Douglas XB-19 airplane model. The Douglas XB-19 was the largest bomber built for the United States Army Air Corps until 1946. It was originally given the designation XBLR-2 (XBLR- denoting Experimental Bomber, Long Range).
The purpose of the XB-19 project was to test the flight characteristics and design techniques associated with giant bombers. Douglas Aircraft Company strongly wanted to cancel the project, because it was extremely expensive. Despite advances in technology that made the XB-19 obsolete before it was even completed, the Army Air Corps felt that the prototype useful for testing. Its construction took so long that competition for the contracts to make the XB-35 and XB-36 occurred two months before its first flight.
The plane finally flew on June 27 1941, more than three years after the construction contract was awarded. In 1943, the original engines were replaced with Allison V-3420-11 V engines. After completion of testing, the XB-19 served as a cargo carrier until it was scrapped in 1949.