 The total mass of the vehicle is 18 metric tons (39,700 lb) at takeoff.The plane has two jet engines, and an oxygen-methane engine with a thrust of 30 tons.The rocket engine uses the technology of the Vulcain (the main engine of Ariane 5), but is reusable thirty times and burns methane instead of hydrogen (hydrogen would require too much tank volume, as the density of methane is 667.2 kg/m³ and the density of hydrogen is 89.9 kg/m³).