THE US AIR FORCE has restricted the peacetime flight envelope for the firing of countermeasure flares from the Rockwell B-1B bomber, because of tail strikes.
In one case described at the Society of Experimental Test Pilots meeting in California on 28 September, the flare impacted the vertical tail and lodged within 1m (3ft) of a major flight-control-surface actuator.
The problem on the B-1B, which carries 96 flares and 960 chaff bundles as part of its defensive armament, was uncovered during conventional-weapons testing to evaluate the recent B-1B offensive- and defensive-systems upgrade.
The test team, from the USAF's 419th flight-test squadron, says that the problem has gone undiscovered because, in previous roles, flares had normally been dispensed in straight-and-level flight.
Computational fluid-dynamics analysis has been used to compute the trajectories of the flares, which have been found to threaten the aircraft as turns tighten and dynamic pressure increases.
The USAF is now looking at fixes, including the development of a lighter flare. A longer-term solution may include the replacement of metallic parts of the flare with plastic.
The work of the test squadron included the clearance of the B-1B to drop Mk82 low-drag bombs, CBU-87, -89 and -97 cluster bombs and several guided bombs, including the GBU-10 and -27 and the Joint Direct Attack Munition. The B-1B will be cleared to drop CBUs from mid-1996. At the same time, it is expected to gain limited clearance for GBUs, four test sorties of which were flown with designation from both ground and "buddy" lasers.
Full clearance for GBUs is expected from around August 1997, but clearance could be immediate in time of emergency.
Source: Flight International
