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Aviation History
1945
1945 - 0962.PDF
534 FLIGHT MAY iyra, 1945 SHORT SHETLAND and the lower edge of the diaphragms correspond- ing to the V bottom are edged with T-section extrusions passing over the beaded webs of the T-section extruded stringers on which the planing bottom is skinned and attached to them with shear cleats. Thus there are limberholes or spaces between the bottom stringers for passage of bilge- water, the diaphragm bulkheads acting as frames for the planing bottom. Keel structure is simple yet immensely strong, with an "anchor" section extruded internal keel member, to the underside of the '' flukes'' of which the planing bottom skin is secured ; a heavy- gauge keel strip similar to a curved butt strap covers the joint externally, the whole being through-riveted in two staggered rows each side. The upper deck is a light alloy floor carried on channel-section beams at each frame station, with Z-section longitudinal "joists" at about Oin. centres running between the athwartships beams and attached to them with shear cleats. This comprises the floor structure, which is additionally supported by two built-up box-section beams spaced about 4ft. 8in. apart and running fore and aft between the mooring compartment bulkhead and the front bulkhead of the after-entrance vesti- bule. These beams vary in length, the greatest depth of section occurring between the stations at which the wing spars" connecting structures span the hull. At these stations are massive bracing structures enclosed with double bulkheads, the heavy-gauge sheathing being stiffened with top-hat-section horizontal stabilisers and large- lipped channel-section " box " posts running vertically beneath the main roof beams. The internal bracing within these bulk- heads is composed of built-up box-section members arranged as a warren-girder-type structure, and a similar bracing struc- ture to the planing bottom is also embodied below floor level. On the upper deck the pilots' floor above the normal flight deck is a simple structure carried on channel-section beams. DATA Wing area (grossi 2,636 sq. ft. Aspect ratio 8.82Dihedral 3°—29' Incidence ... 6°—37'All up Weight 130,0001b. Wing loading 49.3 lb./sq. ft. Span loading Load factor (at 130,000 1b.)Wing aerofoil T/c ratio I -g- = 864 Ib./ft. [W. = 5.75 lb./sq. ft. Fin and rudder area (gross)Tailplane and elevator area (gross) Tail unft aerofoil sectionTailplane dihedral „ incidencePercentage weights (at 130,000 lb.) Structure 30.20Power plants 15.35 Tankage 1.30 Modified Getting™ 436Root; 20 per cent. Tip: 10 per cent.242 sq. ft. 410 sq. ft.Raf 30 6"—tf4°—38' EquipmentAuxiliary generating plants Heating, anticing, etc. CrewFuel HULL VOLUMETotal cabin volume Dining saloon and barToilet and dressing rooms GalleyPurser's office Forward cloak roomAft cloak room Forward vestibule and gangwayAft vestibule and gangway .". Mooring compartmentsCrew's quarters A.G.P. compartmentMail and freight Total volume ... 7.701.07 1.208.40 33.25 3,088 cu. ft.837 781272 j 57 78203 210470 1,500301) 847 8,743 cu. ft. PAYLOAD AT VARIOUS RANGES (at 8,000rt.-still air) 7,620 Ib. for 4,650 statute miles at 184 m.p.h 22,0001b. „ 3,000 185 m.p.h.30.0251b. „ 2,070 .. „ , 188 m.p.h. Hull interior, lower deck. Here is shown the bilge bulkhead construction, hull wall and upper deck structure and the built-up box-frame bracing to the double bulkhead at the main spar station. The framework of the coupe " glasshouse " is, however, worthy of note. It is composed of cast arid extruded sections bolted together on the centre line and at the main side pillars of the front screens, the Perspex glazing being furnished normally. The Shetland's wing is, perhaps, the most unconventional structure of the whole aircraft, this being designed on the main spar torsion box principle used in sailplanes. A modified Gottingen 436 aerofoil section is employed, and the plan form shows a graceful wing of 8.62 aspect ratio with pronounced sweep back of the leading edge, the trailing edge being perpendicular to the hull axis. Three spars are used, although the foremost two are both employed as sides of the torsion box. The front spar is stationed at 5 per cent, of the chord, and consists of a sheet web with L-section extruded booms, and from this extends rearward the very heavy-gauge upper and lower skin plating to pick up the main spar and thus form the torsion box. Similar construction is used for the main spar, although massive T-section extruded booms are used in this case, the skin being attached with ^in. and -ftin- pan head rivets. Webs of both 5 per cent, and main spare are stiffened with vertical T-section extrusions, and the torsion box is divided throughout its span by diaphragm bulkheads at chordal rib stations, each bulkhead being vented with manholes. The remainder of the wing structure is relatively light and comprises diaphragm chordal ribs stiffened with vertical top- hat-section strips and edged with extruded L-section strips on each side, which make a T-section capping at the aerofoil profile line. Skin plating of the wing is attached to Z-section inter- costal stringers bolted to the capping extrusions of the chordal ribs. The rear spar is very like the others in having a heavi* sheet web with T-section extruded booms and L-section ex- truded attachment strips to each inter-spar rib. Frise-type fabric-covered ailerons, each with a trim and servo tab, are employed, and each is swung on five self-aligning ball- race hinges carried in brackets off the rear spar. Flaps are metal-covered and of the Handley Page slotted type; each is actuated by two electric screw jacks with integral motors, the jack rods picking up with a pin joint to lever brackets off the flap. Like the ailerons, flaps are swung in five self-aligning ball bearings, relative flap motion being governed by the offset (which is a good i2in.) between hinge axis and screw-jack attachment. ? Bristol Centaurus 2,500 b.h.p. engines power the Shetland, each equipped with a Rotol fixed cooling-fan and driving de Havilland four-bladed Hydromatic airscrews. The latter are all constant-speed full-feathering airscrews, but those fitted to the inboard engines are also reversing types by means of which handling the boat on the water is facilitated. Fuel is carried only in the wings, there being no fewer than ten tanks in each. Seven narrow, deep tanks are slung choiJ- wise between the inner-spar ribs, and outboard of these are three conventional-type tanks carried on flexible mountings "S stiffeners on the inter-spar rib webs. Oil tanks are housed within the torsion box immediately aft of each nacelle.
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