Rolls-Royce Thrust Measuring Rig
The Rolls-Royce Thrust Measuring Rig (TMR) was a pioneering vertical take-off and landing (VTOL) aircraft developed by Rolls-Royce in the 1950s. It has the distinction of being "the first jet-lift aircraft to fly anywhere in the world".
Source: Wikipedia — Rolls-Royce Thrust Measuring Rig (CC BY-SA 4.0)