Raptor is a family of
full-flow staged-combustion-cycle rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordanc ...
s developed and manufactured by
SpaceX
Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal of ...
for use on the in-development
SpaceX Starship
Starship is a Fully-reusable orbital launch vehicle, fully reusable, super heavy-lift launch vehicle under development by SpaceX, an American aerospace company. With more than twice the thrust of the Saturn V, it is designed to be the most powe ...
. The engine is powered by
cryogenic
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
and
liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
("methalox") rather than the
RP-1
RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is st ...
and liquid oxygen ("kerolox") used in SpaceX's prior
Merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
and
Kestrel
The term kestrel (from french: crécerelle, derivative from , i.e. ratchet) is the common name given to several species of predatory birds from the falcon genus ''Falco''. Kestrels are most easily distinguished by their typical hunting behaviou ...
rocket engines. The Raptor engine has more than twice the thrust of SpaceX's
Merlin 1D
Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. The Merlin eng ...
engine that powers the
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
and
Falcon Heavy
Falcon Heavy is a partially reusable heavy-lift launch vehicle that is produced by SpaceX, an American aerospace manufacturer. The rocket consists of two strap-on boosters made from Falcon 9 first stages, a center core also made from a Falc ...
launch vehicles.
Raptor is used in the
Starship system in both the
super-heavy-lift Super Heavy booster and in the Starship spacecraft which acts as the second stage when launched from Earth and as an independent spacecraft in LEO and beyond.
Starship is planned to be used in various applications, including Earth-orbit
satellite delivery, deployment of a large portion of SpaceX's
Starlink
Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
satellite constellation
A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one sa ...
,
exploration
Exploration refers to the historical practice of discovering remote lands. It is studied by geographers and historians.
Two major eras of exploration occurred in human history: one of convergence, and one of divergence. The first, covering most ...
,
Moon landing
A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.
The United St ...
, and
colonization of Mars
Colonization or settlement of Mars is the theoretical human migration and long-term human establishment of Mars. The prospect has garnered interest from public space agencies and private corporations and has been extensively explored in scien ...
.
History
Conception and initial designs
An advanced rocket engine design project named Raptor, burning
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
propellants, was first publicly discussed by SpaceX's Max Vozoff at the
American Institute of Aeronautics and Astronautics
The American Institute of Aeronautics and Astronautics (AIAA) is a professional society for the field of aerospace engineering. The AIAA is the U.S. representative on the International Astronautical Federation and the International Council of ...
Commercial Crew/Cargo symposium in 2009.
SpaceX had a few staff working on the Raptor upper-stage engine, then still a
/
LOX
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an appli ...
concept, at a low level of priority.
Further mention of the development program occurred in 2011.
In March 2012, news accounts asserted that the Raptor upper-stage engine
development program was underway, but that details were not being publicly released.
In October 2012, SpaceX publicly announced concept work on a rocket engine that would be "several times as powerful as the Merlin 1 series of engines, and won't use Merlin's
RP-1
RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is st ...
fuel", but declined to specify which fuel would be used.
They indicated that details on a new SpaceX rocket would be forthcoming in "one to three years" and that the large engine was intended for the next-generation launch vehicle using multiple of these large engines, that would be expected to launch payload masses of the order of to
low Earth orbit
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...
, exceeding the payload mass capability of the
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
Space Launch System
The Space Launch System (SLS) is an American super heavy-lift expendable launch vehicle developed by NASA. As of 2022, SLS has the highest payload capacity of any rocket in operational service, as well as the greatest liftoff thrust of any r ...
by a wide margin.
Development
![Full flow staged rocket cycle](https://upload.wikimedia.org/wikipedia/commons/4/48/Full_flow_staged_rocket_cycle.svg)
In November 2012, Musk announced a new direction for the propulsion division of SpaceX which was towards developing
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
-fueled rocket engines.
He further indicated that the Raptor concept would now become a methane-based design
and that methane would be the fuel of choice for SpaceX's plans for Mars colonization.
Because of the presence of
water underground and carbon dioxide in the
atmosphere of Mars
The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.8%), and argon (2%). It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and no ...
, methane, a simple
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
, can easily be synthesized on Mars using the
Sabatier reaction
The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures (perhaps 3 MPa ) in the presence of a nickel catalyst. It w ...
.
