After a six-month delay caused by a couple of test failures, the world’s most sophisticated air-launched bomb is back on track. The Raytheon GBU-53/B Small Diameter Bomb II passed the Pentagon’s Milestone C review last month, and will soon enter low-rate initial production. The SDB II has a ”tri-mode” seeker that allows simultaneous attacks in adverse weather and against moving targets at up to 40 nm range, from a subsonic launch at about 35,000 feet.
“We tripped a bit last fall,” admitted Jim Sweetman, Raytheon’s program director. He told AIN that the bomb failed a qualification test of its ability to withstand the type corrosive atmosphere to which it might be exposed on the [U.S.] Navy’s aircraft carriers–salt-water spray and fumes. “That cost time, but we’ve solved it,” he said. Then there was an internal cable failure on the second live fire test that caused the bomb to miss its target. “We found the root cause, and the repeat test was successful,” he added. Sweetman noted that some half-dozen guided test flights last year without a warhead were all successful.
The tri-mode seeker includes a semi-active laser, a millimeter-wave radar and an uncooled imaging infrared seeker. Some other “smart” bombs have dual-mode guidance, but Raytheon officials are not aware of a competing weapon with three guidance options. The predecessor SDB I offered only GPS guidance to fixed targets and did not contain the dual-band two-way datalink of the SDB II. The first version was also heavier, with a necessarily larger warhead that did not feature the multi-effects shaped-charge/blast-fragmentation warhead of the SDB II. The second version is also smart enough to sort, categorize and prioritize targets.
Despite the sophistication, the SDB II is “affordable,” according to Sweetman. U.S. Air Force assistant acquisition secretary Dr. William LaPlante said recently that the cost per round will be about $115,000, some $65,000 below the goal set when the SDB II entered development five years ago. Raytheon has managed its workforce well and controlled costs, he said.
The new weapon will be fielded first on U.S. Air Force F-15E Strike Eagles, where the maximum load will be 28 bombs, although 16 will be the normal loadout, all on fuselage stations. Then the U.S. Navy will add it to the F/A-18E/F Super Hornet. The SDB II is also slated for the F-35B and F-35C versions of the Joint Strike Fighter. The smaller internal weapons bays of the F-35B can each still carry four SDB IIs, plus an AMRAAM missile. But in any case, the Lightning II will not receive the Block 4 software required to drop the SDB II until 2022.
Jeff White, Raytheon’s SDB II business development manager, told AIN that export prospects for the weapon include operators of the F-15E, and all 13 of the F-35 international countries, because it will come ready-integrated with the stealth fighter. Raytheon’s British subsidiary is pitching the SDB II as a “low-cost, low-risk” alternative to MBDA’s proposal to meet the UK’s SPEAR (Selectable Precision Effects At Range) Capability 3 requirement. There is potential for work on the SDB II worth some $500 million to be placed in the UK, including electronic subassemblies, fuses and integration onto the Eurofighter Typhoon, according to TJ Marsden, chief weapons system engineer with Raytheon UK.
Meanwhile, White told AIN that Raytheon is working on “translation software” for low-cost integration onto the F-16. That would allow European countries now flying the Fighting Falcon to start training and using the SDB II before their F-35s arrive.