Silverplate - Wartime Production Versions

Wartime Production Versions

On August 22, 1944, to meet the requirements of the USAAF group about to be formed to train in the atomic mission, a production phase of Silverplate B-29s was ordered under the designation Project 98146-S from the Glenn L. Martin Company's modification center at Omaha, Nebraska. In mid-October the first three of these second increment Silverplate B-29s were delivered to the USAAF and flown to Wendover Army Airfield, Utah. They were fitted with British single-point bomb releases mounted on a re-designed H-frame suspension rack fitted in the forward bomb bay, so that additional fuel tanks could be carried in the aft bay. A new crew position, called the "weaponeer station", was created in the cockpit with a panel to monitor the release and detonation of the bomb during the actual combat drops. Fourteen production aircraft were assigned to the 393rd Bomb Squadron and three to the 216th AAF Base Unit for bomb drop testing.

By February 1945 the seventeen aircraft of the second increment were themselves in need of upgrades, particularly those of the 216th AAF Base Unit. Four of the planes assigned to the 393rd Bomb Squadron (now a squadron of the 509th Composite Group) were immediately transferred to the 216th to meet an increase in its testing tempo. Rather than attempt to modify the existing aircraft a few at a time, a decision was made to start a new production series. The first five of this third increment, known as Project 98228-S, also went to the test unit. The order totaled an additional 28 aircraft, with delivery of 15 designated combat models for the 393rd Bomb Squadron beginning in April; the final 8 were not delivered until after the atomic bomb missions in August.

The final wartime Silverplates incorporated all technical improvements to B-29 aircraft, as well as the final series of Silverplate modifications that included fuel-injected Wright R-3350-41 engines, Curtiss Electric reversible-pitch propellers, and pneumatic actuators for rapid opening and closing of bomb bay doors. Weight reduction was also accomplished by removal of all gun turrets and armor plating. These B-29s represented a significant increase in performance over the standard variants.