The DF was an all-metal high-wing monoplane with fabric covered control surf aces. Smooth sheet metal skin was used except on the forward two-thirds of the wing which had corrugated skin. The hull was of the two-step type and the single-step stabilizing floats were hydraulically-retracted inward and partially recessed into the underside of the wing.
Power was supplied by two 1,000 hp Wright SGR-1820G-2 nine-cylinder driving three-blade constant-speed propellers. Accommodation was for a maximum of 32 passengers in four eight-seat compartments and for night service the normal seating could be replaced by 16 berths. The crew of four consisted of pilot, co-pilot, navigator and stewardess. The aircraft was equipped with galleys, two lavatories, and an aft cargo compartment.
Completed in September 1936, the above pictured first DF was successfully tested, however, as Pan American was not interested in operating a twin-engined flying boat on relatively long overwater flights, Douglas found itself without a domestic customer for the prototype and the three additional DFs it had under construction. Fortunately, the company obtained government authorization to sell them to any interested foreign customer.
The first two of the Douglas flying boats, completed to Specification DF-151 standards, were shipped to Japan. Officially they were for Dai Nippon Koku KK (Greater Japan Air Lines) and were registered as J-ANES and J-ANET on December 21, 1936. However, the letter 'A' after the J- in the registration indicates it was registered to the government and in fact, they were procured for evaluation by the Imperial Japanese Navy Air Service and designated HXD-1 and HXD-2, Navy Experimental Type D flying boat.
One of the two aircraft was temporarily dismantled by Kawanishi to obtain engineering data later used in the design of its four-engined H8K flying boat. Both aircraft served a few years as transport and survey aircraft, being lost shortly after each other. HXD-1 was lost after a forced landing at sea on August 10, 1938, the following September 15 the HXD-2 crashed into Mount Sefuri on the island of Kyushu, all fifteen occupants, two crew and thirteen passengers, were killed.
The last two aircraft, completed as DF-195s, were purchased by the Soviet Government in 1937 and registered CCCP-H-205 and CCCP-H-206 (in Cyrillic, in Arabic SSSR-N-205 and SSSR-N-206) they were flown to the USSR via Alaska and across the Bering Sea. At least one, SSSR-N-205, was operated by Aeroflot on the Leningrad-Sevastopol route until about 1940."
Span: 95 ft 0 in (28.96 m)
Length: 69 ft 10.56 in (21.30 m)
Height: 24 ft 6.25 in (7.47 m)
Wing area: 1,295 sq.ft (120.31 sq.m)
Weight empty: 17,315 lb (7,854 kg)
Max T/O weight: 28,500 lb (12,927 kg)
Max speed: 178 mph (286 kmh) at 6,800 ft (2,075 m)
Cruise speed: 160 mph (257 kmh)
Service ceiling: 9,843 ft (3,000 m)
Initial climb: 800 ft (243 m)/min
Range (fully loaded): 1,500 mls (2,415 km)
