A
rocket or
rocket vehicle is a
missileA missile is a self-propelled projectile used as a weapon. Missiles are typically propelled by rockets or jet engines. Missiles generally have one or more explosive warheads, although other weapon types may also be used...
, spacecraft,
aircraftAn aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil An aircraft is a vehicle which is able to fly by being supported...
or other
vehicleA vehicle is a mechanical means of conveyance, a carriage or transport. Most often they are manufactured , although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.Vehicles may be propelled or pulled by...
which obtains
thrustThrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a proportional but opposite force on that system.-Examples:...
by the
reactionIn classical mechanics, Newton's third law states that forces occur in pairs, one called the Action and the other the Reaction . Both forces are equal in magnitude and opposite in direction...
of the rocket to the ejection of a jet of fast moving
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
exhaust from a
rocket engineA rocket engine or simply "rocket" is a jet engine[Rocket Propulsion Elements; 7th edition- chapter 1] that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
. Chemical rockets create their exhaust by the combustion of
rocket propellantRocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
. The action of the exhaust against the inside of
combustion chamber-Internal combustion engine:The hot gases produced by the combustion occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of the chamber. This pressure can be used to do work, for example, to move a piston on a crankshaft or a turbine...
s and expansion nozzles is able to accelerate the gas to
hypersonicIn aerodynamics, hypersonic speeds are those that are highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 and above...
speed, and this exerts a large reactive thrust on the rocket (an equal and opposite reaction in accordance with Newton's third law).
Rockets, in the form of military and recreational uses, date back to at least the 13th century. Widespread military, scientific, and industrial use did not occur until the 20th century, when rocketry was the enabling technology of the
Space AgeThe Space Age is a contemporary period encompassing the activities related to the Space Race, space exploration, space technology, and the cultural developments influenced by these events...
, including
setting foot on the moonThe Apollo 11 mission was the first human spaceflight to land on the Moon. Launched on July 16, 1969, it carried Mission Commander Neil Alden Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Edwin Eugene 'Buzz' Aldrin, Jr...
.
Rockets are used for
fireworksA firework is a low explosive pyrotechnic device used primarily for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
, weaponry, ejection seats,
launch vehicleIn spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
s for artificial satellites,
human spaceflightHuman spaceflight is spaceflight with a human crew and possibly passengers. This makes it unlike robotic space probes or remotely-controlled satellites...
and
explorationSpace exploration is the use of astronomy and space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
of other planets. While comparatively inefficient for low speed use, they are very lightweight and powerful, capable of generating large accelerations and of attaining
extremely high speedsIn physics, escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy, as calculated by the equation,...
with reasonable efficiency.
Chemical rockets store a large amount of energy in an easily-released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks.
History of rockets
In antiquity
The availability of black powder (
gunpowderGunpowder, also called black powder, is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing volumes of hot solids and gases which can be used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any...
) to propel projectiles was a precursor to the development of the first solid rocket. Ninth Century
ChineseThe term Chinese people may refer to any of the following:*People who reside in and hold citizenship of the People's Republic of China or the Republic of China . This definition stems from a legal perspective...
Taoist
alchemistsAlchemy is both a philosophy and a practice with an aim of achieving ultimate wisdom as well as immortality, involving the improvement of the alchemist as well as the making of several substances described as possessing unusual properties...
discovered black powder while searching for the
Elixir of lifeThe elixir of life, from Arabic: الإكسير, also known as the elixir of immortality or Dancing Water or Persian: Aab-e-Hayaat آب حیات and sometimes equated with the philosopher's stone, is a legendary potion, or drink, that grants the drinker eternal life or eternal youth. Many practitioners of...
; this accidental discovery led to experiments in the form of weapons such as
bombA bomb is any of a range of explosive devices that typically rely on the exothermic chemical reaction of an explosive material to produce an extremely sudden and violent release of energy. The word comes from the Greek word βόμβος , an onomatopoetic term with approximately the same meaning as...
s,
cannonA cannon is any tubular piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
, incendiary
fire arrowThe Fire Arrow is a projectile weapon that uses black powder. The earliest reference to its use comes in the Collection of the Most Important Military Techniques written in 1044.- Design :The Fire Arrow was the first rocket in mechanism and design...
s and rocket-propelled fire arrows. The discovery of gunpowder was probably the product of centuries of alchemical experimentation.
Exactly when the first
flightFlight is the process by which an object moves either through the air, or movement beyond earth's atmosphere , by aerodynamically generating lift, propulsive thrust or aerostatically using buoyancy, or by simple ballistic movement.-Buoyant flight:Humans, although not apparently other animals, have...
s of rockets occurred is contested. Some say that the first recorded use of a rocket in battle was by the Chinese in 1232 against the Mongol hordes. There were reports of fire arrows and 'iron pots' that could be heard for 5
leaguesA league is a unit of length . It was long common in Europe and Latin America, but it is no longer an official unit in any nation. The league most frequently refers to the distance a person or a horse can walk in an hour...
(25 km, or 15 miles) when they exploded upon impact, causing devastation for a radius of 600 meters (2,000 feet), apparently due to shrapnel. The lowering of the iron pots may have been a way for a besieged army to blow up invaders. The fire arrows were either arrows with explosives attached, or arrows propelled by gunpowder, such as the Korean
HwachaHwacha or Hwach'a was an anti-personnel gunpowder weapon developed and used in Korea, inspired by Chinese fire arrows and the cylindrical and box shaped launch platforms that fired them. Hwacha were first developed in the 1400s by Korean scientists. It is a two-wheeled cart carrying a launch pad...
.
Less controversially, one of the earliest devices recorded that used internal-combustion rocket propulsion was the 'ground-rat,' a type of firework, recorded in 1264 as having frightened the Empress-Mother Kung Sheng at a feast held in her honor by her son the Emperor Lizong.
Subsequently, one of the earliest texts to mention the use of rockets was the
HuolongjingThe Huolongjing is a 14th century military treatise that was compiled and edited by Jiao Yu and Liu Ji of the early Ming Dynasty in China...
, written by the Chinese artillery officer
Jiao YuJiao Yu was a Chinese military officer loyal to Zhu Yuanzhang , the founder of the Ming Dynasty . He was entrusted by Emperor Hongwu as a leading artillery officer for the rebel army that overthrew the Mongol Yuan Dynasty, and established the Ming Dynasty...
in the mid-14th century. This text also mentioned the use of the first known
multistage rocketA multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of...
, the 'fire-dragon issuing from the water' (huo long chu shui), used mostly by the Chinese navy.
Spread of rocket technology
Rocket technology first became known to
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
ans following its use by the Mongols
Genghis KhanGenghis Khan , ; 1162–1227), born , was the founder, Khan and Khagan of the Mongol Empire, the largest contiguous empire in history....
and
Ögedei KhanÖgedei Khan, , was the third son of Genghis Khan and second Great Khan of the Mongol Empire by succeeding his father...
when they conquered parts of Russia, Eastern, and Central Europe. The Mongolians had acquired the Chinese technology by conquest of the northern part of China and also by the subsequent employment of Chinese rocketry experts as mercenaries for the Mongol military. Reports of the
Battle of MohiThe Battle of Mohi, or Battle of the Sajó River, was the main battle between the Mongol Empire and the Kingdom of Hungary during the Mongol invasion of Europe. It took place at Muhi, southwest of the Sajó River. After the invasion, Hungary lay in ruins. Nearly half of the inhabited places had...
in the year 1241 describe the use of rocket-like weapons by the Mongols against the Magyars. Rocket technology also spread to
KoreaKorea is a civilization and formerly unified nation currently divided into two states. Located on the Korean Peninsula, it borders China to the northwest, Russia to the northeast, and is separated from Japan to the east by the Korea Strait....
, with the 15th century wheeled
hwachaHwacha or Hwach'a was an anti-personnel gunpowder weapon developed and used in Korea, inspired by Chinese fire arrows and the cylindrical and box shaped launch platforms that fired them. Hwacha were first developed in the 1400s by Korean scientists. It is a two-wheeled cart carrying a launch pad...
that would launch
singijeonSingijeon is a multi-launch rocket made by Korean general Choe Mu-seon in 1377, during the Goryeo Dynasty under King U. These were launched by multiple means, such as the hwacha and other large-barreled guns. The Juhwa were the first singijeon, and the result of efforts to acquire the technology to...
rockets.
Additionally, the spread of rockets into Europe was also influenced by the
OttomansThe Ottoman Empire or Ottoman State , also known by its contemporaries as the Turkish Empire or Turkey , was an empire that lasted from 1299 to November 1, 1922 The Ottoman Empire or Ottoman State (Ottoman Turkish: دَوْلَتِ عَلِیَّهِ عُثْمَانِیَّه Dawlet-il ʿAliyyat-il ʿOs̠māniyye, Modern Turkish:...
at the siege of
ConstantinopleConstantinople was the imperial capital of the Roman Empire , the Byzantine/Eastern Roman Empire , the Latin Empire , and the Ottoman Empire...
in 1453, although it is very likely that the Ottomans themselves were influenced by the Mongol invasions of the previous few centuries. In their history of rockets published on the Internet,
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
says "Rockets appear in Arab literature in 1258 A.D., describing Mongol invaders' use of them on February 15 to capture the city of Baghdad."
Between 1270 and 1280, Hasan al-Rammah wrote
al-furusiyyah wa al-manasib al-harbiyya (
The Book of Military Horsemanship and Ingenious War Devices), which included 107 gunpowder recipes, 22 of which are for rockets. According to
Ahmad Y HassanAhmad Yusuf al-Hassan is a chevalier of the Légion d'honneur and a historian of Arabic and Islamic science and technology, educated in Jerusalem, Cairo and London with a Ph.D. in Mechanical engineering from University College London...
, al-Rammah's recipes were more explosive than rockets used in China at the time.
The name
Rocket comes from the
ItalianItalian is a Romance language spoken by about 60 million people in Italy, and by a total of around 70 million in the world. In Switzerland, Italian is one of four official languages. It is also the official language of San Marino, as well as the primary language of Vatican City...
Rocchetta (i.e.
little fuse), a name of a small firecracker created by the Italian artificer Muratori in 1379.
