THE FLY-BY-WIRE
CONTROL SYSTEM : ONE
OF THE ADVANCED FEATURES OF NH90.
Why
to install a Fly-By-Wire control system on the NH90 helicopter and what are
the advantages ?
The reason is simple: as the threat is becoming more and more sophisticated
and difficult, the future generation helicopter should allow the pilot to concentrate
himself entirely on the mission he has to perform in a very limited time and
in any operational condition. It should not request him to devote the biggest
part of his effort on the flight, as it is happening with the today helicopter
generation. As the helicopter is by nature a very unstable platform difficult
to master, in the present helicopters the pilot is helped both by mechanical
devices (i.e. control cross couplings through the mixing units) and electronic
systems (SAS, SCAS, autopilots). All of them give a valuable support to the
pilot but some aspects are still marginal and to be improved to achieve "Level
1 Handling Qualities within the Operational Flight Envelope" as required for
NH90.
Traditional flight controls and especially mixing unit devices are mechanically
complex and heavy, mechanical control laws are the result of several compromises
thus preventing the necessary output control precision. On the other hand present
autopilots are lacking of the necessary control authority to be able to take
the requested action, in the requested time, in all the flight envelope.
The NH90 Fly-By-Wire solution allows :
- the reduction in weight and complexity of the flight control system including
the elimination of the control mixing units,
- the optimisation of the handling qualities throughout the whole flight envelope
with helicopter responses tailored to the mission tasks requested ,
- the improvement of vulnerability and safety, through a high redundancy of
the system (four independent lines for data transfer with four control processing
units - digital and analogic - and capability to remain operationally efficient
irrespective of the failure type),
- intrinsic growth potential to implement new mission tasks and new advanced
control law concepts including "carefree handling" features.
© NHI 2000
