The Diablo shot was a developmental test of another two stage thermonuclear design. The Swan primary was
fired in a full-sized structural model of the thermonuclear system. The test device measured 16.2 inches in diameter and 68.4
inches in length. Total weight was 1352 lb. This test device was fairly similar to the one used during the
The predicted yield was 11-15kt including the yield produced by the secondary stage. The full scale device test was scheduled to be conducted during the operation Hardtack I.
Another interesting detail about the Diablo shot was that it became one of the Broken Arrows. Originally the test has been planned 17 days earlier, but it misfired. The discussion and investigation lasted over a day, truing to understand what could have gone wrong, and more importantly who was going to disarm and inspect a faulty nuke. Finally the crew of 3 engineers who were the last on the tower was assigned to this dangerous task. Eventually it ended up good, and the device was successfully disarmed. Though disarming a nuclear bomb that didn't go off after firing and potentially could've detonated at any second was more than a tough job. For more info you can check out Nuclear 911, yet another movie from VCE, completely dedicated to Broken Arrows.