Between 1529 and 1556
Conrad HaasConrad Haas was a military engineer of the Holy Roman Empire, who is believed to be the first person to describe a multistage rocket in writing.Haas was perhaps born in Dornbach...
wrote a book in which he described rocket technology, involving the combination of
fireworksA firework is a low explosive pyrotechnic device used primarily for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
and weapons technologies. This manuscript was discovered in 1961, in the Sibiu public records (Sibiu public records
Varia II 374). His work dealt with the theory of motion of multi-stage rockets, different fuel mixtures using liquid fuel, and introduced
deltaDelta is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet...
-shape
finA fin is a surface used to produce lift and thrust or to steer while traveling in water, air, or other fluid media. The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices....
s and bell-shaped
nozzleA nozzle is a mechanical device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....
s.
For over two centuries, the work of
Polish-Lithuanian CommonwealthThe Polish–Lithuanian Commonwealth was formed by the union of the Kingdom of Poland and Grand Duchy of Lithuania in 1569. The new Commonwealth was one of the largest and most populous countries of 16th and 17th-century Europe....
noblemanSzlachta is the noble class in the Kingdom of Poland, the Grand Duchy of Lithuania and the increasingly polonized territories under their control . The nobility arose in the late Middle Ages and existed through the 18th century and into the 20th century...
Kazimierz SiemienowiczKazimierz Siemienowicz was a noble from the Grand Duchy of Lithuania part of the Polish-Lithuanian Commonwealth, General of artillery, gunsmith, military engineer, artillery specialist and pioneer of rocketry. His coat of arms was, possibly, Ostoja...
"
Artis Magnae Artilleriae pars prima" ("Great Art of Artillery, the First Part", also known as "The Complete Art of Artillery"), was used in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
as a basic artillery manual. First printed in
AmsterdamAmsterdam is the capital and largest city of the Netherlands, located in the province of North Holland in the west of the country...
in 1650 it was translated to
FrenchFrench is a Romance language globally spoken by about 65 million people as a first language , by 50 million as a second language, and by about another 200 million people as an acquired foreign language, with significant speakers in 57 countries. Most native speakers of the language live in France,...
in 1651,
GermanGerman is a West Germanic language, thus related to and classified alongside English and Dutch. It is one of the world's major languages and the most widely spoken first language in the European Union. Around the world, German is spoken by approximately 105 million native speakers and also by...
in 1676,
EnglishEnglish is a West Germanic language that developed in England during the Anglo-Saxon era. As a result of the military, economic, scientific, political, and cultural influence of the British Empire during the 18th, 19th, and early 20th centuries, and of the United States since the mid 20th century,...
and
DutchDutch is a West Germanic language spoken by over 22 million people as a native language, and over 5 million people as a second language.
"1% of the EU population claims to speak Dutch well enough in order to have a conversation." Outside the European Union the number of second language...
in 1729 and
PolishPolish is a West Slavic language and the official language of Poland. Its written standard is the Polish alphabet which corresponds basically to the Latin alphabet with a few additions...
in 1963. The book provided the standard designs for creating rockets,
fireballA fireball is a somewhat spherical mass of fire, such as that caused by an explosion.It may also refer to:-Science and technology:*FR Fireball, an American aircraft*Fireball , a sailing boat...
s, and other pyrotechnic devices. It contained a large chapter on caliber, construction, production and properties of rockets (for both military and civil purposes), including
multi-stageA multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of...
rockets, batteries of rockets, and rockets with
delta wingThe delta wing is a wing planform in the form of a triangle, named after the Greek uppercase delta which is a triangle .Conception of this wing and its name have been suggested in the 17th century by Polish inventor Kazimierz Siemienowicz. Its use in the so called "tailless delta", i.e...
stabilizerThe stabilizers provide stability while the aircraft is flying straight, and the airfoil of the horizontal stabilizer balances the forces acting on the aircraft....
s (instead of the common guiding rods).
Metal-cylinder Rocket Artillery
In 1792, the first
ironIron is a metallic chemical element with the symbol Fe and atomic number 26. Iron is a group 8 and period 4 element and is therefore classified as a transition metal. Iron and iron alloys are by far the most common metals and the most common ferromagnetic materials in everyday use...
-cased rockets were successfully developed used militarily by
Hyder AliHyder Ali was the de facto ruler of the Kingdom of Mysore in southern India. He is said to have induced his brother to employ a Parsi to purchase artillery and small arms from the government of Bombay Presidency, and to enrol some thirty sailors of different European nations as gunners, and is...
and his son
Tipu SultanSultan Fateh Ali Tipu November 1750, Devanahalli – 4 May 1799, Srirangapattana), also known as the Tiger of Mysore, was the de facto ruler of the Islamic Kingdom of Mysore from 1782 until his own demise in 1799. He was the first son of Hyder Ali by his second wife, Fatima or Fakhr-un-nissa...
, rulers of the
Kingdom of MysoreThe Kingdom of Mysore was a kingdom of southern India, traditionally believed to have been founded in 1399 in the vicinity of the modern city of Mysore. The kingdom, which was ruled by the Wodeyar family, initially served as a vassal state of the Vijayanagara Empire...
in
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
against the larger
British East India CompanyThe East India Company was an early English joint-stock company that was formed initially for pursuing trade with the East Indies, but that ended up trading mainly with the Indian subcontinent and China...
forces during the
Anglo-Mysore WarsThe Anglo-Mysore Wars were a series of wars fought in India over the last three decades of the 18th century between the Kingdom of Mysore and the British East India Company, represented chiefly by the Madras Presidency...
. The British then took an active interest in the technology and developed it further during the 19th century. The
MysoreMysore is the second-largest city in the state of Karnataka, India. It is the headquarters of the Mysore district and the Mysore division and lies about southwest of Bangalore, the capital of Karnataka. The name Mysore is an anglicised version of Mahishūru, which means the abode of Mahisha...
rockets of this period were much more advanced than what the British had seen, chiefly because of the use of iron tubes for holding the propellant; this enabled higher thrust and longer range for the missile (up to 2 km range). After Tipu's eventual defeat in the
Fourth Anglo-Mysore WarThe Fourth Anglo-Mysore War was a war in South India between the Kingdom of Mysore and the British East India Company under the Earl of Mornington....
and the capture of the Mysore iron rockets, they were influential in British rocket development, inspiring the
Congreve rocketThe Congreve Rocket was a British military weapon designed by Sir William Congreve in 1804.The British were greatly impressed by the Mysorean Rocket artillery made from iron tubes used by the armies of Tipu Sultan and his father, Haidar Ali. Tipu Sultan championed the use of mass attacks with...
, which was soon put into use in the
Napoleonic WarsThe Napoleonic Wars were a series of conflicts declared against Napoleon's French Empire and changing sets of European allies by opposing coalitions that ran from 1803 to 1815. As a continuation of the wars sparked by the French Revolution of 1789, they revolutionized European armies and played...
.
According to Stephen Oliver Fought and John F. Guilmartin, Jr. in
Encyclopedia Britannica (2008): "
Hyder AliHyder Ali was the de facto ruler of the Kingdom of Mysore in southern India. He is said to have induced his brother to employ a Parsi to purchase artillery and small arms from the government of Bombay Presidency, and to enrol some thirty sailors of different European nations as gunners, and is...
, prince of
MysoreMysore is the second-largest city in the state of Karnataka, India. It is the headquarters of the Mysore district and the Mysore division and lies about southwest of Bangalore, the capital of Karnataka. The name Mysore is an anglicised version of Mahishūru, which means the abode of Mahisha...
, developed war rockets with an important change: the use of metal cylinders to contain the
combustionCombustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames, appearance of light flickering.Direct combustion by atmospheric oxygen is a reaction...
powder. Although the hammered soft iron he used was crude, the bursting strength of the container of black powder was much higher than the earlier paper construction. Thus a greater internal pressure was possible, with a resultant greater thrust of the propulsive jet. The rocket body was lashed with leather thongs to a long bamboo stick. Range was perhaps up to three-quarters of a mile (more than a kilometre). Although individually these rockets were not accurate, dispersion error became less important when large numbers were fired rapidly in mass attacks. They were particularly effective against cavalry and were hurled into the air, after lighting, or skimmed along the hard dry ground. Hyder Ali's son, Tippu Sultan, continued to develop and expand the use of rocket weapons, reportedly increasing the number of rocket troops from 1,200 to a corps of 5,000. In battles at Seringapatam in 1792 and 1799 these rockets were used with considerable effect against the British."
Although the technique was familiar to Europeans from the 17th century their use fell out of favor until the late 18th century, when
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
n forces from
MysoreMysore is the second-largest city in the state of Karnataka, India. It is the headquarters of the Mysore district and the Mysore division and lies about southwest of Bangalore, the capital of Karnataka. The name Mysore is an anglicised version of Mahishūru, which means the abode of Mahisha...
led by
Tipu SultanSultan Fateh Ali Tipu November 1750, Devanahalli – 4 May 1799, Srirangapattana), also known as the Tiger of Mysore, was the de facto ruler of the Islamic Kingdom of Mysore from 1782 until his own demise in 1799. He was the first son of Hyder Ali by his second wife, Fatima or Fakhr-un-nissa...
invented
ironIron is a metallic chemical element with the symbol Fe and atomic number 26. Iron is a group 8 and period 4 element and is therefore classified as a transition metal. Iron and iron alloys are by far the most common metals and the most common ferromagnetic materials in everyday use...
rockets for use as rocket artillery against British forces in battle. The British thereafter reverse engineered the iron case design, which led to the British development of the
Congreve rocketThe Congreve Rocket was a British military weapon designed by Sir William Congreve in 1804.The British were greatly impressed by the Mysorean Rocket artillery made from iron tubes used by the armies of Tipu Sultan and his father, Haidar Ali. Tipu Sultan championed the use of mass attacks with...
, and used them in several armed conflicts during the 19th century, including the
Battle of WaterlooIn the Battle of Waterloo forces of the French Empire under Napoleon Bonaparte and Michel Ney were defeated by those of the Seventh Coalition, including an Anglo-Allied army under the command of the Duke of Wellington and a Prussian army under the command of Gebhard von Blücher...
. Ironically, the technology of metal-cylinder missiles developed by
Tipu SultanSultan Fateh Ali Tipu November 1750, Devanahalli – 4 May 1799, Srirangapattana), also known as the Tiger of Mysore, was the de facto ruler of the Islamic Kingdom of Mysore from 1782 until his own demise in 1799. He was the first son of Hyder Ali by his second wife, Fatima or Fakhr-un-nissa...
contributed to the defeat of his ally Napolean in the
Battle of WaterlooIn the Battle of Waterloo forces of the French Empire under Napoleon Bonaparte and Michel Ney were defeated by those of the Seventh Coalition, including an Anglo-Allied army under the command of the Duke of Wellington and a Prussian army under the command of Gebhard von Blücher...
