Liquid fly-back booster
Liquid Fly-back Booster (LFBB) was a German Aerospace Center's (DLR's) project concept to develop a liquid rocket booster capable of reuse for Ariane 1 in order to significantly reduce the high cost of space transportation and increase environmental friendliness.
Once separated, two winged boosters would perform an atmospheric entry, go back autonomously to the French Guiana, and land horizontally on the airport like an aeroplane.
These derivatives include: German Aerospace Center studied Liquid Fly-back Boosters as a part of future launcher research programme from 1999 to 2004.
[citation needed] The German Aerospace Center (DLR) studied potential future launch vehicles of the European Union 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.
[5][6][7] During development, scale models were constructed for testing various configurations in DLR's supersonic Trisonische Messstrecke Köln (TMK; English: Trisonic measuring section at Cologne) and in their Hyperschallwindkanal 2 Köln (H2K; English: Hypersonic wind canal at Cologne) wind tunnels.
[4]: 213 The advantages of reusable boosters include simplicity from using only one type of fuel, environmental friendliness, and lower reoccurring costs.
[3] Eventually, the hardware grew too large and the LFBB project was scrapped, with one member of the French space agency (CNES) remarking: The thing that shocked me was that at the beginning, this reusable flyback booster was just a cylinder with engines and little wings, just a turbo fan in the back.
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.
[4]: 211, 212 A typical mission profile would begin with the ignition of a main stage and both boosters, followed by an acceleration to 2 km/s (1.2 mi/s) and then a separation at the altitude of 50 km (31 mi).
As the main stage continues its flight into orbit, the boosters follow a ballistic trajectory, reaching an altitude of 90–100 km (56–62 mi).
Gliding continues until they achieve an altitude that is optimal for engaging turbofan engines and entering cruise flight.
[3][4]: 215 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.
Flight dynamics simulation revealed that a ballute with a cross-section of 45 m2 (480 sq ft) offered the best compromise between loads on the booster and deceleration by aerodynamic forces.
[4]: 216 The heaviest configuration uses a single booster with an asymmetrically mounted, large, expendable cryogenic stage designated H-185.
This configuration was designed to provide increased capabilities for complex missions, including crewed explorations to the Moon and to Mars, as well as the launch of large solar-powered satellites.
[4]: 218–219 The reusable two-stage-to-orbit (TSTO) launch vehicle variant of LFBB was planned to be implemented about 15 years after the addition of LFBBs to Ariane 5.
For LEO missions, the launch vehicle would be 57.3 metres (188 ft) tall, with a gross lift-off mass of 739.4 tonnes (815.0 short tons).
