v1.2.0 / 01 feb 03 / greg goebel / public domain
* The "Douglas DC-3" airliner was a milestone of aviation, the basis for the introduction of practical commercial airline service in the 1930s. It achieved another major distinction in military service as the "C-47 Dakota" transport. General Dwight Eisenhower described the C-47 as one of the four machines that won World War II, along with the bulldozer, 6x6 truck, and the landing craft. This document provides a short history of the C-47.
* 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 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 685 kW (920 HP) each. The DC-3A featured Pratt & Whitney (P&W) R-1830 Twin Wasp radial engines with 746 kW (1,000 HP) each, and the DC-3B featured Wright R-1820-G-102 Cyclones with 820 kW (1,100 HP) 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.
MILITARY DC-2 SUMMARY TABLE
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production service comments
_____________________________________________________________________
R2D 1 Navy
R2D-1 4 Navy
XC-32 1 Army Evaluation machine.
YC-34 2 Army Minor changes from production DC-2.
C-33 18 Army Added cargo door and taller tailfin.
C-38 - Army C-33 fitted with DC-3 tail for evaluation.
C-39 35 Army DC-2 with DC-3 tail, landing gear, etc.
C-41 - Army C-39 refitted with P&W Twin Wasp engines.
C-42 - Army 3 C-39s fitted with uprated Cyclones.
C-32A - Army 24 DC-2s pressed into service during WWII.
_____________________________________________________________________
Development of the C-41 variant of the DC-2 for the Army had proven some of the modifications required for a militarized DC-3, and 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, of which more is said in the next section, 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 784 kW (1,050 HP) 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 a 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.
DOUGLAS C-47A DAKOTA:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 29 meters 95 feet
wing area 91.69 sq meters 987 sq feet
length 19.6 meters 64 feet 2 inches
height 5.16 meters 16 feet 11 inches
empty weight 7,700 kilograms 16,970 pounds
max loaded weight 11,800 kilograms 26,000 pounds
maximum speed 370 KPH 230 MPH / 200 KT
cruise speed 298 KPH 185 MPH / 160 KT
service ceiling 7,070 meters 23,200 feet
range 2,410 kilometers 1,500 MI / 1,305 NMI
_____________________ _________________ _______________________
In practice, the C-47B wasn't entirely satisfactory, with the Curtis C-46 becoming the champion of the Hump flights, and many were converted to the "C-47D" variant by removal of the high-altitude blower system.
* About 219 of the specialized C-53 Skytrooper paratroop carrier version were also built. They lacked the double doors and reinforced floor, and were fitted with metal seats for 28 paratroopers and an attachment point for a combat glider tow rope. As mentioned, C-53 deliveries preceded deliveries of the C-47, and it was closer in configuration to the original DC-3 than the C-47.
A single "XC-53A" was built as a prototype; followed by eight winterized "C-53Bs", with additional fuel capacity; a batch of 17 "C-53Cs" with a larger passenger door; and finally about 159 "C-53Ds" with a 24-volt DC electrical system. The glider tow attachment later became standard in C-47 production.
The USAAF also ordered a batch of military passenger transport variants of the DC-3 and gave them the designation "C-117". The C-117 had DC-3 style airliner fit and various small features added from current C-47 production, but only one C-117A and sixteen C-117Bs from the order for 131 were actually built, with production terminated by the end of the war in the Pacific.
Two particularly interesting C-47 conversions were the "XC-47C" floatplane and the "XCG-17" heavy cargo glider. The XC-47C had a pair of big Edo Model 78 floats, with each float having front and back retractable wheels and a 1,140 liter (300 US gallon) fuel tank. A number of such conversions were made in the field, and interestingly one of these aircraft has survived to the present.
The single XCG-17 made was modified from a stock C-47 to meet a requirement for a heavy cargo glider. Early tests were performed on a C-47 performing "deadstick" landings, and then the engines were removed and the nacelles faired over. The nacelles were not removed since the USAAF wanted to be able to reconvert the gliders back into powered C-47s. The XCG-17 had an excellent glide ratio, a tribute to the DC-3's clean design, but the Air Force did not go ahead with the concept.
