Navy Super Hornet Conducts First Guided Launch Of Impressive 'Stormbreaker" Miniature Bomb

The testing milestone comes amid difficulties and delays that have pushed back Air Force plans for the weapon and temporarily halted its production.

Raytheon/US Navy

​​​​Raytheon says that a U.S. Navy F/A-18E/F Super Hornet has successfully conducted a guided release of a GBU-53/B StormBreaker glide bomb for the first time. The test comes as deliveries of these bombs to the Navy, as well as the U.S. Air Force, have been halted for months over a number of issues, including the premature failure of clips that help prevent its folding tail fins from springing open and inadvertently, potentially damaging the aircraft carrying them.

The Massachusetts-headquartered defense contractor publicly announced the flight test on June 15, 2020, but did not say when or where it had taken place specifically. The Air Force is also in the process of integrating the GBU-53/B onto its F-15E Strike Eagles, and the weapon is also slated to get added to the arsenal of all three F-35 Joint Strike Fighter variants, which will be able to carry them internally.

"StormBreaker is the only weapon that enables pilots to hit moving targets during bad weather or if dust and smoke are in the area," Cristy Stagg, the StormBreaker program director at Raytheon's Missiles and Defense division, said in a statement. "Super Hornet pilots will be able to use poor visibility to their advantage when StormBreaker integration is complete."

The GBU-53/B, previously known as the Small Diameter Bomb II, has these capabilities thanks to a robust multi-mode guidance system. The bomb can find its mark, on land or at sea, using an imaging infrared seeker or millimeter-wave radar, or by using semi-active laser-homing to zero in on the target. 

The weapon also has a GPS-assisted inertial navigation system to help get it to the general target area first, after gliding first for up to 69 miles, depending on the release profile. The launching aircraft can also use this mode to strike fixed targets directly.

The weapon is also compact, allowing aircraft to carry a large number of them at once, giving them added magazine depth. The F-15E will be able to carry up to 28 of them in total on seven special racks, each loaded with four bombs. 

The Navy's Super Hornets will also be able to use those bomb racks and all three variants of the F-35 will be able to carry four of them in each of their internal bays. This is similar to how U.S. military aircraft carry the existing GBU-39/B Small Diameter Bomb, which is a Boeing product. You can read more about the GBU-53/B, which Raytheon has been working on since 2010, as well as the older GBU-39/B, in this past War Zone piece.

USAF

Marines conduct a fit check to make sure that four GBU-53/Bs fit inside the internal bay of an F-35B Joint Strike Fighter. The B variant has truncated weapons bays due to its short and vertical takeoff and landing configuration and required modifications to accommodate the StormBreakers internally.

Unfortunately, when the Air Force or the Navy may actually begin fielding the weapons is unclear. The Air Force had previously planned to declare initial operational capability with StormBreaker on the F-15E this month, but that has been pushed back at least until August, according to a recent report from the Government Accountability Office (GAO).

"During operational testing in 2018-2019, the program completed 56 mission scenarios and reported 11 failures," the Congressional watchdog reported. "According to program officials, eight were software related and are being addressed through new software releases, two were hardware related and corrective actions have been implemented, and one was the result of an anomaly with the guidance component."

"The program may have to redesign the component and conduct retrofits on all bombs delivered to date," it continued.

Beyond that, the production of the third lot of GBU-53/Bs for both the Air Force and the Navy has been paused for months after the discovery of a number of safety issues and is only scheduled to resume next month at the earliest, which Defense News was first to report. The most glaring of these issues is the untimely failure of retaining clips that secure the bomb's four folding tail fins. Vibrations from the aircraft carrying the weapons during flight were the cause of these parts breakages. 

Raytheon

A GBU-53/B StormBreaker loaded onto an F-15E Strike Eagle during a test. The problematic retaining clip is visible around the tail fins at the rear.

"The problem is related to fatigue of the clips holding the fins in place until the bomb is released from the aircraft," GAO's report explained. "While this problem could affect all aircraft carrying the bomb, officials said the greatest impact is to the F-35, because the bomb is carried in the aircraft’s internal weapons bay and could cause serious damage if the fins deploy while the bomb is in the bay."

Air Force Captain Jake Bailey, a spokesperson for the service, told Defense News last week that the clips are a backup safety measure and in testing, so far, there have been no instances where the bomb's fins accidentally deployed prematurely. The clip issue, which Raytheon is working to mitigate now, is the sole remaining issue to be solved before production can resume. The company will pay out of pocket to develop the replacement part and will refit all of the existing 598 bombs it has delivered so far when the new clip is ready.

As for the third production lot, specifically, 204 of the 312 bombs on order have been delivered so far and will need the upgraded clips. The new parts will also be added to the remaining 108 bombs in that lot, as well as all others going forward.

GAO also revealed that the StormBreaker program had run into a significant supply chain issue regarding circuit boards that Raytheon uses in the manufacture of the weapon's guidance system. The supplier of those boards has said it will stop making them because they're otherwise obsolete, four years earlier than expected. 

"As a result, the program needs to order all circuit cards necessary to complete production by December 2020," the Congressional watchdog's report noted. It's not clear how this might impact further production down the road, but "the program is working with the Office of the Secretary of Defense on a mitigation strategy."

The Navy has said in the past that it expects to reach initial operational capability with the GBU-53/B on its Super Hornets this year, but it's unclear how these various delays might impact those plans. It remains to be seen whether the Air Force will meet its own new goal of having these bombs ready for use on its F-15Es by August. 

Despite these various issues, StormBreaker does appear to be making steady progress toward finally entering service with at least one branch of the U.S. military in the near future.

Contact the author: joe@thedrive.com