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Aviation History
1949
1949 - 2005.PDF
DRY 771 Arrangement of desiccant pack of acti- vated alumina for the canopy cavity. Detail of stringer/rib attachment : use is made of miniature eye- bolts and threaded anchor-cleats. ing, across vrhich passes the taiiplane. This is anchored in pin-joints to the after face of the rearmost pear-frame, • and inside the taiiplane centre section is housed an English Electric linear actuator, the head of which is pin jointed in a saddle bracket on the tailplane top surface, whilst the foot is pin-jointed to an anchorage on the fuselage tail decking. From the latter point, a bracing strut slopes upward through the tailplanr to an attachment point on the neck of the rearmost pear-frame. The taiiplane itself is built on a trapezoidal centre-section, the front wall of which is a massive D.T.D. 683 light-alloy casting uniting the spars, the tailplane pivot points being at the forward lower corners of the spar bridge in the form of pin-joint fork/lug fittings bolted to the pear-frame. The tailplane spars are basically similar to those used in the mainplanes in that, in conjunction with plate webs, they employ extruded booms taper-machined spanwise. Chordal ribs ot plate webs with extruded beaded-angle booms are set normal to the spars and are notched for the extruded beaded-angle stringers: skin panelling forward of the spars is, like that of the wings, in single sheet wrappings. The elevator is built up on a 10-gauge rolled horseshoe-section spar in conjunction with pressed channel ribs carrying the skin plating. At their root ends, the elevator spars embody torque-transfer fittings flange-riveted to vertical arms, the upper ends of which are joined by a swing link ; by this means, the effect of dihedral on elevator motion is com- pensated. The port elevator is fitted with a spring tab, whilst its starboard fellow has a conventional balance tab. Although an orthodox spar-and-rib fabrication is em- ployed for the fin, it is unusual in that it is made of wood ; the reason is that, as in the case of the pilot's canopy, submerged aerials are embodied in the structure. The rudder is skinned on pressed-sheet chordal ribs and, against the front face of its spar, carries the torsion tube and bar assembly serving the spring tab. Structurally, the Canberra wing is essentially of monospar form, in that the complementary rear member is of an auxiliary nature and is fashioned in three separate sections, port and starboard, the outermost sections being in way "of the ailerons and fitted with a curved web to form the shroud wall. As already noted, the Canberra does not employ a conventional centre-section and the wing spars are joined by a bridge member spanning the fuselage, the connection being made in fork/lug fashion direct to the boom ends with double horizontal pins, top and bottom. The wing structure inboard of the nacelles and forward of the spars is essentially a faired stowage box for various auxiliaries and the main undercarriage, and is divided spanwise by a diaphragm forming the forward wall of the wheel-well, the well itself being roofed by built-up box ribs. Drive from each Avon is given to a Rotol/Rolls- Royce auxiliary gearbox, mounted in each leading edge, that on the starboard side being furnished with a generator, Lockheed Mk 6 pump and Hymatic compressor, whilst, on the port side, in addition to the generator and hydraulic As the jack contracts, the bomb doors are swung upwards about the pivot points to retract into the fuselage. pump, a Marshall cabin blower (5 lb/minute) is carried inplace of the Hymatic compressor. As may be seen in the schematic detail sketch, the mixing valve and coolerfor the cabin conditioning system are also embodied in the port leading edge. In conjunction with the main spar, at the outboard rearcorner of the front part of the inner wing is fitted the massive forged (D.T.D. 683) triangulated anchorage forundercarriage mounting. The undercarriage leg and the head of the radius strut are pivoted in a triangulatedmachined-bracket bolted to the main-spar web. The main undercarriage, including the oleo units, is of EnglishElectric design and manufacture, the head of the leg being carried at such an angle that, in retracting, the wheel islifted with a forward swing to enter the leading-edge well. The breaker strut is attached to the leg through an inter-mediate link incorporating a latch lock and, owing to the geometry of motion, the pivotal points of the jack andradius strut necessitate spherical joints. The undercarriage doors are actuated by a separate jack through sequencevalves, and embody toggle-operated positive latch-locking. As well as diverging from current practice in loading andaspect ratio, the Canberra wing is also somewhat unusual in structure. For example, forward of the spar in the outerwing panels, the leading edge structure comprises main ribs with plate webs and extruded booms, flanked on eachside by sub-ribs similar in form but dimensionally smaller. Intercostal to the main ribs, and over the sub-ribs, runextruded stringers stabilizing the skin. All these ribs are normal to the leading-edge line, and the skin plating iscomprised in eight single-wrapping panels. The manner of attaching stringers to the sub-rib booms is extremelyclever and is, in fact, the subject of a company patent; it comprises a miniature eye-bolt, pivoted to the stringerweb and screwed to a small anchor cleat, riveted to the rib. Between the main spar and the auxiliary sub-spar, themain chordal ribs have plate webs and extruded T-booms, and are flanked by secondary ribs of flanged plate throughwhich pass the extruded beaded-angle stringers which run intercostal to the main ribs. The spanwise skin-joints aremade at three beaded-T extruded skin-attachment stringers which run from the outboard rib of the engine out to thewing tip. So compact is the Avon turbojet, even by normal"axial" standards, that it is entirely housed forward of the main spar; the cut-out in the spar web to accommodatethe jet pipe necessarily has to be compensated, so use is made of massive, cast bridging-rings—again of D.T.D. 683—through-bolted on the front and rear face of the spar. The engine-well is bounded by reinforced leading-edge ribsembodying forged, spherical seatings for the main mounting spigots. Front attachment is effected through swing-linktie-rods depending from hemispherical cup-fittings and pivoted to a truss beneath the compressor casing. Thisarrangement permits lateral and axial expansion movement
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