High Quality Content by WIKIPEDIA articles! A lift jet is a jet engine angled to provide an aircraft with aerostatic lift instead of thrust. On a fixed-wing aircraft, lift jets may be installed as auxiliary engines, with a separate engine to provide forward thrust, or, as in the Harrier jump jet, may be vectored in flight to provide both. Lift jets were first designed by German engineers during World War II, but none saw operational service. Many nations had experimental programs involving such engines by the early 1950s: one typical example was Rolls-Royce's Thrust Measuring Rig, nicknamed the "Flying Bedstead," which took its lift solely from engine thrust. An early dedicated lift jet was the Rolls-Royce RB108, first run in 1955.