.
Accuracy of early rockets
William CongreveSir William Congreve, 2nd Baronet was an English inventor and rocket artillery pioneer distinguished for his development and deployment of Congreve rockets. He was son of Lt...
, son of the Comptroller of the Royal Arsenal, Woolwich, London, became a major figure in the field. From 1801, Congreve researched on the oryginal design of Mysore rockets and set on a vigorous development program at the Arsenal's laboratory. Congreve prepared a new propellant mixture, and developed a rocket motor with a strong iron tube with conical nose. This early
Congreve rocketThe Congreve Rocket was a British military weapon designed by Sir William Congreve in 1804.The British were greatly impressed by the Mysorean Rocket artillery made from iron tubes used by the armies of Tipu Sultan and his father, Haidar Ali. Tipu Sultan championed the use of mass attacks with...
weighed about 32 pounds (14.5 kilograms). The Royal Arsenal's first demonstration of solid fuel rockets was in 1805. The rockets were effectively used during the Napoleonic Wars and the War of 1812. Congreve published three books on rocketry.
From there, the use of military rockets spread throughout Europe At the
Battle of BaltimoreIn the Battle of Baltimore, one of the turning points in the War of 1812, American forces warded off a British sea invasion of the busy port city of Baltimore, Maryland...
in 1814, the rockets fired on
Fort McHenryFort McHenry, in Baltimore, Maryland, is a star shaped fort best known for its role in the War of 1812 when it successfully defended Baltimore Harbor from an attack by the British navy in the Chesapeake Bay...
by the
rocket vesselA rocket vessel was a ship equipped with rockets as a weapon. The most famous ship of this type was HMS Erebus, which at the Battle of Baltimore in 1814 provided the "rockets' red glare" that was memorialized by Francis Scott Key in The Star-Spangled Banner.Rocket vessels were also used by the...
HMS ErebusHMS Erebus was a Royal Navy rocket vessel built in 1807, converted to an 18-gun sloop in 1808, to a fire ship in 1809, and to a 24-gun sixth-rate in 1810. She was sold in 1819....
were the source of the
rockets' red glare described by
Francis Scott KeyFrancis Scott Key was an American lawyer, author, and amateur poet, from Georgetown, who wrote the words to the United States' national anthem, "The Star-Spangled Banner."-Life:...
in
The Star-Spangled Banner"The Star-Spangled Banner" is the national anthem of the United States of America. The lyrics come from "Defence of Fort McHenry", a poem written in 1814 by the 35-year-old amateur poet Francis Scott Key after witnessing the bombardment of Fort McHenry by Royal Navy ships in Chesapeake Bay during...
. Rockets were also used in the
Battle of WaterlooIn the Battle of Waterloo forces of the French Empire under Napoleon Bonaparte and Michel Ney were defeated by those of the Seventh Coalition, including an Anglo-Allied army under the command of the Duke of Wellington and a Prussian army under the command of Gebhard von Blücher...
.
Early rockets were very inaccurate. Without the use of spinning or any
gimbal250px|thumb|right|Illustration of a simple two-axis gimbal set.A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to...
ling of the thrust, they had a strong tendency to veer sharply off course. The early British
Congreve rocketThe Congreve Rocket was a British military weapon designed by Sir William Congreve in 1804.The British were greatly impressed by the Mysorean Rocket artillery made from iron tubes used by the armies of Tipu Sultan and his father, Haidar Ali. Tipu Sultan championed the use of mass attacks with...
s reduced this somewhat by attaching a long stick to the end of a rocket (similar to modern bottle rockets) to make it harder for the rocket to change course. The largest of the Congreve rockets was the 32-pound (14.5 kg) Carcass, which had a 15-foot (4.6 m) stick. Originally, sticks were mounted on the side, but this was later changed to mounting in the center of the rocket, reducing drag and enabling the rocket to be more accurately fired from a segment of pipe.
The accuracy problem was greatly improved in 1844 when
William HaleWilliam Hale , was a British inventor and rocket pioneer.- Biography :Hale was born in Colchester, England in 1797. He was self-taught although his grandfather, the educator William Cole, is believed to have tutored him...
modified the rocket design so that thrust was slightly
vectoredThrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine in a direction other than parallel to the vehicle's longitudinal axis. The technique was originally envisaged to provide upward vertical thrust as a means to give aircraft vertical or short ...
, causing the rocket to spin along its axis of travel like a bullet. The Hale rocket removed the need for a rocket stick, travelled further due to reduced air resistance, and was far more accurate.
Theories of interplanetary rocketry
In 1903, high school mathematics teacher
Konstantin TsiolkovskyKonstantin Eduardovich Tsiolkovsky was an Imperial Russian and Soviet rocket scientist and pioneer of the astronautic theory. He is considered by many to be the father of theoretical astronautics...
(1857–1935) published
Исследование мировых пространств реактивными приборами (
The Exploration of Cosmic Space by Means of Reaction Devices), the first serious scientific work on space travel. The
Tsiolkovsky rocket equationThe Tsiolkovsky rocket equation, or ideal rocket equation, is a mathematical equation that relates the delta-v with the effective exhaust velocity and the initial and end mass of a rocket....
—the principle that governs rocket propulsion—is named in his honor (although it had been discovered previously). He also advocated the use of liquid hydrogen and oxygen for propellant, calculating their maximum exhaust velocity. His work was essentially unknown outside the Soviet Union, but inside the country it inspired further research, experimentation and the formation of the
Society for Studies of Interplanetary TravelThe Society for Studies of Interplanetary Travel was founded in Moscow in May 1924. It was a spin off of a military science society at the Zhukovsky Airforce Academy, and was chaired by Grigory Kramarov. Its 200 charter members included important Soviet space-exploration and rocketry experts such...
in 1924.
In 1912,
Robert Esnault-PelterieRobert Albert Charles Esnault-Pelterie was a pioneering French aircraft designer and spaceflight theorist. He was born in Paris, the son of a textile industrialist...
published a lecture on rocket theory and interplanetary travel. He independently derived Tsiolkovsky's rocket equation, did basic calculations about the energy required to make round trips to the Moon and planets, and he proposed the use of atomic power (i.e. Radium) to power a jet drive.
In 1912 Robert Goddard began a serious analysis of rockets, concluding that conventional solid-fuel rockets needed to be improved in three ways.
First, fuel should be burned in a small combustion chamber, instead of building the entire propellant container to withstand the high pressures. Second, rockets could be arranged in stages. And third, the exhaust speed (and thus the efficiency) could be greatly increased to beyond the speed of sound by using a
De Laval nozzleA de Laval nozzle is a tube that is pinched in the middle, making an hourglass-shape. It is used as a means of accelerating the flow of a gas passing through it to a supersonic speed...
. He patented these concepts in 1914. He, also, independently developed the mathematics of rocket flight.
In 1920, Goddard published these ideas and experimental results in
A Method of Reaching Extreme AltitudesA Method of Reaching Extreme Altitudes is a book written by Robert Goddard describing his theories of rocket flight. The book was published in 1919 by the Smithsonian Institution....
. The work included remarks about sending a solid-fuel rocket to the Moon, which attracted worldwide attention and was both praised and ridiculed. A New York Times editorial suggested:
In 1923,
Hermann OberthHermann Julius Oberth , born in Transylvania, România, then part of Austria-Hungary, was a physicist, and, along with the Russian Konstantin Tsiolkovsky and the American Robert H. Goddard, one of the founding fathers of rocketry and astronautics...
(1894–1989) published
Die Rakete zu den Planetenräumen ("The Rocket into Planetary Space"), a version of his doctoral thesis, after the University of Munich rejected it.
In 1924, Tsiolkovsky also wrote about multi-stage rockets, in 'Cosmic Rocket Trains'
Pre-World War II
Modern rockets were born when Goddard attached a supersonic (
de LavalA de Laval nozzle is a tube that is pinched in the middle, making an hourglass-shape. It is used as a means of accelerating the flow of a gas passing through it to a supersonic speed...
) nozzle to a liquid-fueled rocket engine's combustion chamber. These nozzles turn the hot gas from the combustion chamber into a cooler,
hypersonicIn aerodynamics, hypersonic speeds are those that are highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 and above...
, highly directed jet of gas, more than doubling the thrust and raising the engine efficiency from 2% to 64%. In 1926, Robert Goddard launched the world's first liquid-fueled rocket in
Auburn, MassachusettsAuburn is a town in Worcester County, Massachusetts, United States. The population was 15,901 at the 2000 census.- History :Auburn was first settled in 1714 and was officially incorporated in 1778 as the town of Ward, in honor of American Revolution General Artemas Ward...
.
During the 1920s, a number of rocket research organizations appeared worldwide. In the mid-1920s,
GermanThe Weimar Republic is the name given by historians to the parliamentary republic established in 1919 in Germany to replace the imperial form of government, named after Weimar, the place where the constitutional assembly took place. Its official name was still Deutsches Reich , however...
scientists had begun experimenting with rockets which used liquid propellants capable of reaching relatively high altitudes and distances.
1927 the German car manufacturer
OpelAdam Opel GmbH, commonly known as Opel, is a German automaker. The company was founded on 21 January 1863, began making automobiles in 1899, and was acquired by General Motors in 1929...
began to research rocket vehicles together with Mark Valier and the rocket builder Friedrich Wilhelm Sander. In 1928, Fritz von Opel drove with a rocket car, the
Opel-RAKOpel-RAK were a series of rocket vehicles produced by Fritz von Opel, of the Opel car company, in association with others, including Max Valier and Friedrich Wilhelm Sander largely as publicity stunts....
.1 on the Opel raceway in Rüsselsheim, Germany. In 1929 von Opel started at the Frankfurt-Rebstock airport with the
Opel-Sander RAK 1-airplaneThe Opel RAK.1 was the world's first purpose-built rocket-powered aircraft. It was designed and built by Julius Hatry under commission from Fritz von Opel who flew it on September 30, 1929 in front of a large crowd near Frankfurt-am-Main.During the late 1920s, von Opel had undertaken a variety of...
. This was maybe the first flight with a manned rocket-aircraft.
In 1927 and also in Germany, a team of amateur rocket engineers had formed the
Verein für RaumschiffahrtThe Verein für Raumschiffahrt was a German amateur rocket association prior to World War II that included members outside of Germany...
