Graham Warwick/WASHINGTON DC
US Congressional concern over progress with development of software for the Lockheed Martin/Boeing F-22 prompted Boeing to bring its flying testbed (FTB) to Washington DC in late April.
Programme officials say the757-based FTB is a key "risk reducer" in development of the sensor-fused, integrated avionics for the F-22. The FTB will be used to demonstrate software development milestones that must be met if low rate initial production of the F-22 is to be approved as planned at the end of this year. The first avionics test F-22 is not scheduled to fly until next year.
The FTB is flying with Block 1 software, which allows integration testing of the F-22's core avionics and Northrop Grumman APG-77 active-array radar, mounted in the modified nose of the 757 (Flight International, 10-16 March).
During the Washington visit, the testbed flew intercepts against two US Air National Guard Lockheed Martin F-16s, demonstrating the radar's ability to track targets through manoeuvres that could force conventional pulse-Doppler radars to lose lock.
In addition to the radar, the FTB is equipped with simulated F-22 cockpit, vehicle management and store management systems and actual common integrated processor and an inertial reference system (IRS).
FTB test operations manager Yogi Lowell says testbed flying has already uncovered and corrected an IRS problem that could have delayed F-22 flight testing.
The FTB will be grounded in August for installation of the F-22's communication/navigation/identification (CNI) and electronic warfare (EW) systems in the sensor wing above the cockpit. The wing mounting will also be modified to eliminate vibration which has limited the FTB to Mach 0.6.
At that time, Block 2 software will be loaded to allow integrated avionics/radar/CNI/EW testing. The FTB is scheduled to participate in Red Flag exercises later this year to test the Block 2 software. Before the end of the year, a further software upgrade is planned, to Block 3S, which will allow initial sensor fusion testing.
Demonstration of Block 3 software is one of the exit criteria for approval of F-22 low rate initial production, according to programme officials.
Source: Flight International
