typically 10-200 bar (1 to 20 MPa), higher pressures giving better performance. This causes the outermost part of the chamber to be under very large hoop stresses. Hoop stress is mechanical stress applied in a direction perpendicular to the radius of the item in question. ...

Worse, due to the high temperatures created in rocket engines the materials used tend to have a significantly lowered working tensile strength.

Safety

Rocket engines are tested at a test facility before being put into production. Rocket firing at the WSTF A Rocket engine test facility is a location where rocket engines may be tested on the ground, under controlled conditions. ...

Rockets have a reputation for unreliability and danger; especially catastrophic failures. Contrary to this reputation, carefully designed rockets can be made arbitrarily reliable. In military use, rockets are not unreliable. However, one of the main non-military uses of rockets is for orbital launch. In this application, the premium is on minimum weight, and it is difficult to achieve high reliability and low weight simultaneously. In addition, if the number of flights launched is low, there is a very high chance of a design, operations or manufacturing error causing destruction of the vehicle. Essentially all launch vehicles are test vehicles by normal aerospace standards (as of 2006). This article is about vehicles powered by rocket engines. ... 2006 is a common year starting on Sunday of the Gregorian calendar. ...

The X-15 rocket plane achieved a 0.5% failure rate, with a single catastrophic failure during ground test, and the SSME has managed to avoid catastrophic failures in over 350 engine-flights. Description Role: Research Aircraft Crew: one, pilot Dimensions Length: 50. ... Scott Crossfield Albert Scott Crossfield (October 2, 1921 – April 19, 2006), normally referred to as Scott Crossfield, was an American naval officer, aviator and test pilot. ... Space Shuttle Main Engine block The Space Shuttle orbiter has three main engines. ...

Noise

The Saturn V launch was detectable on seismometers a considerable distance from the launch site. As the hypersonic exhaust mixes with the ambient air, shock waves are formed. The sound intensity from these shock waves depends on the size of the rocket, and on large rockets can actually kill. The Space Shuttle generates over 200 dB(A) of noise around its base. For the moon designated Saturn V, see Rhea. ... Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... Boeing X-43 at Mach 7 In aerodynamics, hypersonic speeds are speeds that are highly supersonic. ... Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ... The sound intensity, I, (acoustic intensity) is defined as the sound power Pac per unit area A. The usual context is the noise measurement of sound intensity in the air at a listeners location. ... This article is about the space vehicle. ... The A-weighting curve dB(A) or dBA stands for decibels adjusted. ...

Generally speaking noise is most intense when a rocket is close to the ground, since the noise from the engines radiates up away from the plume, as well as reflecting off the ground. This noise can be reduced somewhat by flame trenches with roofs, by water injection around the plume and by deflecting the plume at an angle.

Chemistry

Although rocket propellants require relatively high energy density (energy per unit mass) many common materials are more energetic. For example, petrol/gasoline or paraffin has as much energy as a typical rocket fuel and far more than the fuel/oxidiser mix used in a rocket engine. This is because the rocket propellant carries its own oxidiser. Fuels for automobile or turbojet engines, utilise atmospheric oxygen and can have much higher energy density. Rocket propellants undergo exothermic chemical reactions which produce hot gas which is used by a rocket for propulsive purposes. ... Turbojets are the simplest and oldest kind of general purpose jet engine. ...

Many rocket propellants use hydrogen in the propellant, as this gives the highest exhaust speeds (primarily due to the low molecular mass, but this is not the whole story)^[3].

Computer programs that predict the performance of propellants in rocket engines are available.^[4].

Ignition

With liquid and hybrid rockets, immediate ignition of the propellant(s) as they first enter the combustion chamber is essential.

Failure to ignite within milliseconds causes too much liquid propellant to be within the chamber, and if/when ignition occurs the amount of hot gas created will often exceed the maximum design pressure of the chamber. The pressure vessel will often fail catastrophically. This is sometimes called a Hard start. A rocketry term refering to an explosion of fuel. ...

Ignition can be achieved by a number of different methods; a pyrotechnic charge can be used, the propellants can ignite spontaneously on contact (hypergolic), a plasma torch can be used, or electric spark plugs may be employed.

Gaseous propellants generally will not cause hard starts, with rockets the total injector area is less than the throat thus the chamber pressure tends to ambient prior to ignition and high pressures cannot form even if the entire chamber is full of flammable gas at ignition.

