Douglas DC-8

The Douglas Aircraft Company announced its inten-tion, on 7 June 1955, to enter the pure jet stakes with the DC-8. Originally powered by the same Pratt & Whitney JT3 turbofans as the 707, it had a fractionally more slender body, less wing sweep, and fully powered flight controls. To reduce drag and avoid stress between wing and fuselage, the aerofoil changes shape toward the root, becoming flatter on top and more curved beneath. Douglas began assembling the first DC-8 in February 1957 and, there being no prototype as such, was rolled out and first flew on 30 May 1958.

There are four main families of DC-8s: Douglas made the first five versions the same size differing only in power and fuel capacity. Douglas had announced that all projected versions would have the same overall dimensions. It adhered to this policy until 1965, and the first five versions of the DC-8 have an identical airframe, with uniform electrical, hydraulic, control and air conditioning systems. The intercontinental versions differ from the domestic models only in having extra fuel capacity and the structural modifications needed to carry the additional fuel. The modifications are limited to the use of thicker skin and stronger material within the wing structure, the aft portion of the fuselage and the tailplane. The landing gear is also more robust in the case of the heavier intercontinental versions.

It was offered in several models, the series 10 for domestic services, the series 30 for longer ranges and the Series 40 powered by the Rolls Royce Conway bypass engine for Trans Canadian Airlines, Air Canada.

On 23 July 1959 the first DC-8 with Rolls-Royce Conway engines made its first flight from Long Beach, California. It was the ninth DC-8 to fly in 14 months.

DC-8 no.9

A DC-8-40 became the first jet airliner to exceed the speed of sound when, in 1961, it reached Mach 1.012 (667 mph) in a shallow dive. In 1959 Douglas introduced an extended wing leading edge and slightly extended tips, allowing weight to reach 310,000 lb.

The DC-8 with JT-3C engines received its FAA Type Approval on 31 August 1959 and went into service with United Airlines and Delta Airlines on 18 September 1959.

 

In 1960 the Series 50 introduced the JT3D turbofan engine, with weights up to 325,000lb. The Series 50 evolved after Pratt and Whitney developed the new JT3D turbofan housed in new nacelles with distinct exhaust louvres on either side. The 50 range was developed into the 51 for domestic operations, the 52, -53 and -55 for long range versions differing in the model of engine fitted. A subsequent version, the -54, was developed as a freighter.

The Series 50 DC-8 had a still air range of around 6900 miles with a maximum cruise of 580 miles an hour at 220,000 lb. The series 52 had a total fuel capacity of 150,055 lb. The forward freight compartment had a capacity of 690 cu ft and the rear a usable capacity of 700 cu ft.

 

In April 1965 Douglas announced the Super Sixty series. This comprised the DC-8-61, stretched by 36ft 8in to seat up to 259 passengers; the -62 with only a small stretch, to seat 189, but with extra fuel for very long range, enhanced by an improved wing and engine pods; the -63, fuselage lengthened by 36.7 ft. (11.18 m.), an extended wing span. Powered by JT3Ds of up to 19,000-lb thrust, these extended the DC-8 line from 293 to 556, production continuing until 1972. The Super Sixties proved such good aircraft that in the early 1980s 110 were retrofitted with the CFM56-2 engine as the DC-8-71.

A total of 556 DC-8s were produced before the production line closed in early 1972.

Gallery

DC-8-10
MTOW: 211,00 lbs.

DC-8-40
Engine: 4 x Conway.

DC-8-50
Engines: 4 x P&WJT-3 D-1 turbofan, 75.7kN
Wingspan: 43.4 m / 142 ft 5 in
Length: 45.9 m / 150 ft 7 in
Height: 12.9 m / 42 ft 4 in
Wing area: 257.6 sq.m / 2772.78 sq ft
Empty weight: 57000 kg / 125664 lb
Max take-off weight: 142880 kg / 314998 lb
Cruise speed: 932 km/h / 579 mph
Range w/max.fuel: 11100 km / 6897 miles
Range w/max.payload: 9200 km / 5717 miles
Crew: 3-5
Passengers: 105-189

DC-8-54
Engine: 4 x JT3D3B turbofan.

DC-8 Super 61
Engines: 4 x Pratt & Whitney JT3D-3B turbofans, 18,000 lbs thrust.
Length: 187 ft 5 in.
Wingspan: 142 ft 5 in.
Ceiling: 30,000 ft.
Range: 3,750 miles.
Pax cap: 259.

DC-8-62
MGTOW: 350,0001b (157,500kg).
Fuel cap: 163,0001b (73,350kg).

DC-8 Super 63
Engines: 4 x 19,000 lb. (8,618 kg.) Pratt & Whitney JT3D.
Length: 187.4 ft. (57.12 m.)
Wing span 148.4 ft. (45.23 m.)
Height: 42 ft 5 in (12.92 m).
Weight empty 153,749 lb. (69,739 kg.)
Max TO wt: 350,000 lb (158,760 kg).
Max. capacity: 251 passengers
Max cruise 600 m.p.h. (965 kph)
Range 4,600 miles (7,400 km.) with max. payload.
Max range: 7,700 miles (12,400 km).
Max level speed: 600 mph (965 kph).  

DC-8-71
Engines: 4 x CFM56-2.