Graham Warwick/WASHINGTON DC
Modification of US Air Force Rockwell B-1B bombers to carry the Boeing Joint Direct Attack Munition (JDAM) has begun at Tinker AFB, Oklahoma. The first two upgrade kits have been delivered to the Oklahoma City Air Logistics Center, and the initial block of seven B-1s is to be modified by January 1999, 18 months ahead of schedule, says the Air Force.
Under the conventional mission upgrade programme, the depot will modify B-1Bs with the global positioning system (GPS), JDAM, communications improvements and the Raytheon ALE-50 towed decoy. Upgraded bombers will be delivered to Ellsworth AFB, South Dakota, where modified multi-purpose rotary launchers will be fitted enabling the B-1B to carry up to 24 of the 900kg JDAMs.
Fleet-wide B-1B JDAM capability is planned for early 2001, with the towed decoy installation to be completed in 2003.
Boeing, meanwhile, has conducted successful drop tests of an anti-jam GPS guidance system which could be fitted to later versions of the JDAM. The company plans eight drop tests of modified JDAMs during the fourth and final phase of the Air Force's Anti-jam GPS Technology Flight Test programme, begun in August 1995.
In the first test, the weapon was dropped from 44,000ft (13,400m) (in a low-power jamming environment and acquired the GPS signal within 12s, impacting within 3m of the target. In the second test, also from 44,000ft, but in a high-power jamming environment, the weapon acquired the GPS signal within 8s and struck within 6m of the target.
The guidance system consists of a Harris-supplied anti-jam module, closely coupled Rockwell Collins GPS receiver and Honeywell inertial measurement unit and a Boeing-developed anti-jam GPS antenna.
Source: Flight International