Solid propellants are usually ignited with one-shot pyrotechnic devices.

Once ignited, rocket chambers are self sustaining and igniters are not needed. Indeed chambers often spontaneously reignite if they are restarted after being shut down for a few seconds. However, when cooled, many rockets cannot be restarted without at least minor maintenance, such as replacement of the pyrotechnic igniter.

Types of rocket engines

See also: Liquid rocket propellants

The highest specific impulse chemical rockets use liquid propellants. ... Water Rocket Launch A water rocket is a type of model rocket using water as its reaction mass. ... Water Rocket Launch A water rocket is a type of model rocket using water as its reaction mass. ... The metre, or meter (symbol: m) is the SI base unit of length. ... A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ – a prime) is a unit of length, in a number of different systems, including English units, Imperial units, and United States customary units. ... A cold gas thruster is a rocket engine/thruster that uses a (typically inert) gas as the reaction mass. ... The Space Shuttle is initially launched with the help of solid-fuel boosters A Solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer). ... Moving parts are the components of a device that undergo continuous or frequent motion, most commonly rotation. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... A hybrid rocket propulsion system comprises propellants of two different states of matter, the most common configuration being a rocket engine composed of a solid propellant lining a combustion chamber into which a liquid or gaseous propellant is injected so as to undergo a strong exothermic reaction to produce hot... A monopropellant rocket (or monoprop rocket) is a rocket that uses a single chemical as its power source and propellant. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... F-1 rocket engine (The kind used by the Saturn V.) A bipropellant rocket engine is a rocket engine that uses two fluid propellants stored in separate tanks that are injected into, and undergo a strong exothermic reaction, in a rockets combustion chamber. ... Dual mode propulsion systems combine the high efficiency of bipropellant rockets with the reliability and simplicity of monopropellant rockets. ... A Tripropellant rocket is a form of spacecraft propulsion that uses two fuels and one oxidizer. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... Air-augmented rockets (also known as rocket-ejector, ramrocket, ducted rocket, integral rocket/ramjets, or ejector ramjets) use the supersonic exhaust of some kind of rocket engine to further compress air collected by ram effect during flight to use as additional working mass, leading to greater effective thrust for any... A turborocket is a type of aircraft engine combining elements of a jet engine and a rocket. ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... Lox can stand for any of several things: Lox (salmon) - a type of salmon produce LOx (oxidizer) - liquid oxygen used as oxidizer in aerospace The Lox - was a Yonkers, NY-based rap trio This is a disambiguation page — a list of articles associated with the same title. ... A liquid air cycle engine (LACE) is a spacecraft propulsion engine that attempts to gain efficiency by gathering part of its oxidizer from the atmosphere. ... The RB545 was an air-breathing rocket engine that was proposed to propel HOTOL to orbit using a single stage. ... French naval officers sabre of the 19th Century From left to right: two bayonets, a short curved infantry or artillery briquet, a straight infantry officers sabre, and a carbine. ... The ATREX engine developed in Japan is an experimental precooled jet engine that works as a turbojet at low speeds and a ramjet up to mach 6. ...

Electric heating

See also: Ion thruster

A resistojet is a way of propulsion that provides thrust by heating a (typically non-reactive) fluid. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... Arcjets are a form of electric propulsion for spacecraft, whereby an electrical discharge (arc) is created in a flow of propellant (typically hydrazine or ammonia). ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... An ion engine test An ion thruster is a type of spacecraft propulsion that uses beams of ions for propulsion. ... Pulsed plasma thrusters use an arc of electric current adjacent to a solid propellant (almost always teflon), to produce a quick and repeatable burst of impulse. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... VASIMR test bed The Variable specific impulse magnetoplasma rocket (VASIMR) is a hypothetical form of spacecraft propulsion that uses radio waves and magnetic fields to accelerate a propellant. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... An ion engine test This article focuses on electrostatic ion thrusters - for a more general description, refer to electric propulsion. ...

