In the early 1930s, Transcontinental & Western Air (TWA) needed new airplanes and wanted to buy the most modern airliners at the time, the Boeing 247. However, Boeing had an order for 70 airplanes from United Airlines and had committed to delivering these first. As a result, Boeing couldn't meet TWA's needs for quite some time. TWA instead approached Douglas and asked if they could develop and produce a new all-metal airliner with at least 12 seats and a cruising speed of at least 146 mph. This led to the DC-1, Douglas Commercial No. 1, which was to become the progenitor of Douglas' entire line of passenger and cargo aircraft. Only one DC-1 was produced, and it made its first flight on July 1, 1933. Douglas further developed the design into a slightly larger 14-seater aircraft, which was designated the DC-2.
As orders for the DC-2 poured in, American Airlines presented requests to further increase the size of the structure so that sleeping berths could be installed for the aircraft operating transcontinental routes. Douglas initially refused, but American managed to convince them by ordering 20 makins if Douglas would develop such an aircraft. Douglas' engineers immediately set to work on the task. The new aircraft was designated DST, which was short for Douglas Sleeper Transport. The cabin was equipped with 14 sleeping berths for night flights from coast to coast, across the North American continent. The aircraft was very similar to the DC-2, but had a wider and longer fuselage, a new wing with a larger wingspan and a new and larger tail fin that was later extended forward on the fuselage. The aircraft was equipped with two Wright Cyclone engines and had a cruising speed of 180 mph. The first DST rolled out of the factory in Santa Monica, California, on December 17, 1935 and flew the same day.
American Airlines and other airlines soon followed with orders for the aircraft type, but with a standard seat layout for shorter routes. The extended fuselage could accommodate 21 passenger seats. Douglas renamed this aircraft type the DC-3, and this is the aircraft type that we know so well today.
What was so special about the DC-3 and the reason for its success? It was neither the fastest nor the largest airliner in operation. But it was the combination of size, speed and reliability that made air travel more affordable, so millions of travelers took their first flights in the 1930s and 1940s in a DC-3. Most importantly, the cost in terms of passengers per mile was only 4 cents with the DC-3 (but the equivalent for the DC-2, for example, was 7 cents), which meant that airlines slowly started to make money from their operations.
American Airlines had the largest fleet before World War II with 86 DC-3s and DSTs in service. Even United Airlines, which with its large order of Boeing 247, had made TWA get Douglas to develop the DC-1, felt the pressure of competition and ordered 82 DC-3As and DST-As with Pratt & Whitney Twin Wasp engines. 607 airliners were built, including 40 DSTs and DST-As, but 149 of these were requisitioned by the U.S. Army Air Corps (USAAC, later the U.S. Army Air Force - USAAF) for military use rather than delivery to airlines. In January 1942, DC-3s and DSTs accounted for 80 percent of US airliners.
After war broke out in Europe and the threat to the US increased, the DC-3 was further developed as a military transport aircraft and as many as 10,048 machines were built for the US and allied forces during the Second World War. The best-known variant was the C-47, but as we will see in the next section, military variants of the DC-3 were known by a wide range of designations and names. Military versions were also produced under license in the Soviet Union under the designation Lisunov Li-2 and in Japan as L2D with the American code name "Tabby". General Eisenhower stated that the C-47, along with the jeep, bulldozer and 2 ½ ton truck, was critical to his troops' success in defeating the enemy in Europe and Africa.
After the Second World War, a large number of transport aircraft became redundant in the American forces. Many aircraft were put into service by air forces around the globe or were sold to civilian airlines.
Designations
The DC-3 is known by a number of designations and names. Here we will explain some of the most important of these.
The Douglas factory's designation was Douglas Commercial No.3, or DC-3. Before the war, the aircraft type was produced in five variants:
- DST - With Wright R1820 Cyclone motors.
- DST-A - With Pratt & Whitney R-1830 Twin Wasp engines.
- DC-3 - With Wright R1820 Cyclone engines.
- DC-3A - With Pratt & Whitney R-1830 Twin Wasp engines.
- DC-3B - With Wright R1820 Cyclone engines and a mix of standard and convertible seats.
The aircraft could be delivered with a passenger door on either the right or left side, according to the customer's wishes.
