USING A SPECIALLY configured Lockheed Martin F-16, pilots recently completed tests on the first block of flight-control laws for the Lockheed Martin-Boeing F-22 which is now 11 months away from its first flight.

The flight-control laws for the F-22 were programmed in the Variable Stability In-flight Simulator Test Aircraft (VISTA), a highly modified F-16D operated by Calspan.

A total of 21 sorties, totalling 27h, was flown on the VISTA in two sessions held in February and May. In the first session, baseline flying qualities of the F-22 were compared with proposed or potential changes in the pitch-and-roll control characteristics for landing, air refuelling and formation flying.

The second phase focused on two aspects of F-22 flying qualities. It explored how the control laws would perform during failures of the hydraulic system and an engine failure. It also considered the effects of not achieving predicted F-22 aerodynamics and structural characteristics. The so-called "parameter-variation" flights tested out laboratory and theoretical predictions for F-22 flying qualities.

Lessons were learned from the F-16 flights, with problems noted concerning rudder sensitivity which may require minor flight-control tuning in flight test.

Source: Flight International