![Ariane 5 Liquid-Fly-Back Booster](https://upload.wikimedia.org/wikipedia/commons/0/0f/Ariane_5_Liquid-Fly-Back_Booster.jpg)
Liquid Fly-back Booster (LFBB) was a
German Aerospace Center
The German Aerospace Center (german: Deutsches Zentrum für Luft- und Raumfahrt e.V., abbreviated DLR, literally ''German Center for Air- and Space-flight'') is the national center for aerospace, energy and transportation research of Germany ...
's (DLR's) project concept to develop a
liquid rocket booster
A liquid rocket booster (LRB) uses liquid fuel and oxidizer to give a liquid-propellant or hybrid rocket an extra boost at take-off, and/or increase the total payload that can be carried. It is attached to the side of a rocket. Unlike solid rock ...
capable of
reusing for
Ariane 5 in order to significantly reduce the high cost of space transportation and increase
environmental friendliness.
LFBB would replace the existing
solid rocket boosters, providing main thrust during the liftoff. Once separated, two winged boosters would perform an
atmospheric entry
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the en ...
, fly back autonomously to the
French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
, and land horizontally on the airport like an aeroplane.
Additionally a family of derivative launch vehicles was proposed in order to take an advantage of
economies of scale
In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...
, further reducing launch costs. These derivatives include:
* A reusable booster in a class of
small and
medium-lift launch vehicles like
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, a ...
and
Arianespace Soyuz.
* A super-heavy-lift launch vehicle capable of lifting nearly to the orbit.
* A two-stage-to-orbit
A two-stage-to-orbit (TSTO) or two-stage rocket launch vehicle is a spacecraft in which two distinct stages provide propulsion consecutively in order to achieve orbital velocity. It is intermediate between a three-stage-to-orbit launcher and a hy ...
system operating a dedicated reusable orbiter.
German Aerospace Center studied Liquid Fly-back Boosters as a part of future launcher research programme from 1999 to 2004. After the cancellation of the project, publications at DLR continued until 2009.
Development
The German Aerospace Center (DLR) studied potential future launch vehicles of the European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
under the ''Ausgewählte Systeme und Technologien für Raumtransport'' ( ASTRA; English: Systems and Technologies for Space Transportation Applications) programme from 1999 to 2005, with additional studies continuing until 2009. The LFBB design was one of two projects within the ASTRA program, the other being Phoenix RLV. During development, scale models were constructed for testing various configurations in DLR's supersonic ''Trisonische Messstrecke Köln'' (TMK; English: Trisonic measuring section at Cologne
Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western state of North Rhine-Westphalia (NRW) and the fourth-most populous city of Germany with 1.1 million inhabitants in the city proper and 3.6 millio ...
) and in their ''Hyperschallwindkanal 2 Köln'' (H2K; English: Hypersonic wind canal at Cologne) wind tunnel
Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...
s. The preliminary mechanical design of other major elements was done by the companies EADS Space Transportation
Astrium was an aerospace manufacturer subsidiary of the European Aeronautic Defence and Space Company (EADS) that provided civil and military space systems and services from 2006 to 2013. In 2012, Astrium had a turnover of €5.8 billion and 18 ...
and MAN
A man is an adult male human. Prior to adulthood, a male human is referred to as a boy (a male child or adolescent). Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chromo ...
.
The advantages of reusable boosters include simplicity from using only one type of fuel, environmental friendliness, and lower reoccurring costs. Studies concluded that reusable fly-back boosters would be the most affordable and the least risky way for European space launch systems to start becoming reusable. These fly-back boosters had the potential to reduce launch costs. However, when other projects, such as Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program ...
or VentureStar
VentureStar was a single-stage-to-orbit reusable launch system proposed by Lockheed Martin and funded by the U.S. government. The goal was to replace the Space Shuttle by developing a re-usable spaceplane that could launch satellites into orbit ...
