| DC-6 | |
|---|---|
|   A Douglas DC-6B of Western Airlines, Oct 1956 | |
| General information | |
| Type | Airliner/transport aircraft | 
| Manufacturer | Douglas Aircraft Company | 
| Status | In limited service | 
| Primary users | Pan American World Airways | 
| Number built | 704 | 
| History | |
| Manufactured | 1946–1958 | 
| Introduction date | March 1947 with American Airlines and United Airlines | 
| First flight | 15 February 1946 | 
| Developed from | Douglas DC-4 | 
| Developed into | Douglas DC-7 | 
The Douglas DC-6 is a piston-powered airliner and cargo aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, Douglas reworked it after the war to compete with the Lockheed Constellation in the long-range commercial transport market. Douglas built over 700, and many still fly in cargo, military, and wildfire control roles.
The DC-6 was known as the C-118 Liftmaster in United States Air Force service and as the R6D in United States Navy service before 1962, after which all U.S. Navy variants were also designated as the C-118.
 
 The United States Army Air Forces commissioned the DC-6 project as the XC-112 in 1944. The Army Air Forces wanted a lengthened, pressurized version of the DC-4-based C-54 Skymaster transport with more-powerful engines. By the time the prototype XC-112A flew on 15 February 1946, the war was over, the USAAF had rescinded its requirement, and the aircraft was converted to YC-112A, being sold in 1955. [1]
Douglas Aircraft modified the design into a civil transport 80 inches (2.0 m) longer than the DC-4, with a notable feature being the use of the Pratt & Whitney Double-Wasp 18-cylinder radial engine, a powerplant that had seen considerable refinement and usage in World War II combat aircraft. The civil DC-6 first flew on 29 June 1946, being retained by Douglas for testing. The first airline deliveries were to American Airlines and United Airlines on 24 November 1946. [1] A series of inflight fires, one of which resulted in the fatal crash of United Airlines Flight 608, grounded the DC-6 fleet in 1947. The cause was found to be a fuel tank vent next to the cabin cooling turbine intake; all DC-6s were modified, and the fleet was back in service after four months on the ground.
 
 In April 1949, United, American, Delta, National, and Braniff were flying DC-6s in the United States. United flew them to Hawaii, Braniff flew them to Rio de Janeiro, and Panagra flew Miami-Buenos Aires; KLM, SAS, and Sabena flew DC-6s across the Atlantic. BCPA DC-6s flew Sydney to Vancouver, and Philippine flew Manila to London and Manila to San Francisco.
Pan Am used DC-6Bs to start transatlantic tourist-class flights in 1952. These were the first DC-6Bs that could gross 107,000 lb (49,000 kg), with CB-17 engines rated at 2,500 hp (1,900 kW) on 108/135 octane fuel. Several European airlines followed with transatlantic services. The DC-6B and C subtypes could often fly nonstop from the eastern US to Europe but needed to refuel in Goose Bay, Labrador, or Gander, Newfoundland, when flying westbound into prevailing westerly winds. [2]
Douglas designed four variants of the DC-6: the basic DC-6, and the longer-fuselage (60 in (150 cm)) higher-gross-weight, longer-range versions—the DC-6A with cargo doors forward and aft of the wing on the left side, with a cargo floor; the DC-6B for passenger work, with passenger doors only and a lighter floor; and the DC-6C convertible, with the two cargo doors and removable passenger seats.
The DC-6B, originally powered by Double Wasp engines with Hamilton Standard 43E60 constant-speed reversing propellers, was regarded as the ultimate piston-engine airliner from the standpoint of ruggedness, reliability, economical operation, and handling qualities. [3]
Similar to the DC-6A, the military version was the USAF C-118 Liftmaster; the USN R6D version used the more powerful R-2800-CB-17 engines. These were later used on the commercial DC-6B to allow international flights. [4] The R6D Navy version (in the late 1950s and early 1960s) had Curtiss Electric constant-speed reversing propellers.[ citation needed ]
The USAF and USN renewed their interest in the DC-6 during the Korean War and ordered 167 C-118/R6D aircraft, some of which later found their way to civil airlines. Harry Truman's first presidential aircraft was an Air Force short-fuselage DC-6 which was designated VC-118, and named The Independence. It is preserved in the National Museum of the United States Air Force at Dayton, Ohio.
Total production of the DC-6 series was 704, including military versions. [5]
In the 1960s two DC-6s were used as transmitter platforms for educational television, based at Purdue University, in a program called the Midwest Program on Airborne Television Instruction. [6]
Many older DC-6s were replaced in airline passenger service from the mid-1950s by the Douglas DC-7, but the simpler, more economical engines in the DC-6 have meant the type has outlived the DC-7, particularly for cargo operations. DC-6/7s surviving into the jet age were replaced in frontline intercontinental passenger service by the Boeing 707 and Douglas DC-8.
Basic prices of a new DC-6 in 1946–47 were around £210,000–£230,000 and had risen to £310,000 by 1951. By 1960, used prices were around £175,000 per aircraft. [7] Prices for the DC-6A in 1957–58 were £460,000–£480,000. By 1960, used prices were around £296,000. [7] Equivalent prices for the DC-6B in 1958 were around £500,000. Used prices in 1960 were around £227,000. [7]
From 1977 to 1990, five yellow-painted Douglas DC-6Bs were used as water bombers in France by the Sécurité Civile. They were registered F-ZBAC, F-ZBAD, F-ZBAE, F-ZBAP, and F-ZBBU. [8]
 
