Planes of the Past - Douglas Aircraft Company and McDonnell Douglas - Part 7

Welcome to (slightly delayed) Part 7 of Planes of the Past - Douglas Aircraft Company and McDonnell Douglas and in this part we will talk about
##DC-7

About

The Douglas DC-7 is a transport aircraft built by the Douglas Aircraft Company from 1953 to 1958. It was the last major piston engine-powered transport made by Douglas, being developed shortly after the earliest jet airliner – the de Havilland Comet – entered service and only a few years before the jet-powered Douglas DC-8 first flew.


Devlopment

In 1945 Pan American World Airways requested a DC-7, a civil version of the Douglas C-74 Globemaster military transport. Pan Am soon canceled their order. That DC-7 was unrelated to the later airliner.

American Airlines revived the designation when they requested an aircraft that could fly the USA coast-to-coast nonstop in about eight hours. (Civil Air Regulations then limited domestic flight crews to 8 hours flight time in any 24-hour period.) Douglas was reluctant to build the aircraft until American Airlines president C. R. Smith ordered 25 at a price of $40 million, thus covering Douglas’ development costs. The DC-7 wing was based on the DC-4 wing with the same span; the fuselage was 40 inches longer than the DC-6B. Four eighteen-cylinder Wright R-3350 Turbo-Compound engines provided power. The prototype flew in May 1953 and American received their first DC-7 in November, inaugurating the first nonstop east-coast-to-west-coast service in the country (unrealistically 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 frequently experienced inflight engine failures, causing many flights to be diverted. Some blamed this on the need for high power settings to meet the schedules, causing overheating and failure of the engines’ power recovery turbines. These recovered power from the exhaust stream and delivered it to the crankshaft; they boosted the R-3350’s power by 600 HP.

The DC-7 was followed by the DC-7B with slightly more power, and on some DC-7Bs (Pan Am and South African Airways), fuel tanks on top behind the engine nacelles, each carrying 220 US gallons. South African Airways used this variant to fly Johannesburg to London with one stop. Pan Am’s DC-7Bs started flying transatlantic in summer 1955, scheduled 1 hr 45 min faster than the Super Stratocruiser from New York to London or Paris.


Operational History

Early DC-7s were purchased only by U.S. carriers. European carriers could not take advantage of the small range-increase of the early DC-7, so Douglas released an extended-range variant, the DC-7C (Seven Seas) in 1956. Two 5 ft (1.5 m) wingroot inserts added fuel capacity, reduced interference drag and made the cabin quieter by moving the engines farther outboard; all DC-7Cs 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 with a 40 in (100 cm) plug behind the wing for the DC-7 and −7B, was lengthened with a 40-inch plug ahead of the wing to give the DC-7C a total length of 112 ft 3 in (34.21 m).

Since the late 1940s Pan Am and other airlines had scheduled a few nonstop flights from New York to Europe, but westward nonstops against the prevailing wind were rarely possible with an economic payload. The L1049G and DC-7B that appeared in 1955 could occasionally make the westward trip, but in summer 1956 Pan Am’s DC-7C finally started doing it 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 on cross-polar flights to North America and Asia. The DC-7C sold better than its rival, the Lockheed L-1649A Starliner, which entered service a year later, but sales were cut short by the arrival of Boeing 707 and Douglas DC-8 jets in 1958–60.

Starting in 1959 Douglas began converting DC-7s and DC-7Cs into DC-7F freighters to extend their useful lives. The airframes were fitted with large forward and rear freight doors and some cabin windows were removed.

The predecessor DC-6, especially the DC-6B, established a reputation for straightforward engineering and reliability. Pratt & Whitney, manufacturer of the DC-6’s Double Wasp engines, did not offer an effective larger engine apart from the Wasp Major, which had a reputation for poor reliability. Douglas turned to Wright Aeronautical for a more powerful engine. The Duplex-Cyclone had reliability issues of its own, and this affected the DC-7’s service record. Carriers who had both DC-6s and DC-7s in their fleets usually replaced the newer DC-7s first once jets started to arrive. Some airlines retired their DC-7s after little more than five years of service, whereas most DC-6s lasted longer and sold more readily on the secondhand market.

Basic price of a new DC-7 was around £570,000 ($823,308).

Price of a DC-7B was around £680,000 ($982,226) in 1955, rising to £820,000 ($1,184,490) in 1957.

Similarly, the price of a DC-7C was £800,000 ($1,155,560) in 1956, increasing to £930,000 ($1,343,385) by 1958.

