55-478: Aft End: 2.4 m (94 in) wide, 2.4 m (94 in) long The Rocketdyne RS-2200 was an experimental linear aerospike rocket engine developed by Rocketdyne for Lockheed Martin 's VentureStar program. The program was ultimately cancelled in 2001 before any RS-2200 engines were assembled. The XRS-2200 was a subscale testbed engine that was intended to be developed into the full-scale RS-2200. This engine, unlike its full-scale counterpart, made it to
110-557: A Bundeswehr contract to design and flight test a linear aerospike engine in April 2023. The company is set to test this new engine on board of its fourth spaceplane demonstrator, DEMO-4 MIRA, in late 2023 at Peenemünde, where the V-2 rockets were developed. The original MIRA demonstrator was catastrophically damaged in a runway accident in February 2024. On 29 October 2024, the company
165-425: A channel becomes supersonic, one significant change takes place. The conservation of mass flow rate leads one to expect that contracting the flow channel would increase the flow speed (i.e. making the channel narrower results in faster air flow) and at subsonic speeds this holds true. However, once the flow becomes supersonic, the relationship of flow area and speed is reversed: expanding the channel actually increases
220-439: A corresponding speed of sound (Mach 1) of 295.0 meters per second (967.8 ft/s; 659.9 mph; 1,062 km/h; 573.4 kn), 86.7% of the sea level value. The terms subsonic and supersonic are used to refer to speeds below and above the local speed of sound, and to particular ranges of Mach values. This occurs because of the presence of a transonic regime around flight (free stream) M = 1 where approximations of
275-407: A gas or a liquid. The boundary can be travelling in the medium, or it can be stationary while the medium flows along it, or they can both be moving, with different velocities : what matters is their relative velocity with respect to each other. The boundary can be the boundary of an object immersed in the medium, or of a channel such as a nozzle , diffuser or wind tunnel channelling the medium. As
330-503: A joint academic/industry team from California State University, Long Beach (CSULB) and Garvey Spacecraft Corporation successfully conducted a flight test of a liquid-propellant powered aerospike engine in the Mojave Desert on September 20, 2003. CSULB students had developed their Prospector 2 (P-2) rocket using a 1,000 lb f (4.4 kN) LOX/ethanol aerospike engine. This work on aerospike engines continues; Prospector-10,
385-432: A linear aerospike engine. The rocket is designed to send up to 100 kg into low-Earth orbit, at a price of US$ 1 million per launch. They later announced that their Executor Aerospike engine would produce 50,500 pounds-force (225 kN) of thrust at sea level and 73,800 pounds-force (328 kN) of thrust in a vacuum. In June 2017, ARCA announced that they would fly their Demonstrator3 rocket to space, also using
440-456: A linear aerospike engine. This rocket was designed to test several components of their Haas 2CA at lower cost. They announced a flight for August 2017. In September 2017, ARCA announced that, after being delayed, their linear aerospike engine was ready to perform ground tests and flight tests on a Demonstrator3 rocket. On December 20, 2019, ARCA tested the LAS 25DA aerospike steam rocket engine for
495-412: A ring around the outer rim. In theory this requires an infinitely long spike for best efficiency, but by blowing a small amount of gas out of the center of a shorter truncated spike (like base bleed in an artillery shell), something similar can be achieved. In the linear aerospike the spike consists of a tapered wedge-shaped plate, with exhaust exiting on either side at the "thick" end. This design has
550-569: A second launch attempt. In November 2021, Spain-based Pangea Aerospace began hot-fire testing of its small-scale demonstration methane-oxygen aerospike engine DemoP1. After successfully testing the demonstrator DemoP1, Pangea plans to up-scale to the 300 kN ARCOS engine. Headquartered in Kent, Washington, Stoke Space is building and testing a distributed architecture LH2/LOX aerospike system for its reusable second stage. The Bremen -based German startup POLARIS Raumflugzeuge GmbH received
605-466: A sharp object, there is no air between the nose and the shock wave: the shock wave starts from the nose.) As the Mach number increases, so does the strength of the shock wave and the Mach cone becomes increasingly narrow. As the fluid flow crosses the shock wave, its speed is reduced and temperature, pressure, and density increase. The stronger the shock, the greater the changes. At high enough Mach numbers
