built for the U.S. Navy in 1921 and 1922. The DT-2 had proven to be a sturdy aircraft that could accommodate interchangeable wheeled and pontoon landing gear. Since the aircraft was an existing model, Douglas stated that a new aircraft, which he named the Douglas World Cruiser (DWC), could be delivered within 45 days after a contract was awarded. The Air Service agreed and sent Lieutenant Erik Henning Nelson (1888–1970), a member of the planning group, to California to work out the details with Douglas. Douglas, assisted by Jack Northrop, began to modify a DT-2 to suit the circumnavigation requirements. The main modification involved its fuel capacity. All the internal bomb carrying structures were removed with additional fuel tanks added to the wings and fuselage fuel tanks enlarged in the aircraft. The total fuel capacity went from 115 gallons (435 liters) to 644 gallons (2,438 liters). Lt. Nelson took the Douglas proposal to Washington where Major General Mason M. Patrick, Chief of the Air Service, approved it on 1 August 1923. The War Department awarded an initial contract to Douglas for the construction of a single prototype. The prototype met all expectations, and a contract was awarded for four more production aircraft and spare parts. The last DWC was delivered on 11 March 1924. The spare parts included 15 extra Liberty engines, 14 extra sets of pontoons, and enough replacement airframe parts for two more aircraft. These spare parts were sent ahead to locations along the route around the world the aircraft planned to follow. The aircraft were equipped with no radios nor avionics of any sort, leaving their crew to rely entirely on their dead reckoning skills to navigate throughout the venture. Douglas World Cruiser aircraft and crew Seattle (No. 1): Maj. Frederick L. Martin (1882–1956), pilot and flight commander, and SSgt. Alva L. Harvey (1900–1992), flight mechanic (failed to circumnavigate) Chicago (No. 2): Lt. Lowell H. Smith (1892–1945), pilot, subsequent flight commander, and 1st Lt. Leslie P. Arnold (1893–1961), co-pilot Boston (No. 3)/Boston II (prototype): 1st Lt. Leigh P. Wade (1897–1991), pilot, and SSgt. Henry H. Ogden (1900–1986), flight mechanic (failed to circumnavigate) New Orleans (No. 4): Lt. Erik H. Nelson (1888–1970), pilot, and Lt. John Harding Jr. (1896–1968), co-pilot The pilots trained in meteorology and navigation at Langley Field in Virginia, where they also practiced in the prototype. From February to March 1924, the crews practiced on