The Japan Air Self Defense Force (JASDF) Air Development and Test Wing (ADTW) is investigating solutions to unexpected vibration encountered during flight tests of the Mitsubishi/ Lockheed Martin F-2 with a new, short design centre pylon.

The new 1.89m (6.2ft) pylon is designed to operate with the same BRU-47 swaybrace as the F-2's standard longer pylon, but at 183mm (7.2in) in height is also aimed at sharing more commonality with the standard F-16 centre pylon. The test team says the problem "caused a vibration of the main landing gear door. which was unacceptable to the pilots", and subsequent analysis showed the cause to be an interaction of the shockwave from the leading edge of the pylon at speeds around Mach 0.95.

Initial solutions tested included a damper to cure the landing gear door vibration and varying length extensions to the pylon itself. "Test results indicate the damper remedy is not effective, and extending the pylon can reduce door vibration in the transonic region," adds the ADTW team. As well as air-to-air missiles, the F-2 can be armed with Mitsubishi ASM-1 and -2 anti-ship missiles, 500lb (230kg) bombs, CBU-87/B cluster bombs and rocket launchers.

Source: Flight International