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#1732797895905660-599: A supersonic compressible flow can be found from the Rayleigh supersonic pitot equation (above) using parameters for air: M ≈ 0.88128485 ( q c p + 1 ) ( 1 − 1 7 M 2 ) 2.5 {\displaystyle \mathrm {M} \approx 0.88128485{\sqrt {\left({\frac {q_{c}}{p}}+1\right)\left(1-{\frac {1}{7\,\mathrm {M} ^{2}}}\right)^{2.5}}}} where: As can be seen, M appears on both sides of
715-769: A supersonic compressible flow is derived from the Rayleigh supersonic pitot equation: p t p = [ γ + 1 2 M 2 ] γ γ − 1 ⋅ [ γ + 1 1 − γ + 2 γ M 2 ] 1 γ − 1 {\displaystyle {\frac {p_{t}}{p}}=\left[{\frac {\gamma +1}{2}}\mathrm {M} ^{2}\right]^{\frac {\gamma }{\gamma -1}}\cdot \left[{\frac {\gamma +1}{1-\gamma +2\gamma \,\mathrm {M} ^{2}}}\right]^{\frac {1}{\gamma -1}}} Mach number
770-749: A ten-chamber aerospike engine, was test-fired June 25, 2008. Further progress came in March 2004 when two successful tests sponsored by the NASA Dryden Flight Research Center using high-power rockets manufactured by Blacksky Corporation , based in Carlsbad, California . The aerospike nozzles and solid rocket motors were developed and built by the rocket motor division of Cesaroni Technology Incorporated , north of Toronto, Ontario. The two rockets were solid-fuel powered and fitted with non-truncated toroidal aerospike nozzles. Flown at
825-442: A test cell at TU Dresden's Institute of Aerospace Engineering, achieving a burn time of 30 seconds. In July 2014 Firefly Space Systems announced its planned Alpha launcher that uses an aerospike engine for its first stage. Intended for the small satellite launch market, it is designed to launch satellites into low-Earth orbit (LEO) at a price of US$ 8–9 million, much lower than with conventional launchers. Firefly Alpha 1.0
880-754: A vacuum. The RS-2200 Linear Aerospike Engine was derived from the XRS-2200. The RS-2200 was to power the VentureStar single-stage-to-orbit vehicle. In the latest design, seven RS-2200s producing 542,000 pounds-force (2,410 kN) each would boost the VentureStar into low Earth orbit. The development on the RS-2200 was formally halted in early 2001 when the X-33 program did not receive Space Launch Initiative funding. Lockheed Martin chose to not continue
935-461: Is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound . It is named after the Austrian physicist and philosopher Ernst Mach . M = u c , {\displaystyle \mathrm {M} ={\frac {u}{c}},} where: By definition, at Mach 1, the local flow velocity u is equal to
990-642: Is a function of temperature and true airspeed. Aircraft flight instruments , however, operate using pressure differential to compute Mach number, not temperature. Assuming air to be an ideal gas , the formula to compute Mach number in a subsonic compressible flow is found from Bernoulli's equation for M < 1 (above): M = 5 [ ( q c p + 1 ) 2 7 − 1 ] {\displaystyle \mathrm {M} ={\sqrt {5\left[\left({\frac {q_{c}}{p}}+1\right)^{\frac {2}{7}}-1\right]}}\,} The formula to compute Mach number in
1045-407: Is allowed to escape in this form, only a small part of the flow will be moving in the correct direction and thus contribute to forward thrust. The bell redirects exhaust moving in the wrong direction so that it generates thrust in the correct direction. Ambient air pressure also imparts a small pressure against the exhaust, helping to keep it moving in the "right" direction as it exits the engine. As
1100-418: Is not a constant; in a gas, it increases proportionally to the square root of the absolute temperature , and since atmospheric temperature generally decreases with increasing altitude between sea level and 11,000 meters (36,089 ft), the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to −56.5 °C (−69.7 °F) at 11,000 meters (36,089 ft) altitude, with
1155-621: Is that range of speeds within which the airflow over different parts of an aircraft is between subsonic and supersonic. So the regime of flight from Mcrit up to Mach 1.3 is called the transonic range. Aircraft designed to fly at supersonic speeds show large differences in their aerodynamic design because of the radical differences in the behavior of flows above Mach 1. Sharp edges, thin aerofoil sections, and all-moving tailplane / canards are common. Modern combat aircraft must compromise in order to maintain low-speed handling. Flight can be roughly classified in six categories: At transonic speeds,
