Douglas C-47A Skytrain

In the early 1930s, Boeing introduced a landmark aircraft, the Boeing "Model 247", that did much to advance the state of the art for commercial airliners. The Boeing 247 entered service with United Air Lines. In 1932 Trans World Airways (TWA), bumped by Boeing to second priority behind United for delivery of Model 247s, contacted Douglas Aircraft to obtain a comparable airliner. Donald Douglas SR put his crew to work on the project, and on 1 July 1933 the "DC-1 (Douglas Commercial 1)" took to the air for the first time. The DC-1 was a low-wing monoplane, with a capacity of 12 passengers, and twin Wright Cyclone R-1820 air-cooled radial engines driving three-bladed propellers. The TWA request had specified three engines, but Douglas managed to convince TWA's technical advisor, Charles Lindberg, that two would do the job.

The DC-1 was a "taildragger", with the main gear partially retracting forward into the engine nacelles, and a nonretractable tailwheel. The DC-1 was an all-metal aircraft, except for some fabric-covered control surfaces. The DC-1 was effectively a prototype and only one was ever built. It was used by TWA for promotional flights and eventually ended its days in Spain. It led to a production aircraft, the "DC-2", which had the same general configuration but was stretched to carry 14 passengers and had more powerful Cyclone engines. It also added rubber pneumatic de-icing boots to the leading edges of all flight surfaces.

TWA ordered an initial batch of 25 DC-2s. The DC-2 first flew on 11 May 1934, and entered TWA service a week later. It proved to be a popular aircraft, with several hundred built in all, and it laid the groundwork for a derivative that would become truly famous. One that would reduce the groundbreaking Boeing Model 247 to relative obscurity.

In 1934, American Airlines (AA) was considering a US transcontinental air service. Given the flight speeds of the time, that implied passenger sleeping facilities on the aircraft, and so AA asked Douglas to build an enlarged version of the DC-2 that could accommodate sleeping berths. Douglas was scrambling to meet orders for the DC-2 at the time and was reluctant to move off in another direction, but the company took the contract. Douglas developed a new version of the DC-2 that had greater wingspan, enlarged tail, longer fuselage, and fuselage width increased by 66 centimeters (26 inches). The new aircraft could accommodate 16 sleeping berths, or 28 seats. Fitted with berths, it was known as the "Douglas Sleeper Transport (DST)". Fitted with seats, it was known as the DC-3. This document will refer to the type as the DC-3 for simplicity, though production totals include some DSTs.

The first DC-3 flew on 17 December 1935, the 32nd anniversary of the Wright Brothers' first powered flight. The first production aircraft was handed over to AA in June 1936 to begin flight services between New York and Chicago. Intercontinental services began in September 1936. Initial production versions of the DC-3 used Wright R-1820-G5 Cyclone engines with 920 (685 kW) each. The DC-3A featured Pratt & Whitney (P&W) R-1830 Twin Wasp radial engines with 1,000 hp (746 kW) each, and the DC-3B featured Wright R-1820-G-102 Cyclones with 1,100 hp (820 kW) each. The DC-3 quickly eclipsed the DC-2. By the time the United States entered World War II in December 1941, 430 DC-3s had been delivered, and that was only the beginning.

The US Navy was the first American military service to buy a Douglas Commercial transport, with the Navy purchasing a single DC-2 in 1934 and designating it the "R2D". The service later bought four more DC-2s as "R2D-1s". In 1936, the US Army Air Corps (USAAC) service ordered a single DC-2 for evaluation purposes. This aircraft was designated "XC-32". The favorable evaluation of the XC-32 led to an order for two "YC-34s", featuring minor changes as specified by the USAAC, and then 18 "C-33s", which had a taller tailfin and a cargo door. One of the C-33s was refitted with a DC-3 tail for evaluation purposes and redesignated "C-38". This evaluation led to a USAAC order for 35 "C-39s", which featured additional DC-3 components, such as landing gear and uprated Wright R-1820-55 Cyclone engines. The first C-39 went into service in 1939.

A few C-39s were modified to other configurations. One was fitted in production with Pratt & Whitney R-1830-21 Twin Wasps and designated "C-41". Another C-39 was similarly fitted in production with uprated Wright R-1820-53 Cyclones and designated "C-42", with two more C-39s converted in the field to C-42 standards.

The USAAC impressed 24 DC-2s into service in 1942, giving them the designation "C-32A". The DC-2 variants in military service had active lives early in the war, with some serving in the US evacuation from the Philippines to Australia in December 1941.

In 1940 the USAAC awarded initial contracts to Douglas for the delivery of such an aircraft. Two main variants were ordered, including the "C-53 Skytrooper" paratroop transport and more significantly the "C-47 Skytrain". Douglas was heavily committed to the production of the DB-7 bomber, predecessor to the A-20 Havoc, at the company's Santa Monica, California, plant, so a new production facility was opened at Long Beach, California.

In late 1941, the first C-53s were delivered to the Army Air Forces (as the Air Corps had become in June), and were followed by the first C-47s in early 1942. The initial production version was simply referred to as the "C-47", and 953 were built. The basic configuration of the C-47 was much like that of the DC-3, but the engines were uprated to supercharged P&W R-1830-92 Twin Wasps with 1,050 hp (784 kW) each, the span was increased by 15 centimeters (6 inches), the fuel tanks were rearranged, the floor was reinforced to handle heavy cargoes, and a navigation astrodome was added behind the cockpit.

The most visible change was fit of twin cargo doors into the rear left side of the fuselage, with a passenger door nested inside the right cargo door. In a sense, the cargo doors were the aircraft's worst feature. They worked as specified, but since the C-47 was originally designed as a commercial transport, it was not optimized for loading cargo as an aircraft with nose or tail doors would have been. Getting large cargoes in and out of a C-47 could be time-consuming and frustrating. A jeep could be driven up a ramp into the aircraft, but it had to be manhandled around to fit inside the fuselage.

The interior could be set up to handle cargo, paratroops, or casualty stretchers. In the cargo role, the interior was fitted with pulleys for moving up to a total of 2,720 kilograms (6,000 pounds) of cargo. For paratroop operations, the interior was fitted with 28 fold-down bucket seats hinged to the the walls. In the medical evacuation ("medevac") role, the interior was fitted with accommodations for 18 stretchers and three medics. Six parachute containers could be attached to racks under the fuselage and released for airdrop supply missions.

With the entry of America into the war in December 1941, USAAF demands for the C-47 skyrocketed. Civilian DC-3s were pressed into military service, and airliners in production were diverted to the USAAF, where they would would be given a bewildering list of different designations, including "C-48", "C-49", "C-50", "C-51", "C-52", "C-68", and "C-84", most of which had a number of subvariants as well. There seems to have been few differences between these machines.

However, even if the military had snapped up every DC-3 built to that time, it wouldn't have come close to meeting demand, and Douglas set up a second production line in Tulsa, Oklahoma. The first production model rolled out of the Tulsa plant was designated "C-47A", which differed from the original C-47 mainly in having a 24 volt DC instead of a 12 volt DC electrical system. Tulsa eventually built 2,099 C-47As, while Long Beach built another 2,832.

The last major production model was the "C-47B", which had still further uprated P&W R-1830-90 or R-1830-90B Twin Wasp engines with two-stage superchargers for high-altitude operation. This requirement apparently surfaced because of the need to fly supplies from India to China over the Himalayas, or the "Hump" as it was called. Tulsa built 2,808 C-47Bs, plus 133 "TC-47B" navigational trainers. Long Beach built 300 C-47Bs as well.

US Planes and Specifications