Apr 9 2021 - Apr 9 2021

Douglas DC-4, DC-6, & DC-7


The DC-4: Transoceanic Landplane

False Start
Following joint discussions in 1936, between Douglas and Pan American and the Big Four U.S. domestic airlines, each of the five subscribed $100,000 towards the cost of developing the DC-4E, designed to carry 11,000 lb. of payload or 60 passengers over a range of more than 1,000 miles. The DC-4E first flew on 7 June 1938 and was the first large airliner to feature a nose wheel as well as the main landing gear. After flying some experimental services, however, United Air Lines, the main sponsor, was unable to persuade its four partners to persevere with it, and it was eventually sold to Japan. Attention was then switched to a smaller aircraft, the DC-4.

A Real Winner
On 26 January 1940 the group of five, with the exception of T.W.A. (Howard Hughes was beginning his close relationship with Lockheed) ordered a total of 61 DC-4s. Pan Am's contract for three was signed on 24 April of that year, and ó unlike the others ó specified a pressurized cabin, although none was so delivered. Juan Trippe must have been impressed, as from September 1941 to March 1942 Pan Am brought the total order up to 28. They cost $160,000 each, a bargain price.

The DC-4 made its first flight on 14 February 1942, by which time the United States was heavily involved in World War II. The Douglas long-range landplane could not have come at a better time. It went into service as the Army's C-54 and the Navy's R5D and altogether, 1,163 were built. Almost 80,000 ocean crossings were made during the war, including a 250-strong armada which delivered two divisions of troops to Japan from Okinawa, following the surrender.

The Floodgates Open
As soon as hostilities ceased, the C-54s and R5Ds were released in great numbers and the big airlines could not get their hands on them quickly enough. Some had already operated them with aircraft leased from the armed forces, and the U.S. airline industry went into high gear. Pan American was no exception. As the accompanying table shows, ten had been delivered by the end of 1945, twenty during the following year, and so on to a total of no less than 92 Douglas DC-4s.

Douglas DC-4: Cinderella Status
The outbreak of war in Europe in September 1939 put an end to four-engined designs and projects such as the German Focke-Wulf Fw 200 Condor, which had flown nonstop from Berlin to New York and then back again in 1938 The British and the French had to abandon four promising designs to concentrate on more pressing requirements. Meanwhile, the Douglas DC-4 in a sense broke the transocean barrier, with its rapid development, massive production, and wide deployment by military and commercial operators alike.

Often remembered is the DC-4's lack of pressurization and its markedly slower speed, compared with its DC-6 and DC-7 developments, and of course with the Lockheed Constellation which broke the Douglas dominance by outstripping the DC-4 rather spectacularly. More often forgotten is the record of the intercontinental airlines, U.S. and foreign alike, almost all of which inaugurated their prestigious postwar trunk routes with DC-4s.

End of an Era
In an epoch-making mission, Pan American dispatched a DC-4 on 21 October 1945 on a 25,000-mile survey flight to Japan, China, southeast Asia, and India. The message was clear. To underscore the point, Pan Am replaced its Boeing 314s on the California-Honolulu route with DC-4s. The daily flight took about 10 hours, compared with the Boeing's 20, and the fare was reduced from $278 one way to $195. The era of the flying boat was at an end.

The DC-6B

The Thoroughbred Airliner
In company with the world's leading airlines, Pan American had resumed full peacetime service after World War II with the reliable Douglas DC-4, already route-proven by the U.S. Army Air Forces as the C-54 (or the Naval R5D). But Juan Trippe had turned promptly to the Lockheed Constellation as this aircraft demonstrated its clear superiority of performance, not to mention its pressurized comfort, over its Douglas rival. Even though the Boeing Stratocruiser supplemented the "Connie" on the prestige routes, however, Pan Am went back to Douglas as the Old Firm responded to Lockheed's challenge, and produced an airliner which could match the Constellation.

Pan American ordered 45 Douglas DC-6B's during the month of September 1950. All were delivered between February 1952 and June 1954. The first one to enter service was the Clipper Liberty Bell which, on 1 May 1952, inaugurated the all-tourist Rainbow service on the prestigious New York-London route. This one was fitted with 82 seats, although a more typical all-tourist arrangement was 88. The DC-6B's capacity varied from 44 first-class to 109 economy class, and it was a truly versatile aircraft. (Pan Am also had five of the DC-6A all-cargo version.)

But it was upstaged. Its contribution to widening the scope of air travel, with its good economics permitting Pan Am to offer the newly-agreed tourist class fares, was all but forgotten in the blaze of publicity that accompanied the opening of the world's first jet airliner service, by the British Comet, on B.O.A.C.ís route from London to Johannesburg, the day after the Liberty Bell's debut.

The two events were perhaps symbolic. As the Comet ushered in the new jet age, the Douglas airliner represented the pinnacle of achievement of the great long-range piston-engined types. Most of Pan American's DC-6B's served until well into the 1960s, and the last fifteen were finally sold on 17 September 1968. They were to make them bigger and faster and with more range than the 6B, but they never made them better.