(German Rocket Society, or VfR), and in 1931 launched a liquid propellant rocket (using
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
and gasoline).
From 1931 to 1937, the most extensive scientific work on rocket engine design occurred in Leningrad, at the Gas Dynamics Laboratory. Well-funded and staffed, over 100 experimental engines were built under the direction of
Valentin GlushkoValentyn Petrovych Glushko was a Soviet engineer, and one of the three principal Soviet "Chief Designers" of spacecraft and rockets during the Soviet/American Space Race.-Biography:At the age of 13 he became interested in aeronautics after reading novels...
. The work included regenerative cooling, hypergolic propellant ignition, and fuel injector designs that included swirling and bi-propellant mixing injectors. However, the work was curtailed by Glushko's arrest during
Stalinist purgesGreat Purge was a series of campaigns of political repression and persecution in the Soviet Union orchestrated by Joseph Stalin in 1937–1938. It involved a large-scale purge of the Communist Party and Government officials, repression of peasants, Red Army leadership, and the persecution of...
in 1938. Similar work was also done by the Austrian professor
Eugen SängerEugen Sänger was an Austrian-German aerospace engineer best known for his contributions to lifting body and ramjet technology.-Early career:...
who worked on rocket powered spaceplanes such as Silbervogel (sometimes called the 'antipodal' bomber.)
On November 12 1932 at a farm in Stockton NJ, the American Interplanetary Society's attempt to static fire their first rocket (based on German Rocket Society designs) fails in a fire.
In 1932, the
ReichswehrThe Reichswehr formed the military organisation of Germany from 1919 until 1935, when it was renamed the Wehrmacht ....
(which in 1935 became the
WehrmachtWehrmacht was the name of the unified armed forces of Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe ....
) began to take an interest in rocketry. Artillery restrictions imposed by the
Treaty of VersaillesThe Treaty of Versailles was one of the peace treaties at the end of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1919, exactly five years after the assassination of Archduke Franz Ferdinand. The other Central Powers on the German side of...
limited Germany's access to long distance weaponry. Seeing the possibility of using rockets as long-range
artilleryArtillery is a military combat Arm that employs weapons capable of discharging large projectiles in combat. They are generally capable of adding considerable fire power to the military capability of an armed force...
fire, the Wehrmacht initially funded the VfR team, but seeing that their focus was strictly scientific, created its own research team. At the behest of military leaders,
Wernher von BraunWernher Magnus Maximilian Freiherr von Braun was a German American rocket physicist and astronautics engineer, becoming one of the leading figures in the development of rocket technology in Germany and the United States...
, at the time a young aspiring rocket scientist, joined the military (followed by two former VfR members) and developed long-range weapons for use in
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
by
Nazi GermanyNazi Germany and the Third Reich are the common English names for Germany between 1933 and 1945, while it was led by Adolf Hitler and the National Socialist German Worker's Party . The name Third Reich refers to the state as the successor to the Holy Roman Empire of the Middle Ages and the German...
.
World War II
In 1943, production of the
V-2 rocketAccording to head of Nazi rocket program Walter Dornberger, the V-2 rocket was the world's first ballistic missile and first human artifact to achieve sub-orbital spaceflight. It was the progenitor of all modern rockets...
began in Germany. It had an operational range of and carried a warhead, with an
amatolNot to be confused with the barbiturate Amytal.Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Amatol was used extensively during World War I and World War II...
explosive charge. It normally achieved an operational maximum altitude of around , but could achieve if launched vertically. The vehicle was similar to most modern rockets, with
turbopumpAs the name suggests, a turbopump comprises basically two main components: a rotodynamic pump and a driving turbine, both mounted on the same shaft....
s,
inertial guidanceA guidance system is a device or group of devices used to navigate a ship, aircraft, missile, rocket, satellite, or other craft. Typically, this refers to a system that navigates without direct or continuous human control...
and many other features. Thousands were fired at various
AlliedThe Allies of World War II were the countries that opposed the Axis powers during the Second World War . The involvement of the Allies in World War II was either natural and inevitable they were invaded or under the direct threat of invasion by the Axis or compelled by concerns that the Axis powers...
nations, mainly England, as well as Belgium and France. While they could not be intercepted, their guidance system design and single conventional warhead meant that it was insufficiently accurate against military targets. 2,754 people in England were killed, and 6,523 were wounded before the launch campaign was terminated. There were also 20,000 deaths of slave labour during the construction of V-2s. While it did not significantly affect the course of the war, the V-2 provided a lethal demonstration of the potential for guided rockets as weapons.
In parallel with the guided missile programme in
Nazi GermanyNazi Germany and the Third Reich are the common English names for Germany between 1933 and 1945, while it was led by Adolf Hitler and the National Socialist German Worker's Party . The name Third Reich refers to the state as the successor to the Holy Roman Empire of the Middle Ages and the German...
, rockets were also used on aircraft, either for assisting horizontal take-off (
JATOJATO is an acronym for Jet-fuel Assisted Take Off. The term is used interchangeably with the term RATO, for Rocket-Assisted Take Off. It is a system for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets...
), vertical take-off (
Bachem Ba 349The Bachem Ba 349 Natter was a World War II era German experimental point-defense rocket-powered interceptor aircraft which was to be used in a very similar way as unmanned surface-to-air missiles. After vertical takeoff which eliminated the need for airfields, the majority of the flight to the...
"Natter") or for powering them (Me 163, etc.)
During the Great Patriotic War the Soviet Union developed and heavily used the Katyusha rocket. It proved to be highly successful against the Nazi military machine.
Post World War II
At the end of World War II, competing Russian, British, and US military and scientific crews raced to capture technology and trained personnel from the German rocket program at
PeenemündePeenemünde is a village in the northeast of the German part of Usedom island. It stands near the mouth of the Peene river, on the easternmost part of the German Baltic coast. The area includes the 1992 :commons:Historisch-technisches Informationszentrum Peenemünde, an Anchor Point of the...
. Russia and
BritainThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
had some success, but the United States benefited the most. The US captured a large number of German rocket scientists (many of whom were members of the
Nazi PartyThe National Socialist German Workers' Party , commonly known in English as the Nazi Party , was a political party in Germany between 1919 and 1945...
, including von Braun) and brought them to the United States as part of Operation Overcast. In America, the same rockets that were designed to rain down on
BritainThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
were used instead by scientists as research vehicles for developing the new technology further. The V-2 evolved into the American Redstone rocket, used in the early space program.
After the war, rockets were used to study high-altitude conditions, by radio
telemetryTelemetry is a technology that allows remote measurement and reporting of information. The word is derived from Greek roots tele = remote, and metron = measure. Systems that need external instructions and data to operate require the counterpart of telemetry, telecommand.Although the term commonly...
of temperature and pressure of the atmosphere, detection of cosmic rays, and further research; notably for the
Bell X-1The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army Air Forces/US Air Force supersonic research project and the first aircraft to exceed the speed of sound in controlled, level flight...
to break the sound barrier. This continued in the US under von Braun and the others, who were destined to become part of the US scientific complex.
Independently, research continued in the
Soviet UnionThe Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...
under the leadership of the chief designer Sergei Korolev. With the help of German technicians, the V-2 was duplicated and improved as the R-1, R-2 and R-5 missiles. German designs were abandoned in the late 1940s, and the foreign workers were sent home. A new series of engines built by Glushko and based on inventions of
Aleksei Mihailovich IsaevAleksei Mihailovich Isaev was a Russian rocket engineer.Aleksei Isaev began work under Leonid Dushkin during World War II, on an experimental rocket-powered interceptor plane. In 1944 he formed his own design bureau to engineer liquid-propellant engines...
formed the basis of the first ICBM, the R-7. The R-7 launched the first satellite-
Sputnik 1Sputnik 1 was the first Earth-orbiting artificial satellite. It was launched into an elliptical low earth orbit by the Soviet Union on 4 October 1957, and was the first in a series of satellites collectively known as the Sputnik program...
, and later
Yuri GagarinYuri Alekseyevich Gagarin , Hero of the Soviet Union, was a Soviet cosmonaut. On 12 April 1961, he became the first human in outer space and the first to orbit the Earth...
-the first man into space, and the first lunar and planetary probes. This rocket is still in use today. These prestigious events attracted the attention of top politicians, along with additional funds for further research.
One problem that had not been solved was
atmospheric reentryAtmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
- it had been shown that an orbital vehicle easily had enough kinetic energy to vaporize itself, and yet it was known that meteorites can make it down to the ground. The mystery was solved in the US in 1951 when H. Julian Allen and
A. J. Eggers, Jr.Alfred J. Eggers, Jr. was NASA's Assistant Administrator for Policy, and devoted efforts to determine the influence of aviation technology in world peace and lectured widely....
of the
National Advisory Committee for AeronauticsThe National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
(NACA) made the counterintuitive discovery that a blunt shape (high drag) permitted the most effective heat shield. With this type of shape, around 99% of the energy goes into the air rather than vehicle, and this permitted safe recovery of orbital vehicles.
The Allen and Eggers discovery, though initially treated as a military secret, was eventually published in 1958. The Blunt Body Theory made possible the heat shield designs that were embodied in the
MercuryMercury Program might refer to:*the first successful American manned spaceflight program, Project Mercury*an American post-rock band, The Mercury Program...
and all other space capsules and space planes, enabling astronauts to survive the fiery re-entry into Earth's atmosphere.
Cold war
Rockets became extremely important militarily in the form of modern intercontinental ballistic missiles (ICBMs) when it was realized that nuclear weapons carried on a rocket vehicle were essentially not defensible against once launched, and ICBM/Launch vehicles such as the R-7,
AtlasAtlas is a family of U.S. space launch vehicles. The original Atlas missile was designed in the late 1950s. It was a liquid-fuel rocket burning LOX and RP-1 in three engines configured in an unusual "stage-and-a-half" or "Parallel Staging" design: two of its three engines were jettisoned during...
and
TitanTitan was a family of U.S. expendable rockets used between 1959 and 2005. A total of 368 rockets of this family were launched.-Titan I:The Titan I was the first version of the Titan family of rockets. It began as a backup ICBM project in case the Atlas was delayed. It was a two-stage rocket...
became the delivery platform of choice for these weapons.
Fueled partly by the
Cold WarThe Cold War was the continuing state of political conflict, military tension, and economic competition existing after World War II , primarily between the USSR and its satellite states, and the powers of the Western world, including the United States...
