Douglas DC-7

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DC-7
Butler Aircraft Services' DC-7, Tanker 66
Role Airliner/transport aircraft
Manufacturer Douglas Aircraft Company
First flight May 1953
Produced 1953-1958
Number built 338
Developed from Douglas DC-6
Swissair DC-7C in 1961
BOAC DC-7C G-AOIC taking off from Manchester UK in April 1958 for a non-stop flight to New York (Idlewild) (later JFK)
File:1254 CAL DC7B.jpg
A Continental Douglas DC-7B in flight, 1958
DC-7 Cockpit - From the display at the National Air and Space Museum in Washington, DC

The Douglas DC-7 was an American transport aircraft built by the Douglas Aircraft Company from 1953 to 1958. It was the last major piston engine powered transport made by Douglas, coming just a few years before the advent of jet aircraft such as the Boeing 707 and Douglas DC-8.

Design and development

Pan American World Airways originally requested the DC-7 in 1945 as a civilian version of the Douglas C-74 Globemaster military transport. It canceled its order shortly afterward.

American Airlines revived the designation when it requested an aircraft that could fly the USA coast to coast non-stop in about eight hours. Robert Rummel (at the time head of engineering at TWA) has stated that pilot union rules limiting flying time to eight hours per day influenced American's request to Douglas.[1] However, Douglas was reluctant to build the aircraft until American Airlines president C. R. Smith placed a firm order for 25 at a price of $40 million, thus covering Douglas' development costs.

The prototype flew in May 1953 and American received its first DC-7 in November, inaugurating the first non-stop east-coast-to-west-coast service in the country (optimistically scheduled just under the eight-hour limit for one crew) and forcing rival TWA to offer a similar service with its Super Constellations. Both aircraft, however, frequently experienced in-flight engine failures, causing many flights to be diverted.

The original DC-7 was followed by another variant, the DC-7B, which was identical except for slightly greater power and, on some DC-7Bs, increased fuel capacity in extended engine nacelles. South African Airways used this variant on their Johannesburg to London route.

Operational history

The early DC-7s were only sold to U.S. carriers. European carriers could not take advantage of the small range increase in the early DC-7, so Douglas released an extended-range variant, the DC-7C (Seven Seas) in 1956. A 10 feet (3.0 m) wing-root insert added fuel capacity, reduced interference drag, and made the cabin quieter by moving the engines further outboard; all DC-7C's had the nacelle fuel tanks previously seen on Pan American's and South African's DC-7Bs. The fuselage, which had been extended over the DC-6B's by a 40 inches (100 cm) plug behind the wing for the DC-7 and -7B, was lengthened by a similar plug ahead of the wing to give the DC-7C a total length of 112 feet 3 inches (34.21 m).

Since the late 1940s Pan Am and other airlines had scheduled some nonstop flights to Europe; westward nonstops were occasionally possible even in the 1940s, but headwinds made westward nonstops doubtful even for the 1049G and DC-7B. In summer 1956 Pan Am's DC-7C finally started making the westward trip fairly reliably. BOAC was forced to respond by purchasing DC-7Cs rather than wait on the delivery of the Bristol Britannia. The DC-7C found its way into several other overseas airlines' fleets, including SAS, which used them for cross-polar service to North America and Asia. The DC-7C sold better than its closest rival, the Lockheed L-1649A Starliner.[2] However, DC-7C sales were cut short by the arrival of Boeing 707 and DC-8 jet aircraft a few years later.

Starting in 1959, Douglas began converting DC-7 and DC-7C aircraft into DC-7F freighters, which extended the life of the aircraft past its viability as a passenger transport.

The predecessor DC-6, especially the DC-6B model, had established, for its time, a reputation for straightforward engineering and reliability. Pratt & Whitney, the DC-6's R-2800 engine manufacturer, did not offer an effective larger engine apart from the R-4360, a very large and overly-complex engine with a poor reliability reputation. Therefore Douglas turned to Wright Aeronautical for a more powerful engine. The Wright R-3350 however had reliability issues of its own and this affected the DC-7's service record and usage. It was noticeable that carriers which had both DC-6s and DC-7s in their fleets, usually replaced the newer DC-7s first once jets started to arrive. Some airlines had to scrap their DC-7s after little more than five years of service, whereas the vast majority of DC-6s lasted longer and then sold more readily on the secondhand market.