* About 600 C-47s and C-53s from the total production were obtained by the US
Navy and Marine Corps under the designation "R4D", with variant designations
as follows:
USAAF USN
_______________ ______
C-47 R4D-1
Impressed DC-3s R4D-2
C-53 R4D-3
C-53C R4D-4
C-47A R4D-5
C-47B R4D-6
TC-47B R4D-7
_______________ ______
* The British were particularly enthusiastic users of the DC-3 and its variants. A few commercial DC-2s and DC-3s were purchased or pressed into military service early in the war, and eventually were given the name "Dakota". This eventually became, more or less, the accepted name for all military DC-3 versions, though the US name of "Gooney Bird" was a strong competitor.
The British eventually received over 1,900 more Dakotas from total production through Lend-Lease, including:
Roughly 200 Dakotas of various types were passed on to the Royal Canadian Air Force (RCAF), which put them to good use. The different versions of the DC-3 in Allied military service will all be generally referred to as "C-47s" in the rest of this document, though as the discussion in this section shows, this is an oversimplification.
* The Soviets manufactured almost three thousand DC-3 variants under license. They were built under the direction of Boris Lisunov, who had acquired his education in putting together the aircraft at the Douglas Santa Monica plant during a stint there from 1936 through 1939. The type went into production as the "PS-84", meaning "Passenger Aircraft from State Factory (GAZ) 84", and was in principle to be used as a civilian airliner by Aeroflot. After the Nazi invasion of June 1941, GAZ-84 relocated to Tashkent in Central Asia, and the aircraft acquired the military designation "Li-2".
Although the Soviet plan had been to avoid changes in the design, many tweaky modifications were incorporated in the Lisunov-built machines. The Li-2s featured:
Li-2 variants included:
In the postwar period, the Li-2 was given the NATO codename "Cab". The career of the DC-3 / C-47 wearing the Red Star remains very obscure in the West and such details as are available tend towards the contrary and untrustworthy. Hopefully more information will be available in the future.
* Very surprisingly, DC-3s were also built in Japan during the war. Two Japanese trading firms, Mitsui and Far Eastern Trading, bought a total of 20 Douglas-built DC-3s, which went into service with Dai Nippon Air Lines and served through the war.
In 1938, Mitsui went on to obtain a manufacturing license for $90,000 USD in 1938, not bothering to tell Douglas that they were doing so at the request of the Imperial Japanese Navy. Mitsui obtained all specifications, and then also bought two unassembled DC-3s from Douglas as manufacturing pattern machines. Mitsui arranged delivery of the unassembled machines to the Showa company, which was to cooperate with Nakajima for manufacture.
The two unassembled DC-3s were put together by Showa and delivered in October 1939 and April 1940, with the designation "L2D1". In the meantime, Showa and Nakajima had been working to modify the design to use 764 kW (1,000 HP) Mitsubishi Kinsei 43 radials in place of the US-built engines, This resulted in the first Japanese production variant, the "L2D2". Nakajima built 71 of this model, delivering the last in November 1942, when the company got out the business of building DC-3 clones.
However, Showa remained in the trade, and in fact the Imperial Japanese Navy selected the type as their standard transport aircraft. Showa delivered their first L2D2 in March 1941, quickly moving on to improved variants.
The "L2D2-1" was a cargo hauler, with a reinforced floor and cargo doors on the left side of the rear fuselage. The "L2D3" was an improved passenger version, with Kinsei 51 radials providing 970 kW (1,300 HP) each and cockpit windows distinctively extended back along the fuselage. An equivalent cargo version, the "L2D3-1", was also built. Both these variants were later built with improved Kinsei 53 engines, also with 970 kW (1,300 HP), and designated "L2D3a" and "L2D3-1a" respectively.
