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Aviation History
1949
1949 - 0910.PDF
I r Photographed early in May, the first production Marathon is making good progress. The four engines are now installed. system incorporates anti-freezers to eliminate the failure at high altitude. From the passenger's point of view the roomy cat the Marathon will be an appealing feature. The clear space available, coupled with a level floor near the ground and a large door, will also be most convenient for freight work. The average height of the cabin is 6ft 3in, the length is 18ft, and the volume 760 cu ft. Various seat- ing plans for from 14 to 22 passengers have been worked out. The cabin is sound-proofed and air-conditioned, and the nine large rectangular windows, in conjunction with the high-wing layout, will give an excellent view of the countryside. At the rear of the cabin there can be a toilet compart- ment, a luggage hold and a wardrobe, while between the front seats and the cockpit there is another small compart- ment for radio and such things as diplomatic mail. Its capacity is 104 cu ft. A Daniels heater together with its fuel tank are located at the aft end of the fuselage, and heat for the cabin and cockpit is led forward in two ducts beneath the floor. This heater is also used to warm the cockpit and to de-mist the windscreen. Recent Modifications Close examination of the latest Marathon reveals a number of modifications, while certain differences are immediately apparent. The third centrally placed fin fitted to the first prototype, but omitted on the second, has been finally adopted. The small but unsightly external mass- balances for the control surfaces have also been removed. Another visible alteration to the empennage is the slight modification to the shape of the rudder horn balance. The forward point is no longer part of the rudder. The elevator has been altered, although the change is barely visible. In fact, the hinge point is iin farther aft and a tin extension has been made to the elevator nose. This is a simpler modification than it may sound, the hinge bracket having been mounted on a iin distance-block on the tailplane spar instead of on the rear face of the spar. Detail changes farther forward include the deletion of the small freight door which was originally positioned close to the first pilot's seat, and a modification to the air-intake scoops for file Gipsy Queen 70 engines. All the foregoing modifications are shown in the new cut-away drawing overleaf. From the production point of view there has been a number of changes, and in several respects procedure now follows Handley Page practice more closely. The fuselage, for example, is divided horizontally as well as into front and rear sections. The four units are more accessible and more work can be done on them at the earlier stages. The four main frame members of the fuselage have been stiffened by the addition of straps on sides, top and bottom, following restressing of the structure for 18,000 Ib a.u.w. The nose section is built in one piece on the original Miles- type spider jig. The spar booms for the mainplanes are milled at Crickle- wood and the spar is assembled at Woodley. The Marathon was first described in detail in Flight of September 4th, s are now mounted in the Marathon 2. The Note t/HLstno// dummy outboard nacelle The main fuselage units are now split horizontally for production. A pair of hot-air ducts is located under the floor. 1947, and it may be recalled that the wing has one main spar and a subsidiary spar at 70 per cent chord. The nose section of the wing is now attached to the spar to form a D-box at an early stage instead of waiting until the spar is in the main wing-jig, when it would be a much less convenient operation. Extensive use of thin skin on the Marathon—only 26 s.w.g.—adds to the problems of production. Provision for de-icing has occasioned a great deal of thought, and the opinion is held that thermal de-icing will be the only satisfactory solution. Accordingly, a thermal system is being developed and it is expected that it will be incorporated in No. 6 production machine. On the first five provision will be made for the attachment of Goodyear boots. The incorporation of thermal de-icing will entail a major modification to the wing leading-edge, but not a rebuild. A detachable leading edge to the outer wings, tailplane and fins is envisaged. The first five Marathons will probably be delivered to West African Airways, and the thermal de-icing system for the subsequent B.E.A. machines should be ready for trial installation by next winter. An important modification in production Marathons is the addition of four extra fuel tanks in the wings. They are, in effect, 15-gallon extensions of the existing four tanks, with which they are interconnected through the wing ribs. Outboard engines have their fuel tanks and extensions out- board, and the inboard engines have them inboard. The total capacity is now 280 gallons, and the tanks in the pro- duction machine are of the flexible, crash-proof type, by Fireproof Tanks, Ltd. Each engine has its separate fuel system and there is a cross-feed cock between the outer and inner tanks on each side.
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