Variants

  • DC-7
  • DC-7B
  • DC-7C
  • DC-7D (Unbuilt)

Operators

Main article: Douglas DC-7 operators
DC-7 in Delta Air Lines livery

Airlines

Historical operators of the DC-7 include Aeromexico, Alitalia, American Airlines, BOAC, Braniff Airways, Caledonian Airways, Delta Air Lines, Eastern Air Lines, Japan Airlines, KLM, National Airlines, Northwest Orient, Panair do Brasil, Pan American World Airways, Sabena, SAS, South African Airways, Swissair, THY, TAI, and United Airlines.

In 2010, 17 DC-7s remained on the U.S. civil aviation registry,[3] used mainly for cargo and as airtankers. Due to its engine problems, the DC-7 has not had the same longevity as the DC-6, which is still used by a number of commercial operators.[citation needed]

Military Operators

Orders and production

Airline DC-7 DC-7B DC-7C Notes
Alitalia 0 0 6
American Airlines 34 24 0
British Overseas Airways Corporation 0 0 10
Braniff Airways 0 0 7
Continental Air Lines 0 5 0
Delta Air Lines 10 10 0
Eastern Air Lines 0 49 0
Japan Air Lines 0 0 4
KLM 0 0 15
Mexicana 0 0 4
National Airlines 4 4 0
Northwest Orient Airlines 0 0 14
Pan American-Grace Airways 0 6 0
Pan American World Airways 0 6 27
Panair do Brasil 0 0 2
Sabena 0 0 10 3 were leased
Scandinavian Airlines System 0 0 14
South African Airways 0 4 0
Swissair 0 0 5
Transports Aériens Intercontinentaux 0 0 4
United Air Lines 57 0 0
Douglas Aircraft 0 2 0 Written off before delivery
0 1 0 DC-7B prototype delivered to Delta Air Lines
0 0 1 DC-7C prototype delivered to Panair do Brasil
Totals 105 111 122 Total built 338

Accidents and incidents

Specifications (DC-7)

DC-7 cockpit

General characteristics

  • Crew: 3 or 4
  • Capacity: 99 to 105 passengers

Performance

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

References

Notes
  1. ^ Rummel, Robert W. Howard Hughes and TWA. Washington, DC: Smithsonian Publications, 1991. ISBN 978-1560980179.
  2. ^ Breffort, Dominique. Lockheed Constellation: From Excalibur to Starliner, Civilian and Military Variants. Paris: Histoire and Collecions, 2006. ISBN 2915239622.
  3. ^ "FAA registration database." FAA. Retrieved: November 26, 2010.
  4. ^ Hill, Gladwyn. ""7 Die as Planes Collide and One Falls in Schoolyard: Planes Collide, School Yard hit; Roar Alerts Students 'Everything on Fire' Witness Describes Crash." The New York Times, February 1, 1957, p. 1. Retrieved: February 3, 2010.
  5. ^ 31-JAN-1957 "Douglas DC-7B N8210H." Aviation Safety Network. Retrieved: February 3, 2010.
  6. ^ "Roberto Clemente While Flying A Relief Mission To Earthquake Torn Nicaragua Dies In Plane Crash." avstop.com. Retrieved: November 26, 2010.
Bibliography
  • Pearcy, Arthur. Douglas Propliners: DC-1–DC-7. Shrewsbury, UK: Airlife Publishing, 1995. ISBN 1-85310-261-X.
  • United States Air Force Museum Guidebook. Wright-Patterson AFB, Ohio; Air Force Museum Foundation , 1975.
  • Whittle, John A. The Douglas DC-6 and DC-7 Series. Tonbridge, Kent, UK: Air Britain (Historians) Ltd., 1971. No ISBN.
  • Wilson, Stewart. Airliners of the World. Fyshwick, ACT, Australia: Aerospace Publications Pty Ltd, 1999. ISBN 1-875671-44-7
  • Yenne, Bill. McDonnell Douglas: A Tale of Two Giants. Greenwich, Connecticut: Bison Books, 1985. ISBN 0-517-44287-6.


External links

Wikimedia Commons has media related to Douglas DC-7.
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