3.6 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| 509th Composite Group | 5/7 | https://en.wikipedia.org/wiki/509th_Composite_Group | reference | science, encyclopedia | 2026-05-05T13:04:33.596552+00:00 | kb-cron |
Special Mission 13, attacking Hiroshima, was flown as planned and executed without significant problems or diversion from plan. Enola Gay took off at 02:45, 7.5 long tons (7.6 t) overweight and near maximum gross weight. Arming of the bomb began eight minutes into the flight and took 25 minutes. The three target-area aircraft arrived over Iwo Jima approximately three hours into the mission and departed together at 06:07. The safeties on the bomb were removed at 07:30, 90 minutes before time over target, and 15 minutes later the B-29s began a climb to the 30,000-foot (9,100 m) bombing altitude. The bomb run began at 09:12, with the drop three minutes later, after which the B-29s immediately performed steep diving turns. The detonation followed 45.5 seconds after the drop. Primary and "echo" shock waves overtook the B-29s a minute following the blast, and the smoke cloud was visible to the crews for 90 minutes, by which time they were almost 400 miles (640 km) away. Enola Gay returned to Tinian at 14:58.
Special Mission 16 was moved up two days from 11 August because of adverse weather forecasts. Weather also dictated a change in rendezvous to Yakushima, much closer to the target, and an initial cruise altitude of 17,000 feet (5,200 m) instead of 9,300 feet (2,800 m), both of which considerably increased fuel consumption. Pre-flight inspection discovered an inoperative fuel transfer pump in the 625-US-gallon (2,370 L) aft bomb bay fuel tank, but a decision was made to continue anyway. The plutonium bomb did not require arming in flight, but did have its safeties removed 30 minutes after the 03:45 takeoff (all times Tinian; Nagasaki times were one hour earlier) when Bockscar reached 5,000 feet (1,500 m) of altitude. When the daylight rendezvous point was reached at 09:10, the photo plane failed to appear. The weather planes reported both targets within the required visual attack parameters while Bockscar circled Yakushima waiting for the photo plane. Finally the mission proceeded without the photo plane, thirty minutes behind schedule. When Bockscar arrived at Kokura 30 minutes later, cloud cover had increased to 70% of the area, and three bomb runs over the next 50 minutes were fruitless in bombing visually. The commanders decided to reduce power to conserve fuel and divert to Nagasaki, bombing by radar if necessary. The bomb run began at 11:58. (two hours behind schedule) using radar; but the Fat Man was dropped visually when a hole opened in the clouds at 12:01. The photo plane arrived at Nagasaki in time to complete its mission, and the three aircraft diverted to Okinawa, where they arrived at 13:00. Trying in vain for 20 minutes to contact the control tower at Yontan Airfield to obtain landing clearance, Bockscar nearly ran out of fuel. While the Nagasaki mission was in progress, two B-29s of the 509th took off from Tinian to return to Wendover. The crews of Classen in the unnamed Victor 94, and Captain John A. Wilson in Jabit III, together with ground support crews, were sent back to the United States to stage for the possibility of transporting further bomb pre-assemblies to Tinian. Groves expected to have another atomic bomb ready for shipment on 13 August and use on 19 August, with three more available in September and a further three in October. Groves ordered that all shipments of material be stopped on 13 August, when the third bomb was still at Site Y.