The "L2D4" was an armed variant, with a top gun position mounting a single 13 millimeter gun, and a single 7.9 millimeter gun firing from a hatch on each side of the aircraft. The "L2D4-1" was the cargo transport equivalent. Neither went beyond prototypes. The last in the series, the "L2D5", was basically an L2D4 that was designed to be built with as much non-strategic materials (wood and steel version aircraft alloys) and powered by Kinsei 62 radials, with 1,165 kW (1,560 HP) each, but the prototype was not completed before the end of the Pacific War.
Showa built a total of 416 L2Ds, in addition to the 71 built by Nakajima. The L2D was codenamed "Tabby" by the Allies. It created a degree of confusion that apparently led to some deadly "friendly fire" incidents.
* The C-47 was put to use by US armed forces immediately on America's entry to the war. The Naval Air Transport Service was established just a few days after Pearl Harbor, and would make extensive use of the type. The USAAF Air Transport Command was formed in the middle of 1941, and also proved an enthusiastic user.
The C-47's most prominent claim to fame in World War II combat was in support of airborne assaults, mostly under the umbrella of the USAAF Troop Carrier Command and the British Royal Air Force (RAF) Transport Command. The RAF Transport Command found them far superior for parachute assaults than the hand-me-down Whitley bombers and other obsolescent aircraft they had been using as stopgaps. 59 Dakotas were also supplied to the British Overseas Airways Corporation (BOAC) to service regular transport routes.
Although the British dropped a brigade of paratroops into North Africa with the Dakota in November 1942, the C-47's first large-scale introduction to combat was in July 1943, when they dropped about 4,000 paratroopers and glider troops in support of the Allied invasion of Sicily. This was followed by the massive airdrops in support of the Allied invasion of Normandy in June 1944, with 1,000 C-47s providing the backbone of the airlift capacity and delivering 60,000 paratroops and equipment in 60 hours.
The C-47 was also used extensively in Burma, with the aircraft providing supply for Orde Wingate's Chindit commandos operating behind enemy lines during the winter of 1942:1943. They also supported the airborne assaults on the Japanese in Burma in early March 1944.
Other C-47s flew the Hump from India to China and back, carrying a total of 590,000 tonnes (650,000 tons) of supplies in all. These flights were often difficult due to severe winds, weather, and deep cold temperatures, not to mention enemy action. During one of these flights, a C-47 was attacked by a Japanese Nakajima Ki-43 Oscar fighter. The lightly armed Oscar was not able to fatally damage the sturdy C-47, and either in clumsiness or suicidal determination the fighter actually rammed the transport. The Oscar lost a wing and fell to earth. The C-47, with a great hole torn in its roof, returned to base.
Even when severely damaged, a C-47 could make a relatively safe wheels-up landing, because its main gear did not fully retract and took up some of the load. The "taildragger" configuration of the aircraft was also an advantage for rough-field operation, since having the aircraft's center of gravity behind the main wheels meant that the C-47 had less of a tendency to pitch forward when riding over obstructions, and also kept the engines and cockpit riding high above dust and debris.
In addition to relatively small airdrops in Italy, Greece, and the Philippines, the C-47 also conducted large airdrops during the invasion of southern France in August 1944; the assault on Arnhem in the Netherlands in September 1944, where Dakota pilots distinguished themselves in determined attempts to resupply surrounded British paratroops under severe enemy anti-aircraft fire; during the Rhine crossing in March 1945; and in offensive operations in Burma in March and May 1945.
The Rhine crossing, codenamed OPERATION VARSITY, was the largest airborne operation in history. It involved two divisions and 1,700 transport aircraft. Participants describe the air fleet as shadowing the ground beneath, and the drops as filling the sky with parachutes.
* Although airborne assault was the C-47's greatest claim to fame, it was an excellent "flying truck" and performed almost every imaginable transport task, from ferrying critical cargoes, evacuating wounded, dropping supplies to resistance groups, and even ferrying a V-1 jet flying bomb back from Poland. A number of Dakotas were unsurprisingly used as VIP transports, in a few recorded cases transporting the British Royal family, and both General Dwight Eisenhower and British Field Marshal Sir Bernard Montgomery used the Dakota as his personal transport.
