Aircraft

Integrating a 13,600kg (30,000lb) bomb on the Boeing B-52 must wait at least 10 months because of a programme delay, causing a 33% cost increase for the US Air Force's proposed new bunker-buster.

The first live drop of the Boeing Massive Ordnance Penetrator (MOP), containing 2,500kg of explosive, is now scheduled for June, says Sandy Davis, Air Force Research Laboratory (AFRL) programme manager. The first B-52 drop test was originally planned for August 2007.

The programme has slipped because of technical problems with a "common carriage" bomb-release rack, says Davis. The undisclosed difficulties have forced the AFRL to design a new bomb rack for the MOP.

Development of the weapon's components, including guidance system, control surfaces, fuses and arming device, remain on track, says Davis. AFRL has increased the test programme's budget to $30 million - a $10 million jump - to cover development of the unique bomb rack.

It is not clear how the delays will affect the timetable for the US Air Forces's plan to integrate the same weapon on the Northrop Grumman B-2. US Congress has blocked the funding request to integrate the MOP into the B-2.

The MOP is being designed to attack the most deeply buried targets, such as underground bunkers hardened against smaller bombs. The 2,000kg GBU-28, with the BLU-113 penetrating warhead, is the largest bunker buster in the USAF's current inventory.

The Defense Threat Reduction Agency is sponsoring the B-52 test programme. The goal is to compare the MOP's performance to a lighter-weight, high-speed missile, to determine which weapon is more effective.

Boeing is funded to build four MOPs to perform live tests from June to December.