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Aviation History
1947
1947 - 2121.PDF
DECKMBER IITH, 1947 FLIGHT 667 Advanced Amphibian plate web, as have the front auxiliary and rear auxiliary spars* the latter extends only over the outer portions of the centre section. Structurally the outer wing panels are of more than usual interest in having no shear webs /or the main spar. There are three latch pins, one each at the front auxiliary spar, rear auxiliary spar and rear spar respectively. The heavy ribs are of the plate web type and the lighter ribs are of girder construction through- out the outer wing panels and centre section. Though divided at the centre section joints, the Handley- Page slats extend over the entire lead- ing edge and are mechanically inter- connected with slotted flaps fitted over the whole of the trailing edge, includ- ing those portions forward of the slotted ailerons. On these latter por- tions both flap and aileron droop together, in unison with the inboard flap section, the ailerons, of course, retaining their independent movement. To permit wing folding there is a iynged flap between the aileron and inboard flap. Housed in the wing are eight sets of flap and slot operating gear, with jacks, track bars and guide r0(is—four sets in the centre sectionand two in each outer mainplane. The centre section flaps slide rearwards on track bars and are drooped by a con- necting rod moving through a shorter distance than the track bar. The flaps on the outboard wing panels are carried on faired hinges below the under surface of the wing. Partly to facilitate replacement, but also to minimize interference with the search radar, the wing tips are of wood. The aileron spar booms are half-circle drawn sections and the ribs are carried under the top boom and over the lower boom. Spar webs are inserted only to take local loads at the hinges. Similar construction is used in the 0 5 K> 15 20 25 30 DEC- INCIDENCE OF CHORD LINE AT t OF AIRCRAFT Lift curves for the Seagull (engine off). --AILERON SCREW- JACKS SLOTTED FLAP WING-FOLDING HINGE A schematic representation of the variable-incidence system used on the new Submarine amphibian. Flap and slot interconnection is also indicated. outer flaps. Strong points for bomb carriers are located on the main spar, and when the aircraft is used for A.S.R. work these will each carry a 60-gallon jettisonable tank, or a rescue assembly. . Conventional construction is used for the lateral stabilizing floats. The keel is stiffened by angle members and there are six frames, five bulkheads and top/side and bottom stringers. Attachment to the mam spar is by a raked cantilever strut. Each float houses a telescopic strut for bracing the folded wing to the hull. Much of the centre section is occupied by six tanks tor the internal fuel'load of 285 gallons. There are two main metal tanks, between the main and rear spars, and four flexible tanks forward of the main spar. Fuel is automati- cally transferred by air pressure, taken from the exit side of a Pesco pump, from the forward outer tanks to the forward inner tanks, and thence to the rear main tanks. A similar delivery system is used in conjunction with the jettisonable tanks. Although the variable incidence gear, the principle ot which has already been tried on the Supermarine Type 322, or "Dumbo." has been discussed in general terms (see Flight, April 25th, 1946), special attention must be paid to this feature as applied to the Seagull, and some ex- planation given of its purpose, By varying the incidence of the wing it is possible to maintain the hull at its best angle for take-off, the wing angle being changed, if required, to suit con- ditions during the actual take-off run. Moreover, by setting the wing at high incidence the leading-edge slots are rendered fully effective. Another im- portant consideration is that, with the wing at a high angle of attack, the pilot is enabled to approach the deck of a carrier with the hull of his air- craft in a less nose-up attitude, and accordingly to improve his view for landing. Varying Incidence In essentials the variable-incidence gear is extremely simple. The wing pivots on spherical phosphor bronze bearings on the front spar and the change in incidence is effected, either by electrical power or by manual means, through screw jacks connecting the rear spar to the trunk superstructure. The wing is nor- mally at 2| degrees to the hull datum, and the maximum incidence is 12\ degrees. The A.C. electrical system for operating the high-lift devices is novel. There is a B.T.-H. engine-driven alter- , nator (8 5 K.V.A. at 200 volts, 400 •:- cycles, 3 phase) and the incidence change is effected by B.T.-H. actua- tors. An emergency system is incor- porated for lowering the flaps, using power supplied from the accumulator through a B.T.-H. DC/AC converter. The two prototypes are each powered by a Rolls-Royce Griffon 29, but any subsequent aircraft would have the RG 30 SM. The Griffon 29 is basically a Griffon VIII and delivers a take-off power of 1,815 n-P- A 0.59:1 reduction gear ratio and a two-speed blower with solenoid operation are features of this engine. The RG 30 SM is basically the Griffon 57 and is notable for its take-off power, using water-methanol injection, of 2,500 h.p. The water-methanol is injected into the supercharger eye by an auto- matically operated metering unit. An- other point of interest is that high supercharger gear is used for take-off to achieve the maximum boost of 25 lb/sq in. The engine is carried forward of the leading edge on built-up bearers braced by two vertical tubular struts. A contra-rotating six-blade Rotol airscrew is fitted, irrespective of engine mark, and, as on the Supermarine Seafire fighters in service with Naval Aviation, should prove invaluable by eliminating the effects of engine torque. Ratings of the Griffon RG30SM engine are: take-off (low gear) 2,500 h.p. at +25 1b boost; combat, 2,055 h.p. at 2,250ft at +18 1b boost, international 1,680 h.p. at 6,500ft at +12 1b boost. Max r.p.m. are 2,750.
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