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Aviation History
1956
1956 - 0084.PDF
84 FLIGHT, 20 January 1956 Accessibility of the Mamba ASM.6 powerplant is of a high order. Also seen open (or removed) in this photograph are the access panels to the starboard accessory gearbox and cockpit instrumentation. SHORT SEAMEW v,<. "..... travel main oleos and low-pressure tyres being well suited tooperation from rudimentary surfaces. General construction of the ailerons and flaps is clearly shownin the large drawing. The former are of the Frise type, and have an area aft of the hinge line no less than eight per cent of thegross wing area. Each aileron is fitted with a large servo tab and a ground-adjustable tab is also provided. The slotted flapsare arranged in four sections, each of which rotates about a fixed hinge axis below the lower surface of the wing, the posi-tion of the axis being so selected as to place each portion of the flap in its optimum position at the landing setting. Thearrangement prevents the attainment of the optimum perform- ance at the take-off setting, but the penalty is very slight and hasbeen considered well worth while in the interests of achieving a very simple mechanical design. The total flap area is 166 sq ftand die maximum angle of depression 45 deg. A small section of fixed slat is provided at the leading edge, inline with the junction between the ailerons and flaps. Each slat is held by four small brackets, those at the extremities sealing theslot to form a box assembly. It has been found that this signi- ficantly improves the stalling characteristics, with only a veryslight effect on performance. On the underside of each wing centre-section of the SeamewAS.l there is a hook for catapulting. A simple sting-like arrester hook is also fitted, the attachment of the hook being shown inone of the two upper illustrations on p. 85. A hydraulic jack is fitted for raising the hook from the dropped position and rebounddamping and centralizing are incorporated. Also visible in the photograph is the tongue-fitting which engages the hold-backrelease during the catapulting sequence. Owing to the unusual design of the Seamew, and to the slim-ness of the Armstrong Siddeley Mamba ASM.6* power plant, it has been found possible to accommodate the entire engine bayunder the strong ditching floor beneath the crew compartment. The basic engine is built up into an engine-change unit incor-porating engine accessories, starter, oil tank, various pipes and cables, the tubular steel mounting structure and all the appro-priate firewalls and nose cowling. This complete unit can be removed and replaced with extreme facility, and it is, in addition,readily accessible for routine servicing through the numerous access panels, as indicated in the adjacent photograph. Starting is effected by a Rotax twin-breech cartridge starter,the exhaust from which is carried round the top of the powerplant to an orifice on the starboard side of the nose. Directly abovethe front of the engine is arranged a rearwards-facing accessory drive capable of transmitting 100 h.p. Extension shafts transmitthis power to a dividing unit which provides power for two gear- boxes. Between them, these boxes provide drives for two6 kW (or 9 kW) electric generators, two Pesco vacuum pumps, one Messier hydraulic pump and one 30 or 40 kVA alternator. The airscrew is a Rotol product with four solid light-alloyblades and a diameter of 10ft. To reduce airscrew stresses the thrust line is tilted upwards at 2 deg to the fuselage datum, anda Lockheed brake is fitted for bringing the airscrew to rest quickly after shut-down. Exhaust from the Mamba is ledaway through a downward-curving jet pipe which discharges below the fuselage towards the starboard side. . Basic electrical supplies are drawn from a regulated 28 Vdirect-current system. The total available power of 12 kW provides approximately 50 per cent reserve over the normal loadrequired for anti-submarine operation. Provision has also been made for an increase in D.C. output up to 18 kW should futurerequirements make this necessary. Inverters provide various secondary supplies including the following: 360 VA, 115 V,1,600 c.p.s for radar; a similar supply for special electronic gear; 626 VA, 115 V, 400 c.p.s., three-phase for radar and emergencysupplies; and 187 VA, 115 V, 400 c.p.s., three-phase for automatic jet-pipe temperature control and the gyro compass. An ad hocelectric supply is also provided for de-icing purposes, and is referred to later. Fuel is contained in four bag tanks housed in smooth-linedcontainers, two being accommodated in each half of the centre wing. The total capacity is 350 Imperial gallons, excluding airspace. Hydraulic power is provided by an engine-^iriven Messierpump which energizes the main system at 4,000 lb/sq in. The system is quite conventional and serves flaps, bomb doors, brakes,tailwheel castoring leg, arrester-hook retraction and wing folding. A hand pump provides an emergency source of power, andaccumulators are fitted to serve the flap system and also to provide for ten full applications of the wheel brakes. Hot air for the cockpit is drawn from a tapping on the com-pressor casing of the engine, from where it is fed into the cockpit through a mixing valve which gives manual control of interiortemperature. Concentrated jets of hot air are provided for de-misting, and a cold-air system is also included. Two forms of de-icing are provided. The main aerofoil sur-faces are all equipped with pneumatically operated rubber over- shoes fed with compressed air from the exhaust side of thevacuum pumps. This type of system was found to be the lightest of the various alternatives available. The airscrew and engineintakes are all de-iced electrically, there being a special 40 kVA engine-driven alternator supplying 400 c.p.s., three-phase currentat 115 V for this purpose. The airscrew spinner and blade roots are continuously heated, the remainder of"the blades receiving acyclic supply. The engine-intake guide vanes, aerofoil spokes MM details of this Mamba are at present withheld. Twice last year the Seamew completed carrier acceptance trials from H.M.S. "Bulwark". The air- craft is seen (left) being taken down on the lift with the Mamba 6 still turn- ing. The right-hand photograph shows the starboard wing-told, the locking unit in line with the front spar being risible on the oblique centre- section terminal rib.
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