Aircraft

By Graham Warwick at the Farnborough air show

Gulfstream's advanced flight controls demonstrator, a modified GV that will fly in August, will test fly-by-wire, fly-by-light and even "fly-by-wireless" technologies for future business jets.

"The aircraft will test advanced signalling and advanced actuation," says Pres Henne, senior vice-president programmes, engineering and test. In the first phase, the aircraft will test fly-by-wire (FBW) wing spoilers, followed later in the year by a FBW elevator. Later phases are still being formulated.

Bombardier flew a modified Challenger fly-by-wire testbed between 1999 and 2004, but the first business jet with digital flight controls is Dassault's Falcon 7X, which will enter service next year. "This is a research and development effort to build, test and understand advanced flight controls," Henne says. Work began in 2004 and has included simulation, an integration test facility and iron-bird test rig.

The mid- and inboard spoilers have been modified with electromechanical actuators (EMA) supplied by Smiths Aerospace, while the outboard spoiler has a rotary EMA and the elevator an electric-backup hydraulic actuator, both supplied by Parker Aerospace. Thales has supplied the flight-control computer.

The FBW system will be flown from the right-hand seat, and is capable of being switched on and off, with the left-hand pilot's position retaining the existing mechanical controls. The conventional control wheel is retained, but Gulfstream may test an active sidestick in a later phase, says Henne.

The programme includes control-law software development. Gulfstream's philosophy is "the pilot has control", says Henne, but some "soft protection", such as a control-force gradient change, may be used to alert the pilot that the aircraft is approaching the limits of its flight envelope.