Solar heating

The Solar thermal rocket would make use of solar power to directly heat reaction mass, and therefore does not require an electrical generator as most other forms of solar-powered propulsion do. A solar thermal rocket only has to carry the means of capturing solar energy, such as concentrators and mirrors. The heated propellant is fed through a conventional rocket nozzle to produce thrust. The engine thrust is directly related to the surface area of the solar collector and to the local intensity of the solar radiation. Solar thermal propulsion is a form of spacecraft propulsion that makes use of solar power to directly heat reaction mass, and therefore does not require an electrical generator as most other forms of solar-powered propulsion do. ... Working mass is a mass against which a system operates in order to produce acceleration. ... At the equator, the Sun provides approximately 1000 watts per square meter on Earths surface. ... A mirror, reflecting a vase. ...

Solar thermal propulsion is a form of spacecraft propulsion that makes use of solar power to directly heat reaction mass, and therefore does not require an electrical generator as most other forms of solar-powered propulsion do. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ...

Beamed power

Beam-powered propulsion is a class of spacecraft propulsion mechanisms that use energy beamed to the spacecraft from a remote power plant. ... Beam-powered propulsion is a class of spacecraft propulsion mechanisms that use energy beamed to the spacecraft from a remote power plant. ...

Nuclear heating

Nuclear propulsion includes a wide variety of propulsion methods that use some form of nuclear reaction as their primary power source. Various types of nuclear propulsion have been proposed, and some of them tested, for spacecraft applications: Nuclear propulsion can include a wide variety of methods, the commonality of which is the use of some form of nuclear reaction as their primary power source. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide to produce products different from the initial particles. ...

The radioisotope rocket is a type of rocket engine that uses the heat generated by the decay of radioactive elements to heat a working fluid, which is then exhausted through a rocket nozzle to produce thrust. ... Sketch of nuclear thermal rocket In a nuclear thermal rocket a working fluid, usually hydrogen, is heated in a high temperature nuclear reactor, and then expands through a rocket nozzle to create thrust. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... Gas core reactor rockets are a conceptual type of rocket that is propelled by the exhausted coolant of a gaseous fission reactor. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... The fission-fragment rocket is a rocket engine design that directly harnesses hot nuclear fission products for thrust, as opposed to using a separate fluid as working mass. ... The fission sail is a type of spacecraft propulsion proposed by Robert Forward that uses fission fragments to propel a large solar sail-like craft. ... A nuclear salt-water rocket is a type of nuclear thermal rocket designed by Robert Zubrin that would be fueled by water bearing dissolved salts of plutonium or U235. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... An artists conception of the Orion basic spacecraft, powered by nuclear pulse propulsion. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... Antimatter catalysed nuclear pulse propulsion is a variation of nuclear pulse propulsion based upon the injection of antimatter into a mass of nuclear fuel which normally would not be useful in propulsion. ... This article does not cite any references or sources. ... This article does not cite any references or sources. ...

History of rocket engines

According to the writings of the Roman Aulus Gellius, in c. 400 BC, a Greek Pythagorean named Archytas, propelled a wooden bird along wires using steam.^[5] However, it would not appear to have been powerful enough to take off under its own thrust. Aulus Gellius ( 125 - after 180), Latin author and grammarian, possibly of African origin, probably born and certainly brought up at Rome. ... The Celtics claim Vienna, Austria. ... The Pythagoreans were an Hellenic organization of astronomers, musicians, mathematicians, and philosophers; who believed that all things are, essentially, numeric. ... Archytas Archytas (428 BC - 347 BC) was a Greek philosopher, mathematician, astronomer, statesman, strategist and commander-in-chief. ...

The aeolipile invented in the first century (known as Hero's engine) was a rocket-like reaction engine and the first recorded steam engine. It essentially consists of a hot water rocket on a bearing. It was created almost two millennia before the industrial revolution. Apparently Hero's steam engine was taken to be little more than a toy, the principles behind it were not well understood, and its full potential not realized for a millennium. An illustration of Herons aeolipile An aeolipile is a device consisting of an air-tight chamber (usually a sphere or cylinder) with bent or curved pipes projecting from it, through which steam is expelled perpendicular to the radius of rotation. ... The 1st century was that century that lasted from 1 to 100 according the Gregorian calendar. ... A modern replica of Heros aeolipile An illustration of Heros aeolipile A classroom model of an aeolipile An aeolipile is a device consisting of an air-tight chamber (usually a sphere or cylinder) with bent or curved pipes projecting from it, through which steam is expelled. ... // The term steam engine may also refer to an entire railroad steam locomotive. ...

