Douglas DC-1 and DC-2

The single Douglas DC-1 was the direct ancestor of the DC-3, an aircraft that would revolutionise civil aviation, and of the C-47/ Dakota family of military transport aircraft, the most important Allied transport aircraft of the Second World War.
The Douglas DC-2 was the production version of the DC-1, and helped to revolutionise the civil aviation industry in the mid 1930s.
The designation Douglas R2D-1 was given to the first DC-2s to enter US military service, serving as staff transport aircraft for the US Navy
The designation Douglas C-32 was given to one DC-2 purchased by the USAAC in 1936, and to twenty-four civilian DC-2 airliners that were impressed by the War Department after the start of the Second World War.
The Douglas C-33 was the first purpose-built military transport aircraft to be based on the Douglas DC-2, and was thus the ancestor of the thousands of C-47s, C-53s and Dakotas that would be built during the Second World War.
The Douglas C-34 was the designation given to two military versions of the DC-2 purchased for use by the Secretary of War.
The single Douglas C-38 was producing in an attempt to improve the stability of the DC-2/ C-33 series of aircraft.
The Douglas C-39 was a military transport aircraft that combined the fuselage and outer wings of the DC-2 with the centre wing section, engine nacelles and larger tail of the DC-3.
The Douglas C-41 was the designation given to a single transport aircraft based on the DC-2 and produced as a transport for the Chief of Staff of the Army Air Corps
Like the C-41 the Douglas C-42 was the designation given to a single transport aircraft similar to the C-39, with the fuselage of the DC-2 but the tail and wing centre section of the DC-3.