In-situ resource production on Mars has been examined by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
and found to be viable for oxygen, water, and methane production.
When first mentioned by SpaceX in 2009, the term "Raptor" was applied exclusively to an upper-stage engine concept
—and 2012 pronouncements indicated that it was then still a concept for an
upper stage
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''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 ...
engine
—but in early 2014 SpaceX confirmed that Raptor would be used both on a new second stage, as well as for the large (then, nominally a 10-meter-diameter) core of the
Mars Colonial Transporter
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and t ...
(subsequently, in 2016, on both stages of the
Interplanetary Transport System
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and the ...
and then, in 2017 on the
Big Falcon Rocket).
Public information released in November 2012 indicated that SpaceX might have a family of Raptor-designated rocket engines in mind;
this was confirmed by SpaceX in October 2013.
However, in March 2014 SpaceX COO
Gwynne Shotwell
Gwynne Shotwell ( Rowley; born November 23, 1963) is an American businesswoman and engineer. She is the president and chief operating officer of SpaceX, an American space transportation company, where she is responsible for day-to-day operation ...
clarified that the focus of the new engine development program is exclusively on the full-size Raptor engine; smaller subscale methalox engines were not planned on the development path to the very large Raptor engine.
In October 2013, SpaceX announced that they would be performing methane
engine tests of Raptor engine components at
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
's
John C. Stennis Space Center
The John C. Stennis Space Center (SSC) is a NASA rocket testing facility in Hancock County, Mississippi, United States, on the banks of the Pearl River at the Mississippi–Louisiana border. , it is NASA's largest rocket engine test facility. ...
and that SpaceX would add equipment to the existing test stand infrastructure to support
liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
and hot
gaseous
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), ...
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
engine component testing.
In April 2014, SpaceX completed the requisite upgrades and maintenance to the Stennis test stand to prepare for testing of Raptor components,
and the engine component testing program began in earnest, focusing on the development of robust startup and shutdown procedures. Component testing at Stennis also allowed hardware characterization and
verification
Verify or verification may refer to:
General
* Verification and validation, in engineering or quality management systems, is the act of reviewing, inspecting or testing, in order to establish and document that a product, service or system meets ...
.
SpaceX successfully began development testing of injectors in 2014 and completed a full-power test of a full-scale oxygen
preburner
The staged combustion cycle (sometimes known as topping cycle, preburner cycle, or closed cycle) is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is th ...
in 2015. 76 hot-fire tests of the preburner, totaling some 400 seconds of test time, were executed from April–August 2015.
SpaceX completed its planned testing using NASA Stennis facilities in 2014 and 2015.
In January 2016, the US Air Force awarded a development contract to SpaceX to develop a prototype version of its methane-fueled reusable Raptor engine for use on the
upper stage
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''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 ...
of the
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
and
Falcon Heavy
Falcon Heavy is a partially reusable heavy-lift launch vehicle that is produced by SpaceX, an American aerospace manufacturer. The rocket consists of two strap-on boosters made from Falcon 9 first stages, a center core also made from a Falc ...
launch vehicles. Work under the contract was expected to be completed in 2018, with engine performance testing to be done at Stennis Space Center and at
Los Angeles Air Force Base
Los Angeles Air Force Base (LAAFB) is a United States Space Force Base located in El Segundo, California. Los Angeles Air Force Base houses and supports the headquarters of the United States Space Force's Space Systems Command (SSC), which ...
,
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
.
Testing
![Raptor-test-9-25-2016](https://upload.wikimedia.org/wikipedia/commons/d/dd/Raptor-test-9-25-2016.jpg)
Initial
development
Development or developing may refer to:
Arts
*Development hell, when a project is stuck in development
*Filmmaking, development phase, including finance and budgeting
*Development (music), the process thematic material is reshaped
* Photograph ...
testing
An examination (exam or evaluation) or test is an educational assessment intended to measure a test-taker's knowledge, skill, aptitude, physical fitness, or classification in many other topics (e.g., beliefs). A test may be administered verba ...
of Raptor methane engine components was done at NASA's
Stennis Space Center, where SpaceX added equipment to the existing infrastructure to support
liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
engine testing.
The development Raptor engine discussed in the October 2013 time frame relative to Stennis testing was designed to generate more than vacuum thrust.