  
  
  
  
  
 Today, most DC-6s are inactive, stored, or preserved in museums. Several DC-6s fly in northern bush operations in Alaska, while several are based in Europe, and a few are still in operation for small carriers in South America.
Many airlines and air forces from several countries included the DC-6 in their fleets at some point in time; these are further detailed in the list of Douglas DC-6 operators. In the 1980s, several DC-6Bs were used as fire retardant tankers by Conair Aerial Firefighting of Abbotsford, Canada. Douglas sold the last aircraft to Everts Air Cargo in Fairbanks, AK, in the late 2000s.
 
  
 | Variant | DC-6 | DC-6A | DC-6B | 
|---|---|---|---|
| Crew | Three to four | ||
| Capacity | 48-68 passengers | 28,188 lb (12,786 kg) of cargo | 42-89 passengers | 
| Length | 100 ft 7 in (30.66 m) | 105 ft 7 in (32.18 m) | |
| Wingspan | 117 ft 6 in (35.81 m) | ||
| Height | 28 ft 5 in (8.66 m) | ||
| Wing area | 1,463 sq ft (135.9 m2) | ||
| Empty weight | 52,567 lb (23,844 kg) | 45,862 lb (20,803 kg) | 55,357 lb (25,110 kg) | 
| Max takeoff weight | 97,200 lb (44,100 kg) | 107,200 lb (48,600 kg) | 107,000 lb (49,000 kg) | 
| Powerplant (4x) | Pratt & Whitney R-2800-CA15 "Double Wasp" radial engine, 2,400 hp (1,800 kW) with water injection each | Pratt & Whitney R-2800-CB16 "Double Wasp" radial engine, 2,400 hp (1,800 kW) with water injection each | Pratt & Whitney R-2800-CB17 "Double Wasp" radial engine, 2,500 hp (1,900 kW) with water injection each | 
| Propellers | Hamilton Standard 43E60 "Hydromatic" constant-speed props with autofeather and reverse thrust | ||
| Cruise speed | 311 mph (501 km/h) | 315 mph (507 km/h) | |
| Fuel capacity | 4,260 US gal (16,100 L) 4,722 US gal (17,870 L) | up to 5,512 US gal (20,870 L) | |
| Range | 3,983 nmi (7,377 km) | 2,948 nmi (5,460 km) Max payload 4,317 nmi (7,995 km) Max fuel | 2,610 nmi (4,830 km) Max payload 4,100 nmi (7,600 km) Max fuel | 
| Service ceiling | 21,900 ft (6,700 m) | 25,000 ft (7,600 m) | |
| Rate of climb | 1,070 ft/min (330 m/min) | ||
Related development
Aircraft of comparable role, configuration, and era
Related lists