Douglas DC-6

The Douglas DC-6 is a piston-powered airliner and transport aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, it was reworked after the war to compete with the Lockheed Constellation in the long-range commercial transport market. More than 700 were built and many still fly today 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 prior to 1962, after which all U.S. Navy variants were also designated as the C-118.

Design and development
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 popular 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 By the time the prototype XC-112A flew on 15 February 1946 the war was over, the USAAF had rescinded its production requirement for the transport, and the aircraft was converted to YC-112A, being sold in 1955.

Douglas Aircraft modified the design into a civil transport and the civil DC-6 first flew on 29 June 1946, being retained by Douglas for testing. The first airline deliveries were made to American Airlines and United Airlines on 24 November 1946. A series of inflight fires (including the fatal crash of United Airlines Flight 608) grounded the DC-6 fleet in 1947. The cause was found to be a fuel vent next to the cabin cooling turbine intake; all DC-6s were modified and the fleet was flying again after four months on the ground.

Operational history
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 trans-Atlantic tourist class flights in 1952. These were the first DC-6Bs that could gross 107,000 lb, with CB-17 engines rated at 2,500 hp on 108/135 octane fuel. Several European airlines followed with their own transatlantic services. The DC-6A/B/C sub-types could perhaps fly non-stop from the eastern US to Europe but needed to refuel in Newfoundland (and perhaps elsewhere) when westbound against the wind.

Douglas designed four variants of the DC-6: the basic DC-6, and the longer fuselage, higher-gross-weight, longer-range versions—the DC-6A with cargo doors forward and aft of the wing on the port (left hand 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.

The military version, similar to the DC-6A, 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. The R6D Navy version (in the late 1950s and early 1960s) had Curtiss Electric constant-speed reversing propellers.

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.

In the 1960s two DC-6s were used as transmitter platforms for educational television, based at Purdue University, in a program called MPATI (Midwest Program on Airborne Television Instruction).

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 has meant that the type has outlived the DC-7, particularly for cargo operations. DC-6/7s surviving into the Jet Age were replaced in front line inter-continental passenger service by Boeing 707 and Douglas DC-8 aircraft.

2006 marked the 60th anniversary of the introduction of the DC-6.

Basic prices of a new DC-6 in 1946–47 was around £210,000–£230,000 and had risen to £310,000 by 1951. By 1960 used prices were around £175,000 per aircraft.

Prices for the DC-6A in 1957–58 were £460,000–£480,000. By 1960, used prices were around £296,000.

Equivalent prices for the DC-6B in 1958 were around £500,000. Used prices in 1960 were around £227,000.

Variants



 * XC-112A
 * United States military designation of an improved version of the C-54 (DC-4); became the prototype DC-6. Eventually designated YC-112A, pressurized, P&W R-2800-83AM3 engines


 * DC-6
 * Initial production variant produced in two versions.
 * DC-6-1156 a 53- to 68-seat domestic variant with 2,400 hp R-2800-CA15 engines
 * DC-6-1159 a 48- to 64-seat trans-ocean variant with extra crew, increased fuel capacity to 4722 US Gallons, increased take-off weight to 97,200 lbs and 2,400 hp R-2800-CB16 engines.


 * DC-6A
 * Freighter variant; fuselage slightly lengthened from DC-6; fitted with cargo door; some retained cabin windows, others had windows deleted. Originally called "Liftmaster" as USAF models. The rear cargo door came standard with a built in 4,000 lb lift elevator and a Jeep. The Jeep was a public relations stunt and shortly after, dropped.


 * DC-6B
 * All-passenger variant of DC-6A, without cargo door.
 * DC-6B-1198A a 60- to 89-seat domestic variant with 2,400 hp R-2800-CB16 engines
 * DC-6B-1225A a 42- to 89-seat trans-ocean variant with increased fuel capacity to 5,512 US Gallons and 2,500 hp R-2800-CB17 engines and increased take off weight to 107,000 lbs.


 * DC-6B-ST
 * Swing tail freighter conversion to the DC-6B done by Sabena. Two converted.


 * DC-6C
 * Convertible cargo/passenger variant.


