Julian Moxon/PARIS
The take-off weight of the Airbus Industrie A3XX will be reduced by 2-3t through the use of a new, high-pressure hydraulic system, if tests being carried out by Aerospatiale at Toulouse prove it to be economically and technically viable.
"We have decided to go for a system running at 310/345 bar [4,500/5,000lb/in2], which is about a third higher than those of current civil aircraft," says Robert Lafontan, Airbus vice-president for engineering and product development.
The decision follows the consortium's rejection of all-electric aircraft actuators, which have been successfully tested on military aircraft. These move the flying surfaces using internally generated hydraulic pressure, eliminating the extensive network of hydraulic pipes necessary today. "We can't go for full electric actuators yet because they are not developed enough for the heavyweight A3XX applications," he adds. "The main landing gear will weigh more than 20t, for example."
Hydraulic-equipment suppliers have been asked to respond to Airbus' call for technical information on high-pressure hydraulic equipment, which is used widely on military aircraft and Concorde, although the A3XX application is more demanding, says Lafontan, "because the aircraft's flying surfaces will be worked harder".
The use of a high-pressure system will save around 1t on the empty weight, which now stands at 238.5t. "That translates to 3t at take-off, because you need less fuel," says Lafontan.
Other weight-saving ideas being considered for the A3XX include an all-titanium main landing gear. "We're still looking at the cost versus weight equations," says Lafontan. The use of carbonfibre composites for the outer wing and welded fuselage sections is still under consideration. Two major programmes are under way in France and Germany to study the technology of very large welded aluminium components, one for circular sections, the other for sections of varying diameter, such as the nose.
"We have found a design which allows us to repair a welded joint with rivets," he says.
Source: Flight International
