Walter 109-500 rocket engine, c 1944.
© Science Museum / Science & Society Picture Library
These engines were developed by the Germans for use as rocket-asisted take-off (RATO) units to aid heavily laden bomber aircraft to take off, particularly from short runways in conditions of little or no wind. They were used particularly on the Arado Ar 234, a pioneering jet bomber and reconnaisance aircraft which first flew in 1943. Once airborne, the engines, which only burned for 30 seconds, would be jettisoned and parachuted to the ground so that they could be re-used. Their thrust was developed by the catalytic decomposition of hydrogen peroxide.