 * VC-118
 * United States military designation for one DC-6 bought as a presidential transport with special 25-seat interior and 12 beds.


 * C-118A
 * Designation of DC-6As for the United States Air Force, 101 built.


 * VC-118A
 * C-118As converted as staff transports.


 * C-118B
 * R6D-1s re-designated.


 * VC-118B
 * R6D-1Zs re-designated.


 * R6D-1
 * United States Navy designation for the DC-6A, 65 built.


 * R6D-1Z
 * Four R6D-1s converted as staff transports.

Current operators
Today most DC-6s are inactive, stored, or preserved in museums; although a number are still flying in northern bush operations in Alaska and Canada, while several are based in Europe and a few other DC-6s are still in operation for small carriers in South America.


 * One DC-6A, G-APSA, is based in the UK and available for private charter.
 * One DC-6B is in use by Red Bull in Salzburg, Austria.
 * One DC-6B V5-NCG "Bateleur" is in use with Namibia Commercial Aviation. This was the last DC-6 off the Douglas production line and the last DC-6 in the world in passenger configuration still flying commercially.
 * , several are in use as freighters or waterbombers in Canada. They are no longer used as retardant bombers in the western United States.
 * As of 2011, Everts Air Cargo operates eight DC-6s and two C-46s.

Former operators
A great number of 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 article listing the operators of the Douglas DC-6.

Survivors
Several DC-6s are preserved in museums. In all, There are 147 surviving aircraft including 47 airworthy ones.
 * The most well-known is President Harry S. Truman's VC-118 Independence (s/n 46-505), which is preserved at the National Museum of the United States Air Force, at Wright-Patterson Air Force Base in Dayton, Ohio. The aircraft is on display in the Museum's Presidential Hangar.
 * A DC-6B currently owned by Red Bull was once the private luxury transport of Yugoslav President Josip Broz Tito.
 * As of March 2010, there was a C-118 located in the "bone yard" of MCAS Cherry Point, North Carolina. This was at one time the official aircraft of the Commandant of the Marine Corps. The aircraft was often left open to the weather and has deteriorated quite a bit. The interior is damaged, but the airframe is largely intact.
 * The Navy's initial R6D, Bureau Number ("BuNo") 128424, was converted along with six other 128XXX-series Buno R6Ds to VC executive transport configuration. BuNo 128424 was delivered to VR-21, NAS Barbers Point in February 1955 and remained in service $28 1/2$ more years until October 1, 1983. It was used as a flag transport for the Commander, U.S. Pacific Fleet. BuNo 128424 is now located at the National Museum of Naval Aviation at NAS Pensacola, Florida.
 * A C-118A is in the collection of the Jimmy Doolittle Air & Space Museum, located located at Travis Air Force Base in Fairfield, California. This aircraft served first in the US Air Force (s/n 51-17651), and was later transferred to the US Navy (BuNo131602).
 * A DC-6B ZS-MUL #45329 named Empress of Suva is preserved on a small holding at Wallmanstahl, north of Pretoria South Africa. This aircraft was stored at Swartkop Air Force Base for over 10 years. After two years of restoration by enthusiasts, it was ferried to Wallmanstahl, where a temporary runway had to be constructed.
 * A restored USAF C-118 Liftmaster is located at Joint Base McGuire-Dix-Lakehurst, New Jersey. This aircraft is notable as the aircraft in which Elvis Presley returned to the United States after serving in the US Army in Germany. Presently,, under restoration.
 * DC-6B G-SIXC, built in September 1958, spent most of its life in Southeast Asia, and now resides at Coventry Airport, England. After serving with the CIA and Royal Air Lao, it was bought by Air Atlantique Group in 1987. Its last commercial flight was on October 26, 2004, although it was later featured in the 2006 James Bond film, Casino Royale. No longer flying, it has now been turned into a static restaurant based at Coventry airport, as the "DC-6 Diner".

Specifications


A note of interest is that the diagram depicts the sleeper version of the early short fuselage DC-6. The very small windows above the standard ones permitted passengers in their Pullman-style bunks a view of the outside.