Why did the Concorde lower its nose?

The Concorde's sharp nose was an aerodynamic requirement: at Mach 2 and 18,000 m (60,000 ft), any blunt surface causes drag and heating to spike. But that same nose, extending several meters ahead of the pilots, formed an opaque wall whenever the aircraft adopted a high pitch attitude. And the Concorde did so often: its ogival delta wing has no flaps or slats, so to generate lift at low speed it had to fly at a high angle of attack, around 11° on approach compared with 3-4° for a conventional jet.

The solution from Aérospatiale and BAC was a hydraulically actuated, hinged nose with three positions. In cruise it was fully raised (0°) and covered by a retractable transparent visor that protected the windscreen from kinetic heat, which reached 127 °C (261 °F) at the tip. For taxiing and takeoff it was lowered to 5° with the visor retracted, enough to see the runway without penalizing aerodynamics too much. For landing it dropped to 12.5°, which cleared the view over the runway despite the aircraft's nose-up attitude. After braking, it was raised again to 5° for taxiing to the terminal.

The drooped nose became the aircraft's most recognizable silhouette, but it was pure necessity: the alternative, a fixed nose with periscopes or cameras, was considered unacceptable for daily commercial operation. The Soviet Tupolev Tu-144 adopted an almost identical solution. All 14 production Concordes kept the system until retirement in 2003, and museum examples, such as those at Brooklands, Toulouse, and the Smithsonian, are usually displayed with the nose down, the position the public associates with the aircraft. The early prototypes reached 17.5°, an angle that was reduced in production aircraft because it wasn't needed.