, the 1960s became the decade of rapid development of rocket technology particularly in the Soviet Union (
VostokVostok was a family of rockets derived from the Soviet R-7 Semyorka ICBM designed for the human spaceflight programme but later used for other satellite launches. It was a subset of the R-7 family of rockets....
, Soyuz,
ProtonProton is an expendable launch system used for both commercial and Russian government space launches. The first Proton rocket was launched in 1965 and the launch system is still in use as of 2009, which makes it one of the most successful heavy boosters in the history of spaceflight...
) and in the United States (e.g. the X-15 and
X-20 Dyna-SoarThe X-20 Dyna-Soar was a United States Air Force program to develop a spaceplane that could be used for a variety of military missions, including reconnaissance, bombing, space rescue, satellite maintenance, and sabotage of enemy satellites...
aircraft). There was also significant research in other countries, such as Britain, Japan, Australia, etc. and their growing use for
Space explorationSpace exploration is the use of astronomy and space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
, with pictures returned from the far side of the
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
and unmanned flights for Mars exploration.
In America the manned programmes,
Project MercuryProject Mercury was the first human spaceflight program of the United States. It ran from 1959 through 1963 with the goal of putting a human in orbit around the Earth...
,
Project GeminiProject Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini operated between Projects Mercury and Apollo, with 10 manned flights occurring in 1965 and 1966...
and later the Apollo programme culminated in 1969 with the first manned
landing on the moonA moon landing is arrival of a spacecraft on the surface of the Moon. This includes both manned and unmanned missions. The first human-made object to reach the surface of the Moon was the Soviet Union's Luna 2 mission on September 13, 1959...
via the
Saturn VThe Saturn V was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. In total NASA launched thirteen Saturn V rockets with no loss of payload. It remains the largest and most powerful launch vehicle ever brought to operational status from a...
, causing the New York Times to retract their earlier editorial implying that spaceflight couldn't work:
In the 1970s America made further lunar landings, before cancelling the Apollo programme. The replacement vehicle, the partially reusable '
Space ShuttleThe Space Shuttle, part of the Space Transportation System , is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches...
' was intended to be cheaper, but this large reduction in costs was largely not achieved. Meanwhile in 1973, the expendable
ArianeAriane is a series of a European civilian expendable launch vehicles for space launch use. The name comes from the French spelling of the mythological character Ariadne; the word is also used in French to describe some types of hummingbird....
programme was begun, a launcher that by the year 2000 would capture much of the geosat market.
Current day
Rockets remain a popular military weapon. The use of large battlefield rockets of the V-2 type has given way to guided missiles. However rockets are often used by
helicopterA helicopter is an aircraft that is lifted and propelled by one or more horizontal rotors, each rotor consisting of two or more rotor blades. Helicopters are classified as rotorcraft or rotary-wing aircraft to distinguish them from fixed-wing aircraft because the helicopter achieves lift with the...
s and light aircraft for ground attack, being more powerful than
machine gunA machine gun is a fully automatic mounted or portable firearm, usually designed to fire rifle bullets in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute...
s, but without the recoil of a heavy
cannonA cannon is any tubular piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
and by the early 1960s
air-to-air missileAn air-to-air missile is a guided missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...
s became favoured. Current artillery systems as MLRS or Smerch launch multiple rockets to saturate battlefield targets with munitions.
Economically, rocketry is the enabler of all
space technologiesSpace technology is technology that is related to entering space, maintaining and using systems during spaceflight and returning people and things from space....
particularly
satelliteIn the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavor. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
s, many of which impact people's everyday lives in almost countless ways.
Scientifically, rocketry has opened a window on the universe, allowing the launch of
space probeA robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
s to explore the
solar systemThe Solar System consists of the Sun and those celestial objects bound to it by gravity, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago...
and space-based telescopes to obtain a clearer view of the rest of the
universeThe Universe comprises everything that physically exists, the entirety of space and time, all forms of matter and energy, and the physical laws and constants that govern them...
.
However, it is probably manned spaceflight that has predominantly caught the imagination of the public. Vehicles such as the
Space ShuttleThe Space Shuttle, part of the Space Transportation System , is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches...
for scientific research, the
SoyuzSoyuz ; English: Union) is a series of spacecraft designed for the Soviet space program by the Korolyov Design Bureau. The Soyuz succeeded the Voskhod spacecraft and was originally built as part of the Soviet Manned Lunar program...
increasingly for orbital tourism and
SpaceShipOneSpaceShipOne is a rocket-powered aircraft that completed the first privately funded human spaceflight on June 21, 2004. It was developed by Scaled Composites....
for suborbital tourism may show a trend towards greater commercialisation of manned rocketry.
Vehicle configurations
Many rockets are the archetypal tall thin "rocket" shape- that take off vertically, but there are many different types of rockets including:
- tiny models
A model rocket is a small rocket capable of being launched by anybody, to generally low altitudes and recovered by a variety of means....
such as water rocketA water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle...
s, skyrocketA skyrocket is a type of firework that uses a solid rocket motor to rise quickly into the sky. At the apex of its ascent, it is usual for a variety of effects to be emitted...
s or small solid rockets that can be purchased at a hobby storeA hobby store sells recreational modelling and craft supplies and specialty magazines for model airplanes , train models, ship models, house and building models. Some hobby shops may also sell dolls, and collectible coins and stamps. A subtype of hobby store is a game store,which sells board...
- missile
A missile is a self-propelled projectile used as a weapon. Missiles are typically propelled by rockets or jet engines. Missiles generally have one or more explosive warheads, although other weapon types may also be used...
s
- space rocket
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
s such as the enormous Saturn VThe Saturn V was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. In total NASA launched thirteen Saturn V rockets with no loss of payload. It remains the largest and most powerful launch vehicle ever brought to operational status from a...
used for the Apollo program
- rocket car
A rocket car is a land vehicle powered by a rocket engine.Because rockets have higher thrust/weight ratios than any jet engine, very large accelerations and high speeds are possible...
s
- rocket bike
- rocket powered aircraft
- rocket sled
A rocket sled is a test platform that slides along a set of rails, propelled by rockets.As its name implies, a rocket sled does not use wheels. Instead, it has sliding pads, called "slippers", which are curved around the head of the rails to prevent the sled from flying off the track...
s
- rocket train
Opel-RAK were a series of rocket vehicles produced by Fritz von Opel, of the Opel car company, in association with others, including Max Valier and Friedrich Wilhelm Sander largely as publicity stunts....
s
- rocket torpedo
The VA-111 Shkval torpedo and its descendants are supercavitating torpedoes developed by the Soviet Union. They are capable of speeds in excess of 200 knots .-Design and capabilities:...
s
- rocket powered jet pack
Jet pack, rocket belt, rocket pack, and similar names, are various types of device, usually worn on the back, that use jets of escaping gases to allow a single user to fly....
s
- rapid escape systems such ejection seats and launch escape system
A Launch Escape System is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate the crew module from the rest of the rocket in case of emergency...
s
- Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
s
Hardware
Rockets at minimum have
propellantRocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
, a place to put propellant (such as a
propellant tankA propellant tank is a container which is part of a vehicle, where propellant is stored prior to use. Propellant tanks vary in construction, and may be a fuel tank in the case of many aircraft....
), one or more
rocket engineA rocket engine or simply "rocket" is a jet engine[Rocket Propulsion Elements; 7th edition- chapter 1] that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
s and nozzle, directional stabilization device(s) (such as
finsFINS is a network protocol used by Omron PLCs, over different physical networks like Ethernet, Controller Link, DeviceNet and RS-232C....
, attitude jets or engine
gimbal250px|thumb|right|Illustration of a simple two-axis gimbal set.A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to...
s for
thrust vectoringThrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine in a direction other than parallel to the vehicle's longitudinal axis. The technique was originally envisaged to provide upward vertical thrust as a means to give aircraft vertical or short ...
,
gyroscopeA gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. A mechanical gyroscope is essentially a spinning wheel or disk whose axle is free to take any orientation...
s) and a structure (typically
monocoqueMonocoque, from Greek for single and French for shell , is a construction technique that supports structural load by using an object's external skin as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin. Monocoque construction was first widely used in...
) to hold these components together. Rockets intended for high speed atmospheric use also have an aerodynamic fairing such as a
nose coneThe term nose cone is used to refer to the forwardmost section of a rocket, guided missile or aircraft. The cone is shaped to offer minimum aerodynamic resistance...
, which usually holds the payload.
As well as these components, rockets can have any number of other components, such as wings (rocketplanes), wheels (
rocket carA rocket car is a land vehicle powered by a rocket engine.Because rockets have higher thrust/weight ratios than any jet engine, very large accelerations and high speeds are possible...
s), even, in a sense, a person (rocket belt). Vehicles frequently possess
navigation systemNavigation system may refer to* Automotive navigation system* GPS navigation device* Inertial guidance system* Global Positioning System* Robotic mapping...
s and
guidance systemA guidance system is a device or group of devices used to navigate a ship, aircraft, missile, rocket, satellite, or other craft. Typically, this refers to a system that navigates without direct or continuous human control...
s which typically use satellite navigation and
inertial navigation systemAn Inertial Navigation System is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references...
s.
Rocket engines
Rocket engines employ the principle of
jet propulsionA jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets...
. The rocket engines powering rockets come in a great variety of different types, a comprehensive list can be found in
rocket engineA rocket engine or simply "rocket" is a jet engine[Rocket Propulsion Elements; 7th edition- chapter 1] that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
. Most current rockets are chemically powered rockets (usually internal combustion engines, but some employ a decomposing
monopropellantMonopropellants are propellants composed of chemicals or mixtures of chemicals which can be stored in a single container with some degree of safety. While stable under defined storage conditions, they react very rapidly under certain other conditions to produce a large volume of energetic gases...
) that emit a hot
exhaust gasExhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal...
. A rocket engine can use gas propellants,
solid propellantSolid rocket boosters are used to provide thrust in spacecraft launches from the launchpad up to burnout of the SRBs. Many launch vehicles include SRBs, including the Ariane 5, Atlas V, and the NASA Space Shuttle...
,
liquid propellantA liquid-fuel rocket or a liquid rocket is a rocket with an engine that uses propellants in liquid form. Liquids are desirable because their reasonably high density allows the volume and hence the mass of the tanks to be relatively low, resulting in a high mass ratio...
