Andrew Doyle/LONDON
DUNLOP AVIATION is targeting large civil airliners as the next application for its dual-redundant "brake-by-wire" (BBW) and anti-skid technology, which the company has developed for combat aircraft.
The latest version of UK-based Dunlop's BBW landing-gear control system, combined with carbon/carbon composite brakes, has been selected for the Eurofighter EF2000 fourth-generation air-superiority fighter.
"We are now in a position to offer dual-redundant braking and anti-skid systems for civil aircraft," says Mike Knight, manager of systems and electronic-controls new-product development at Dunlop. "In the near future," he believes, "BBW will be the norm for passenger aircraft of 50 seats and above which are to be fitted with this [dual-redundant braking] capability."
The BBW system consists of two independent hydraulic and electrical-control systems connected by shuttle valves, to a single set of pistons in each brake. If the primary system fails, or is overridden by the pilot, the remaining one is brought into operation. The company claims that, as a result, there is no degradation in braking or anti-skid-system performance.
The braking force applied to each wheel is monitored, using transducers in the brake lines. This enables adaptive, independent, anti-skid control systems on the wheels to achieve optimum braking, without exceeding "skid pressure", says Dunlop. Other features of the system include retraction braking, touchdown control and hydroplaning protection.
The electronic-control unit, meanwhile, is fully integrated into the aircraft's monitoring and maintenance systems. It consists of two electrically and mechanically isolated brake-control and monitoring systems, mounted in a single box alongside the landing-gear control and monitoring systems.
Dassault Aviation recently introduced a Messier-Bugatti-developed dual-redundancy BBW system on its Falcon 2000 business jet (Flight International, 14-20 February, P27).
Dunlop is also developing a real-time aircraft simulator to assist in the design and development of aircraft-braking and anti-skid systems. It is designed to simulate aircraft performance during taxiing, take-off and landing manoeuvres, to enable the performance of the braking system to be evaluated before the aircraft is rolled out.
The stiffness and damping characteristics of main and nose landing-gear configurations are modelled, as well as the aerodynamic characteristics. Braking-system integration tests can be done on the simulator, using an electronic controller and hydraulic rig, which are input with computer-generated wheel speeds and control signals.
Source: Flight International