Raptor engine component testing began in May 2014 at the
E-2 test complex which SpaceX modified to support
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
engine tests.
SpaceX completed a "round of main injector testing in late 2014" and a "full-power test of the oxygen
preburner
The staged combustion cycle (sometimes known as topping cycle, preburner cycle, or closed cycle) is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is th ...
component" for Raptor by June 2015.
By early 2016, SpaceX had constructed a new engine test stand at their
McGregor test site in central Texas for Raptor testing.
By August 2016, the first integrated Raptor rocket engine, manufactured at the
SpaceX Hawthorne
Space Exploration Technologies Corp. (SpaceX) is an American Aerospace manufacturer, spacecraft manufacturer, space launch, launcher, and a Telecommunication, satellite communications corporation headquartered in Hawthorne, California. It wa ...
facility in California, was shipped to SpaceX McGregor for development testing.
The engine had thrust, less than half the thrust of the full-scale Raptor engine used for flight tests in 2019.
It is the first full-flow staged-combustion methalox engine ever to reach a test stand.
It performed an initial 9-second firing test on 26 September 2016, the day before Musk's talk at the International Aeronautical Congress.
On 26 September 2016, Elon Musk disclosed that the engine used multi-stage turbopumps. Substantial additional technical details of the ITS propulsion were summarized in an article on the Raptor engine published the next week.
In September 2016, at the 67th
International Astronautical Congress
Every year, the International Astronautical Federation with the support of the International Academy of Astronautics and the International Institute of Space Law (IISL), holds the International Astronautical Congress (IAC) which is hosted by ...
, Musk mentioned several Raptor engine designs that were planned for the
Interplanetary Transport System
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and the ...
. In addition, a much smaller subscale development engine had already been built for design validation. At that time, this first subscale Raptor development engine had recently been tested on a
ground test stand in
McGregor
McGregor may refer to:
People
* McGregor (surname)
* Clan MacGregor, a Scottish highland clan
* McGregor W. Scott (born 1962), U.S. attorney
Characters
* Mr. McGregor, a fictional character from Peter Rabbit
Places
in Canada:
* McGregor Lake ...
, but for only one brief firing.
The Raptor subscale development engine produced approximately thrust.
To eliminate
flow separation
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake.
A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous fo ...
problems while being tested in Earth's atmosphere, the test nozzle expansion ratio had been limited to 150.
NASASpaceFlight
''NASASpaceflight.com'' is a private news website and forum which launched in 2005, covering crewed and uncrewed spaceflight and aerospace engineering news. Its original reporting has been referenced by various news outlets on spaceflight-spe ...
reported that the development engine was only one-third the size of any of the several larger engine designs that were discussed for the later flight vehicles.
By September 2017, the development Raptor engine—with chamber pressure—had undergone 1200 seconds of test fire testing in ground-test stands across 42 main engine tests, with the longest test being 100 seconds, which is limited by the capacity of the ground-test propellant tanks. The first version of the flight engine is intended to operate at a chamber pressure of , with the intent to raise it to at a later time.
By September 2017, the sub-scale test engine, with a thrust of and "a new alloy to help its oxygen-rich turbopump resist oxidization, ... had completed 1200 seconds of firings across 42 tests."
This alloy is known as SX500, created by the SpaceX metallurgy team which is used to contain hot oxygen gas in the engine at up to 12000 psi.
Heavy-lift vehicles
![BFR in flight (cropped)-2018 version](https://upload.wikimedia.org/wikipedia/commons/3/30/BFR_in_flight_%28cropped%29-2018_version.png)
While plans for Raptor
flight test
Flight testing is a branch of aeronautical engineering that develops specialist equipment required for testing aircraft behaviour and systems. Instrumentation systems are developed using proprietary transducers and data acquisition systems. D ...
ing have consistently been on the new-generation
fiber-composite-material construction flight vehicles since 2016, the specific vehicle was not clarified until October 2017, when it was indicated that initial
suborbital
A sub-orbital spaceflight is a spaceflight in which the spacecraft reaches outer space, but its trajectory intersects the atmosphere or surface of the gravitating body from which it was launched, so that it will not complete one orbital r ...
test flights would occur with a Big Falcon Ship.