After the war, further varieties were added:
- DC-3C - C-47 converted to DC-3 standard. Bought back from the US government during and after the war. Assigned new construction numbers.
- DC-3D - C-117A converted to DC-3 standard. Also aircraft that towards the end of the war were assembled from undelivered parts for the C-117A. Assigned new construction numbers.
Civilian DC-2s and DC-3s requisitioned for USAAC were assigned a number of different designations. Each airline had different equipment and configurations, and the Air Force gave each configuration its own designation. In addition, specially designed military aircraft were given their own designations. The C-33 was a version of the DC-2 that was built to military specifications with a reinforced floor, large cargo door and seats removed. Other military designations for DC-2 variants were C-32, C-34, C-38, C-39 and C-41.
Of the military versions of the DC-3, it is the C-47 Skytrain that is best known.
The different variants of the C-47 Skytrain were:
- C-47 (no suffix) - Pratt & Whitney R-1830-92 Twin Wasp engines. 12 volt electrical system.
- C-47A - As C-47 but with 24 volt electrical system.
- C-47B - Like the C-47 but with Pratt & Whitney R-1830-90 or R-1830-90B Twin Wasp engines and two-stage compressor to operate at higher altitudes.
- C-47D - C-47B which had its compressors removed after the war.
The USAAF also needed a variant for troop transport only, without the extra requirements for transport aircraft that the C-47 had, thus saving weight. This variant was designated C-53 and named Skytrooper. Another variant without a cargo door was the C-117. The C-53 and C-117 are essentially very similar to the DC-3A. The different variants of the C-53/C-117 Skytrooper were:
- C-53 (no suffix) - Pratt & Whitney R-1830-92 Twin wasp engines. 12 volt electrical system. 26" wide cabin door.
- C-53B - Like the C-53, but equipped for winter operations, with expanded fuel capacity and separate navigator's station.
- C-53C - Like the C-53, but with a 30" wide cabin door.
- C-53D - Same as C-53C, but with 24-volt electrical system and separate navigator station.
- C-117A - Began C-47B which was completed to airliner standard.
Other military designations for DC-3 variants were C-42, C-48, C-49, C-50, C-51, C-52, C-68, C-84 and C-129. After the war, many machines were equipped and partly rebuilt to perform specialized missions. At the same time, these were assigned new sub-designations. The list of sub-designations is too extensive to include here.
Approximately 600 C-47 and C-53 variants were transferred to the U.S. Navy from USAAF Material Command. Until 1962, the U.S. Navy and the U.S. Marine Corps had their own aircraft designation system. Their main designations ranged from R4D-1 to R4D-8 and were used for passenger transportation and freight. Before the war, the U.S. Navy also acquired five DC-2s. DC-2s, which were given the designation R2D-1.
- R4D-1 - Corresponds to C-47
- R4D-2 - Corresponds to DC-3
- R4D-3 - Equivalent to C-53C
- R4D-4 - Corresponds to DC-3A
- R4D-5 - Equivalent to C-47A
- R4D-6 - Equivalent to C-47B
- R4D-7 - Corresponds to TC-47B
In our part of the world, the DC-3 is perhaps best known by the name Dakota. This is the British military designation for the DC-3. The first deliveries to the RAF were in February 1943. In total, more than 1,900 machines were delivered to the RAF, divided into four variants:
- Dakota Mk.I - Similar to C-47
- Dakota Mk.II - Similar to C-53
- Dakota Mk.III- Equivalent to C-47A
- Dakota Mk.IV - Equivalent to C-47B
In order to meet greater demands after the war, Douglas offered a conversion of existing DC-3 machines with, among other things, a longer fuselage, larger tail surfaces, new outer wings and more powerful engines. The new variant was called the DC-3S or "Super DC-3" by Douglas. More than 75% of the original design had been changed, so in practice it was a new type of aircraft. The U.S. Navy was the largest user and gave the aircraft type the designation R4D-8, later C-117D after the common designation system was introduced in 1962.
The DC-3 is still doing well around the world, 75 years after the aircraft was first built. Several have been rebuilt to give them an extended life, e.g. with new turboprop engines (including a third engine installed in the nose). No doubt they will continue to fly for many years to come, and will surely get to celebrate their centenary where they belong - in the air.