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#17327978959051210-750: The Navier-Stokes equations used for subsonic design no longer apply; the simplest explanation is that the flow around an airframe locally begins to exceed M = 1 even though the free stream Mach number is below this value. Meanwhile, the supersonic regime is usually used to talk about the set of Mach numbers for which linearised theory may be used, where for example the ( air ) flow is not chemically reacting, and where heat-transfer between air and vehicle may be reasonably neglected in calculations. Generally, NASA defines high hypersonic as any Mach number from 10 to 25, and re-entry speeds as anything greater than Mach 25. Aircraft operating in this regime include
1265-483: The Space Shuttle and various space planes in development. The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit. The transonic speed range
1320-551: The compressibility characteristics of fluid flow : the fluid (air) behaves under the influence of compressibility in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere , dry air at mean sea level , standard temperature of 15 °C (59 °F), the speed of sound is 340.3 meters per second (1,116.5 ft/s; 761.23 mph; 1,225.1 km/h; 661.49 kn). The speed of sound
1375-400: The sound barrier ), a large pressure difference is created just in front of the aircraft . This abrupt pressure difference, called a shock wave , spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone ). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this. The higher
1430-558: The Launch Assist System. Another spike engine concept model, by KSF Space and Interstellar Space in Los Angeles, was designed for orbital vehicle named SATORI. Due to lack of funding, the concept is still undeveloped. Rocketstar planned to launch its 3D-printed aerospike rocket to an altitude of 50 miles in February 2019 but canceled the mission three days ahead of liftoff citing safety concerns. They are working on
1485-399: The Mach number is defined as the ratio of two speeds, it is a dimensionless quantity. If M < 0.2–0.3 and the flow is quasi-steady and isothermal , compressibility effects will be small and simplified incompressible flow equations can be used. The Mach number is named after the physicist and philosopher Ernst Mach , in honour of his achievements, according to a proposal by
1540-730: The Pecos County Aerospace Development Center, Fort Stockton, Texas, the rockets achieved apogees of 26,000 ft (7,900 m) and speeds of about Mach 1.5. Small-scale aerospike engine development using a hybrid rocket propellant configuration has been ongoing by members of the Reaction Research Society . In 2020 the TU Dresden and Fraunhofer IWS started their CFDμSAT-Project for research on additively manufactured aerospike-engines. A prototype has already been tested in
1595-631: The VentureStar program without any funding support from NASA. An engine of this type is on outdoor display on the grounds of the NASA Marshall Space Flight Center in Huntsville Alabama. The cancellation of the Lockheed Martin X-33 by the federal government in 2001 decreased funding availability, but aerospike engines remain an area of active research. For example, a milestone was achieved when
1650-399: The absence of the plug tail. However, a full-length plug nozzle may also be called an aerospike. The purpose of any engine bell is to direct the exhaust of a rocket engine in one direction, generating thrust in the opposite direction. The exhaust, a high-temperature mix of gases, has an effectively random momentum distribution (i.e., the exhaust pushes in any direction it can). If the exhaust
1705-424: The advantage of being stackable, allowing several smaller engines to be placed in a row to make one larger engine while augmenting steering performance with the use of individual engine throttle control. Rocketdyne conducted a lengthy series of tests in the 1960s on various designs. Later models of these engines were based on their highly reliable J-2 engine machinery and provided the same sort of thrust levels as
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1760-456: The aeronautical engineer Jakob Ackeret in 1929. The word Mach is always capitalized since it derives from a proper name, and since the Mach number is a dimensionless quantity rather than a unit of measure , the number comes after the word Mach. It was also known as Mach's number by Lockheed when reporting the effects of compressibility on the P-38 aircraft in 1942. Mach number is a measure of
1815-406: The base of the spike maintains the pressure in that zone to a fraction of 1 bar , higher than the near-vacuum in front of the vehicle, thus giving extra thrust as altitude increases. This effectively behaves like an "altitude compensator" in that the size of the bell automatically compensates as air pressure falls. The disadvantages of aerospikes seem to be extra weight for the spike. Furthermore,