The availability of black powder to propel projectiles was a precursor to the development of the first solid rocket. Ninth Century Chinese Taoist alchemists discovered black powder in a search for the Elixir of life; this accidental discovery led to fire arrows which were the first rocket engines to leave the ground. Black powder was the original gunpowder and practically the only known propellant and explosive until the middle of the 19th century. ... As a means of recording the passage of time the 9th century was the century that lasted from 801 to 900. ... For other uses of the words tao and dao, see Dao (disambiguation). ... For other uses, see Alchemy (disambiguation). ... Black powder was the original gunpowder and practically the only known propellant and explosive until the middle of the 19th century. ... The elixir of life, also known as the elixir of immortality or Dancing Water and sometimes equated with the Philosophers stone, is a legendary potion, or drink, that grants the drinker eternal life or eternal youth. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Slow development of this technology continued up to the later 20th Century, when the writings of Konstantin Tsiolkovsky first talked about liquid fuelled rocket engines. Konstantin Eduardovich Tsiolkovsky Konstantin Eduardovich Tsiolkovsky (Константин Эдуардович Циолковский, Konstanty Ciołkowski) (September 5, 1857 new style – September 19, 1935) was a Russian and Soviet rocket scientist and pioneer of cosmonautics who spent most of his life in a log house on the outskirts of the Russian town of Kaluga. ... A liquid rocket engine has fuel and oxidizer in liquid form, as opposed to a solid rocket or hybrid rocket or gaseous propellant. ...

These independently became a reality thanks to Robert Goddard. Robert Goddard Robert Hutchings Goddard (October 5, 1882 – August 10, 1945) was one of the pioneers of modern rocketry. ...

References

This article or section is missing citations or needs footnotes. Using inline citations helps guard against copyright violations and factual inaccuracies.

Encyclopædia Britannica, the eleventh edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... Image File history File links Emblem-important. ...

See also

• NERVA - NASA's Nuclear Energy for Rocket Vehicle Applications, a US nuclear thermal rocket programme
• Project Prometheus, NASA development of nuclear propulsion for long-duration spaceflight, begun in 2003