Cost of the DC-7F “Speedfreighter” conversion was around £115,000 ($166,112) per-aircraft.


Variants

DC-7
Production variant, 105 built.

DC-7B
First long-range variant with higher gross weight and fuel capacity, with most of the added fuel in saddle tanks in enlarged engine nacelles. (Only Pan Am and South African DC-7Bs had the saddle tanks.) 112 built.

DC-7C Seven Seas
Longer-range variant with non-stop transatlantic capability, improved 3400hp (2540kW) R-3350 engines and increased fuel capacity mainly in longer wings, 121 built.

DC-7D
Unbuilt variant with Rolls-Royce Tyne turboprops.

DC-7F
Freight conversion of all three variants with two large freight doors.


Operators

Civil Operators

DC-7s were used by Alitalia, American Airlines, BOAC, Braniff Airways, Caledonian Airways, Delta Air Lines, Eastern Air Lines, Japan Airlines, KLM, Mexicana de Aviacion, National Airlines, Northwest Orient, Panair do Brasil, Pan American World Airways, Sabena, SAS, South African Airways, Swissair, Turkish Airlines, Transports Aériens Intercontinentaux, and United Airlines.

Seventeen DC-7s remained on the U.S. registry in 2010, used mainly for cargo and as aerial firefighting 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.

Military Operators

🇨🇴 Colombia
🇫🇷 France
🇲🇽 Mexico
image Rhodesia
🇺🇸 United States of America


Specifications

DC-7

Crew: 2 Pilots, 1 Flight Engineer, 2 Flight Attendants
Capacity: 64 to 95 Passengers
Length: 108 ft, 11 in (33.20 m)
Wingspan: 117 ft, 6 in (35.81 m)
Height: 28 ft, 7 in (8.71 m)
Empty weight: 58,150 lbs (26,376 kg)
Max. takeoff weight: 114,600 to 122,000 lbs (51,982 to 55,338 kg)
Powerplant: 4 × Wright R-3350-30W radial piston engines, 3,250 hp (2,423 kW) each
Maximum speed: 405 mph (652 km/h)
Cruise speed: 359 mph (578 km/h)
Stall speed: 97 mph (156 km/h)
Range: 5,164 mi w/ max fuel & 3,565 mi w/ max payload (8,311 km w/ max fuel & 5,737 km w/ max payload)
Service ceiling: 28,400 ft (8,656 m)

DC-7C

Crew: 2 Pilots, 1 Flight Engineer, 4 Flight attendants
Capacity: 105 Passengers
Length: 112 ft, 3 in (34.21 m)
Wingspan: 127 ft, 6 in (38.86 m)
Height: 31 ft, 10 in (9.70 m)
Empty weight: 72,763 lbs (33,005 kg)
Max. takeoff weight: 143,000 lbs (64,864 kg)
Powerplant: 4 × Wright R-3350-988TC18EA1-2 radial piston engines, 3400 hp (2,536 kW) each
Maximum speed: 406 mph (653 km/h)
Cruise speed: 359 mph (578 km/h)
Stall speed: 97 mph (156 km/h)
Range: 5,600 mi (9,012 km)
Service ceiling: 28,400 ft (8,656 m)


Images


Source - https://en.m.wikipedia.org/wiki/File:Douglas_DC-7_cockpit_photo_D_Ramey_Logan.jpg


Source - https://en.m.wikipedia.org/wiki/File:Butler-dc7-N6353C-071102-fox-tanker66-01-16.jpg\


Source - https://en.m.wikipedia.org/wiki/File:Delta_DC-7.jpg


Source - https://en.m.wikipedia.org/wiki/File:Douglas_DC-7F_G-AOIJ_BOAC_Frt_RWY_10.61_edited-2.jpg


Source - https://en.m.wikipedia.org/wiki/File:SR_DC7.jpg

image
Source - https://en.m.wikipedia.org/wiki/File:BOAC_DC-7C_Taking-off_from_Manchester.jpg


Source - https://en.m.wikipedia.org/wiki/File:Butler-dc7-N6353C-071029-fox-tanker66-04-16.jpg


This topic was made by @B747fan (in hurry) with the help of Wikipedia. Link to the previous one -

9 Likes

I don’t know what you class as a hurry, but writing all this doesn’t pass as one in my book! I love the detail

3 Likes

MaxSez: DC-7 cockpit. Days of Steam Gage’s and Giants!

image

4 Likes

wow, those cockpits looks old, but I love it !

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