Designed in response to a 1934 U.S. Army Air Corps requirement for a replacement for the B-10, the B-18 was based on the Douglas DC-2 airliner using similar wings, tail and engines. The Bolo entered production in 1936 and by 1940 most of the bomber squadrons in the Air Corps were equipped with B-18s. When the United States entered World War II the B-18 was obsolete as a bomber and was in the process of being replaced by the B-17, however 122 were modified with a nose mounted radar replacing the bombardier and magnetic anomaly detectors for locating submarines installed in the tail and called B-18B. These aircraft served in the Caribbean and Atlantic hunting for German submarines through 1943. Most B-18s were retired to transport duties for the remainder of the war and were then sold as surplus in 1945 and 1946.
25th Antisubmarine Wing, 4th Antisubmarine Squadron, Langley AAF, Virginia, July 1942
Pima Air & Space Museum