F-35A Primed for Nuclear Mission with New-generation Bomb

 - June 24, 2020, 7:00 AM
A 461st FLTS F-35A releases an inert B61-12 in a test on November 25, 2019. (Photo: U.S. DoD/F-35 Joint Program Office)

A series of photographs released by the F-35 Joint Program Office on June 22 show that the U.S. Air Force’s Lockheed Martin F-35A has been undergoing Dual Capable Aircraft (DCA) tests. DCA refers to the ability to deliver both conventional and nuclear weaponry. In the nuclear case that involves the new B61-12 weapon that is currently in the early stages of production. The F-35A is expected to introduce its DCA capability in early 2023 with the Block 4 software upgrade.

The released imagery shows a number of separation tests being undertaken in 2019/20 by the trials aircraft AF-1 and an aircraft from the 461st Flight Test Squadron, part of Air Force Materiel Command’s 412th Operations Group at Edwards AFB.

The B61 Mod 12 is the latest iteration of the “Silver Bullet” weapon that has been in the U.S. nuclear stockpile since 1968, and which became the most common air-dropped nuclear weapon, able to be employed in both strategic and tactical applications. It was designed by Los Alamos National Laboratory (LANL) from 1963 as a versatile weapon with various fuzing options (air-burst, ground-burst, time delay) and delivery profiles (including high-altitude release, loft/toss, and low-level laydown), and with a “dial-a-yield” capability that permitted the force of the detonation to be pre-set to values from 0.3 to 340 kilotons in some versions. The only major departure in terms of external appearance was the B61-11, a hard-case earth-penetrating “bunker-buster,” of which a few were produced for delivery by the Northrop Grumman B-2.

Development of the B61-12 began as part of the B61 Life Extension Program in 2012, and the first developmental test drop was conducted from a Boeing F-15E in 2015. Subsequent trials have also involved the B-2 and the Lockheed Martin F-16.

Marking a major departure from earlier versions of the B61, the Mod 12 introduces a GPS guidance capability. Whereas the B61-0 to B61-10 versions were equipped with a retarding parachute in the tail section, the B61-12 has a Boeing tailkit that functions in a similar fashion to that used by the conventional Joint Direct Attack Munition (JDAM) bomb that is in widespread service. Alternatively, the weapon can still be delivered in an unguided drop. On initial reflection, the idea of a guided nuclear weapon may seem somewhat unnecessary, but by ensuring more precise targeting the bomb’s yield can be set at a lower value to achieve the desired objective. It is understood that Mod 12 has four programmable yield settings between 0.3 and 50 kilotons.

The B61-12 is intended to replace all current versions of the B61 and recycles the warhead taken from the B61-4, combined with new safety systems and the tail guidance assembly. Development has been undertaken by LANL and Sandia National Laboratories, the latter also overseeing developmental and system verification tests at its Tonopah Test Range site in Nevada.

In early June Sandia announced that it had completed certification tests of the B61-12 on the F-15E, with the final two flights having been conducted in March, with the aircraft flying over Tonopah from Nellis AFB. In one drop the bomb was released at transonic speeds from an altitude of 1,000 feet. The bomb—with full systems and a mock nuclear package—impacted its designated point after 35 seconds of flight. The second test was conducted from 25,000 feet, the bomb taking 55 seconds to reach its impact point.

In addition to being cleared for the U.S. Air Force’s F-15E, F-16C, F-35A, and B-2A, the B61-12 is expected to arm the Northrop Grumman B-21 Raider and possibly the Panavia Tornados of Germany and Italy, some of which can be armed with B61s owned by the U.S. as part of the NATO nuclear weapons sharing program. Germany has selected the Boeing F/A-18 Super Hornet to continue this role in the future.