1870-487: The class of altitude compensating nozzle engines. Aerospike engines were proposed for many single-stage-to-orbit (SSTO) designs. They were a contender for the Space Shuttle main engine . However, as of 2023 no such engine was in commercial production, although some large-scale aerospikes were in testing phases. The term aerospike was originally used for a truncated plug nozzle with a rough conical taper and some gas injection, forming an "air spike" to help make up for
1925-659: The conventional engines they were based on; 200,000 lbf (890 kN ) in the J-2T-200k , and 250,000 lbf (1.1 MN) in the J-2T-250k (the T refers to the toroidal combustion chamber). Thirty years later their work was revived for use in NASA 's X-33 project. In this case the slightly upgraded J-2S engine machinery was used with a linear spike, creating the XRS-2200 . After more development and considerable testing, this project
1980-404: The drag experienced by the vehicle. It gives no overall thrust, but this part of the nozzle also doesn't lose thrust by forming a partial vacuum. The thrust at the base part of the nozzle can be ignored at low altitude. As the vehicle climbs to higher altitudes, the air pressure holding the exhaust against the spike decreases, as does the drag in front of the vehicle. The recirculation zone at
2035-473: The equation, and for practical purposes a root-finding algorithm must be used for a numerical solution (the equation is a septic equation in M and, though some of these may be solved explicitly, the Abel–Ruffini theorem guarantees that there exists no general form for the roots of these polynomials). It is first determined whether M is indeed greater than 1.0 by calculating M from the subsonic equation. If M
2090-408: The flow field around the object includes both sub- and supersonic parts. The transonic period begins when first zones of M > 1 flow appear around the object. In case of an airfoil (such as an aircraft's wing), this typically happens above the wing. Supersonic flow can decelerate back to subsonic only in a normal shock; this typically happens before the trailing edge. (Fig.1a) As the speed increases,
2145-412: The larger cooled area can reduce performance below theoretical levels by reducing the pressure against the nozzle. Aerospikes work relatively poorly between Mach 1–3, where the airflow around the vehicle has reduced the pressure, thus reducing the thrust. Several versions of the design exist, differentiated by their shapes. In the toroidal aerospike the spike is bowl-shaped with the exhaust exiting in
2200-414: The other side being formed by the outside air. The idea behind the aerospike design is that at low altitude the ambient pressure compresses the exhaust against the spike. Exhaust recirculation in the base zone of the spike can raise the pressure in that zone to nearly ambient. Since the pressure in front of the vehicle is ambient, this means that the exhaust at the base of the spike nearly balances out with
2255-463: The speed of sound is known, the Mach number at which an aircraft is flying can be calculated by M = u c {\displaystyle \mathrm {M} ={\frac {u}{c}}} where: and the speed of sound varies with the thermodynamic temperature as: c = γ ⋅ R ∗ ⋅ T , {\displaystyle c={\sqrt {\gamma \cdot R_{*}\cdot T}},} where: If
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2310-779: The speed of sound is not known, Mach number may be determined by measuring the various air pressures (static and dynamic) and using the following formula that is derived from Bernoulli's equation for Mach numbers less than 1.0. Assuming air to be an ideal gas , the formula to compute Mach number in a subsonic compressible flow is: M = 2 γ − 1 [ ( q c p + 1 ) γ − 1 γ − 1 ] {\displaystyle \mathrm {M} ={\sqrt {{\frac {2}{\gamma -1}}\left[\left({\frac {q_{c}}{p}}+1\right)^{\frac {\gamma -1}{\gamma }}-1\right]}}\,} where: The formula to compute Mach number in
2365-418: The speed of sound. At Mach 0.65, u is 65% of the speed of sound (subsonic), and, at Mach 1.35, u is 35% faster than the speed of sound (supersonic). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas. The Mach number is primarily used to determine the approximation with which a flow can be treated as an incompressible flow . The medium can be
2420-405: The speed, the more narrow the cone; at just over M = 1 it is hardly a cone at all, but closer to a slightly concave plane. At fully supersonic speed, the shock wave starts to take its cone shape and flow is either completely supersonic, or (in case of a blunt object), only a very small subsonic flow area remains between the object's nose and the shock wave it creates ahead of itself. (In the case of