, or a
hybrid mixture of both solid and liquidA hybrid rocket is a rocket with a rocket engine which uses propellants in two different states of matter - one solid and the other either gas or liquid. The Hybrid rocket concept can be traced back at least 75 years....
. Some rockets use heat or pressure that is supplied from a source other than the chemical reaction of propellant(s), such as steam rockets,
solar thermal rocketSolar 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. A solar thermal rocket only has to carry the means of capturing solar...
s,
nuclear thermal rocketIn a nuclear thermal rocket a working fluid, usually hydrogen, is heated to a high temperature in a nuclear reactor, and then expands through a rocket nozzle to create thrust. The nuclear reactor's energy replaces the chemical energy of the reactive chemicals in a traditional rocket engine...
engines or simple pressurized rockets such as
water rocketA water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle...
or
cold gas thrusterA cold gas thruster is a rocket engine/thruster that uses a gas as the reaction mass.A cold gas thruster usually simply consists of a pressurised tank containing gas, a valve to control its release and a nozzle, and plumbing connecting them....
s. With combustive propellants a chemical reaction is initiated between the
fuelFuel is any material that is burned or altered to obtain energy and to heat or to move object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion...
and the oxidizer in the
combustionCombustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames, appearance of light flickering.Direct combustion by atmospheric oxygen is a reaction...
chamber, and the resultant hot gases accelerate out of a rocket engine nozzle (or
nozzleA nozzle is a mechanical device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....
s) at the rearward-facing end of the rocket. The
accelerationIn physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up or slows...
of these gases through the engine exerts force ("thrust") on the combustion chamber and nozzle, propelling the vehicle (in accordance with Newton's Third Law).
Rocket propellant
Rocket propellant is mass that is stored, usually in some form of
propellantA propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid....
tank or casing, prior to being used as the propulsive mass that is ejected from a
rocket engineA rocket engine or simply "rocket" is a jet engine[Rocket Propulsion Elements; 7th edition- chapter 1] that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
in the form of a
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
jetA jet is a coherent stream of fluid that is projected into a surrounding medium, usually from some kind of a nozzle or aperture. Jets can travel long distances without dissipating. In the Earth's atmosphere there exist jet streams that travel thousands of miles.Some animals, notably cephalopods use...
to produce
thrustThrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a proportional but opposite force on that system.-Examples:...
. For chemical rockets often the propellants are a fuel such as
liquid hydrogenLiquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H
2 form....
or
keroseneKerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
which is burned with an oxidizer such as
liquid oxygenLiquid oxygen is a form of the element oxygen. It has a pale blue color and is strongly paramagnetic and can be suspended between the poles of a powerful horse shoe magnet...
or
nitric acidNitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure older samples tend to acquire a stronger yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as...
to produce large volumes of very hot gas. The oxidiser is either kept separate and mixed in the combustion chamber, or comes premixed, as with solid rockets.
Sometimes the propellant is not burned but still undergoes a chemical reaction, and can be a 'monopropellant' such as
hydrazineHydrazine is an inorganic chemical compound with the formula N2H4. It is a colourless liquid with an ammonia-like odor and is derived from the same industrial chemistry processes that manufacture ammonia...
,
nitrous oxideNitrous oxide, commonly known as happy gas or laughing gas, is a chemical compound with the chemical formula N
2O. At room temperature, it is a colorless non-flammable gas, with a pleasant, slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
or
hydrogen peroxideHydrogen peroxide is a very pale blue liquid, slightly more viscous than water, that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant...
that can be catalytically decomposed to hot gas.
Alternatively, an inert propellant can be used that can be externally heated, such as in steam rocket,
solar thermal rocketSolar 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. A solar thermal rocket only has to carry the means of capturing solar...
or
nuclear thermal rocketIn a nuclear thermal rocket a working fluid, usually hydrogen, is heated to a high temperature in a nuclear reactor, and then expands through a rocket nozzle to create thrust. The nuclear reactor's energy replaces the chemical energy of the reactive chemicals in a traditional rocket engine...
s.
For smaller, low performance, rockets such as attitude control thrusters where high performance is less necessary, a pressurised fluid is used as propellant that simply escapes the spacecraft through a propelling nozzle.
Uses
Rockets or other similar
reaction devicesA reaction engine is an engine which provides propulsion by expelling reaction mass, in accordance with Newton's third law of motion. This law of motion is most commonly paraphrased as: "For every action force there is an equal, but opposite, reaction force"....
carrying their own propellant must be used when there is no other substance (land, water, or air) or force (gravity,
magnetismIn physics, the term magnetism is used to describe how materials respond on the microscopic level to an applied magnetic field; to categorize the magnetic phase of a material. For example, the most well known form of magnetism is ferromagnetism such that some ferromagnetic materials produce their...
,
lightLight is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye ....
) that a
vehicleA vehicle is a mechanical means of conveyance, a carriage or transport. Most often they are manufactured , although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.Vehicles may be propelled or pulled by...
may usefully employ for propulsion, such as in space. In these circumstances, it is necessary to carry all the
propellantA propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid....
to be used.
However, they are also useful in other situations:
Military
Some military weapons use rockets to propel
warheadThe term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...
s to their targets. A rocket and its payload together are generally referred to as a
missile, especially when the weapon has a
guidance systemA guidance system is a device or group of devices used to navigate a ship, aircraft, missile, rocket, satellite, or other craft. Typically, this refers to a system that navigates without direct or continuous human control...
(not all missiles use rocket engines, some use air breathing jets, turbojets, pulse jets or ramjets.) Anti tank and anti aircraft missiles use rocket engines to engage targets at high speed at a range of several miles, while intercontinental ballistic missiles can be used to deliver multiple nuclear warheads thousands of miles, and anti-ballistic missiles try to stop them.
Science & Research
Sounding rocketA sounding rocket, sometimes called a research rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The origin of the term comes from nautical vocabulary, it refers to to sound, which means to throw a weighted...
s are commonly used to carry instruments that take readings from to above the surface of the Earth, the altitudes between those reachable by
weather balloonA weather or sounding balloon is a balloon which carries instruments aloft to send back information on atmospheric pressure, temperature, and humidity by means of a small, expendable measuring device called a radiosonde...
s and satellites.
Rocket engines are also used to propel
rocket sledA rocket sled is a test platform that slides along a set of rails, propelled by rockets.As its name implies, a rocket sled does not use wheels. Instead, it has sliding pads, called "slippers", which are curved around the head of the rails to prevent the sled from flying off the track...
s along a rail at extremely high speed. The world record for this is Mach 8.5.
Spaceflight
Larger rockets are normally launched from a
launch padA launch pad is the area and facilities where rockets or spacecrafts liftoff. A Spaceport can contain one or many launch pads. A typical launch pad consists of the service and umbilical structures. The service structure provides an access platform to inspect the launch vehicle prior to launch....
which serves as stable support until a few seconds after ignition. Due to their high exhaust velocity - (
MachMach number is the speed of an object moving through air, or any fluid substance, divided by the speed of sound as it is in that substance...
~10+), rockets are particularly useful when very high speeds are required, such as orbital speed (Mach 24+.) Spacecraft delivered into orbital trajectories become artificial satellites which are used for many commercial purposes.
Indeed, rockets remain the only way to launch
spacecraftA spacecraft is a craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflight carry people on board as...
into orbit and beyond. They are also used to rapidly accelerate spacecraft when they change orbits or de-orbit for
landingthumb|right|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...
. Also, a rocket may be used to soften a hard parachute landing immediately before touchdown (see
Soyuz spacecraftSoyuz ; English: Union) is a series of spacecraft designed for the Soviet space program by the Korolyov Design Bureau. The Soyuz succeeded the Voskhod spacecraft and was originally built as part of the Soviet Manned Lunar program...
).
Rescue
Rockets are used to propel a line to a stricken ship so that a
Breeches buoyA breeches buoy is a crude rope-based rescue device used to extract people from wrecked vessels, or to transfer people from one location to another in situations of danger. The device resembles a round emergency personal flotation device with a leg harness attached...
can be used to
rescueRescue refers to operations that usually involve the saving of life, or prevention of injury.Tools used might include search dogs, search and rescue horses, helicopters, and the "Jaws of Life" and other hydraulic cutting and spreading tools used to extricate individuals from wrecked vehicles...
those on board. Rockets are also used to launch emergency flares.
Some crewed rockets, notably the
Saturn VThe Saturn V was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. In total NASA launched thirteen Saturn V rockets with no loss of payload. It remains the largest and most powerful launch vehicle ever brought to operational status from a...
and
SoyuzSoyuz is Russian for "Union", and was often used as an abbreviation for the "Union of Soviet Socialist Republics" during the Communist era. In English, the term is left untranslated in the names of several Soviet-related concepts...
have
launch escape systemA Launch Escape System is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate the crew module from the rest of the rocket in case of emergency...
s. This is a small, usually solid rocket that is capable of pulling the crewed capsule away from the main vehicle towards safety at a moments notice. These types of systems have been operated several times, both in testing and in flight, and operated correctly each time.
Solid rocket propelled ejection seats are used in many military aircraft to propel crew away to safety from a vehicle when flight control is lost.
Hobby, sport and entertainment
Hobbyists build and fly
model rocketA model rocket is a small rocket capable of being launched by anybody, to generally low altitudes and recovered by a variety of means....
s of various types and rockets are used to launch both commercially available
fireworksA firework is a low explosive pyrotechnic device used primarily for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
and professional fireworks displays.
Hydrogen peroxideHydrogen peroxide is a very pale blue liquid, slightly more viscous than water, that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant...
rockets are used to power jet packs, and have been used to power
carsA rocket car is a land vehicle powered by a rocket engine.Because rockets have higher thrust/weight ratios than any jet engine, very large accelerations and high speeds are possible...
and a rocket car holds the all time (albeit unofficial)
drag racingDrag racing is a competition in which vehicles compete to be the first to cross a set finish line, usually from a standing start, and in a straight line. First gaining popularity in the USA after World War II , the sport steadily grew in popularity and spread across the globe...
record.
Noise
For all but the very smallest sizes, rocket exhaust compared to other engines is generally very noisy. As the
hypersonicIn aerodynamics, hypersonic speeds are those that are highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 and above...
exhaust mixes with the ambient air,
shock waveA shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
s are formed. The
sound intensityThe sound intensity, I, 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 listener's location...
from these shock waves depends on the size of the rocket as well as the exhaust speed. The sound intensity of large, high performance rockets could potentially kill at close range.
