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Aviation History
1949
1949 - 1728.PDF
492 FLIGHT, 13 October 194$ AMERICAN NOTEBOOK By " Favonius DOUGLAS DIVERTISSEMENTS WE confess—without a blush—that our linguistic know-ledge of French has much the evanescent quality of apoorly designed rudder in a spin, so we looked up this label for a Douglas vintage in our favourite dictionary. "Divertissement," it said, is a short entertainment between the acts of a longer piece—and this translation seems to fit the present status of the Douglas Super DC-3, which is the standard "old faithful" now undergoing rejuvenation at Santa Monica. After about 20 hours of test flying, the Super DC-3 is now (at the time of writing) being re-tested with further revisions to its tail surfaces and at a higher gross weight. For this reason we have kept company with the angels who fear to tread and purposely refrained from jumping in where the printers' devils love to leap, since during the divertisse- ment phase there was little object in quoting facts that ceased to become facts before the printer's ink was dry. Thus, although a few weeks ago the maximum permissible take-off gross weight (with auto-feathering props) was quoted at 29,500 lb, the current figure is now 31,000 lb. Without the refinement (and current teething troubles) of auto-feathering airscrews, the maximum take-off weight is limited to 28,500 lb. What we can say at this time, from personal inspection, is that although both the vertical and horizontal tail surfaces were increased in span and area over those of the standard DC-3, they have now been modified a second time. The dorsal and vertical fins have increased in area, with a corresponding increase in height of the rudder by some 15m. Likewise, a new horizontal tail about 3ft longer in span has been substi- tuted for the earlier mod. The vertical-tail geometry is now strictly utilitarian, to the point of austerity. This is in keep- ing with Douglas design philosophy, which postulates that any unnecessary departure from the linear is purely emotional —as well as expensive. Retailoring Skipping, then, lightly over our aesthetic emotions and keep-ing strictly to bread-and-butter economics, we must judge the Super DC-3 conversion as a modern example of how toturn an honest dollar in a dollar-hungry world. The Douglas idea is akin to the time-honoured English custom of ha\'ingone's suit turned inside-out and made as good as new for another ten years. (The canny Scot, we understand, is evenmore adroit—he merely wraps his kilt round the other way !) All you need is good material and sound workmanship in thefirst place which, in the case of Douglas, can be taken for granted. Following this old-worldly fashion, Douglas plan to have •a. "Executive model " of the Douglas Super DC 3, now on a demonstration tour. operators return their DC-3S to Santa Monica for renovatingto modern airworthiness standards. The standard DC-3, inci- dentally, reaches the end of its airworthy life some time in1952, but the conversion plan is designed to meet the latest civil air regulations and should keep the Super DC-3 flyingwell into the next decade. The complete retailoring bill is expected to run somewhere between $150,000 and $200,000,which is less than half the price of a new twin-engined trans- port ; the performance, moreover, will be little inferior topost-war types in the same class. Included in this package conversion deal are two new 1,275h.p. Wright Cyclones giving 550 more take-off horses than the standard DC-3 can muster. Weight and performancefigures are now being finalized, but there is no reason to quibble over Douglas's estimate that the Super DC-3 willcruise at least 50 m.p.h. faster than its predecessor. At a gross weight of 31,000 lb and normal rated power of 1,275 h-P-per engine, the predicted top speed is 269 m.p.h. at 5,900ft while the cruising speed at 67 per cent of normal rated poweris 250 m.p.h. at 15,400 feet. Because, however, the Super DC-3 is n°t pressurized, a more useful operational height is10,000 feet, and at this height on 60 per cent normal power the cruising speed is 226 m.p.h. Accommodation As a short-haul transport, the former 21-passenger accom- modation of the standard DC-3 has been superseded by a choice of three alternative interior arrangements seating 30, 31 or 37 passengers. This has been done by splicing an extra 39 inches in the fuselage structure forward of the wing, thereby adding one more cabin window on each side. The other main structural changes—apart from the new tail unit already noted —comprise an entirely new flush-riveted outer wing panel with more sweep-back and shorter span (90ft instead of 95); new kangaroo-type engine nacelles completely enclosing the main landing gear when retracted; and a partially retracted tail- wheel, leaving only the lower portion of the wheel exposed. Less obvious retailoring touches include: a passenger door at the rear of the cabin, having bottom hinges and incorporat- ing an integral stairway with hand-rail; an enlarged cargo hold aft of the cabin with a waist-high door easily accessible from the ground; and a new combustion-type cabin heating system, which also supplies hot air for anti-icing the pilots' bird-proof windshield. The landing gear retraction and wing flap hydraulic system has also been reworked from 800 to 1,100 lb/sq in pressure, an increase which cuts down the landing gear retraction time to 7 sec. This new replacement plan for the DC-3 global work-horse should provide a good standby bread-and-butter business for Douglas. It certainly makes a lot better sense, in our opinion. than did Douglas's earlier bid for this market in 1947 with the proposed DC-9, which blew hot and cold for many months. The DC-9, it may be recalled, was a 30,000 lb 28- passenger twin using the same type en- gines as the Super DC-3. About the only post-war innovations it could claim over the latter were a nosewheel landing gear and structural provision for cabin pres- surizing. The passenger revenue poten- tial would have been lower and the capital cost more than double—probably triple, with the added complications of pressurization. Anyway, now that this latest diver- tissement has crossed the boards and been shown to the public, our Douglas engineering friends will be able to return to the piece de resistance—they can pin a new sheet on the drawing board and rework-up that new jet transport which has been in the study stage for the past year or so. We say "rework " with our tongue-in-cheek because we have a hunch that the recent air disclosure of the D.H. Comet will cause a lot of rubbing out and redrafting on American drawing boards. Which in itself would be divertissement in this dollar-conscious world. D 4
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