Development of the DC-6B
Responding to the challenge of Lockheed to outclass its four-engined DC-4, already route-proven with the U.S. Air Forces during the latter part of World War II as the C-54 and the R5D, Douglas stretched the DC-4's fuselage by seven feet, and pressurized it. The launching airline was United, which put the new DC-6 into service on 27 April 1947. After being grounded for four months in the winter of 1947-48 because of inflight fire problems, this aircraft was further improved when Slick Airways, an all-cargo operator, ordered the DC-6A, a freighter version, and even longer. This type was then produced in a passenger version, the DC-6B, five feet longer than the DC-6 (and twelve feet longer than the DC-4). United put it into service on 11 April 1951.

The aircraft was considered to be marginally more economical to operate than the Constellation, and from an engineering viewpoint was easier to put through the system of inspection, maintenance, and overhaul checks, for both airframes and engines. Although later developments of the Douglas line were to outperform the 6B, this was the aircraft that wise old airline folk would refer to as a thoroughbred. A total of 288 DC-6B's were built for the airlines, plus 175 DC-6s. Including military versions, 704 of the DC-6/DC-6A/ DC-6B type were produced by Douglas.

The DC-7C

Non-Stop Trans Atlantic At Last - The Competition Intensifies
The U.S. coast-to-coast competition between Douglas and Lockheed was repeated on the North Atlantic. Aiming for the non-stop prize, Pan American matched its best equipment against T. W. A.'s Super Constellations, constantly being improved by Kelly Johnson and Lockheed at Burbank. At first Pan Am fitted some of its Stratocruisers with extra tanks, and then introduced the DC-7B, a slightly improved version of the DC-7, on 13 June 1955. T.W.A.ís L.1049G, the Super-G, began service on 1 November 1955, and Pan Am answered back with the DC-7C, the Seven Seas, on 1 June 1956.

Juan Trippe stuck with the Seven Seas to see Pan American through to the Jet Age. On the North Atlantic, which by now had become the prestige air route of the world, he had to watch patiently as the British airline, B.O.A.C., stole some traffic away with the Britannia (see opposite page). T. W A. also lost some ground, and came close to ordering the British aircraft, and might have done so, had Howard Hughes learned more about it sooner. But the die was cast in preparation for the Jet Era and Juan Trippe had been a major instrument in the casting process.

The Polar Route
With the growing importance of California as a leading economic center with an affluent and mobile population, direct service from Europe to the West Coast became justified. The Scandinavian airline S.A.S. was the pioneer, opening service with DC-6Bs on 15-16 November 1954, using airfields in Greenland and Canada as en route stops. The time saved was considerable: as the flight took about 20 hours instead of about 30 via New York. Canadian Pacific Airlines joined S.A.S. on 3-4 June 1955, but Pan American waited for the availability of enough DC-7Cs so that it could open service on the Great Circle Route on 11 September 1957 with fewer stops. T.W.A. followed suit with L.1649A Star-liners on 2 October of that year.

Prelude to the Jet Age
For such an advanced aircraft, the DC-7C had a short service life. Pan American's first DC-7B had been delivered in May 1955, but it only had seven of this series, and had ordered 26 DC-7Cs, including the freighter version, on 14 July 1954. The first one was delivered on 23 April 1956, only two and a half years before Pan American itself was into the Jet Age. They cost $2,250,000 each but within ten years most were disposed of to aircraft traders or the occasional nonscheduled airline; and some were even sold as scrap, an ignominious end to a fine example of commerical airliner technical development.

Douglas DC-7C The "Seven Seas" - The Spur of Competition
Lockheed had stolen a march on Douglas by producing the Constellation, sleek, fast, and pressurized, to threaten the Santa Monica manufacturer's grip of the commercial market. Douglas was forced to act quickly with an improved version of the DC-4, the DC-6 series. Then, T.W.A. introduced the first U.S. transcontinental nonstop service in October 1953 with the L.1049C version of the Super Connie. One month later, American Airlines responded with the Douglas DC-7, matching the nonstop capability.

The Seven Seas
Douglas then produced a development of the DC-7, the DC-7B, with a slightly higher gross weight, permitting either more payload or longer range. Pan American was the first to place this into service, but was followed by only three other U.S. domestic operators before Douglas developed the breed even further. Hitherto, all the four-engined Douglases had flown on the same wing ó only the fuselage was stretched. Now in 1956, an extra wing section was added, increasing the wing area by 12 percent, thus enabling weights, payloads, and tankage all to be increased. The wing also allowed the engines to be placed five feet further away from the fuselage, which was a definite advantage, as the Wright turbo-compound R-3350s tended to have high noise and vibration levels. This DC-7C was neatly called The Seven Seas. Douglas sold just over 300 of all three DC-7 types, less than the DC-6B production and sales alone. It was the end of the line.

Swan Song of an Airline Generation
Lockheed and T.W A. played one more competitive card with the L.1649A Star-liner which had marginally more range than the DC-7C. Its debut was on 1 June 1957, and the British Bristol Britannia, agonizingly delayed by a series of misfortunes, entered service on the London-New York route non-stop in both directions, on 19 December 1957. The Whispering Giant, as it was called, because of its quiet engines, was the harbinger of Things to Come; for the engines were Bristol Proteus turboprops.
  • Apr 9 2021 - Apr 9 2021

  • Pressurized Planes

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