 The final wartime Silverplates incorporated all technical improvements to B @-@ 29 aircraft , as well as the final series of Silverplate modifications that included Curtiss Electric reversible @-@ pitch propellers , and pneumatic actuators for rapid opening and closing of bomb bay doors . The British F @-@ type bomb release and G @-@ type attachment were installed , along with dual electrical and mechanical bomb release mechanisms . Early model B @-@ 29s were plagued by a host of engine problems , and the early Silverplate bombers were no exception . One was written off after being badly damaged as a result of an engine fire in February 1945 . The fuel @-@ injected Wright R @-@ 3350 @-@ 41 engines in the later model bombers delivered in July and August 1945 were greatly improved and far more reliable . This was an important factor in the success of the 509th Composite Group 's operations . 
