The Douglas Aircraft Corporation manufactured the Douglas C-1, a cargo and transport aircraft, for the United States Army Air Service, commencing production in 1925.
In 1925, Douglas was commissioned to produce nine single-engine transport aircraft, with the inaugural flight taking place on 2 May of that year from the company’s factory in Santa Monica, California.
The C-1 was the first aircraft to be designated under the new C-category.
Drawing on earlier designs from the early 1920s, including the Douglas World Cruisers used in the first round-the-world flight in 1924, the C-1 boasted an enclosed passenger compartment capable of accommodating six passengers or approximately 2,500 lb (1,100 kg) of cargo.
To facilitate the loading of large and/or heavy cargo, such as aircraft engines, a trap door was installed in the lower fuselage, while an auxiliary door for passengers and light cargo was situated on the right side of the centre fuselage.
The C-1 biplane was equipped with the Liberty L-12 engine and accommodated a crew of two in an exposed cockpit.
A C-1 was successfully flown in the 1926 Ford National Reliability Air Tour.
Subsequently, seventeen additional aircraft were procured between 1926 and 1927 by the United States Army Air Corps, designated as C-1Cs, which were marginally larger than the original C-1s.
Several C-1s were employed in experimental programs, serving as an engine test platform, a prototype air ambulance, and as refuelling aircraft for early air-to-air refuelling trials.
Notably, two of these aircraft were utilized as “tankers” in the 1929 record endurance flight of the Fokker C-2 Question Mark Aircraft. Variants C-1 Single-engined cargo/passenger transport aircraft, powered by a 435 hp (324 kW) Liberty V-1650-1 piston engine, accommodation for two crew and six to eight passengers. C-1A One C-1 was used to test a variety of engines and cowlings, it was also used for several experiments with ski landing gear. C-1C Single-engined cargo/passenger transport aircraft, fitted with a metal cabin floor, and modified landing gear, it had a higher gross landing weight and increased dimensions, plus a new balanced rudder; 17 built. Specifications Douglas C-1 Crew 2 Capacity 6 or 8 pax / 2,500 lb (1,100 kg) payload Length 35 ft 4 in (10.77 m) Wingspan 56 ft 7 in (17.25 m) Height 14 ft (4.3 m) Wing area 805 sq ft (74.8 m2) Airfoil Clark Y Empty weight 3,836 lb (1,740 kg) Gross weight 6,443 lb (2,922 kg) Powerplant 1 × Liberty V-1650-1 V-12 water-cooled piston engine, 435 hp (324 kW) Propellers 2-bladed fixed-pitch propeller Performance Maximum speed 116 mph (187 km/h, 101 kn) at sea level Cruise speed 85 mph (137 km/h, 74 kn) Range 385 mi (620 km, 335 nmi) Service ceiling 14,850 ft (4,530 m) Rate of climb 645 ft/min (3.28 m/s) Wing loading 8 lb/sq ft (39 kg/m2) Power/mass 0.0676 hp/lb (0.1111 kW/kg). Sources The National Museum of the U.S. Air Force,
McDonnell Douglas aircraft since 1920: Volume I-René J Francillon,
