GBU-53/B

The GBU-53/B Small Diameter Bomb II is an American air-launched, guided bomb.

Development was started in 2006 for a 250 lb class bomb that can identify and strike mobile targets from standoff distances in all weather conditions. It will be integrated on the F-15E and F-35 Joint Strike Fighter. Its first flight was announced on May 1, 2009.

The bomb is being developed by Raytheon. A Boeing/Lockheed Martin team attempted to develop it but lost in a U.S. Air Force competition. Boeing won the original competition but the project was on hold for several years due to a corruption scandal involving Darleen Druyun. The competition was reopened in September, 2005.

Usage
The bomb uses GPS/INS system to guide itself into the general vicinity of a moving target during the initial search phase, with any necessary course correction updates provided using a Link 16 or UHF data link. The bomb has three modes of target acquisition: millimeter-wave radar, uncooled imaging infrared, and semi-active laser. The weapon is capable of fusing the information from the sensors to classify the target and can prioritize certain types of targets as desired when used in semi-autonomous mode.

The shaped charge warhead in the bomb has both blast and fragmentation effects, which makes it effective against infantry, armor (including MBTs), unhardened structures and buildings, as well as patrol craft sized boats and other soft targets. The bomb would be the first purpose-built no-drive zone enforcement weapon.

The use of uncooled imaging infrared has been cited as innovative and effective in reducing costs. An important feature of the new weapon is the maximization of the number of the bombs carried by the strike aircraft. A total of 28 GBU-53/B can be carried by the F-15E Strike Eagle utilizing 7 BRU-61/A suspension units, each carrying 4 bombs, and eight bombs along with two AIM-120 AMRAAM missiles in the weapons bay of the F-22 Raptor or the F-35 Lightning II (even the STOVL F-35B).

The bomb is being tested using F-15E aircraft and a UH-1 helicopter.

History
The original Small Diameter Bomb (SDB) was developed by Boeing and made for non-moving targets. The SDB II is designed to destroy moving targets in dust and bad weather. The Raytheon version was deployed successfully in 26 missions over 21 days. Raytheon was awarded the contract in August, 2010. The North American division of MBDA continues to produce the wings. The Raytheon contract is worth US$450 million. Boeing announced that it would not protest the Raytheon award.

Testing
On July 17, 2012, the SDB II successfully engaged and hit a moving target during a flight test at the White Sands Missile Range. The bomb was dropped from an F-15E Strike Eagle, then acquired, tracked, and guided itself onto a moving target using its tri-mode seeker, scoring a direct hit.

In January 2013, four SDB IIs were loaded into the weapons bay of an F-35 Lightning II alongside an AIM-120 AMRAAM missile. The successful fit check validated that the SDB II was compatible with the F-35 and gave adequate clearance in sweeps of inboard and outboard bay doors.

Planned deployment
The United States Air Force plans to use the bomb on the F-15E Strike Eagles as a no-drive zone enforcement weapon. The U.S. Navy and U.S. Marines plan to use it on their versions of the F-35 Joint Strike Fighter. Delivery for the first batch is planned for late 2014. Government requirements specify a 2016 delivery date.