Some uses of the aircraft were imaginative. In June 1943, an RAF Dakota Mark I towed a Waco transport glider over the Atlantic as a means of increasing transatlantic cargo lift capacity. The experiment was a success, but there was no follow-up to the concept. Allied forces in also developed procedures where a C-47 could "hook" an empty glider from a drop zone and return it to base for re-use.
* A total of 10,926 DC-3s and C-47s were built in all up to the end of the war, the vast bulk of them being C-47s. Unlike many aircraft used in World War II, the C-47 did not go into rapid decline at the end of the war. It was not a victim of the mad scramble to scrap aircraft that reduced the numbers of other famous aircraft of the war from thousands to handfuls, since the C-47 was just too useful. It was overbuilt, making it almost indestructible. As one Dakota pilot put it: "You can wreck a Dak, but you can't wear it out."
In fact, Douglas hoped to build and sell more DC-3s in the postwar period, and in 1947 produced two examples of the "Super DC-3", also known as the "DC-35". These two aircraft were conversions from older DC-3s, and featured fully retractable main gear, a longer fuselage with an improved interior fit for 30 passengers, a taller tailfin, and distinctive squared-off wingtips. The first Super DC-3 was fitted with Wright R-1820-C9HE Cyclones with 1,100 kW (1,475 HP) each, while the second was fitted with P&W R-2000-D7 radials with 1,080 kW (1,450 HP) each.
First flight of the Super DC-3 was in June 1949. However, the DC-3 was no longer the best aircraft available to the airlines, and only three went into commercial service. The US Air Force (USAF) acquired the first prototype, but passed it on to the US Navy, which had 100 R4Ds updated to Super DC-3 standard. The Navy designated the type the "R4D-8", though it appears to also have been known by its US Air Force (USAF, the USAAF having become an independent service in 1947) designation, "C-117D".
* The C-47 remained in first-line service with too many air forces to list into the 1950s, and was a prominent contributor to the Berlin Airlift in 1948 and 1949. The French used them during the first Indochina War, and also used one as flying command post during the Anglo-French-Israeli Suez intervention in 1956.
The USAF operated a large number of modifications, including the "VC-47A", "VC-47B", and "VC-47D" staff transport conversions; the "RC-47A" and "RC-47D", described as "reconnaissance" machines and apparently used for battlefield spotting and flare dropping during the Korean War; the "SC-47A" and "SC-47D" search and rescue aircraft, redesignated "HC-47A" and "HC-47D" in 1962.
* The C-47 had a very lively career in the Vietnam War. As as excellent "bush" aircraft, it was of course used to fly cargos into the backwoods of Laos in support of anti-Communist tribes working with the Americans, but it was also used for both electronic intelligence (ELINT) and as a gunship.
The ELINT C-47s were designated "EC-47" and were known as "Electric Goons" by their crews, following the old "Gooney Bird" name for the C-47. They were equipped with signals intercept and emitter location gear, and were used to target enemy radio transmissions.
A few C-47s were converted to ELINT configurations in the early 1960s, with these machines performing some service in Vietnam. By 1966, the Army was operating their own fleet of ELINT aircraft over Vietnam, but they didn't have enough of them, and the C-47 was felt to be more capable than the Army aircraft. In response, the Air Force instituted a crash program to convert C-47s to the EC-47 configuration, with the first reaching service in the spring of 1966. Roughly 50 EC-47s were obtained in all.
There were several variations on the Electric Goons, subtly differing in electronic gear fit, including the "EC-47N", "EC-47P", and "EC-47Q". They saw plenty of combat, in particular serving with distinction in helping to call in strikes during the siege of Khe Sanh in early 1968, and several were lost in action. The EC-47s were phased out of service with the gradual disengagement of the US from the conflict in the early 1970s.
