Douglas B-18 Bolo

The Douglas B-18 Bolo is an American heavy bomber which served with the United States Army Air Corps and the Royal Canadian Air Force (as the Digby) during the late 1930s and early 1940s. The Bolo was developed by the Douglas Aircraft Company from their DC-2, to replace the Martin B-10. By 1940 standards, it was slow, had an inadequate defensive armament, and carried too small a bomb load. A B-18 was one of the first USAAF aircraft to sink a German U-boat, on 22 August 1942 in the Caribbean. By 1942, surviving B-18s were relegated to antisubmarine, training and transport duties. Design and development In 1934, the United States Army Air Corps requested for a twin-engine heavy bomber with double the bomb load and range of the Martin B-10 then entering service. During the evaluation at Wright Field the following year, Douglas offered its DB-1. It was competing against the Boeing Model 299 (later developed into the Boeing B-17 Flying Fortress) and Martin 146. While the Boeing design was clearly superior, the 299's four engines eliminated it from consideration despite being the favorite, and the crash of the prototype — caused by taking off with the controls still locked — put its purchase on hold. The Martin 146 was a minor improvement on the B-10, and was never seriously considered. During the depths of the Great Depression, the lower price of the DB-1 at $58,500 compared to $99,620 for the Model 299 also favored the Douglas entry, and it was ordered into immediate production in January 1936 as the B-18.