Themis launch vehicle

French winged orbital launch vehicle. Themis was a planned ESA booster stage demonstrator, to validate integrated propellant tank technology necessary for a reusable Ariane 5 successor. The demonstrator engine would be derived from the Vulcain of the Ariane 5. Estimated cost was up to 2.5 billion dollars. THEMIS would carry 33 metric tons of propellant, enough to reach Mach 11. Expendable boosters might permit orbital flight.