The Last Mission to Nagasaki Was In Jeopardy Before It Even Got Off the Ground
Perhaps the second most famous Boeing B-29 Superfortress bomber ever, B-29-36-MO Air Force serial number 44-27927, flew a mission that up until three days earlier had never been flown. 44-27927 was a specially modified block 35 B-29. The aircraft was built not by Boeing but by the Glenn L. Martin Aircraft Plant in Bellevue, Nebraska. Martin built a total of 536 B-29s for the US Army Air Forces (USAAF), the first of them being accepted by the USAAF in mid-1944. 44-27927, modified to Block 36 Silverplate standards, was named Bockscar. Bockscar dropped the second and last wartime atomic bomb on 9 August 1945.
Silverplate B-29s were modified to enable them to carry the atomic bombs of their day. Revisions to these special Superforts included pneumatically operated bomb bay doors, dual redundant British bomb attachment and release systems, improved Wright R-3350-41 Duplex-Cyclone turbo-supercharged radial engines with revised fuel injection and cooling systems turning reversible propellers, and the removal of the dorsal and ventral remote-controlled gun turrets. A weaponeer crew position was added in the cockpit area.
Working Her Way West to Tinian
B-29 44-27927 was accepted by the USAAF on 19 March 1945 and assigned to Captain Frederick C. Bock and crew C-13 of the 393rd Bombardment Squadron (BS) of the 509th Composite Group. However, like all 509th bombers the name of the B-29 was not painted on it until after its 9 August mission. Bockscar was flown to Wendover Army Airfield (AAF) in Utah, arriving in April of 1945. The aircraft was used for crew training at Wendover until 11 June 1945, when it departed for points west. After arrival in the Marianas Islands after stops in California and Hawaii a few days later, Bockscar received final modifications at Guam and arrived at North Field on Tinian, at the time the world’s largest airport, on 16 June.
Spurious Markings to Confuse Enemy Spies
After arrival at North Field, the USAAF painted the bomber to resemble an aircraft assigned to another Bombardment Group (BG) to confuse any potential spies. Once declared operational, Bockscar flew 10 training missions. The bomber also flew three combat practice missions, dropping 10,000 pound “pumpkin” bombs on the Japanese cities of Niihama, Musashino, and Koromo. As with all 509th Composite Group Silverplate bombers, several different crews flew missions in Bockscar during these practice missions.
The Great Artiste and a Big Stink
Bockscar had been flown by 393rd BS commander Major Charles W. Sweeney on three dress rehearsal practice flights leading up to the 9 August mission. For the 9 August mission, Bockscar was flown again by Sweeny and not by Captain Bock. Bockscar was accompanied by two other Silverplate B-29s: The Great Artiste, normally flown by Sweeney but flown by Bock on 9 August and designated as the observation and instrumentation aircraft that day. The Great Artiste had already been fitted with the instrumentation equipment for the 6 August mission. Also flying with Bockscar on 9 August was The Big Stink, designated the mission photography aircraft and flown by Major James I. Hopkins. Or at least that was the plan…
5,000 Pounds of Unusable Fuel?
After loading the now-live Fat Man atomic bomb aboard Bockscar, routine pre-flight inspection revealed that an inoperative fuel transfer pump made it impossible to use the 640 gallons of fuel carried in a reserve tank. Replacing the pump was not an option; moving the Fat Man bomb to another aircraft wasn’t either. The fuel would add two and a half tons of dead weight to the already overloaded bomber. Even with the risks, Group Commander Colonel Paul Tibbets and Sweeney decided to fly the mission in Bockscar.