Droop nose (aeronautics)

Lore & Background

The first supersonic delta to receive a drooped nose was the Fairey Delta 2, a British experimental high-speed aircraft. Nicknamed 'Droop Snoot,' the Delta 2 featured a relatively long tapered nose, which smoothly flowed into its cylindrical cross-section fuselage, to generate a high level of aerodynamic efficiency. It was recognised that such a lengthy nose would negatively impact the pilot's forward vision during landing, take-off and ground movements; thus, to retain the aerodynamically optimised nose cone while also providing adequate downwards visibility, the drooped nose was devised. Accordingly, the nose section of the Delta 2, including the cockpit, could be drooped by 10° using a hydraulically actuated mechanism. A similar arrangement was subsequently adopted on Concorde.

Concorde was furnished with a droop nose which was developed and manufactured at BAC Hurn, Dorset, UK, which also developed and manufactured additional components including the cockpit visors under contract by Marshall's of Cambridge, by a team led by Norman Harry OBE. Needing to endure temperatures in excess of 100 °C at supersonic flight, the nose window and visor glass were developed by Triplex. The droop nose enabled the airliner to switch between being streamlined to reduce drag for optimal aerodynamic efficiency and not obstructing the pilot's view during taxi, take-off, and landing operations. Concorde's droop nose was accompanied by a moving transparent visor that retracted into the nose prior to being lowered. When the nose was raised to horizontal, the visor would rise in front of the cockpit windscreen for aerodynamic streamlining. A controller in the cockpit allowed the visor to be retracted and the nose to be lowered to 5° below the standard horizontal position for taxiing and take-off. Following take-off and after clearing the airport, the nose and visor were raised. Prior to landing, the visor was again retracted and the nose lowered to 12.5° below horizontal for maximal visibility. Upon landing, the nose was raised to the 5° position to avoid the possibility of damage. There was also a standby droop system if the main system failed, operated from the cockpit central console, and as a last resort if both hydraulic systems failed, a lever could be pulled in the cockpit to release the mechanical latches, allowing the nose to fall under gravity to the 12.5° position.

The Tupolev Tu-144, a contemporary counterpart to Concorde that was developed by the Soviet Union, also featured a droop nose. Its configuration was not identical to that of Concorde however as the visor of the Tu-144 was fixed to the nose. The Tu-144 exhibited a noticeable tendency for the nose to pitch downward, which was cancelled out via the addition of retractable canards that would deploy when the nose was lowered. The Soviet Union also developed a prototype Mach 3 strategic bomber, the Sukhoi T-4, that functioned as the Soviet counterpart to America's North American XB-70 Valkyrie. The T-4 featured a sizable droop nose, which completely covered the cockpit windscreen when raised; a periscope was provided for the pilots to obtain forward visibility.

Reader's Guide

The droop nose is notable as a solution to the conflicting aerodynamic and visibility requirements of supersonic delta-wing aircraft. The Fairey Delta 2 first demonstrated the concept, using a hydraulically actuated 10° droop to allow the pilot to see during low-speed operations while retaining a long, aerodynamically efficient nose for high-speed flight. This design was carried over to Concorde, where it was refined with a moving visor and multiple droop angles: 5° for taxi and take-off, and 12.5° for landing. The system included redundant hydraulic and manual backup mechanisms. The droop nose also appeared on the Soviet Tupolev Tu-144, though with a fixed visor, and on the Sukhoi T-4 strategic bomber, where the raised nose completely obscured the windscreen, requiring a periscope for forward visibility. The Fairey Delta 2's success as a high-speed testbed, including breaking the world airspeed record on 10 March 1956, and its conversion into the BAC 221 for ogival wing testing, directly contributed to Concorde's development. The droop nose thus represents a key engineering compromise that enabled practical operation of supersonic aircraft with limited forward vision at low speeds.

Did You Know?

• The Fairey Delta 2 was nicknamed 'Droop Snoot' and could droop its nose by 10° using a hydraulically actuated mechanism.
• Concorde's droop nose could be lowered to 12.5° below horizontal for landing, and a manual lever could release the nose to fall under gravity if both hydraulic systems failed.
• The Tupolev Tu-144's visor was fixed to the nose, unlike Concorde's retractable visor.
• The Sukhoi T-4's droop nose completely covered the cockpit windscreen when raised, so pilots used a periscope for forward visibility.