In November 2016, the first
flight test
Flight testing is a branch of aeronautical engineering that develops specialist equipment required for testing aircraft behaviour and systems. Instrumentation systems are developed using proprietary transducers and data acquisition systems. D ...
s of the Raptor engine were projected to be on the
Interplanetary Transport System
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and the ...
, no earlier than the early 2020s.
By July 2017, the plan had been modified to do flight testing on a much smaller launch vehicle and spacecraft, and the new system architecture had "evolved quite a bit" since the ITS concept in 2016. A key driver of the 2017 architecture was to make the new system useful for substantial Earth-orbit and
cislunar
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, predo ...
launches so that the new system might
pay for itself, in part, through economic spaceflight activities in the near-Earth space zone.
Elon Musk announced in September 2017 that the initial flight platform for any Raptor engine would be some part of the
Big Falcon Rocket. BFR was a -diameter launch vehicle.
[Elon Musk speech: Becoming a Multiplanet Species](_blank)
, 29 September 2017, 68th annual meeting of the International Astronautical Congress
Every year, the International Astronautical Federation with the support of the International Academy of Astronautics and the International Institute of Space Law (IISL), holds the International Astronautical Congress (IAC) which is hosted by ...
in Adelaide, Australia
Adelaide ( ) is the capital city of South Australia, the state's largest city and the fifth-most populous city in Australia. "Adelaide" may refer to either Greater Adelaide (including the Adelaide Hills) or the Adelaide city centre. The demo ...
In October 2017, Musk clarified that "
nitial flight testing will be witha full-scale 9-meter-diameter ship doing short hops of a few hundred kilometers altitude and lateral distance ...
rojected to befairly easy on the vehicle, as no heat shield is needed, we can have a large amount of reserve propellant and don't need the high area ratio, deep-space Raptor engines."
For the flight vehicles, Elon Musk discussed two engines: a sea-level variant (expansion ratio 40:1) for the first stage or
ITS booster
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and t ...
and a vacuum variant (expansion ratio 200:1) to obtain higher performance with the second stage. 42 of these sea-level engines were envisioned in the high-level design of the first stage, with a thrust per engine of at sea level and in the
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
.
In addition, three
gimbaled sea-level Raptor engines would be used for performing
landings of the ITS second stage on Earth and Mars. Six vacuum-optimized Raptor engines, providing of thrust each, would also be used on the ITS second stage, for a total of nine engines. The higher-efficiency Raptor Vacuum engines for in-space conditions were envisioned then to target a
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse i ...
of 382s, using a much
larger nozzle giving an expansion ratio of 200.
Six of these non-gimbaled engines were planned to provide primary propulsion for the 2016 designs of the ITS second stage.
A year later, at the 68th
IAC in September 2017, and following a year of development by the propulsion team, Musk said that a smaller Raptor engine—with slightly over half as much thrust as the previous concept designs for the ITS — would be used on the next-generation rocket, now a -diameter launch vehicle and publicly referred to as
Big Falcon Rocket (BFR). With the much smaller launch vehicle, fewer Raptor engines would be used on each stage. BFR was then slated to have 31 Raptors on the first stage and 6 on the second stage.
By mid-2018, SpaceX was publicly stating that the sea-level flight version Raptor engine design, with a nozzle exit diameter of , was expected to have thrust at sea level with a specific impulse of increasing to a specific impulse of in vacuum.
The vacuum flight version, with a nozzle exit diameter of , was expected to exert force with a specific impulse of .
The earliest versions of the flight engine are designed to operate at
chamber pressure
Within firearms, chamber pressure is the pressure exerted by a cartridge case's outside walls on the inside of a firearm's chamber when the cartridge is fired. The SI unit for chamber pressure is the megapascal (MPa), while the American SAAMI uses ...
; but SpaceX is expected to increase this to in later iterations.
In the BFR update given in September 2018, Musk showed a video of a 71-second fire test of a Raptor engine, and stated that "this is the Raptor engine that will power BFR, both the ship and the booster; it's the same engine. ... approximately a 200 (metric) tons engine aiming for roughly 300 bar chamber pressure. ... If you had it at a high expansion ratio, has the potential to have a specific impulse of 380."
Production
In July 2021, SpaceX announced that they would be building a second production facility for Raptor engines, this one in south Texas near the
existing rocket engine test facility.