The
Space ShuttleThe Space Shuttle, part of the Space Transportation System , is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches...
generates over 200 dB(A) of noise around its base. A
Saturn VThe Saturn V was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. In total NASA launched thirteen Saturn V rockets with no loss of payload. It remains the largest and most powerful launch vehicle ever brought to operational status from a...
launch was detectable on
seismometerSeismometers are instruments that measure and record motions of the ground, including those of seismic waves generated by earthquakes, nuclear explosions, and other seismic sources...
s a considerable distance from the launch site.
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.
For crewed rockets various methods are used to reduce the sound intensity for the passengers as much as possible, and typically the placement of the astronauts far away from the rocket engines helps significantly. For the passengers and crew, when a vehicle goes
supersonicThe term supersonic is used to define a speed that is over the speed of sound . In dry air at 20 °C , the threshold value required for an object to be traveling at a supersonic speed is approximately 343 m/s, . Speeds greater than 5 times the speed of sound are often referred to as hypersonic...
the sound cuts off as the sound waves are no longer able to keep up with the vehicle.
Operation
In all rockets, the exhaust is formed from
propellantA propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid....
s carried within the rocket prior to use. Rocket thrust is due to the rocket engine, which propels the rocket forwards by exhausting the propellant rearwards at extreme high speed.
In a closed chamber, the pressures are equal in each direction and no acceleration occurs. If an opening is provided in the bottom of the chamber then the pressure is no longer acting on the missing section. The remaining pressures give a resultant thrust on the side opposite the opening, as well as permitting exhaust to escape. Using a nozzle increases the forces further since the pressure of expanding exhaust also acts on it, multiplying the thrust as a function of the area ratio of the nozzle. As a side effect the pressures act on the exhaust in the opposite direction and accelerate this to very high speeds (in accordance with Newton's Third Law).
If propellant gas is continuously added to the chamber then this disequilibrium of pressures can be maintained for as long as propellant remains.
Due to conservation of momentum the speed of the exhaust of a rocket determines how much momentum increase is created for a given amount of propellant. This is called the rocket's
specific impulseSpecific impulse is a way to describe the efficiency of rocket and jet engines. It represents the impulse per unit of propellant. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum...
. Because a rocket, propellant and exhaust in flight, without any external perturbations, may be considered as a closed system, the total momentum is constant at all times. Therefore, the faster the net speed of the exhaust in one direction, the greater the speed of the rocket can achieve in the opposite direction, especially since the rocket mass is typically far lower than the final total exhaust mass.
As the remaining propellant decreases, rocket vehicles become lighter and their acceleration per unit of propellant tends to increase until the propellant is exhausted. This means that much of the speed change occurs towards the end of the burn when the vehicle is much lighter.
Forces on a rocket in flight
The general study of the
forceIn physics, a force is any agent that causes a change in the motion of a free body, or that causes stress in a fixed body. It can also be described by intuitive concepts such as a push or pull that can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a...
s on a rocket or other spacecraft is part of
ballisticsBallistics is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance.A ballistic body is a body which is...
and is called
astrodynamicsOrbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and Newton's law of universal gravitation. It...
.
Flying rockets are primarily affected by the following:
- Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a proportional but opposite force on that system.-Examples:...
from the engine(s)
- Gravity from celestial bodies
- Drag
In fluid dynamics, drag refers to forces that oppose the relative motion of an object through a fluid . Drag forces act in a direction opposite to the oncoming flow velocity...
if moving in atmosphere
- Lift
A fluid flowing past the surface of a body exerts a force on it. Lift is defined to be the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is defined to be the component of the fluid-dynamic force parallel to the flow...
; usually relatively small effect except for rocket-powered aircraftA rocket-powered aircraft or rocket plane is an aircraft that uses a rocket for propulsion, sometimes in addition to airbreathing jet engines. Rocket planes can achieve much higher speeds than similarly-sized jet aircraft, but typically for at most a few minutes of powered operation, followed by a...
In addition, the inertia/centrifugal pseudo-force can be significant due to the path of the rocket around the center of a celestial body; when high enough speeds in the right direction and altitude are achieved a stable
orbitIn physics, an orbit is the gravitationally curved path of one object around a point or another body, for example the gravitational orbit of a planet around a star....
or
escape velocityIn physics, escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy, as calculated by the equation,...
is obtained.
These forces, with a stabilizing tail present will, unless deliberate control efforts are made, naturally cause the vehicle to follow a roughly
parabolicIn mathematics, the parabola is a conic section, the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface...
trajectory termed a
gravity turnA gravity turn or zero-lift turn is a maneuver used in launching a spacecraft into, or descending from, an orbit around a celestial body such as a planet or a moon. This launch trajectory offers two main advantages over a thrust-controlled trajectory where the rocket's own thrust steers the vehicle...
, and this trajectory is often used at least during the initial part of a
launchA rocket launch is the first phase of the flight of a rocket. Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform such as the San Marco platform, or the Sea Launch launch vessel.Launches...
. (This is true even if the rocket engine is
mounted at the noseThe pendulum rocket fallacy is a common fundamental misunderstanding of the mechanics of rocket flight and how rockets remain on a stable trajectory....
). Vehicles can thus maintain low or even zero
angle of attackAngle of attack is a term used in fluid dynamics to describe the angle between a reference line on a body and the vector representing the relative motion between the body and the fluid through which it is moving. In general, the reference line could be any line on any arbitrarily shaped body in...
which minimizes transverse
stressIn continuum mechanics, the concept of stress, introduced by Cauchy around 1822, is a measure of the average amount of force exerted per unit area of a surface within a deformable body on which internal forces act...
on the launch vehicle; permitting a weaker, and hence lighter, launch vehicle.
Net thrust
A typical rocket engine can handle a significant fraction of its own mass in propellant each second, with the propellant leaving the nozzle at several kilometres per second. This means that the
thrust-to-weight ratioThrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....
of a rocket engine, and often the entire vehicle can be very high, in extreme cases over 100. This compares with other jet propulsion engines that can exceed 5 for some of the better engines.
The propellant flow rate of a rocket is often deliberately varied over a flight, to provide a way to control the thrust and thus the airspeed of the vehicle. This, for example, allows minimization of aerodynamic losses and can limit the increase of
g-forcesThe g-force experienced by an object is its acceleration relative to free-fall. The term g-force is considered a misnomer, as g-force is not a force but an acceleration....
due to the reduction in propellant load.
It can be shown that the net thrust of a rocket is:
where:
propellant flow (kg/s or lb/s)
the effective exhaust velocity (m/s or ft/s)
The of a rocket engine is often almost constant in a vacuum, but in practice the effective exhaust velocity of rocket engines goes down when operated within an atmosphere as the atmospheric pressure goes up. In space, the effective exhaust velocity is equal to the actual exhaust velocity. In the atmosphere, the two velocities are close in value.
Impulse
The total impulse of a rocket burning its propellant is simply:
When there is fixed thrust, this is simply:
Specific impulse
As can be seen from the thrust equation the effective speed of the exhaust controls the amount of thrust produced from a particular quantity of fuel burnt per second.
An equivalent measure, the net thrust-seconds (
impulseIn classical mechanics, an impulse is defined as the integral of a force with respect to time. When a force is applied to a rigid body it changes the momentum of that body...
) per weight unit of propellant expelled is called
specific ImpulseSpecific impulse is a way to describe the efficiency of rocket and jet engines. It represents the impulse per unit of propellant. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum...
"" and this is one of the most important figures that describes a rocket's performance. It is defined such that it is related to the effective exhaust velocity by:
where: has units of seconds is the acceleration at the surface of the Earth
Thus, the greater the specific impulse, the greater the net thrust and performance of the engine. is determined by measurement while testing the engine. In practice the effective exhaust velocities of rockets varies but can be extremely high, ~4500 m/s, about 15 times the sea level speed of sound in air.
Delta-v (rocket equation)
The
delta-vIn astrodynamics, the term delta-v, literally "change in velocity" , has a specific meaning: it is a scalar which takes units of speed that measures the amount of "effort" needed to carry out an orbital maneuver, i.e., to change from one trajectory to another.Where is the instantaneous thrust is...
capacity of a rocket is the theoretical total change in velocity that a rocket can achieve without any external interference (without air drag or gravity or other forces).
When is constant, the delta-v that a rocket vehicle can provide can be calculated from the
Tsiolkovsky rocket equationThe Tsiolkovsky rocket equation, or ideal rocket equation, is a mathematical equation that relates the delta-v with the effective exhaust velocity and the initial and end mass of a rocket....
:
where: is the initial total mass, including propellant, in kg (or lb) is the final total mass in kg (or lb) is the effective exhaust velocity in m/s or (ft/s) is the delta-v in m/s (or ft/s)
When launched from the Earth practical delta-v's for a single rockets carrying payloads can be a few km/s. Some theoretical designs have rockets with delta-v's over 9 km/s.
The required delta-v can also be calculated for a particular manoeuvre; for example the delta-v to launch from the surface of the Earth to
Low earth orbitA low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
is about 9.7 km/s, which leaves the vehicle with a sideways speed of about 7.8 km/s at an altitude of around 200 km. In this manoeuvre about 1.9 km/s is lost in air drag,
gravity dragIn astrodynamics and rocketry, gravity drag is a measure of the loss in the net performance of a rocket while it is thrusting in a gravitational field...
and
gaining altitudePotential energy is energy stored within a physical system as a result of the position or configuration of the different parts of that system. It is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy, and to do work in the process...
.
The ratio is sometimes called the
mass ratio.
Mass ratios
Persons not familiar with spaceflight rarely realize that almost all of a launch vehicle's mass consists of propellant. Mass ratio is, for any 'burn', the ratio between the rocket's initial mass and the mass after. Everything else being equal, a high mass ratio is desirable for good performance, since it indicates that the rocket is lightweight and hence performs better, for essentially the same reasons that low weight is desirable in sports cars.
Rockets as a group have the highest
thrust-to-weight ratioThrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....
of any type of engine; and this helps vehicles achieve high
mass ratioIn aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than without; that is, it is the ratio of the rocket's wet mass to its dry mass...
s, which improves the performance of flights. The higher the ratio, the less engine mass is needed to be carried. This permits the carrying of even more propellant, enormously improving the delta-v. Alternatively, some rockets such as for rescue scenarios or racing carry relatively little propellant and payload and thus need only a lightweight structure and instead achieve high accelerations. For example, the Soyuz escape system can produce 20g.
