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Aviation History
1969
1969 - 0472.PDF
Background to the tenth in the Douglas Commercial line OPERATIONAL VERSATIUTY has been one of the keynotes of the 40-year history of Douglas Commercial (DC) air-craft. With the DC-10 now on the drawing board, backed by substantial orders from leading carriers, the famous line from Long Beach. Calif, is once again well placed to capture a wide market, with a single family of aircraft. Versatility of this high order has not actually been achieved since the piston-engined DC-6B of the early fifties. Jet trans ports up to now have rather tended to be specialised according to design range, but with the low fuel consumption and high power: weight ratio of the new high-bypass turbofan things are changing and becoming more to the liking of the airlines. Significantly, perhaps, it has been American Airlines, players of a leading part in the conception of the ubiquitous DC-2/-3. who were the inspiration behind the DC-10. The DC-10. in common with the near identical Lockheed 1011 TriStar made over on the other side of Los Angeles, stems from a US domestic airlines requirement, expressed publicly by American Airlines in April 1966. for a large- capacity medium-range aircraft. AA wanted a machine to carry a full load of passengers plus 5.0001b of freight from Chicago to Los Angeles, and have a sufficiently good airfield performance to fly out of New York La Guardia on a 90°F day for Chicago with a full payload. Both Douglas and Lockheed first tackled the spec with large-capacity twins of more than 300-seat capacity. But. as more US domestic route airlines were contacted, it became apparent that by increasing the range to US coast-to-coast without, if possible, sacrificing the shorter-range economics, the machine would be more widely acceptable. However, the only way in which a range of that order could be achieved satisfactorily was by the use of three engines. Since there had been some concern among the ranks of the operators to the idea of a large-capacity twin in view of the limited overwater range, less acceptable weather limits for take-off and landing, the impossibility of engine-out ferry, and of more severe hot and high performance limitations, the makers soon came around to the idea of the medium-range trijet with coast-to-coast capability. It is claimed that the trijet's economics on the Chicago-Los Angeles route are as good or better than an equivalent twin. As mentioned earlier, it is a reduction of some 20 per cent in the specific fuel consumption of the new generation of high bypass turbofan engines and their improved powenweight ratio that have been more instrumental than anything else in providing the airframe designers with the opportunity to design a single airframe that is adaptable to carrying, at one extreme, a full load off 6.000ft runways or less for short-range, and of carrying a similar payload over stages in excess of 3.000 miles (over 4,000 miles with a capacity passenger load only) off 10,000ft runways. This new realm of versatility means that one basic type of aircraft can do a very large share of the world's air transport—Lockheed puts it at 70 per cent, and Douglas says 99 per cent. Although Doughs was a few agonising weeks slower than Lockheed in securing enough airline support for the DC-10 go-ahead last spring, the company Is ahead in its announce ments of longer-range versions. The basic DC-10 for the US domestic market (coast-to-coast with a capacity load of passengers) is the Series 10 with a gross weight of 410,0001b and powered by three 40,0001b-thrust General Electric CF6-6s. This version has been ordered by American Airlines (25 on order plus 25 on option) and by United Air Lines (30 on order plus 30 on option). Last autumn the first longer-range version was announced with an order for 14 from Northwest, who specified 45,0001b-thrust Pratt & Whitney JT9D-15s for commonality with the Boeing 747. This version is called the DC-10 Series 20 and P&W is paying a large share of the extra development cost of the changeover in powerplant type. Also on offer by Douglas, but not yet ordered, is the Series 30. This long range version is of identical gross weight to the 20. but powered by the 45,600lb-thrust GE CF6-10. The 20 and the 30 have a nearly identical performance with the latter having a slight advantage in payload-range and airfield performance, but a fractionally inferior altitude performance at high weight and/or high Mach number. Last January GE offered the 47,3001b-thrust CF6-50 for 1972 delivery in the series 30. This option has yet to be ordered and the associated aircraft performance details have not been annnounced; Series 30 data in this report is with the CF6-I0 installed. As with TriStar. the DC-10 is largely a conventional- technology aircraft other than for the engines. The structure follows DC-9 and DC-8 practice pretty closely. The straight-
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