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Concorde Landing Gear Braking Systems
Dunlop and Concorde changed the design of big aircraft brakes forever. Still powered from a main hydraulic system with emergency operation supplied from standby hydraulics. Still a multi-disc unit using five rotors keyed to the wheel and six stators keyed to the axle. But now these discs are structural carbon fibre – solid discs of carbon fibre
Most of the test flights of the Concorde program were conducted using the conventional steel brakes, but during this time Dunlop were experimenting with carbon fibre and of course the production methods needed. The first production unit was cleared for trials in 1972 and fitted to a BOAC VC10, in 1974 they became the standard, for Concorde to fit and the industry followed. These brakes with the assistance of reverse thrust, had to be able to bring 184 tonnes of Concorde from 165kts down to a standstill. In engineering terms, convert the aircraft Kinetic Energy (KE=1.5 mv sq) into heat and store that heat safely until it is dissipated either by natural cooling or by forced ventilation as with the brake fans fitted to Concorde.
Due to a relatively high average takeoff speed of 250 mph (400 km/h), Concorde needed good brakes. Concorde used an anti-lock braking system,which stop the wheels from locking when fully applied, allowing greater deceleration and control during braking, particularly in wet conditions. The brakes, developed by Dunlop,were carbon-based and could bring Concorde, weighing up to 185 tons (188 tonnes)and travelling at 190 mph (305 km/h), to a stop from an aborted takeoff within one mile (1600 m). This braking manoeuvre brought the brakes to temperatures of 300 °C to 500 °C, requiring several hours for cooling using the fans.
Concorde’s carbon discs brakes are controlled by a hinged toe-plate attached to the pilots’ rudder pedals. They are powered hydraulically and controlled by electrical signals from the toe-plates. An advance anti-skid system modulates the braking pressures applied by the pilot. Concorde uses signals from its nose wheels (which is not braked and therefore does not skid) to vary the reference value so that the modulation of the brake pressure always happens close to the optimum at all speeds.
A brake control lever is located at the co-pilot’s side of the centre console: fully forward for normal brakes, first position rearwards selects emergency brakes – no electronics, but with an accumulator charged to 3,000ils/sq in; depress the lever’s button and move to second rearwards position for parking brake, operating via emergency system.
Normal brakes and anti-skid systems are supplied by the Green hydraulic system. In the event of a Green system pressure loss there is an automatic changeover to the Yellow hydraulic system provided YELLOW-GREEN has been selected on the Servo Control yellow rotary selector.
A brakes accumulator charged by the Yellow hydraulic system supplies the emergency and parking brakes system only
2, Generator drive shaft:
5, Tachometer generator:
6, Brake fan control