Here's A Rare Glimpse Of The F-35A's Internal 25mm Cannon Firing

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This is not a view you get very often. It’s the F-35A’s GAU-22/A 25mm internal cannon opened up for the world to see its mechanical firing process, including the barrels hydraulically spinning up, the low-observable gun door and the vent door popping open. And of course lots of smoke and flames.

You can see a naked test of the F-35’s cannon below, along with all the bits and pieces that go with it, dated back to 2007. Based on the proven GAU-12/A 25mm cannon, used by the AV-8B Harrier, the LAV-AD amphibious vehicle and AC-130U Gunship, the F-35’s GAU-22/A has one less barrel than its predecessor. This saves weight and space so that the cannon could fit into the F-35A’s left shoulder and into a streamlined external gun pod destined for the F-35B and F-35C.

The choice of a 25mm cannon is a departure from America’s traditional use of the 20mm M61 Vulcan cannon in its fighters dating back to the F-104 Starfighter. The 25mm round hits much harder than the 20mm round, but it also fires at a slower rate (about half as slow at 3,000 rounds per minute) and because the 25mm round is larger, less rounds can be carried in a set volume.


For the F-35A, 180 rounds can be housed in the gun’s linkless ammunition handling system. For the F-35B and F-35C, they both rely on an external gun pod carrying the GAU-22. The gun pod can hold 220 rounds in a helical magazine that wraps around the gun’s barrels within the pod.

The F-35’s gun is not without some controversy as the jet will not be able to employ any gun, podded or internal, until 2017. This is not due to the gun itself but is instead due to the lack of software, and its integration into the the jet’s hardware, such as the pilot’s Helmet Mounted Display, needed for aiming the gun precisely at its target.


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