BOAC DC-7C G-AOIC taking off from Manchester UK in April 1958 for a non-stop flight to New York (Idlewild) (later JFK)Swissair DC-7C in 1961DC-7CF freighter of BOAC in 1961 converted with forward and rear freight doors
The Douglas DC-7 is a retired American airliner built by the Douglas Aircraft Company from 1953 to 1958. A derivative of the DC-6, it was the last major piston engine-powered passenger aircraft 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 in 1958. A large number of both DC-7B and DC-7C variants were also built, with a handful of aircraft converted for the purpose of cargo hauling or fire-fighting after their commercial transport days had passed.
Unlike other propeller-driven Douglas aircraft that were far more successful, such as the DC-3 and DC-6, no examples of the DC-7 remain in service as of 2020.
Design and development
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 proposed DC-7 was unrelated to the later DC-6-derived airliner.
American Airlines revived the designation when they requested an aircraft that could fly across the United States coast-to-coast non-stop 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 total price of $40 million, thus covering Douglas' development costs.
The DC-7 wing was based on that of the DC-4 and DC-6, with the same span; the fuselage was 40 inches (100cm) longer than the DC-6B. Four eighteen-cylinder Wright R-3350 Duplex-Cyclone Turbo-Compound engines provided power. The prototype flew in May 1953 and American received their first DC-7 in November, inaugurating the first non-stop 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 national schedules, causing overheating and failure of the engines' power recovery turbines.
DC-7B
The DC-7 was followed by the DC-7B with slightly more power and optional fuel tanks over the wing in the rear of the engine nacelles (selected by Pan Am and South African Airways), each carrying 220 US gallons (833L; 183impgal). 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.
DC-7C
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 5ft (1.5m) wingroot inserts added fuel capacity, reduced interference drag and made the cabin quieter by moving the engines farther outboard; the optional nacelle fuel tanks previously seen on Pan American's and South African's DC-7Bs were made standard. The fuselage, which had been extended over the DC-6Bs with a 40-inch (100cm) plug behind the wing for the DC-7 and DC-7B, was lengthened again with a 40-inch plug ahead of the wing to give the DC-7C a total length of 112ft 3in (34.21m).
Operational history
Since the late 1940s Pan Am and other airlines had scheduled a few non-stop flights from New York to Europe, but westward non-stops against the prevailing wind were rarely possible with an economic payload. The Lockheed Super Constellation 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-6s Double Wasp engines, did not offer an effective larger engine apart from the Wasp Major. Douglas turned to Wright Aeronautical for a more powerful engine. The Duplex-Cyclone had reliability issues, 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.
Morten Beyer, an airline executive who participated in the decision to buy second-hand DC-7s at Riddle Airlines (later known as Airlift International), said Riddle became comfortable with buying the DC-7, notwithstanding known engine problems, after seeing its success with carriers like Swissair that made an effort to "baby" the Wright engine. According to Beyer, many passenger carriers had competed on speed and operated the engine at its limits, where it tended to break down. Riddle apparently was able to operate the DC-7 reliably by similarly babying the engine.
Basic price of a new DC-7 was around $823,308 (£570,000).
Price of a DC-7B was around $982,226 (£680,000) in 1955, rising to $1,184,490 (£820,000) in 1957.
Similarly, the price of a DC-7C was $1,155,560 (£800,000) in 1956, increasing to $1,343,385 (£930,000) by 1958.
Cost of the DC-7F "Speedfreighter" conversion was around $166,112 (£115,000) 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 3,400hp (2,500kW) R-3350 engines and increased fuel capacity mainly in longer wings, 121 built.
DC-7D
Proposed turboprop development powered by four Rolls-Royce RB.109 engines. It was considered by BOAC in 1954, but no order was placed and the aircraft was not built.
Freighter conversions
DC-7-series aircraft were converted for main-deck cargo service in several configurations. FAA-approved conversions included the DC-7B Cargo and DC-7C cargo configurations; some original DC-7 aircraft were converted and redesignated as DC-7B Cargo. Conversions varied, but could include a large main-deck cargo door and cargo floors; certain aircraft were additionally modified to meet Class E main-cabin cargo-compartment requirements.
Erickson Aero Tanker DC-7B Tanker 60, N838D, at Redmond, Oregon, in 2001. Its October 2020 retirement flight has been described as likely the final flight of any DC-7 airframe.
After their airline careers, some DC-7s were converted for cargo and aerial firefighting use. The type remained in active aerial firefighting service until October 2020, when Erickson Aero Tanker's DC-7B Tanker 60, N838D, completed its final firefighting season and was retired after its Oregon contract ended. On October 14, 2020, it departed Medford for Madras, Oregon. Propliner Information Exchange described the flight as possibly the final flight of any DC-7, noting that there were no other operating DC-7s and that Erickson's 2021 Oregon contract did not include DC-7 tankers.[citation needed] N838D was the last airworthy aircraft of the DC-7 family and made its retirement flight from Medford to Madras, Oregon, in October 2020.
