Although the USAF/Boeing GBU-39 Small Diameter Bomb has been touted as a close air support weapon, increasing the number of air-to-surface weapons carried by fighters like the F-35, it may not be the best solution for close air support, according to a Royal Air Force officer with extensive experience in Afghan CAS operations. He was talking at the IPQC Close Air Support conference in London on Tuesday.
Paradoxically, the problem is that the weapon may be too efficient. Specifically, its slender profile and diamond wing are designed to give it a long glide range - but that means that if it's released over the target, it will circle down, seeking the best attack trajectory, taking much longer to reach the ground than the 10-17 seconds for a conventional guided or dumb bomb. "Unless you can guarantee that there's no change in the collateral damage situation, it has little utility in the CAS environment", the officer says.
None of this is surprising since the SDB was designed as a hard-target weapon, with a secondary destruction of enemy air defenses (DEAD) role. However, it's worth considering when you see models of aircraft set up in CAS configurations with wall-to-wall SDBs.