Achievable mass ratios are highly dependent on many factors such as propellant type, the design of engine the vehicle uses, structural safety margins and construction techniques.
The highest mass ratios are generally achieved with liquid rockets, and these types are usually used for orbital launch vehicles, a situation which calls for a high delta-v. Liquid propellants generally have densities similar to water (with the notable exceptions of
liquid hydrogenLiquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H
2 form....
and liquid
methaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, and the principal component of natural gas. Methane's bond angles are 109.5 degrees. Burning methane in the presence of oxygen produces carbon dioxide and water. The relative abundance of methane and its clean...
), and these types are able to use lightweight, low pressure tanks and typically run high-performance turbopumps to force the propellant into the combustion chamber.
Some notable mass fractions are found in the following table (some aircraft are included for comparison purposes):
Staging
Often, the required velocity (delta-v) for a mission is unattainable by any single rocket because the
propellantA propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid....
, tankage, structure,
guidanceA guidance system is a device or group of devices used to navigate a ship, aircraft, missile, rocket, satellite, or other craft. Typically, this refers to a system that navigates without direct or continuous human control...
, valves and engines and so on, take a particular minimum percentage of take-off mass that is too great for the propellant it carries to achieve that delta-v.
For example the first stage of the Saturn V, carrying the weight of the upper stages, was able to achieve a
mass ratioIn aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than without; that is, it is the ratio of the rocket's wet mass to its dry mass...
of about 10, and achieved a specific impulse of 263 seconds. This gives a delta-v of around 5.9 km/s whereas around 9.4 km/s delta-v is needed to achieve orbit with all losses allowed for.
This problem is frequently solved by staging — the rocket sheds excess weight (usually empty tankage and associated engines) during launch. Staging is either
serial where the rockets light after the previous stage has fallen away, or
parallel, where rockets are burning together and then detach when they burn out.
The maximum speeds that can be achieved with staging is theoretically limited only by the speed of light. However the payload that can be carried goes down geometrically with each extra stage needed, while the additional delta-v for each stage is simply additive.
Acceleration and thrust-to-weight ratio
From Newton's second law the acceleration of a vehicle is simply:
Where m is the instantaneous mass of the vehicle and is the net force acting on the rocket (mostly thrust but air drag and other forces can play a part.)
Typically, the acceleration of a rocket increases with time (if the thrust stays the same) as the weight of the rocket decreases as propellant is burned, but the thrust can be throttled to offset or vary this if needed. Discontinuities in acceleration will also occur when stages burn out, often starting at a lower acceleration with each new stage firing.
Peak accelerations can be increased by designing the vehicle with a reduced mass, usually achieved by a reduction in the fuel load and tankage and associated structures, but obviously this reduces range, final speed and burn time. Still, for some applications that rockets are used for, a high peak acceleration applied for just a short time is highly desirable.
The minimal mass of vehicle consists of a rocket engine with minimal fuel and structure to carry it. In that case the
thrust-to-weight ratioThrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....
of the rocket engine limits the maximum acceleration that can be designed. It turns out that rocket engines generally have truly excellent thrust to weight ratios (137 for the
NK-33NK-33 and NK-43 were rocket engines designed and built in the late 1960s and early 1970s by the Kuznetsov Design Bureau. They were intended for the ill-fated Soviet N-1 rocket moon shot. The NK-33 engine achieves the highest thrust-to-weight ratio of any Earth-launchable rocket engine, whilst...
engine, some solid rockets are over 1000), and nearly all really
high-gThe g-force experienced by an object is its acceleration relative to free-fall. The term g-force is considered a misnomer, as g-force is not a force but an acceleration....
vehicles employ or have employed rockets.
The high accelerations that rockets naturally possess means that rocket vehicles are often capable of
vertical takeoffVTOL is an abbreviation for Vertical Take-Off and Landing aircraft. See also V/STOL. This classification includes fixed-wing aircraft that can hover, take off and land vertically as well as helicopters and other aircraft with powered rotors, such as tiltrotors...
; this can be done provided the vehicles engines provide more than the local gravitational acceleration away from the Earth or gravity source.
Drag
The effect of drag is to apply force to which slows the vehicle as well as presenting structural loads.
Drag can be minimised by an aerodynamic
nose coneThe term nose cone is used to refer to the forwardmost section of a rocket, guided missile or aircraft. The cone is shaped to offer minimum aerodynamic resistance...
and by using a shape with a high ballistic coefficient (the "classic" rocket shape- long and thin).
During a rocket launch, as the vehicle speed increases, and the atmosphere thins, there is a point of maximum aerodynamic drag called
Max QIn aerospace engineering, max Q is the point of maximum dynamic pressure, the point at which aerodynamic stress on a spacecraft in atmospheric flight is maximized....
. This determines the minimum aerodynamic strength of the vehicle, as the rocket must avoid
bucklingIn engineering, buckling is a failure mode characterized by a sudden failure of a structural member subjected to high compressive stresses, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding. This...
under these forces.
Energy efficiency
Rocket launch vehicles take-off with a great deal of flames, noise and drama, and it might seem obvious that they are grievously inefficient. However, while they are far from perfect, their energy efficiency is not as bad as might be supposed.
The energy density of a typical rocket propellant is often around 1/3 that of conventional hydrocarbon fuels; the bulk of the mass is in the form of (often relatively inexpensive) oxidizer. Nevertheless, at take-off the rocket has a great deal of energy in the form of fuel and oxidizer stored within the vehicle. It is of course desirable that as much of the energy of the propellant end up as
kineticThe kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its...
or
potential energyPotential energy is energy stored within a physical system as a result of the position or configuration of the different parts of that system. It is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy, and to do work in the process...
of the body of the rocket as possible.
Energy from the fuel is lost in air drag and
gravity dragIn astrodynamics and rocketry, gravity drag is a measure of the loss in the net performance of a rocket while it is thrusting in a gravitational field...
and is used for the rocket to gain altitude and speed. However, much of the lost energy ends up in the exhaust.
100% efficiency within the engine (engine efficiency ) would mean that all of the heat energy of the combustion products is converted into kinetic energy of the jet. This is not possible, but the high expansion ratio nozzles that can be used with rockets come surprisingly close: when the nozzle expands the gas, the gas is cooled and accelerated, and an energy efficiency of up to 70% can be achieved. Most of the rest is heat energy in the exhaust that is not recovered. The high efficiency is a consequence of the fact that rocket combustion can be performed at very high temperatures and the gas is finally released at much lower temperatures, and so giving good Carnot efficiency.
However, engine efficiency is not the whole story. In common with the other
jet-based enginesA jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets...
, but particularly in rockets due to their high and typically fixed exhaust speeds, rocket vehicles are extremely inefficient at low speeds irrespective of the engine efficiency. The problem is that at low speeds, the exhaust carries away a huge amount of
kinetic energyThe kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its...
rearward. This phenomenon is termed
propulsive efficiencyIn aircraft and rocket design, overall propulsive efficiency is the efficiency, in percent, with which the energy contained in a vehicle's propellant is converted into useful energy, to replace losses due to air drag, or gravity, or to accelerate the vehicle....
.
However, as speeds rise, the resultant exhaust speed goes down, and the overall vehicle energetic efficiency rises, reaching a peak of around 100% of the engine efficiency when the vehicle is travelling exactly at the same speed that the exhaust is emitted. In this case the exhaust would ideally stop dead in space behind the moving vehicle, taking away zero energy, and from conservation of energy, all the energy would end up in the vehicle. The efficiency then drops off again at even higher speeds as the exhaust ends up travelling forwards- trailing behind the vehicle.
From these principles it can be shown that the propulsive efficiency for a rocket moving at speed with an exhaust velocity is:
And the overall energy efficiency is:
Since the energy ultimately comes from fuel, these joint considerations mean that rockets are mainly useful when a very high speed is required, such as ICBMs or
orbital launchAn orbital spaceflight is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To do this around the Earth, it must be on a free trajectory which has an altitude at perigee above...
, and they are rarely if ever used for general aviation. For example, from the equation, with an of 0.7, a rocket flying at Mach 0.85 (which most aircraft cruise at) with an exhaust velocity of Mach 10, would have a predicted overall energy efficiency of 5.9%, whereas a conventional, modern, air breathing jet engine achieves closer to 35% efficiency. Thus a rocket would need about 6x more energy; and allowing for the ~3x lower specific energy of rocket propellant than conventional air fuel, roughly 18x more mass of propellant would need to be carried for the same journey.
Thus jet engines which have a better match between speed and jet exhaust speed such as turbofans (in spite of their worse ) dominate for subsonic and supersonic atmospheric use while rockets work best at hypersonic speeds. On the other hand rockets do also see many short-range
relatively low speed military applications where their low-speed inefficiency is outweighed by their extremely high thrust and hence high accelerations.
Safety, reliability and accidents
Rockets are not inherently highly dangerous. In military use, adequate reliability and safety is obtained. However, for space use, most flights have some risk.
Because of the enormous chemical energy in useful
rocket propellantRocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
s (greater energy by weight than explosives, but lower than
gasolineGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines...
), accidents can, have and will happen. The number of people injured or killed is usually small because of the great care normally taken, but their record is not perfect.
Costs and economics
The costs of rockets can be roughly divided into propellant costs, the costs of obtaining and/or producing the 'dry mass' of the rocket and the costs of any required support equipment and facilities.
Most of the takeoff mass of a rocket is normally propellant. However propellant is seldom more than a few times more expensive than gasoline per kg (as of 2009 gasoline is about $1/kg or less), and although substantial amounts are needed, for all but the very cheapest rockets it turns out that the propellant costs are usually comparatively small, although not completely negligible.
The costs of the dry mass of the rocket depend largely on the manufacturing processes needed to shape and assemble it; the materials used are rarely expensive in and of themselves. For complete aerospace materials average costs of ~$10,000/kg (as of 2009) are common. This high cost is largely due to the manpower and equipment needed to form lightweight structures that perform well in rockets. Even though the dry mass of the rocket is usually a small fraction of the rocket (often between 1/10 and 1/40 of the rocket), nevertheless this cost dominates.
However the structure of simple rockets that are produced in large quantities can be many times cheaper, while very high performance, complex structures that are produced in small quantities tend to be more expensive, although give more performance.
The costs of support equipment, range costs and launch pads generally scale up with the size of the rocket, but vary less with launch rate, and so may be considered to be approximately a fixed cost.
External links
Governing agencies
Information sites