Dallas Morning News
''The Dallas Morning News'' is a daily newspaper serving the Dallas–Fort Worth area of Texas, with an average print circulation of 65,369. It was founded on October 1, 1885 by Alfred Horatio Belo as a satellite publication of the ''Galvesto ...
reported in July that SpaceX will "break ground soon" and that the facility will concentrate on the serial production of Raptor 2, while the California facility will produce Raptor Vacuum and new/experimental Raptor designs. The new facility is expected to eventually produce 800 to 1000 rocket engines each year.
["We are breaking ground soon on a second Raptor factory at SpaceX Texas test site. This will focus on volume production of Raptor 2, while California factory will make Raptor Vacuum & new, experimental designs."](_blank)
, Elon Musk, 10 July 2021. SpaceX aims at a lifetime of 1000 flights for Raptor. In 2019 the (marginal) cost of the engine was stated to be approaching $1 million. SpaceX plans to mass-produce up to 500 Raptor engines per year, each costing less than $250,000. Each Starship booster will use 33 sea-level Raptors, while each Starship spacecraft will use 3 sea-level Raptors plus 3 Vacuum-optimized Raptors.
By late 2021, SpaceX said that scaling Raptor production to support the frequent Starship test program planned for 2022 was "currently the biggest constraint on how many vehicles we can make" and that failing to achieve a flight rate of at least once every two weeks by late 2022 would open up the possibility of bankruptcy for SpaceX. The reason given was that Starship orbital launch capability is necessary to deliver the next generation Starlink satellites needed to operationalize the massively capital-intensive Starlink broadband internet constellation.
Raptor Vacuum
Raptor Vacuum
(also RVac) is a variant of Raptor with an extended,
regeneratively-cooled nozzle for higher specific impulse in the
vacuum of space. While the optimized Raptor vacuum engine is aiming for a specific impulse of ~,
the v1.0 Raptor vac design to support early Starship development has been made more conservative and is projecting a specific impulse of only , intentionally decreasing engine performance to obtain test engines sooner. In addition, Raptor Vacuum v1 will have a smaller engine nozzle to avoid
flow separation
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake.
A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous fo ...
when the engine is fired at sea-level
atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
. A full-duration test of version 1 of the Raptor Vacuum engine was completed in September 2020 at the SpaceX development facility in McGregor, Texas.
The first three operational Raptor Vacuum engines were slated to fly on
SpaceX Starship prototype S20 and were installed on 4 August 2021. However, SN20 was retired before it flew.
Raptor 2
Raptor 2 is the newest version of Raptor
and is a complete redesign of the version 1 Raptor engine. The turbomachinery, chamber, nozzle, and electronics were all redesigned, as well as deleting some parts and converting many
flange
A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...
s to
welds.
[
In September 2019, SpaceX stated their "current plan" was to use Raptor 2 for the three "sea-level" engines on the Starship second-stage and also for all booster engines — both those that ]gimbal
A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...
and those that do not — on the Super Heavy first stage. As of February 2022, no Raptor 2 engines have flown on the various Starship prototype vehicles.[ These engines will eventually be produced at SpaceX's new engine development facility near McGregor, Texas; no date has yet been made public as to when the facility might be operational for production.] On 18 December 2021, Elon Musk announced on his Twitter account that Raptor 2 started production, and it will have over 230 tons of force. In a Starship update on 10 February 2022, Musk showed the capabilities of Raptor 2 and how it is simplified but more powerful than the original Raptor.
Raptor 2 engines were achieving of thrust consistently by February 2022, although SpaceX expects to be able to tune engine parameters and design over time to achieve at least . Moreover, Musk indicated that the engine production cost was approximately half that of the Raptor 1 version SpaceX had been using in 2018–2021.[ In June 2022, Musk tweeted that 250 tons was achievable.
Production rate for Raptor 2 had reached five per week by February 2022 and was expected to achieve 7 per week by March.][
]
Components
The Raptor engine is powered by subcooled
The term subcooling (also called undercooling) refers to a liquid existing at a temperature below its normal boiling point. For example, water boils at 373 K; at room temperature (293 K) the water is termed "subcooled". A subcooled liqu ...
liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
, and subcooled liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
in a full-flow staged combustion cycle. This is a departure from the simpler "open-cycle" gas generator system and LOX/kerosene propellants that the current Merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
engines use.[ Also, the ]RS-25
The Aerojet Rocketdyne RS-25, also known as the Space Shuttle Main Engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is currently used on the Space Launch System (SLS).