A total of 338 DC-7-series aircraft were built, consisting of 105 DC-7s, 112 DC-7Bs and 121 DC-7Cs. American Airlines was the launch customer for the DC-7. The following table lists new-build deliveries by first operator.
The Aviation Safety Network lists 97 DC-7 accidents and incidents between 1955 and 1993, with 728 fatalities in the DC-7 fatality column when only the DC-7 side of split mid-air-collision entries is counted.
A DC-7 (N8210H) still owned by Douglas crashed into a school yard in the Pacoima area of Los Angeles, California, following a midair collision with Northrop F-89J Scorpion52-1870, resulting in the deaths of the four crewmembers aboard the DC-7, the pilot of the Scorpion jet, and three students on the ground.
March 5, 1957
An American Airlines DC-7B (N316AA) on a flight from Idlewild International Airport (now JFK Airport) in New York City to Dallas Love Field in Dallas, TX suffered failure of the #1 engine. The propeller and nose section detached and struck the fuselage, leading to decompression. The pilot made a successful emergency landing at Memphis; there were no fatalities or injuries. The plane was repaired and returned to service.
June 28, 1957
An Eastern Air Lines DC-7B (N808D) collided with a parked Eastern Air Lines Lockheed L-1049 (N6212C) at Miami International Airport after returning from a training flight. Fuel leaked and both aircraft burned out.
February 1, 1958
Pan Am Flight 70, a DC-7C (N733PA, Clipper Blue Jacket), landed wheels-up at Schiphol Airport as a result of pilot error; all 16 on board survived. The aircraft was repaired and returned to service as a freighter. See also July 26, 1970 below.
March 10, 1958
A DC-7B (N846D) still owned by Douglas crashed at Long Beach, California during a test flight before delivery to Eastern Air Lines.
March 25, 1958
Braniff Flight 971, a DC-7C (N5904), crashed shortly after takeoff from Miami while attempting to return after an engine caught fire. Nine passengers out of 24 people aboard died in the accident.
A Sabena DC-7C (OO-SFA) crashed near Casablanca–Anfa Airport during the attempted landing. All nine crewmembers and 52 of the 56 passengers died.
September 24, 1959
TAI Flight 307, a DC-7C, crashed at Bordeaux airport with the loss of 54 lives. After takeoff, the aircraft failed to gain altitude and collided with trees 3km (1.9mi) from the start of the takeoff.
November 16, 1959
National Airlines Flight 967, a DC-7B on a flight from Tampa, Florida, to New Orleans, crashed into the Gulf of Mexico. All 42 occupants perished. Although sabotage was suspected, no definite cause of the crash was determined due to a lack of evidence. The aircraft was owned by Delta Air Lines.
February 26, 1960
AlitaliaFlight 618, a DC-7C (I-DUVO), crashed at Shannon Airport, Ireland, shortly after takeoff following a loss of altitude while making a left turn with 34 fatalities out of 52 passengers and crew. No cause was established for this accident.
Northwest Orient Airlines Flight 1-11, a DC-7C (N292), ditched off Polillo Island, Philippines due to failure of the number two engine and fire; one person (out of 58 on board) died when the number two propeller separated and penetrated the fuselage.
February 18, 1961
A Pan Am DC-7CF (N745PA) struck a mound of earth short of the runway in Stuttgart while attempting an ILS approach, shearing off the undercarriage and #1 engine. The pilots retained control and were able to climb away, then make a belly landing at Nurnberg airport. The aircraft was written off.
November 1, 1961
A Panair do Brasil DC-7C (PP-PDO) flying from Sal to Recife crashed into a hill about 2.7km (1.7mi) short of the runway at Recife. Forty-five passengers and crew out of the 88 persons aboard lost their lives. The accident was attributed to pilot error.
Northwest Airlines Flight 292, a DC-7C (N285) with 7 crew and 95 passengers, made a successful water landing in Sitka Sound just before 1 p.m. local time after struggling with propeller problems for 45 minutes while operating as a military charter flight between McChord Air Force Base and Elmendorf Air Force Base. The plane stayed afloat for 24 minutes after coming to rest in the water, giving the occupants ample time to evacuate into life rafts with only 6 minor injuries reported. All passengers and crew were quickly rescued by U.S. Coast Guard ships. The cause was an overspeeding propeller when the blower section on engine number two failed.
Eastern Air Lines Flight 663 crashed a few minutes after takeoff from John F. Kennedy Airport in New York after taking evasive action to avoid a possible collision with another airliner (Pan Am Flight 212, a Boeing 707). All 84 passengers and crew died.