* The electronic mission conversions of the Dakota are very obscure, but another C-47 conversion of the war, the "AC-47D" gunship, became one of the most famous variants of the series.
Late in World War II, an Army Air Force lieutenant colonel named G.C. McDonald had come up with the idea of mounting side-firing weapons in aircraft for the ground attack mission. The pilot of a conventional attack aircraft had to make a pass on a target and fire his weapons, then come around for another pass. The pilot of an attack aircraft with side-firing weapons could simply perform a banking "pylon turn" around a target, line up the target along his wingtip, and then hose it down with a "cone of fire" for as long as ammunition held out.
The idea was tested and seemed workable, but with the war winding down nothing was done with the notion until 1961. The USAF was trying to come to grips with the difficulties of fighting the growing jungle war in Southeast Asia, in particular searching about for a way to perform effective close air support for ground operations. The service sponsored a conference in December 1961, which McDonald, then in the AF Reserves, attended. He resurrected his idea, which some of the other attendees picked up and ran with, leading to limited funding an evaluation program in 1963.
The evaluation confirmed the merits of the idea. In the summer of 1964, the war in Southeast Asia began to escalate drastically with the Tonkin Gulf incident in August 1964, and the gunship program went from low on the priority list to near the top.
A number of different aircraft had been used during the test evaluation, but the C-47 was selected as the best candidate for an operational system due to its availability and capability. The C-47 gunships were originally given the designation of "FC-47D", but this was presently changed to "AC-47D" in response to loud complaints by fighter pilots that calling any kind of a C-47 a "fighter" was seriously stretching the definition of the term. The type is referred to as AC-47D in the following discussion for the sake of simplicity.
The AC-47Ds was fitted with three 7.62 millimeter (0.30 caliber) Gatling-style Miniguns firing out the left side of the aircraft. The Miniguns had a selectable rate of fire of 3,000 or 6,000 rounds per minute, and the gunship typically carried about 24,000 rounds of ammunition. Early gunships used improvised cargo-hold mounts for SUU-11A/A underwing Minigun pods. Later gunships carried GAU-2B/A Miniguns more specifically designed for the task, and then the far more satisfactory MXU-470/A Miniguns, which used an ammunition drum instead of a belt-feed from ammunition cans, with great improvement in convenience and reliability. After some experience, the guns would be fixed pointing 12 degrees downward, reducing the aircraft bank angle required for attacks.
Ballistic curtains were fitted to the left side of the aircraft to protect crew and systems; new radio and navigation equipment were installed; a Mark 20 gunsight salvaged from the Douglas A-1 Skyraider attack aircraft was fitted to the cockpit left-side window; and a trigger button from the same source was attached to the pilot's control wheel. The AC-47Ds also carried a bin of illumination flares for night fighting next to the cargo door, with the flares tossed out of the aircraft by the flight crew by hand. The bin was later armored to prevent the flares from being set off by ground fire.
The AC-47Ds flew in combat evaluations in Vietnam in late 1964, leading to deployment in 1965. Vietnamese who observed attacks by the gunships compared them to roaring, fire-spouting dragons, and so the gunships acquired the name "Puff", after a contemporary pop tune, "Puff the Magic Dragon". They were more informally called "Spooky" after their radio callsign, and were well-liked by US ground forces for their ability to literally rip enemy assaults to shreds.
About 50 AC-47Ds were built. A small number of gunships were fitted with ten 7.62 millimeter Browning machine guns for a time, until they were upgraded to Miniguns. Some C-47s were also converted to gunships in the field by fitting them with 12.7 millimeter (0.50 caliber) Browning machine guns.
Although the AC-47Ds were highly effective, the aircraft were old and getting weary, and attempts to operate over Laos in the face of substantially tougher enemy air defenses did not go well, with a number of Spookys shot down in combat. The Spookies were phased out of US service in 1969, with most of them were passed on to other Southeast Asian air forces.
