- Aircraft History, Specification and Information -
Douglas DC-7

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. Of the 348 were produced, about 40 are still in service.

Design and development

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

American Airlines revived the designation when it requested an extended-range DC-6 for its transcontinental services. At the time, the Lockheed Constellation was the only aircraft capable of making a non-stop coast-to-coast flight in both directions. However, Douglas was reluctant to build the aircraft until American Airlines president C. R. Smith placed a firm order for twenty-five at a price of $40 million, thus covering Douglas's development costs.

The prototype flew in May 1953 and American received its first DC-7 in November, inaugurating the first non-stop coast-to-coast service in the country (taking 8 hours) and forcing rival Trans World Airways 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 increased fuel capacity in extended engine nacelles, which resulted in greater flight range. South African Airways used this variant on their Johannesburg to London route.

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 induced drag, and made the cabin quieter by moving the engines further outboard. 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).

Pan Am used DC-7C aircraft to inaugurate the first non-stop London to New York service against the strong westerly headwinds. The DC-6B and Super Constellation had been able to fly non-stop eastbound since 1952. British Overseas Airways Corporation were 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. However, DC-7C sales were cut short by the arrival of Boeing 707 and Douglas 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 impacted on the DC-7s service record and usage. It was noticeable that at carriers which had both DC-6s and DC-7s in their fleets, the newer DC-7s were usually the first to go once jets started to arrive. Some airlines had to scrap their DC-7s after little more than 5 years of service, whereas the vast majority of DC-6s lasted longer and then sold more readily on the secondhand market.

Operators

Civil operators

Belgium
- SABENA

Bermuda
- ARCO Bermuda

Bolivia

Brazil
- Panair do Brasil

Canada
- Pacific Western Airlines

Colombia

Costa Rica

Denmark
- Conair
- Flying Enterprise
- Scandinavian Airlines System

Dominican Republic

Ecuador
- AREA Ecuador

France
- Transportes Aeriens Reunis

Gabon
- Affretair

Germany
- Atlantis
- Sudflug

Honduras
- TAN Airlines

Iran
- Persian Air Services

Ireland
- Aer Turas
- Shannon Air

Italy
- Alitalia

Jamaica
- Air Caribbean Transport

Japan

Jordan
- Royal Jordanian Airlines

Lebanon
- Lebanese International Airways

Malawi

Mauritius

Mexico
- Mexicana

Netherlands
- KLM
- Martinair
- Schreiner Airways

Norway
- Scandinavian Airlines System

Panama
- Aerovias Panama
- Talingo Airlines

Paraguay

Peru
- Aerolineas Peruanas

Philippines
- Fleeming Air System Transport

Spain
- Spantax
- TAE
- TASSA
- Trans Europa

Rhodesia
- Affretair
- Air Trans Africa

South Africa
- South African Airways

Sweden
- Internord
- Ostermanair Charter
- Scandinavian Airlines System
- Swedish Red Cross
- Transair Sweden

Switzerland
- Swissair

Suriname

United Kingdom
- British Overseas Airways Corporation
- Caledonian Airways
- Dan-Air
- Trans Meridian

United States
- Air Tankers
- Airlinft International
- American Airlines
- Braniff Airways
- Delta Air Lines
- Eastern Air Lines
- Federal Aviation Administration
- Interocean Airlines
- Liberty Air
- National Airlines
- Northwest Orient Airlines
- Overseas National Airways
- Pan American Grace Airways
- Pan American World Airways
- Riddle Airlines
- Saturn Airways
- Standard Airways
- United Airlines
- United States Forest Service
- Universal Airlines
- US Overseas Airlines
- Vance International Airways
- Zantop Air Transport

Military operators

Colombia
- Colombian Air Force 1 x DC-7B and 1 x DC-7C

France
- French Air Force 3 x DC-7C

Mexico
- Mexican Air Force 1 x DC-7B

Rhodesia
Rhodesian Air Force 1 x DC-7C

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 2007, 73 DC-7s remained on the U.S. civil aviation registry, 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.

Specifications (DC-7)

General characteristics
Crew: 3 or 4
Capacity: 99 to 105 passengers
Length: 112 ft 3 in (37 m)
Wingspan: 127 ft 6 in (42 m)
Height: 31 ft 10 in (10.5 m)
Wing area: 1,637 ft2 (152 m2)
Empty weight: 72,763 lb (33,005 kg)
Max takeoff weight: 143,000 lb (65,000 kg)
Powerplant: 4× Wright R-3350-18EA1 Turbo-Compound radial piston engines, 3,400 hp (2,535 kW) each

Performance
Maximum speed: 406 mph (653 km/h)
Cruise speed: 355 mph (570 km/h)
Range: 4,605 mi (7A) / 5,635 mi (7C) (7,410 km (7A) / 9,070 km (7C))
Service ceiling: 25,000 ft (7,600 m)
Rate of climb: 1,043 ft/min (318 m/min)
Wing loading: 87.4 lb/ft² (427.6 kg/m²)
Power/mass: 0.10 hp/lb (160 W/kg)

Last updated December 16, 2009
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Douglas DC-7".
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