, undertook this objective, they failed to meet their goals. Supporting technologies needed for LFBB construction can be developed within 10 years, and additional launchers can be developed based on fly-back boosters to minimise costs and provide maintenance synergy across multiple classes of launch vehicles.
Eventually, the hardware grew too large and the LFBB project was scrapped, with one member of the French space agency (CNES
The (CNES; French: ''Centre national d'études spatiales'') is the French government space agency (administratively, a "public administration with industrial and commercial purpose"). Its headquarters are located in central Paris and it is und ...
) remarking:
Description
The overall concept of the liquid boosters in the LFBB programme was to retain the Ariane 5's core and upper stages
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* S ...
, along with the payload fairings, and replace its solid rocket boosters (EAP P241, from French ''Étages d’Accélération à Poudre'') with reusable liquid rocket booster
A liquid rocket booster (LRB) uses liquid fuel and oxidizer to give a liquid-propellant or hybrid rocket an extra boost at take-off, and/or increase the total payload that can be carried. It is attached to the side of a rocket. Unlike solid rock ...
s. These boosters would provide the main thrust during take-off. After separation, they would return to a spaceport
A spaceport or cosmodrome is a site for launching or receiving spacecraft, by analogy to a seaport for ships or an airport for aircraft. The word ''spaceport'', and even more so ''cosmodrome'', has traditionally been used for sites capable ...
in French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
for landing. This vertical take-off, horizontal landing (VTHL
Aircraft can have different ways to take off and land. Conventional airplanes accelerate along the ground until sufficient lift (force), lift is generated for takeoff, and reverse the process to landing, land. Some airplanes can take off at low spe ...
) mode of operation would allow liquid fly-back boosters to continue operating from the Guiana Space Centre
The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...
, thus avoiding any major changes to the ascend profile of Ariane 5. Launch vehicle payload performance of the Cryogenic Evolution type-A (ECA) variant would increase from to .
In the reference design, each LFBB consists of three engines installed in a circular arrangement at the aft of the vehicle. Each engine is a Vulcain engine with reduced 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. ...
. An additional three turbofan
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which achieves mechanic ...
air-breathing engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power g ...
s, installed in the nose
A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes ...
section, provide power for fly-back. The fuselage
The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraf ...
is long, with an outer tank diameter of , specifically designed to match the existing Ariane 5 core stage and to reduce manufacturing costs. A low-wing
A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...
V-tail
The V-tail or ''Vee-tail'' (sometimes called a butterfly tail or Rudlicki's V-tailGudmundsson S. (2013). "General Aviation Aircraft Design: Applied Methods and Procedures" (Reprint). Butterworth-Heinemann. p. 489. , 9780123973290) of an aircraft ...
canard configuration was selected, with a wingspan
The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan o ...
of approximately and an area of .[ The ]aerofoil
An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. ...
was based on a transonic
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transoni ...
profile from the Royal Aircraft Establishment (RAE 2822). The gross lift-off mass (GLOW) of each booster is , with upon separation and dry mass. In comparison, the GLOW for EAP P241 is .
The booster was designed to have four independent propulsion systems, the first of which – main rocket propulsion – would be based on three gimbaled Vulcain engines fueled by of propellant. Second, Eurojet EJ200
The Eurojet EJ200 is a military low-bypass turbofan used as the powerplant of the Eurofighter Typhoon. The engine is largely based on the Rolls-Royce XG-40 technology demonstrator, which was developed in the 1980s. The EJ200 is built by the ...
fly-back turbofan engines would be propelled with hydrogen to reduce fuel mass. Further, ten thrusters placed on each side of the vehicle would be used by the reaction control system
A reaction control system (RCS) is a spacecraft system that uses thrusters to provide attitude control and translation. Alternatively, reaction wheels are used for attitude control. Use of diverted engine thrust to provide stable attitude cont ...