The AC-47Ds were replaced by the Fairchild AC-119G Boxcar gunship for in-country operations, where the enemy didn't have heavy anti-aircraft weapons. Out-country operations were farmed out to the much more fearsome Lockheed AC-130A Hercules / Spectre gunship.
* Although numbers of Dakotas in military service have continuously declined since World War II, they still remain in operation in many countries, particularly in Latin America. At least a hundred are still hauling freight across North America on a commercial basis, while about 200 are flying in the US as showpieces and trophy aircraft. The Dakota remains in commercial service because it is cheap to buy and operate, and there are ample supplies of parts to keep it in the air.
The major problem is that the R-1830 Twin Wasp engines are at the end of their lifetimes. As a result, there is an active trade in re-engining old Dakotas, invariably to turboprop operation.
The earliest turboprop conversion was done by Armstrong Siddeley in 1949 to flight-test Mamba turboprop engines, though the aircraft was eventually refitted with Twin Wasps and sold. Rolls-Royce similarly refitted a Dakota with Dart turboprops in 1950. These were strictly engine test fits and not intended for production. However, in recent decades several different types of "Turbo Dakotas" have seen operational service.
One of the earlier operational Turbo Dakotas was the US Conroy "Tri Turbo-3", which was fitted with three Pratt & Whitney Canada PT6A-45 turboprops with 876 skW (1,174 SHP) each. Two of the turboprops replaced the radial engines, while the third was fitted in the nose. The Tri Turbo appears to have had mixed success. Although it had an excess of power and good short-field characteristics, the fit of the nose information was something of a "kluge", and the flight crews suffered from engine exhaust inhalation.
Modern Turbo Dakotas use twin engines, almost always some version of the popular PT6A. Basler Corporation of Oshkosh, Wisconsin, has been particularly successful with their "BT-67 Turbo Dakota". Basler buys old Dakotas in good condition for about $150,000 US, "zero-lifes" the airframe by replacing worn components and adding reinforcement, replaces the R-1830s with PT6A-67R turboprops driving five-bladed Hartzell propellers, and in general modernizes the aircraft.
The modernizations include adding a 1 meter (40 inch) plug and eliminating the unnecessary radio operator's compartment so that the cargo bulkhead can be moved forward, giving the BT-67 35% more internal volume. The radio operator is no longer requires because a BT-67 has up-to-date avionics, as well as new electrical, hydraulic, and fuel systems. The wings are modified to give them improved low-speed capabilities and a "squared-off" appearance.
A BT-67 can carry 1,800 kilograms (4,000 pounds) more cargo than a DC-3, and increases the cruise speed by 72 KPH (45 MPH), while reducing approach speed. A bright shiny "new" BT-67 costs $4 million US. Five BT-67s were fitted with a forward looking infra-red (FLIR) turret under the nose, armed with 12.7 millimeter machine guns slaved to the FLIR turret, and sold to Columbia to combat drug insurgents. BT-67s are used all over the world, with the aircraft flown in Thailand to seed clouds and by the US Forest Service in America to drop smoke jumpers.
By the way, Basler now owns the Conroy Tri-Turbo and hopes to eventually recondition it as an important landmark in the Dakota's history.
The South African Air Force (SAAF) has performed at least 30 "C-47TP Turbodak" conversions. The SAAF uses their Turbodaks for everything from VIP transport to electronic intelligence and maritime patrol. The C-47TPs used in maritime patrol are fitted with FLIR turrets in the nose.
* The DC-2 not only led to the DC-3 / C-47, it also led to a series of bomber derivatives, the "B-18 Bolo" and its successor, the "B-23 Dragon".
The Bolo was developed in response to an Air Corps request issued in August 1934 for a new multi-engine bomber to replace the current first-line USAAC bomber, the Martin B-10. The request specified a multi-engined bomber aircraft that could carry a useful bombload at a cruising speed of 354 KPH (220 MPH) at an altitude of 3.05 kilometers (10,000 feet) for ten hours. Top speed was to be 400 KPH (250 MPH). Douglas engineers basically attached the DC-2 wings, tail, and engines to a new bomber fuselage, and entered their candidate, which they called the "DB-1 (Douglas Bomber 1)", into the competition.