2475-425: The speed. The obvious result is that in order to accelerate a flow to supersonic, one needs a convergent-divergent nozzle, where the converging section accelerates the flow to sonic speeds, and the diverging section continues the acceleration. Such nozzles are called de Laval nozzles and in extreme cases they are able to reach hypersonic speeds (Mach 13 (15,900 km/h; 9,900 mph) at 20 °C). When
2530-399: The temperature increases so much over the shock that ionization and dissociation of gas molecules behind the shock wave begin. Such flows are called hypersonic. It is clear that any object travelling at hypersonic speeds will likewise be exposed to the same extreme temperatures as the gas behind the nose shock wave, and hence choice of heat-resistant materials becomes important. As a flow in
2585-485: The test stand and accumulated approximately 1,600 seconds of hot-fire testing. [REDACTED] This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration . Aerospike engine The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes . It belongs to
2640-415: The thrust of the engine. An aerospike rocket engine seeks to eliminate this loss of efficiency. Instead of firing the exhaust out of a small hole in the middle of a bell, an aerospike engine avoids this random distribution by firing along the outside edge of a wedge-shaped protrusion, the "spike", which serves the same function as a traditional engine bell. The spike forms one side of a "virtual" bell, with
2695-403: The vehicle travels upward through the atmosphere, ambient air pressure is reduced. This causes the thrust-generating exhaust to begin to expand outside the edge of the bell. Since this exhaust begins traveling in the "wrong" direction (i.e., outward from the main exhaust plume), the efficiency of the engine is reduced as the rocket travels because this escaping exhaust is no longer contributing to
2750-437: The zone of M > 1 flow increases towards both leading and trailing edges. As M = 1 is reached and passed, the normal shock reaches the trailing edge and becomes a weak oblique shock: the flow decelerates over the shock, but remains supersonic. A normal shock is created ahead of the object, and the only subsonic zone in the flow field is a small area around the object's leading edge. (Fig.1b) When an aircraft exceeds Mach 1 (i.e.
2805-560: Was cancelled when the X-33's composite fuel tanks repeatedly failed. Three XRS-2200 engines were built during the X-33 program and underwent testing at NASA's Stennis Space Center . The single-engine tests were a success, but the program was halted before the testing for the two-engine setup could be completed. The XRS-2200 produces 204,420 lbf (909,300 N) thrust with an I sp of 339 seconds at sea level, and 266,230 lbf (1,184,300 N) thrust with an I sp of 436.5 seconds in
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#17327978959052860-410: Was designed to carry payloads of up to 400 kilograms (880 lb). It uses carbon composite materials and uses the same basic design for both stages. The plug-cluster aerospike engine puts out 90,000 pounds-force (400 kN) of thrust. The engine has a bell-shaped nozzle that has been cut in half, then stretched to form a ring with the half-nozzle now forming the profile of a plug. This rocket design
2915-624: Was first tested at the UK Race to Space National Propulsion Competition in 2023. The team is developing a flight-ready version of the engine they are planning to fly for the first time at EuRoC24 . SpaceFields, incubated at IISc, has successfully tested India's first AeroSpike Rocket Engine at its Challakere facility on 11-Sep-2024. The engine achieved a peak thrust of 2000N and featured altitude compensation for optimal efficiency. Mach number The Mach number ( M or Ma ), often only Mach , ( / m ɑː k / ; German: [max] )
2970-507: Was never launched. The design was abandoned after Firefly Space Systems went bankrupt. A new company, Firefly Aerospace , has replaced the aerospike engine with a conventional engine in the Alpha 2.0 design. However, the company has proposed Firefly Gamma, a partially reusable spaceplane with aerospike engines. In March 2017 ARCA Space Corporation announced their intention to build a single-stage-to-orbit (SSTO) rocket, named Haas 2CA , using
3025-663: Was the first ever to ignite an aerospike engine in a flight over the Baltic Sea, powering a four-engine, kerosene-fueled, turbojet MIRA-II demonstrator. The test involved a three-second burn to collect data with minimal engine stress. The vehicle achieved an acceleration of 4 m/s², producing 900 newtons of thrust. Based at the University of Bath , the Bath Rocket Team has been developing their own hybrid rocket engine with an aerospike nozzle since 2020. The engine
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