Classic Aviation Photography

DC-7

The last piston engine aircraft produced in Long Beach by the Douglas Aircraft Company

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NC4201 Douglas C-74 of Pan American World Airways impression in 1945.
Pan American via Zoggavia collection

The original project of the Douglas DC-7 was a civil version of the military transport C-74 'Globemaster 1' but never reached the market introduction despite a first order of 26 aircraft from Pan American World Airlines.

As the limited military production run increased the cost per civilian aircraft Pan American canceled its order. Douglas then dropped the DC-7 project. The DC-7 designation was later used for a completely different civilian airliner project in the early 1950s, having no relationship to the C-74.


DC-7 

After much persuasion of the President of American Airlines, C.R. Smith, Douglas decided to modify the DC-6B around the new Curtiss-Wright R-3350 turbo-compound engine available for civil use late in 1951. This new power plant developed 3'250 hp for take-off and the increased power brought the speed up to 360 mph (560km/h), which also gave an improved range allowing transcontinental operations the first time. The DC-7 differed further from the DC-6B in having a 40inch (1,02m) stretch in fuselage length, and four bladed propellers.

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N304AA Douglas DC-7 of American at Los Angeles in 1956. Zoggavia collecetion

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Magnificent view of the mighty Curtiss Wright R-3350 988TC-DA-2 turbo compound radials each delivering 3250 hp of an American Airlines Douglas DC-7 on route from Idlewild to San Diego on on 1955. Zoggavia collection

The first flight was on 18 May 1953, and American Airlines introduced the first of totally 25 ordered new airliner on the daily non-stop New York - Los Angeles service on 29 November 1953, reducing the coast to coast flying time to 8hrs 45min westbound and 8hrs eastbound. The DC-7 was not as economical per seat mile as the DC-6B and the market was limited to four major U.S. airlines; American (24), National (4), Delta (10) and United (57 in total), resulting in a total production of 105 aircraft.


DC-7B

The DC-7B was basically designed as a long range version of the DC-7, which included greater fuel capacity the nacelles to from saddle tanks and an increased all-up weight. Many of the aircraft delivered did not incorporate these arrangements.

As an interim measure to compete with the Super Constellations Pan American World Airways introduced DC-7B's on its transatlantic service from New York to London 13 June 1955, though they were later transferred to more suitable routes owing to the inadequacy of their range on these transatlantic routes.

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N51700 Douglas DC-7 B 'El Americano' of Panagra at Miami International in 1957. Mel Lawrence via Zoggavia collection

DC-7C

When the development of the DC-7B was under way, Douglas realized the potential of the new 3 '400 hp version of the Wright R-3350 engine in manufacturing an even longer version of the DC-7 capable of flying the most important transatlantic routes non-stop in both directions and in all but the most adverse weather conditions.

This ability was later used under the synonym 'Seven Seas', meaning all seas could be crossed non-stop.

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Douglas DC-7C HB-IBK of Swissair seen air to air in November 1956. This DC-7 was later the only type used in military service as F-ZBCA operated by the l'Armee de l'Air, French Air Force, in 1963. Zoggavia collection

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N70C, the Douglas DC-7C prototype during one of the its test flight along the Californian coast. This version was called Seven Seas as it was capable to cross every sea due to its increased range. This aircraft was later sold to Panair do Brasil as PP-PDO. Zoggavia collection

The fuel capacity was increased by an additional 5 foot (1,5 ) wing section inserted between the inboard engine and the wing root, thus giving the DC-7C an extra 10 foot (3m) wing span. This gave an additional capacity of 1'000 gallons (4'450 l) resulting in a range of 5'600 miles (9'000 km). A further 42 inch (1,06 m) fuselage ahead of the wings, and a taller fin and rudder to cope with the greater power and weight. The DC-7C's managed the a considerable share of the passenger traffic across the North Atlantic until the Boeing 707 and DC-8 jetliners were introduced in 1959 and 1960. Plans for a turboprop version, designated DC-7D, with Rolls Royce Tyne engines never materialized. All DC-7 built; 338 of all series.

DC-7B/F and DC-7C/F

There were no all-freighter aircraft as such, built by Douglas, with the sole purpose of use for cargo operations only. All conversions made by Douglas involved standard series DC-7 aircraft, with the installation of two large freight doors and a stronger cabin floor plus other modifications based on specifications of the individual airline were made.

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American Airlines converted several DC-7B aircraft into freighters. Here N345AA is seen receiving its load in 1963, Clinton H. Groves via Zoggavia collection

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PH-DSG DC-7C/F KLM pictured together with a sister ship in the cargo area of the airport of Amsterdam in 1965, Zoggavia collection

The first DC-7A went in service with American Airlines in September 1959. Conversion orders were placed by American Airlines, 15 DC-7B, United 6 DC-7B, Panagra one DC-7B, KLM two DC-7C, Alitalia two DC-7C, BOAC two DC-7C, Japan Air Lines two DC-7C and Riddle three DC-7C (plus seven more on option).

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N6344C Douglas DC-7A in United Airlines colors with its forward  freight door open. San Francisco in 1965. Zoggavia Collection

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Same aircraft showing the rear cargo door. San Francisco in 1965. Zoggavia Collection

Other DC-7 series conversions were carried out by other companies and airlines. These conversions merely had the letter 'F' added to the original designation. The DC-7 freighters replaced the Douglas C-54 / DC-4 and Douglas DC-6 freighters until the introduction of DC-8F and Boeing B707C on the major long haul routes.

Operators

Civil

Military

Aerochago
Aerolineas Peruanas
Aeronorte Colombia
Aerovias Panama
Aer Turas
Affretair
Air Caribbean Air Transport
Airlift
Air Tankers
American Airlines
AMSA
Alitalia
Arco Bermuda
Area
Atlantis
Boac
Butler Aviation
Braniff
Caledonian
Conair
Continental
Dan-Air London
Denver Ports of Call
Delta
Eastern Air Lines
FAA
Flying Enterprise
Internord
Interocean
Japan Air Lines
KLM
Liberty Air
Madair
Martinair
Mexicana
Modern Air
National Airlines
Nordseeflug
Northwest Orient
Ostermanair
Overseas National
Pacific Air Transport
Pacific Western
Panagra
Pan American World Airways
Panair do Brasil
Riddle Airlines
Royal Jordanian Airlines
Sabena
SAS
Saturn
Schreiner Airways
Shannon Air
South African Airways
Spantax
Standard Airways
Swedish Red Cross
Swissair
TAE
TAI
Tan Airlines
Tassa
Teca Trans Europa
THY Turkish Airlines
Trans Meridian
Transair
Transair Sweden
United
United States Overseas
Vance International
Zantop

French Air Force