Evaluations of the DB-1 and its competitors, the Boeing "Model 299" and the "Martin 146", were conducted by the USAAC at Wright Field in August 1935. The Model 299 would eventually become the B-17 Flying Fortress, but the Boeing aircraft crashed, and was felt to be much too expensive anyway. The Martin 146 was an evolved version of the B-10 and basically older technology. The DB-1 was somewhat more state-of-the-art, not to mention cheap, and won the competition.
A batch of 133 were immediately ordered, to include delivery of the DB-1 prototype to the USAAC. The new bomber was given its B-18 designation in January 1936, and the Bolo began operational service with USAAC units in 1937. The B-18 featured Wright R-1820-45 Cyclones with 694 kW (930 HP) each and driving three-bladed variable pitch propellers. While the wing was derived from the DC-2, the wingspan was also shortened by 1.68 meters (5 feet 6 inches). The new fuselage was deeper than the DC-2's, giving the aircraft a somewhat whale-like appearance.
The B-18 carried a crew of six and up to 2,040 kilograms (4,500 pounds) of bombs, and was armed with three 7.62 millimeter (0.30 caliber) machine guns, firing from flexible positions in the nose, from the belly, and from a peculiar dorsal turret that looked like a glassed-in hatbox and could be retracted. The B-18 had a range of 1,930 kilometers (1,200 miles) and a top speed of 350 KPH (215 MPH).
The last of the 133 B-18s built was fitted with a power-operated nose turret and given the company designation "DB-2", but the Air Corps wasn't impressed with this feature. Instead, in 1937 they ordered 177 improved "B-18As", followed by another order for 40 in 1938. The B-18A featured uprated Wright R-1820-53 engines with 746 kW (1,000 HP) each, an extended glass nose that gave the aircraft a somewhat more sharklike appearance, and replacement of the odd glass hatbox turret with a dorsal "greenhouse".
The Bolo was the USAAC's firstline bomber in 1940, and indeed 33 were lined
up in rows at Hickam Field in Hawaii when the Japanese struck at Pearl Harbor
on 7 December 1941, with most of these aircraft destroyed. They were no
great loss, since the Bolo's low speed and pathetic defensive armament made
combat missions in them over defended territory sheer suicide. The Bolo was
quickly replaced in firstline service by better bombers, most ironically the
B-17, the descendant of the Model 299 that the Bolo had defeated in the USAAC
competition in 1935.
DOUGLAS B-18 BOLO:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 27.28 meters 89 feet 6 inches
wing area 89.09 sq meters 959 sq feet
length 17.27 meters 56 feet 8 inches
height 4.62 meters 15 feet 2 inches
empty weight 7,144 kilograms 15,750 pounds
MTO weight 12,286 kilograms 27,097 pounds
max speed at altitude 349 KPH 217 MPH / 189 KT
cruise speed 269 KPH 167 MPH / 145 KT
service ceiling 7,375 meters 24,000 feet
range (typical) 1,368 kilometers 850 MI / 739 NMI
_____________________ _________________ _______________________
Twenty B-18As were also operated by the Royal Canadian Air Force as "Digby 1s" for coastal patrol until 1943. Some Bolos were converted, in another irony, for use as transports, two of these conversions being given the designation "C-58", and other Bolos were flown as hacks. During the war, 18 B-18As were stripped down of most combat gear and used as trainers, being given the new designation "B-18AM", and then another batch of 22 B-18As were similarly converted to trainers and redesignated "B-18M".
* The Army Air Corps had misgivings about the B-18 early on, as might be expected for an aircraft whose major virtue was that it was cheap. Although there was thought of fitting the B-18 with uprated Wright R-2600-3 Cyclone 14 radial engines with 1,195 kW (1,600 HP) each, with this improved variant to be given the new designation of "B-22", but it never happened.
