SAAB MILITARY Aircraft has completed initial flight trials of its latest flight-control software for the JAS39 Gripen fighter.

The latest P11 software incorporates a filter function, which prevents the onset of pilot-induced oscillations (PIO) which have led to the loss of two aircraft to date.

In earlier versions of the software, it was possible for extreme control movements to saturate the aircraft's computers, and this, combined with limitations in the speed of control-surface movements, led to delays in control response and PIOs.

The 11 filters now included in the system cover pitch, roll and yaw, and limit stick movements when the control surfaces approach their maximum angular velocities. The new software eliminates phase delay in control response when the pilot rapidly changes the direction of stick movement.

After 30 test flights, the P11 software will be maturity-tested in all development aircraft before installation in production aircraft.

Source: Flight International