. Finally, the fourth propulsion system would be based on solid rocket motors that separate the boosters from the core stage. An up-scaled version of the motors used in existing EAP boosters would be mounted in the attachment ring and inside the wing's main structure.
A typical mission profile would begin with the ignition of a main stage and both boosters, followed by an acceleration to and then a separation at the altitude of . As the main stage continues its flight into orbit, the boosters follow a ballistic trajectory
Projectile motion is a form of motion experienced by an object or particle (a projectile) that is projected in a gravitational field, such as from Earth's surface, and moves along a curved path under the action of gravity only. In the part ...
, reaching an altitude of . After low-energy atmospheric entry
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the en ...
, the boosters reach denser layers of the atmosphere where they perform a banking turn toward the target airfield. Gliding continues until they achieve an altitude that is optimal for engaging turbofan engines and entering cruise flight
Cruise is the phase of aircraft flight that starts when the aircraft levels off after a climb, until it begins to descend for landing. Cruising usually consumes the majority of a flight, and it may include changes in heading (direction of flight ...
. At this point, about from the launch point, the boosters would be flying over the Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
. The cruise back to the airport requires about of hydrogen fuel and takes over two hours to complete. An undercarriage is deployed and each booster lands autonomously. After separation, the boosters are not under threat of collision until they land due to small differences in their initial flight trajectories.
Derivatives
The development of liquid fly-back boosters has the potential to enable three additional space transportation systems with an objective of increasing production and creating economies of scale
In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...
. The aim of the LFBB project at DLR was to reduce Ariane 5 operational costs and to develop future derivatives, including a reusable first stage of a small-to-medium launch vehicle, a super-heavy launch vehicle capable of lifting 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 ...
, and a reusable two-stage-to-orbit
A two-stage-to-orbit (TSTO) or two-stage rocket launch vehicle is a spacecraft in which two distinct stages provide propulsion consecutively in order to achieve orbital velocity. It is intermediate between a three-stage-to-orbit launcher and a hy ...
launch vehicle. Initially, LFBBs would be used only on Ariane 5. Over time, alternative configurations could phase out Arianespace Soyuz and Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, a ...
.
Reusable first stage
The LFBB was studied with the three upper stage composites, to attain a Reusable First Stage (RFS) configuration. The first was a Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, a ...
derivative, with a Zefiro 23 second stage, a Zefiro 9 third stage and an AVUM upper stage. With the LFBB replacing the P80 stage, the payload to sun-synchronous orbit (SSO) would increase to , compared to the of the Vega. The second was an Ariane 4
The Ariane 4 was a European expendable space launch system, developed by the '' Centre national d'études spatiales'' (CNES), the French space agency, for the European Space Agency (ESA). It was manufactured by ArianeGroup and marketed by Ari ...
derivative called H-25. It was based on an H10 upper stage with a Vinci rocket engine and of cryogenic fuel
Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. These fuels are used in machinery that operates in space (e.g. rockets and satellites) where ordinary fuel cannot be used, d ...
. Depending on the method of deceleration, the payload to SSO is between . The third was a large cryogenic upper stage, called H-185, based on an alternative, yet-to-be-developed Ariane 5 main stage with of cryogenic fuel. Its payload to SSO is .
Two of the lighter configurations (the Zefiro 23 and the H-25) use upper stages mounted on top of the booster. Due to the lower weight, it might have been necessary to lower the amount of fuel in a booster to ensure that the separation velocity, the flight path, and the reentry do not exceed design bounds. In the case of H-25, it might be necessary to accelerate the fly-back boosters to above to help the upper stage achieve its desired orbit. Consequently, two solutions were proposed to decelerate the boosters after separation. The first option was to actively decelerate them using of fuel and reduce the velocity by . However, launch performance would drop below that of the Vega derivative. Another option is to use aerodynamic forces to decelerate. However, a hypersonic parachute was deemed too expensive and too complex. As a result, an alternative ballute was proposed. Flight dynamics simulation revealed that a ballute with a cross-section of offered the best compromise between loads on the booster and deceleration by aerodynamic forces. In this configuration, a launch performance of up to could be achieved, partly thanks to a higher separation velocity.