Instead, in 1938 Douglas came up with a comprehensive redesign of the B-18. The USAAC liked the proposal and ordered 38 of the improved derivatives under the designation "B-23 Dragon". The first B-23 performed its initial flight on 27 July 1939. It was a production-specification machine, a prototype having been judged unnecessary, and the rest of the batch was delivered in 1939.
The B-23 had a general appearance along the lines of the B-18, but it differed greatly in detail, being aerodynamically much cleaner, and fitted with DC-3 wings and a much taller tailfin reminiscent of that of the Boeing B-17.
The B-23 was one of the first US bombers with a tail gun position, the tail gunner being armed with a single 12.7 millimeter (0.50 caliber) Browning machine gun on a flexible mount. There were also flexible mounts for a single 7.62 millimeter (0.30 caliber) Browning in the nose, and in a dorsal and a ventral position, for a total defensive armament of four machine guns. Bombload was 2,000 kilograms (4,400 pounds), carried in an internal bomb bay, and the Dragon could also be fitted for photo-reconnaissance.
The B-23 was powered by twin R-2600-3 Cyclone 14s, fitted in lengthened
nacelles that featured full retractable landing gear. In between the cleaner
airframe and the more powerful engines, the B-23 was expected to demonstrate
substantial performance improvements over the B-18, but evaluations showed
that it didn't meet expectations. Furthermore, with a war going on in
Europe, by 1940 the B-23 was increasingly seen as inadequate for combat in
all respects.
DOUGLAS B-23 DRAGON:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 28.04 meters 92 feet
wing area 92.25 sq meters 993 sq feet
length 17.8 meters 58 feet 5 inches
height 5.63 meters 18 feet 6 inches
empty weight 8,659 kilograms 19,089 pounds
MTO weight 14,696 kilograms 32,400 pounds
max speed at altitude 454 KPH 282 MPH / 245 KT
cruise speed 338 KPH 210 MPH / 185 KT
service ceiling 9,360 meters 31,600 feet
range (typical) 2,255 kilometers 1,400 MI / 1,215 NMI
_____________________ _________________ _______________________
However useless the B-23 was for combat, it was a solid and airworthy machine, and after the war many B-23s and UC-67s were converted to executive aircraft, mostly by Pan Am, with a crew of two and up to 12 passengers. Some of them survived in civil service into the 1970s. The careers of the Bolo and Dragon were as undistinguished as the C-47's was illustrious. A number of Bolos and Dragons survive today as museum exhibits.
* I found some interesting details in the sources that didn't fit conveniently in any of the sections above. One of the details was that apparently some British DC-2s or DC-3s that were pressed into service in Britain were actually fitted with Bristol Pegasus radial engines, though I have no specifics. Another tale is that of the "DC-2-1/2", which was thrown together on an emergency basis in China, and had one DC-2 wing and one DC-3 wing. This is obviously an interesting story and it seems unfortunate that more details aren't available.
* As this document is part of a series on WINGS OF THE USAAF, I chose to write it about the C-47, not the DC-3, and my apologies to purists who may be annoyed by that decision. The selection of the name Dakota is a little more arbitrary, but it does seem like the predominant name for the aircraft in military service, and I like the sound of it anyway.
* Sources include:
I picked up a few details from a Discovery Channel TV show called THE MACHINES THAT WON THE WAR, and I found a surprising number of detailed websites on the Dakota. There's some really dedicated fans out there, but I should caution that I'm really not among them. I do like the C-47 and anybody who has read this document should realize I have a lot of respect for it, but I wrote this just to provide some variety in my WINGS OF THE USAAF series. One grows tired of "fighters, fighters, fighters", and besides, as Eisenhower put it, it was one of the machines that really won the war.
* Revision history:
v1.0 / 01 apr 00 / gvg
v1.1 / 01 jun 00 / gvg / Cleanup and tweaks, added B-18 Bolo section.
v1.2.0 / 01 feb 03 / gvg / Cleanup, added B-23, details on Li-2 & L2D.