Designed and manufactu ...
engines (which were first used on the Space Shuttle) use a simpler form of a staged combustion cycle, as do several Russian rocket engines, including the RD-180
The RD-180 ( rus, РД-180, Ракетный Двигатель-180, Raketnyy Dvigatel-180) is a rocket engine designed and built in Russia. It features a dual combustion chamber, dual-nozzle design and is fueled by a RP-1/LOX mixture. The RD-18 ...
[ and the RD-191.][
The Raptor engine is designed for the use of ]deep
Deep or The Deep may refer to:
Places United States
* Deep Creek (Appomattox River tributary), Virginia
* Deep Creek (Great Salt Lake), Idaho and Utah
* Deep Creek (Mahantango Creek tributary), Pennsylvania
* Deep Creek (Mojave River tributary), ...
cryogenic
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
propellants—fluids cooled to near their freezing point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
s, rather than using the cryo-propellants at their boiling point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
The boiling point of a liquid varies depending upon the surrounding envir ...
s as it is more typical for cryogenic rocket engines. The use of subcooled propellants increases propellant density to allow more propellant mass to be stored within the vehicle's tanks. Engine performance is also increased with subcooled propellants. Specific impulse is increased, and the risk of cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, cal ...
at inputs to the turbopumps is reduced due to the higher propellant fuel mass flow rate per unit of power generated. The oxidizer
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...
to fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
ratio of the engine would be approximately 3.8 to 1, as stated by Elon Musk.[How (and Why) SpaceX Will Colonize Mars](_blank)
, accessed 19 August 2015. Musk: "''The critical elements of the solution are rocket reusability and low cost propellant (CH4 and O2 at an O/F ratio of ~3.8). And, of course, making the return propellant on Mars, which has a handy CO2 atmosphere and lots of H2O frozen in the soil.''"
Musk revealed that their target performance for Raptor was a vacuum specific impulse of , with a thrust of , a chamber pressure of , and an expansion ratio The expansion ratio of a liquefied and cryogenic substance is the volume of a given amount of that substance in liquid form compared to the volume of the same amount of substance in gaseous form, at room temperature and normal atmospheric pressure. ...
of 150 for the vacuum-optimized variant.
Engine ignition for all Raptor engines, both on the pad and in flight, is handled by dual-redundant spark-plug lit torch igniters, eliminating the need for a dedicated, consumable igniter fluid, as used on Merlin.
Raptor has been claimed to be able to deliver "long life ... and more benign turbine environments". Specifically, Raptor utilizes a full-flow staged combustion cycle, where all the oxygen will power an oxygen turbopump, and all the fuel will power a methane turbopump. Both streams—oxidizer and fuel—will be mixed completely in the gas phase
In the outline of physical science, physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, ref ...
before they enter the combustion chamber
A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.
Interna ...
. Before 2014, only two full-flow staged-combustion rocket engine designs had ever progressed sufficiently to be tested on test stands: the Soviet RD-270
RD-270 (russian: Раке́тный дви́гатель 270, Rocket Engine 270, 8D420) was a single-chamber liquid-bipropellant rocket engine designed by Energomash (USSR) in 1960–1970. It was to be used on the first stages of proposed heavy ...
project in the 1960s and the Aerojet Rocketdyne Integrated Powerhead Demonstrator in the mid-2000s. The flight engine is designed for extreme reliability, aiming to support the airline-level of safety required by the point-to-point Earth transportation market.
Many components of early Raptor prototypes were manufactured using 3D printing
3D printing or additive manufacturing is the Manufacturing, construction of a three-dimensional object from a computer-aided design, CAD model or a digital 3D modeling, 3D model. It can be done in a variety of processes in which material is ...
, including turbopumps and injectors, with the effect of increasing the speed of development and iterative testing. The 2016 subscale development engine had 40% (by mass) of its parts manufactured by 3D printing. In 2019, engine manifolds were cast from SpaceX's in-house developed SX300 Inconel
Inconel is a registered trademark of Special Metals Corporation for a family of austenitic nickel-chromium-based superalloys.