The heaviest configuration uses a single booster with an asymmetrically mounted, large, expendable cryogenic stage designated H-185. It was proposed as a future variant of the Ariane 5 core stage (H158), eventually meant to phase out the main stage in a standard launch configuration with LFBB. H-185 would use a new Vulcain 3 main engine, with increased vacuum thrust. When launched with a single booster, both stages would be operated in parallel, and be delivered to a orbit before separation. The remaining upper stage composite would weigh , with a payload performance to SSO. When launching 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 ...
, payload mass can be increased to over .
Super-Heavy Lift Launcher (SHLL)
The Super-Heavy Lift Launcher (SHLL) would consist of a new cryogenic main stage, five liquid fly-back boosters, and a re-ignitable injection stage. This configuration was designed to provide increased capabilities for complex missions, including manned explorations to the Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and to Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
, as well as the launch of large solar-powered satellites.
The new core stage would stand tall and have a diameter of , feeding of 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 ...
/ LH2 to three Vulcain 3 engines. The increased circumference of the main stage allows five LFBBs to be integrated with either retractable or variable-geometry wing
The wing configuration of a fixed-wing aircraft (including both glider (aircraft), gliders and powered aeroplanes) is its arrangement of lifting and related surfaces.
Aircraft designs are often classified by their wing configuration. For examp ...
s. The upper stage would be a derivative of the Ariane 5 ESC-B, with the size upped to , and strengthened to bear higher loads. The Vinci engine was proofed to be sufficiently powerful for orbital insertion
Orbit insertion is the spaceflight operation of adjusting a spacecraft’s momentum, in particular to allow for entry into a stable orbit around a planet, moon, or other celestial body. This maneuver involves either deceleration from a speed in e ...
. Payload would be enclosed in an fairing. The launch vehicle would have a total height of and a mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
of . The payload to LEO would be .
When launched to a Low Earth transfer orbit, the LFBBs would separate at an altitude of , at a speed of . To avoid simultaneous separation of all boosters, either a cross-feed to the main stage, or throttling
A throttle is any mechanism by which the power or speed of an engine is controlled.
Throttle or throttling may also refer to:
Fiction
* ''Throttle'' (film), a 2005 thriller
* ''Throttle'' (novella), a 2009 novella by Stephen King and his son Jo ...
could be used. The return flight of the boosters would require an estimated of fuel, including a 30% reserve.
Two-stage-to-orbit
The reusable two-stage-to-orbit
A two-stage-to-orbit (TSTO) or two-stage rocket launch vehicle is a spacecraft in which two distinct stages provide propulsion consecutively in order to achieve orbital velocity. It is intermediate between a three-stage-to-orbit launcher and a hy ...
(TSTO) launch vehicle variant of LFBB was planned to be implemented about 15 years after the addition of LFBBs to Ariane 5. However, only a preliminary analysis of TSTO was completed. The proposed configuration consisted of two boosters with retractable wings attached to the external fuel tank, and a reusable orbiter with fixed wings carrying payload on top of it. During geostationary transfer orbit (GTO) missions, an additional, expandable upper stage would be used.
The external tank, being a core of the system, would have a diameter of and a height of , carrying of propellant. The attached orbiter would be tall and in diameter, carrying of propellant. The payload fairing mount atop the orbiter would be . For LEO missions, the launch vehicle would be tall, with a gross lift-off mass of . The payload to LEO would be , with an increase to to GTO when using an expandable upper stage.
See also
*
*
*
*
External links
ASTR LFBB
with technical details
References
{{European Space Agency
European Space Agency
Ariane (rocket family)
Space launch vehicles of Germany
Former proposed space launch system concepts
Cancelled space launch vehicles