For other uses, see Nerva (disambiguation). ... The National Aeronautics and Space Administration (NASA) (IPA [ˈnæsÉ™]) is an agency of the United States government, responsible for the nations public space program. ... Nuclear reactors may be used to power ion engines such as this one used on Deep Space 1 Project Prometheus was established in 2003 by NASA to develop nuclear-powered systems for long-duration space missions. ... A heat engine is a physical or theoretical device that converts thermal energy to mechanical output. ... A thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. ... A thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. ... A stroke is a single action of certain engines. ... The Crower six-stroke engine or Crower Cycle is a concept under development by Bruce Crower. ... Today Internal combustion engines in cars, trucks, motorcycles, construction machinery and many others, most commonly use a four-stroke cycle. ... A One-stroke cycle is a two-stroke cycle that uses a double acting piston; and thus both strokes are powered, and each stroke is half of two two-stroke cycles. ... The Split Cycle Engine is a type of internal combustion engine. ... A six stroke engine is an automobile engine in which the piston of the engine move up and down an additional time for each injection of fuel. ... The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by completing the same four processes (intake, compression, power, exhaust) in only two strokes of the piston rather than four. ... A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons. ... The Britalus rotary engine was invented in 1982 by Kenneth W. Porter, P.E., M.S.A.E, of King County, Washington. ... A combustion chamber is part of an engine in which fuel is burned. ... Controlled Combustion Engine (CCE) is a type of internal combustion engine designed by Brad Howell-Smith in 1995. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... An orbital engine is a type of internal combustion engine, featuring rotary rather than reciprocating motion of its internal parts. ... Components of a typical, four stroke cycle, DOHC piston engine. ... The Quasiturbine or Qurbine engine is a proposed pistonless rotary engine using a four-sided rhomboid rotor whose sides are hinged at the vertices. ... This article does not cite any references or sources. ... The Toroidal engine design is a form of internal combustion engine that features pistons that rotate within a toroidal space. ... The trochilic engine is composed of two mirror image gull wing segments intermeshed and rotating about a common central axis. ... The Twingle engine is a small-capacity two-stroke gasoline engine. ... Wankel Engine in Deutsches Museum Munich, Germany The Wankel rotary engine is a type of internal combustion engine, invented by German engineer Felix Wankel, which uses a rotor instead of reciprocating pistons. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The D Slide Valve was a form of rectilinear slide valve for use in rotative steam engines invented by William Murdoch and patented in 1799. ... Internal combustion engines using either four-stroke or two-stroke cycle with spark ignition and compression ignition, use poppet valves to allow air to flow through the cylinder head cylinder and exhaust gases out. ... Left side of a Ford Cologne V6 engine, clearly showing a (rusty) cast iron exhaust manifold - three exhaust ports into one pipe. ... In automotive engineering, an engine is referred to as multi-valve (or multivalve) when each cylinder has more than two valves. ... Piston valve in a brass instrument A piston valve is a device used to control the motion of a fluid along a tube or pipe by means of the linear motion of a piston within a chamber or cylinder. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... Figure 1: A de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow The main type of rocket engine nozzles used in modern rocket engines is the de Laval nozzle which is used to expand and accelerate the combustion gases, from burning propellants... piston engine Bristol Perseus The sleeve valve is a type of valve mechanism for piston engines which have traditionally relied on the more common poppet valve. ... For the American composer, see Walter Piston. ... The Bourke engine was designed by Russell Bourke in the late 1930s, who endeavored to improve upon the Otto cycle engine. ... This page is a candidate for speedy deletion, because: not an article, just links to pictures If you disagree with its speedy deletion, please explain why on its talk page or at Wikipedia:Speedy deletions. ... The hydraulic cylinders on this excavator control the machines linkages. ... Fairbanks-Morse opposed piston diesel engines on the submarine USS Pampanito. ... The radial engine is an internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Four-stroke cycle (or Otto cycle) A single cylinder engine, colloquially known as a one-lunger or thumper, is an engine configuration consisting of just one cylinder, the simplest arrangement possible for an Otto or Diesel engine. ... The Stelzer engine is a diesel engine design proposed by Frank Stelzer. ... Usually found in 4 and 6 cylinder configurations, the straight engine (often designed as inline engine) is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset. ... This article is about rotation as a movement of a physical body. ... In Euclidean geometry, an arc is a closed segment of a differentiable curve in the two-dimensional plane; for example, a circular arc is a segment of a circle. ... The motion of a non-offset piston connected to a crank through a connecting rod (as would be found in internal combustion engines), can be expressed through several mathematical equations. ... For other uses, see CAM. Animation showing rotating cams and cam followers producing reciprocating motion. ... piston (top) and connecting rod from typical automotive engine (scale is in centimetres) Components of a typical, four stroke cycle, DOHC piston engine. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... The parallel motion was a mechanical linkage invented by James Watt in 1784 for his double-acting steam engine. ... The Peaucellier-Lipkin linkage (or Peaucellier-Lipkin cell), invented in 1864, was the first linkage capable of transforming rotary motion into perfect straight-line motion. ... In a piston engine, a piston rod joins a piston to a connecting rod. ... The primary claimed benefit of the revolving cylinder, axial piston engine is that a 4-cycle, reciprocating piston engine can be achieved without the need for a complex and expensive valve train. ... Cut away diagram of a Rhombic Drive Beta Stirling Engine Design Pink - Hot cylinder wall, Dark grey - Cold cylinder wall (with coolant inlet and outlet pipes in Yellow), Dark Green - Thermal insulation separating the two cylinder ends, Light Green - Displacer piston, Dark Blue - Power piston, Light Blue - Flywheels, Not Shown... The Scotch Yoke is a mechanism for converting the horizontal motion of a slider into rotational motion or vice-versa. ... The swashplate is the device that translates the pilots (or autopilots) commands via the helicopter flight controls into motion of the main rotor blades. ... Almen A-4 barrel engine The swashplate engine is a type of reciprocating engine that replaces the common crankshaft with a circulate plate. ... Watts Linkage The Watts linkage was invented by James Watt (1736--1819) to constrain the movement of a piston in a steam engine to move in a straight line. ... The Toroidal engine design is a form of internal combustion engine that features pistons that rotate within a toroidal space. ... The trochilic engine is composed of two mirror image gull wing segments intermeshed and rotating about a common central axis. ...

External links

• Designing for rocket engine life expectancy
• Rocket Engine performance analysis with Plume Spectrometry
• Rocket Engine Thrust Chamber technical article