Heritage Concorde

 

The mechanism for the nose and visor is hydraulically controlled by Concorde’s green hydraulic system, and movement is initiated from the four position locking lever on the front panel of the flight deck, to the right of the engine instruments, next to the first officer position. The so called ‘traffic lights’ give the status of the nose during the operation along with an electro-magnetic “barber-pole” indicator.

There is also a back-up control that is available on the centre pedestal that allows the nose and visor to be lowered using the yellow hydraulic system that is if the green system were to fail. In that situation the visor will be hydraulically retracted, but the nose will only be unlocked hydraulically, with its downward movement occurring under gravity or aerodynamic forces Add to that should the yellow system also fail then a 3rd manual, up-lock release, system allows the nose and visor to freefall (to the 5 degree position).

The nose is situated to the front of the forward pressure bulkhead of the airframe, but is hinged roughly under the pilot’s seats. The nose moves on carriages that run on either side of this pressure bulkhead. The nose is actuated by a pair of tandem hydraulic jacks that work in parallel; both jacks have their upper cylinders attached to the forward pressure bulkhead and their lower cylinders to the nose structure. The two jacks provide alternate load bearing paths, then a pair of up-locks engage in the up position to secure the nose to the bulkhead, this allows the hydraulic pressure to be removed from the jacks. When the nose is lowered hydraulic pressure keeps it in place and stops the strong aerodynamic forces acting on it and moving it out of its position.

Nose and Visor Positions

 

The high angle of attack on landing dictates the need for a moveable nose – a fixed one would completely obscure the runway, as the available downward view to the pilot would be only about 5 degrees. So the nose, which must form a streamlined shape for supersonic flight, has to droop for landing. There are in fact, four positions of the combined visor and nose. Three of them are used on every flight. The nose and visor are fully up at all speeds above the indicated airspeed of 250 knots, which is about equal to 290 miles per hour. The visor alone can be lowered (it slides down and forward into a recess in the nose), but this position is seldom used, except at a transit stop, when the windscreen needs cleaning.

Below 250 knots the angle of attack in beginning to increase to about 7 degrees and the aircraft is likely to be within the outer traffic pattern of an airfield. In the USA all aircraft below an altitude of 10,000 feet are required to fly at 250 knots or less, as they are within the area of light aircraft, moving at slower speeds can fly largely unrestricted. To provide vision along the flight path, the nose is lowered to its 5 degrees position, giving a downward view of about 10 degrees.

On landing, once the wheels are lowered, the nose is lowered all the way, producing the famous birdlike appearance we all know and love.

 

Pictures of the Four Nose and Visor Positions

 

POSITION 1: Nose and visor fully up: – Used for supersonic flight, and while parked on the ground

POSITION 2: Nose fully up, Visor retracted: – Used for short subsonic cruise, windscreen cleaning

POSITION 3: Nose down at 5 degrees Visor retracted: – Used for take- off and taxi 

POSITION 4: Nose down at 12.5 degrees up, Visor retracted: – Used for landings and taxi

 

 

 

Operating the Nose and Visor  

 

The visor has two positions: Up and down

-          Up position is maintained by a mechanical uplock

-          Down position is maintained by hydraulic pressure and mechanical springs

 

The nose has three positions: UP, down at 5 deg. & down at 12.5 deg.

-          Up is maintained by mechanical uplock

-          5 deg. down position is maintained by 2 jacks internal locks

-          Down position is maintained by hydraulic pressure, aerodynamic loads and nose weight.

This gives 4 normal configurations of nose/visor ( See the pictures above):

1. Visor up, nose up.
2. Visor down, nose up.
3. Visor down, nose down 5 deg.
4. Visor down, nose down 12.5 deg.

 

There are three different operational modes:

Normal, Standby & Emergency.

 

NORMAL MODE

 

Green hydraulic power supplies

-          a single jack which operates the visor

-          a pair of jacks working in parallel to operate the nose.

It also supplies power to release visor and nose uplocks.

The picture below shows the nose/visor control lever and indicators

 

 

 

 

 

 

 

 

 

 

 

 

STANDBY MODE

 

The yellow system is available only for lowering the visor and nose. This standby system unlocks and lowers the visor through the normal jacks but only releases the locks of the nose thus allowing its own weight and aerodynamic loads to lower it to the 5 degrees down or 12.5 degrees positions.

 

 

EMERGENCY OPERATION MODE

 

Should there be a complete failure of the green and yellow hydraulic systems, the nose uplocks can be released mechanically thereby allowing the nose to fall freely to the 5 degrees position. The downward movement of the nose automatically releases the visor uplock and the visor is then lowered by gravitational and aerodynamic loads assisted by spring action.

NOSE & VISOR OPERATING LIMITATIONS

 

Nose/Visor

Visor down, or operating.

Nose down 5 degrees, or operating between the UP & 5 degrees positions: ~ 325 kt/M = 0.8

 Nose down or operating between 5 degrees and DOWN: ~  270 kt / 20,000ft

Nose and Visor up but unlocked:~ 325 kt/M = 0.95

The nose must be in the 5 degrees down position for take-off.

Below 250 kt the visor must be in the DOWN position with the nose at 5 degrees or lower.

Nose and/or visor operation must not be made below 500ft above the terrain.

Parking

To avoid the possibility of water being trapped in the manometric system, the aircraft must not be parked with the nose in the DOWN (12.5 degrees) position.