Eurofighter is aiming to expand the EF2000 flight envelope to Mach 2 as the next phase of flight testing in Phase Two of the test programme.

Test pilots flying the DA2, the second development aircraft, based at British Aerospace's Warton site, are assigned to envelope expansion and will lead the effort. Following the Mach 2-plus speed tests, further sorties include evaluation of the emergency power unit, "-and then engine mishandling at the top left hand of the envelope in preparation for high angle-of-attack testing", says test pilot John Turner.

In flights so far, the aircraft has been taken to Mach 1.82 at 40,000ft (12,200m) and 716kt (1,325km/h) calibrated air speed. It has reached 20í angle of attack and 6.38G. The last 0.08G was added while at the UK Farnborough air show in September. The first four development aircraft have amassed more than 240h of air time on over 270 sorties, the longest of which has been 1h 50min. Fifteen pilots have flown the aircraft, including pilots from all four customer air forces, Germany, Italy, Spain and the UK.

A spin gantry will be fitted for the third test phase, which will evaluate the second-phase flight-control-system (FCS) software. The test phases appear to be out of step because the first FCS load was known as Phase Zero. The third phase is scheduled to include air-to-air refuelling and will test upgrades developed as a result of early handling problems discovered with phase-two software.

"In general it was relatively snag free, and pilots love it," says Turner. Tests revealed, however, that the pitch-integration rate was slower than expected, and the aircraft undergoes "roll ratcheting" during rapid roll manoeuvres. The cause is a pilot's hand-and-arm inertia effect on the stick during rapid rolls and will be cured through adjustments to the FCS.

Three more subsequent FCS phases are planned, the first timed for around 2001 when the aircraft gets its initial operational release to the Royal Air Force. This will open up the permitted "G" envelope to 9G and will be followed by a fourth phase. This will expand the envelope to cover the release of air-to-ground weapons.

A further phase will open up all remaining cockpit modes.

Source: Flight International