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Aviation History
1983
1983 - 0653.PDF
DASH 8 ORDERS AND OPTIONS CANADA Air Atonabee Time Aif norGmatf Trans North Air Home Oil Unnamed Options Total USA Rio Airways Benson Airlines 5 4 2 2 1 2 Tg 10 26 6 8 Southern Jersey Aviation Enterprises Mesaba Airlines Unnamed Options Total INTERNATIONAL Talair Options Total Total orders and options DASH 8 MILESTONES June 1978-March 1980 September 1980 November 1982 April 19, 1983 June 1983 September 1984 January 1986 Preliminary design studies Programme go-ahead Assembly begins Roll-out First flight Certification 4 3 3 1 25 25 So 4 39 43 119 Six aircraft/month production rate TWIN OTTER DASH 8 DASH 7 Comparison with its older brothers reveals how de Havilland have cleaned up the Dash 8 to give it a 270kt cruising speed. Note engine nacelles and nose considers Sperry's electromechanical instrument to be excellent, and more compatible with Third World operators having no "glass cockpit" experience. Efis weighs an extra 351b, it notes, and costs more to buy, although it is cheaper to operate. De Havilland says that it hopes to offer microwave landing system equipment on the Dash 8 before long. When approved by the authorities, this will enable the aircraft to land on stub ends of inter secting runways while larger transports land on the main runway. Structural design of the Dash 8 is straightforward, with many lessons derived from Dash 7 experience. The use of Kevlar/Nomex honeycomb composites has, however, more than doubled, to about 10 per cent of airframe empty weight, (see diagram, page 1007). As well as saving weight, composites contribute significantly to aerodynamic smoothness, especially in areas such as the wing leading edge de-icing boots. The boots, which are pneumatic, have now been moulded into the composite leading edge instead of being bonded onto it, a process which used to leave the surface irregular. Structural testing of the Dash 8 will be carried out on three segments of the airframe. The front fuselage, rear fuselage and empennage, and the wing, engine, nacelles and a small portion of the fuse lage are each being tested separately. The idea is to speed up the process, so that all critical cases will have been demonstrated by the certification date. The airframe is designed for 40,000 crack-free flight hours, and to have an economic life of "at least 80,000hr, or 160,000 landings", says DHC. Composites on the Dash 8 now account for 9001b of aircraft weight, or 9-6 per cent of empty weight. The majority of components are of Kevlar/Nomex. Internal structures made from composites include cabin floor panels, wardrobe, lavatorv compartment, and buffet Wing leading edges Wing/fuselage fairings "~~~-~- Radome JC/\ Nose bay M„„„ „ ' Nose g Tailplane leading edges- Aileron Firf leading edges- ^^-~- tabs >x/^§5s. Dorsal fin (\_J\y- '-^ - . --- iM^r^^^^ ^j^^yt=^f^ — Lower cowls / & intake Main gear ear doors J/ Jf : "**C^>-~ doors Fin/tailplane fairing _/T Elevator tips / Elevator tabs -\* Tail cone —Aft nacelles >^_^ Flap shrouds -- >^? Wing tip fairings FLIGHT International, 9 April 1983 Primary structure is of conventional high- strength aluminium alloy, with vacuum- melted steel in some landing gear and airframe parts. Extensive use is made of bonded stringers and reinforcements for windows and other cutouts, to minimise weight and permit a flush-riveted skin. Flightdeck and forward fuselage struc ture is refined over that of the Dash 7. The older aircraft has flat side windows which open, while those on the Dash 8 are curved, load-carrying fixtures. Also, the nose gear, which retracts forwards, is mounted ahead of the front pressure bulk head, so that the nosewheel does not intrude into the pressurised part of the fuselage. DHC notes that this improves structural efficiency, as well as releasing all of the space under the flight deck for control runs and equipment. The 50in wide by 60in high rear cargo door is standard to both versions of the Dash 8, and the rear cabin bulkhead is rapidly adjustable to three positions, giving capacities of 36, 28, and 20 passengers. The cargo compartment increases in size from 300ft3 with a full passenger load to a maximum of 775ft!. With its aspect ratio of 12, Dash 8's high, aft-loaded supercritical wing is more efficient than that of its four-engined brother. An 18 per cent thickness-to- chord ratio confers more structural effi ciency, too, so that large-chord, single- slotted Fowler-type flaps can be carried. Wing construction is conventional, a tip- to-tip torsion box being formed by spars, ribs, and skin. Dihedral breaks occur at the outboard side of each nacelle. Fuel tank capacity on the commuter version is 846 US gal (5,8751b). On the corporate Dash 8 inboard wing tanks increase the capacity by another 342gal. Flaps extend from the fuselage side to the inboard side of the engine nacelle, and are sealed against both to increase end 7007
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