Inconel alloys are oxidation-corrosion-resistant materials well suited for service in extreme environments subjected t ...
superalloy, soon to be changed to SX500. The Raptor engine uses a large number of coaxial swirl injectors to admit propellants to the combustion chamber, rather than pintle injectors used on the previous Merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
rocket engines that SpaceX mass-produced for its Falcon family of launch vehicles.
Starship
Thirty-three sea-level variant Raptor engines will power the Super Heavy booster, while the Starship spacecraft contains six Raptor engines, three optimized for sea‑level and three optimized for vacuum. The bottom-most section, informally called the "skirt", houses the Raptor engines, as well as composite overwrapped pressure vessels that store helium gas used to spin up the Raptor turbopumps
A turbopump is a propellant pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The purpo ...
. Above that section are the liquid oxygen and liquid methane propellant tanks, separated by a "common dome" containing a small, spherical methane "header tank" used to contain propellant for landing. Six Raptor engines power the spacecraft, three designed for sea-level operation and three Raptor Vacuum engines optimized for use in the vacuum of space, producing a cumulative thrust of about .
Proposed Falcon 9 upper stage
In January 2016, the United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
(USAF) awarded a development contract to SpaceX to develop a prototype
A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
version of its methane-fueled reusable Raptor engine for use on the upper stage
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''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 ...
of the Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
and Falcon Heavy
Falcon Heavy is a partially reusable heavy-lift launch vehicle that is produced by SpaceX, an American aerospace manufacturer. The rocket consists of two strap-on boosters made from Falcon 9 first stages, a center core also made from a Falc ...
launch vehicles. The contract required double-matching funding by SpaceX of at least . Work under the contract was expected to be completed no later than December 2018, and engine performance testing was planned to be completed at NASA's Stennis Space Center in Mississippi
Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...
under US Air Force supervision. The USAF contract called only for the development and build of a single prototype engine with a series of ground tests, with no upper-stage launch vehicle design funded by the contract. The Air Force was working with the US Congress
The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washingto ...
in February 2016 to pursue new launch systems.[
]
In October 2017 the US Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
(USAF) awarded a modification for the development of the Raptor engine prototype for the Evolved Expendable Launch Vehicle
National Security Space Launch (NSSL) — formerly Evolved Expendable Launch Vehicle (EELV) from 1994 to 2019 — is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and ...
program, with work under that contract expected to be completed by April 2018.
As a DoD military project, little technical detail was ever publicly released about the USAF second stage engine or the results of the prototype build and test program. The prototype however was to be designed to serve the theoretical purpose of servicing an upper stage that could be used on the existing Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and payl ...
and Falcon Heavy
Falcon Heavy is a partially reusable heavy-lift launch vehicle that is produced by SpaceX, an American aerospace manufacturer. The rocket consists of two strap-on boosters made from Falcon 9 first stages, a center core also made from a Falc ...
launch vehicles, with liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
and liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
, propellants, a full-flow staged combustion cycle, and explicitly to be a reusable engine.
Comparison to other engines
See also
* Comparison of orbital rocket engines
*SpaceX Mars program
The SpaceX Mars program is a set of projects through which the aerospace company SpaceX hopes to facilitate the colonization of Mars. The company claims that this is necessary for the long-term survival of the human species and that its Mars pr ...
*SpaceX rocket engines
Since the founding of SpaceX in 2002, the company has developed four families of rocket engines — Merlin, Kestrel, Draco and SuperDraco — and is currently (since 2016) developing another rocket engine: Raptor, and after 2020, a new line of ...
*SpaceX Starship
Starship is a Fully-reusable orbital launch vehicle, fully reusable, super heavy-lift launch vehicle under development by SpaceX, an American aerospace company. With more than twice the thrust of the Saturn V, it is designed to be the most powe ...
*SpaceX Starship development history
SpaceX Starship development began in 2012, when Elon Musk, CEO of American aerospace company SpaceX, first publicly described a high-level plan to build a reusable rocket system with substantially greater capabilities than the Falcon 9 and the ...
References
External links
SpaceX Raptor Engine Test on 25 September 2016
''SciNews'', video, September 2016.
Adam Lichtl and Steven Jones, GPU Technology Conference
Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...
, spring 2015.
unofficial raptor engine log infographic
{{DEFAULTSORT:Raptor
Rocket engines using methane propellant
SpaceX rocket engines
Rocket engines using full flow staged combustion cycle
Rocket engines of the United States
SpaceX Starship