December 7, 1968
A North American Aircraft Trading DC-7C (VR-BCY) crashed during approach to Uli Airstrip following triple engine failure during a relief flight, killing all four crew.
June 5, 1969
A Swedish Red Cross DC-7B (SE-ERP) was shot down by a Nigerian Air Force MiG-17 and crashed at Eket, Nigeria, killing all four crew. The aircraft was operating a supply flight from Fernando Po (now Bioko) to Biafra.
July 26, 1970
An ARCO ferry flight of a DC-7CF (VR-BCT), from Kinshasa suffered an explosive failure of the #3 engine. The pilots succeeded in making a belly landing on 2 engines (engine #4 having been inoperable for the entire flight), however the plane was damaged beyond repair. This aircraft had previously crashed in 1958.
October 2, 1970
A Spantax DC-7C (EC-ATQ) was written off at Barajas Airport.
December 31, 1972
Professional Baseball player Roberto Clemente and 4 others in a chartered DC-7 died when the plane crashed shortly after takeoff from San Juan, Puerto Rico. Only parts of the fuselage and the body of pilot Jerry Hill were recovered. The cause was traced to maintenance and pilot errors.
June 21, 1973
A Skyways International DC-7C (N296) crashed in the Everglades six minutes after takeoff from Miami International Airport, apparently caused by an onboard fire and/or severe turbulence. Three crew members, the sole occupants, died. The aircraft was on lease to Warnaco Incorporated.
March 3, 1974
A Douglas DC-7C/F (EI-AWG) operating an Aer Turas Teo charter flight from Dublin landed at Luton Airport on runway 08 just after midnight but failed to achieve reverse thrust. Normal braking application also was ineffective and the emergency pneumatic brakes were applied. All main wheel tires burst. The aircraft overran the runway and continued over the steep bank at the eastern perimeter finally coming to rest in soft ground 90 metres beyond. The situation had also been made worse by an inadvertent application of forward thrust by the crew in trying to achieve reverse thrust. Three of the six passengers and two of the four crew were injured. The badly damaged aircraft was written off.
October 4, 1976
An Emirates Air Transport DC-7CF (TZ-ARC) struck Mount Kenya due to a premature descent, killing the four crew.
September 12, 1977
A Safe Air Cargo DC-7BF (N6314J) crashed on climbout from Yakutat Airport after an engine lost power and caught fire, killing the four crew. 14 CFR 91 subpart D was revised in the wake of this accident.
September 6, 1978
An Advance Aviation Inc. DC-7CF (N244B) was being used to smuggle marijuana when it crashed near Farmerville, Louisiana due to pilot error, killing one of six on board. Thirty-five bales of marijuana were recovered from the wreckage.
June 22, 1979
A Go Transportation DC-7CF (N357AL) crashed on climbout from Barstow Airport due to overloading and loss of engine power (caused by improper 100 octane fuel), killing one of six crew.
September 14, 1979
A Butler Aircraft Inc. DC-7 (N4SW) transporting company employees to Medford, Oregon, crashed on the crest of Surveyor Mountain near Klamath Falls, Oregon. The crash, which claimed the 12 occupants aboard, was attributed to the crew's decision to undertake a night flight at low altitude.
1980
An Aero Services Corp. DC-7CF (N8219H) was shot down and crashed in Colombia during a smuggling flight.
July 27, 1980
A Lambda Air Cargo DC-7CF (CP-1291) burned out on the ground at Trujillo Airport.
November 28, 1980
A Central Air Service DC-7B (N816D) crashed near Pecos Municipal Airport, Texas, soon after takeoff killing the pilot and co-pilot on board. The plane entered a steep 90° left bank after takeoff, descended fast with the no. 2 prop feathered and crashed in a field.
October 9, 1986
A T&G Aviation DC-7C (N5903) ditched off Dakar due to engine problems, killing three of four crew.
December 8, 1988
A T&G Aviation DC-7CF (N284) was shot down by a SAM-7 missile fired by the Polisario Front and crashed in the Western Sahara, killing the five crew. A second T&G DC-7 (N90984) was also hit, losing an engine, but was able to land safely. Polisario soldiers thought the aircraft were Moroccan C-130s.
c/n 44285 "Charlie 21" – DC-7 fuselage used as a kindergarten classroom at Iliff Preschool in Denver, Colorado. Originally delivered to United Airlines as N6321C in 1954, it was moved to the school in 1971.
↑Breffort, Dominique. Lockheed Constellation: From Excalibur to Starliner, Civilian and Military Variants. Paris: Histoire and Collecions, 2006. ISBN2-915239-62-2
Germano da Silva, Carlos Ari César. "Buraco negro." O rastro da bruxa: história da aviação comercial brasileira no século XX através dos seus acidentes 1928–1996 (in Portuguese). Porto Alegre: Edipucrs, Second edition, 2008. ISBN978-85-7430-760-2.
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