Germany[/size] had started the Allgemeine Rückkehr Technologie (general re-entry technology) ([/size]ART[/size]) programme in which Dornier, Erno and MBB worked together and in which the Bumerang development work merged. Work began on [/size]1 April 1973[/size], to define an initial vehicle configuration by the end of the year, aiming at first free-flight model trials in 1975. A long-term plan has been laid down, aiming at supersonic operation in 1976-77, landing in 1979, hypersonic operation in 1977-81, full-scale hypersonic operation in 1980-82 and a full-scale re-entry in 1982-83. By the end of 1973 the development had reached a configuration called [/size]ART[/size] 24. Whether this configuration was a direct development of the LB-21 lineage, is not clear from the literature that has survived.
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Reference: Flight International, 25 October 1973, p.724