The XB-16 was designed to meet the
United States Army Air Corps (USAAC) request for a bomber that could carry of bombs . The XB-16 (Model 145A) was to use four
Allison V-1710 liquid-cooled reciprocating
V-engines; contemporary American aircraft used air-cooled
radial engines. In
1935, Martin revised the XB-16 design as the Model 145B. The wingspan was increased from to , and a set of V-1710 engines added to the trailing edge. This version had a wingspan 20% greater than that of the
B-29 Superfortress, the first operational bomber that would fill the role intended for the XB-16. The XB-16 was canceled for essentially the same reason that the
Boeing XB-15 project was, as it was not fast enough to meet the requirements set by the Army. Since both were canceled around the same time, Martin did not have time to produce an XB-16. ==Specifications (Model 145A)==