Concorde Nose and Visor

Concorde’s airframe needed to be streamlined like that of a bullet to allow it to fly at supersonic speeds, which would then reduce drag and improve the aerodynamic efficiency of the aircraft. This means that unlike other passenger jets, she needed a very long pointed nose which also had to be of a streamlined shape for supersonic flight.Concorde landed and took-off with a very high angle of attack, this was due to the way that the delta wing produced lift at low speeds. At these high angles of attack, a fixed streamlined nose would of completely obscure the runway, on landing the available view to the pilot would have been only about 5 degrees.

The engineers came up with a solution to this problem; they designed a drooping nose, one that could be configured during the different stages of the flight. The nose also incorporated a streamlined protective visor for the windscreens(Made of special heat-resistant, tinted glass). this was required due to the high temperatures and aerodynamic loads of supersonic the speeds

Above: The nose and visor cycles through it's various positions

Above: The pilots view once the nose and visor have been lowered:

Both the prototypes had a full metal visor with just two small glazed panels: from the pre-production 101, G-AXDN currently stored at Duxford in the UK, onwards all Concordes were fitted with the fully glazed visor which was also an altogether more attractive look for the aircraft, both practically and aesthetically.

Above: Prototype vs Production 

Above: A Concorde prototype nose and visor in operation

The film below shows the production nose and visor in operation from within the flight deck

While it was normal practice to perform a take-off with the visor/nose down at 5 degrees, the aircraft can, and has, made take-offs with them both ‘up’, quite satisfactorily. However, should one consider an approach and landing with nose/visor up, then firstly, 25ft of nose would give a distinctly poor view of the runway and secondly, the wheels wouldn’t come down! When the visor is raised up, an interlock isolates the ‘landing gear down’ circuits – which was a positive preclusion to inadvertent gear deployment at Mach 2: for thesake of a few feet of wire, probably worthwhile. The interlock always released, and it never interfered with normal ‘gear down’ selection.The visor glass panels are laminations of two plies plus a thin non-stressed interlayer; gold film heating is applied to the inner surface of the outer panel. Total thickness is about 1.5 inch of heat-proof, very tough, impact-resistant glass.Although flights up to 325kts and Mach 0.8 were authorised with the visor down, anything above 270kts was very noisy. During the flight test program of Concorde, 350 kts and Mach 0.8 had been achieved before the visor was raised for the very first time on flight number 11.Initially 17.5 degrees was evaluated as the full down position, although this was later rejected as there was an apparently strong visual sensation of there being nothing ahead of the pilots as the nose then disappeared completely from their view.

Both the nose and visor mechanism are hydraulically controlled from the aircraft’s number 3 green hydraulic system, and its movement is controlled from a four position locking lever in the cockpit, next to the first officer’s panel

The images above and right show the four position switch and it's position within the flightdeck of Concorde

A back up control is available on the centre pedestal that allows the nose and visor to be lowered using the yellow hydraulic systems if the green were to fail. The visor will be hydraulically retracted, but the nose will only be unlocked hydraulically, with its downward movement occurring under gravity or aerodynamic forces.

In the event of a total hydraulic failure (If the yellow system was also to fail) or electrical failure, the nose uplocks could be released mechanically, allowing a nose free-fall to 5 deg. (the normal position for take-off, as opposed to the normal 12 deg, also as the nose lowered, the visor uplock would be automatically released to allow it to lower too. This was seen as acceptable for a landing).

The aircraft would never have been certified if such a system was not included!

Concorde’s droop nose and retracting visor were designed and manufactured under sub contract by Marshall Aerospace, at Cambridge Airport, UK, on behalf of the British Aircraft Corporation. http://www.marshallgroup.co.uk/index.html

1. Pitot Head

2. Radome

3. Weather radar scanner

4. Visor Hydraulic jack and retraction linkage

5. Secondary pivot head

6. Droop nose: Down position

7. Incidence probe

8. Visor rails

9. Drooping nose hydraulic jack

10. Retractable visor

11. Internal Windscreen panels

Above: Concorde nose section

Above: Concorde Prototype nose and visor

Above: The Prototypes 001 & 002 along with the first Pre-production Concorde 01. You can see the changes that were made to the Nose & Visor

Above: Concorde 002 showing her prototype nose, which were fitted to the first two Concorde's

The Radical approach to the Pilots Vision

As already stated the radical approach to nose geometry and pilots visibility was forced on the Concorde designers by the general aerodynamic problems of supersonic flight and the nose-high approach and landing of the slender delta. Ideally from the aerodynamic viewpoint the front fuselage would taper smoothly to a point; anything resembling a conventional flight-deck windscreen would impose a drastic penalty in drag at supersonic cruise, even if such a windscreen could be built to withstand the kenetic heat, which it could not.

Since pilots have an old-fashioned desire to look out of the aircraft they are flying and to see where it is going (and observe what else is going on out there) there was clearly going to be a problem, both in cruise – although it was argued by many at that time that forward visibility in cruise was not needed – and during take-off and landing.

To give a smooth line to the nose and to protect the windscreen from kinetic heating during cruise, the first Concorde nose design featured a metal, two-piece visor which would be raised in front of a normal type of windscreen. For take-off and landing the visor would be lowered. Next, a small window was to be inserted in the visor (not so much to improve visibility as to ‘minimise claustrophobic effects’).

Next a longer, highly cambered nose was tried, to improve the downward vision.

Next came the two types on nose design that were actually built for Concorde, both of which featured a ‘droop-nose’ which could be lowered to two positions – 5 degrees for take-off and a 17.5 degree (changed to 12.5 degree on the production aircraft) for approach and landing. This was found essential for good visibility because of the steep take-off and landing attitude of the slender delta. In the prototype Concordes, this was accompanied by a two-piece metal visor (with small upper windows and periscope). In the pre-production and production aircraft versions, the metal visor was replaced by a single-piece glazed visor, much to the relief of the pilots.But the original intention, incredible as it seems today, was that a metal visor would be used on the production Concordes. Glass technology at the time could not produce a glazed visor which could have withstood 120C plus the other forces of Mach 2 flight. Fortunately glass technology advanced.

 

Basically the metal visor with its internal periscope through which the pilots viewed the outside world, was a metal cover with a very narrow kidney-shaped slot on each side. The whole set-up was rather claustrophobic in the old prototypes, but it did allow sufficient visibility to be able to fly Concorde. But the pilots believed that the aircraft would not be certified with a visor of this type. To give them credit, it was the American Federal Aviation Administration, when first came into Concorde, who said: “No way. We’re not going to accept the aircraft if it can’t have better forward vision than that.” That was the spur to getting the gazed visor which, of course, was an enormous advantage. It gave a great feeling of confidence and comfort to the pilots.With the nose and visor down the flight deck environment was quite noisy. So only when they were flying the aircraft below 250 kt, did they keep the visor down, during the rest of the flight with the nose and visor fully up, it was a deathly quiet on the flight deck. In fact during the test flights of Concorde, the first time that the nose and visor was put up, the pilots thought that the engines had stopped; this was due to that dramatic change noise level on the flight deck.John Cochrane of BAC (now BAe Systems) also remembers the visor on prototype 002. ‘ The visor had two windows in it, the only snag was that the windows were at the top of the visor, so they would give you good views of the clouds, if there had been any, above you. They were no damn good for looking out forward, that’s for sure. Flying the prototype was like flying inside a letter-box.’