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Aviation History
1923
1923 - 0711.PDF
NOVEMBER 22, 192S THE AEROMARINE METAL-HULL FLYING BOAT RECONSTRUCTED war-time aircraft have been used by theAeromarine Airways in the U.S.A. since the beginning of their operations in 1920 with more or less success, yet these opera-tions clearly indicated that for futnre use a more efficient, particularly from the point of maintenance and reserve power,flying boat would be needed. The problem of development of a boat of this type wasplaced in the hands of the engineers of the Aeromarine 'Plane and Motor Company, Keyport, N.J., early in 1922. Pre-liminary work on the design and construction was immediately started. The boat to be replaced was the old convertedH.S.-2L-six passenger, beach-hopping machine. Beach-hopping requires a flying boat with a strong bottom,quick take ofE, good climb, and with sufficient fuel capacity for either short or long distance flights. The hull must be sea-worthy as much of the flying is over open ocean, and the whole machine must be so constructed as to require as little main-tenance as possible while anchored in a protected harbour. The Liberty motor, which is available in quantities in theUnited States, was decided upon for the power plant, and in bracings of hard wiie ; the upper wing is of three panels.The centre section panel, which supports the petrol tanks is rigidly mounted on the motor support. The outer panels arecut away for the ailerons, which are narrow and fitted to the upper wing only and extend two-thirds the total wing spread.The small balancing panels, mounted on duralumin masts, with general narrowness and straight ends, constitute a verylight and effective lateral control. The aileron control cables are run in tubes inside the wing panels, which reducesjairresistance and makes the controls readily removable All air controls are mounted on ball bearings. Seventeen S alloy is used for the framework of the tailsurfaces. Channelled sections of 22 B. and S. gauge metal are employed for the wings and minor braces ; 20 gauge materialfor the built-up boxed sections, and 18 gauge is used for the fin post, while l/16th in. wall tubes are used for the rearbeam of the stabiliser and for the elevator and rudder beams. All joints are riveted. The weight of this structure while muchstronger than the usual wooden construction is but 53 lbs per sq. ft. of area. THE AEROMARINE METAL-HULL FLYING BOAT : Three views of the complete machine : Top, left, sideview ; right, three-quarter front view ; and, below, front view of the machine in the water. It is fitted with a 400 h.p. Liberty engine. accordance with these requirements a design was laid downfor a biplane flying boat with a metal hull and tail surfaces and spruce and fabric wings. The upper wing was made with alarger span and chord than the lower in order to improve the aerodynamical efficiency of the structure and avoid damagein high seas. The ailerons were fitted to the upper wings only and were designed to be very large for control at low speed. The comfort of the passengers in the hull was the firstconsideration. Seaworthiness, ease of take-pff, and low air resistance were also given consideration. The hull, as laiddown, is wide enough to accommodate four passengers abreast in the rear seat and three in the forward seat, a crew of two,with dual control, being located back of the passengers and directly forward of the lower front wing beam. The bottomhas a V with an inclined angle of 152° at the step and the angle is still sharper at the bow. The step is 5 ins. deep and thebottom back of it raises up to an angle of 8° towards the stern and is V-shaped, ensuring clean running before take-off, andseaworthiness. The wing tip pontoons are of very good streamline section,square in cross section, turned up on edge so as to break the force of the water in case of contact in high seas. Details of Construction.—The wings are constructed of built-np trussed ribs and spruce I-beams, braced with internal As low maintenance was the first consideration, the powerplant installation received very careful attention. The motor support is built up of heavy steel tubing with theexception of the motor-beds, which are of laminated spruce and ash. This support is attached to the hull, which affords a widebase. The whole structure requires no cable bracing what- soever. .:•'•'-. A cartridge tube radiator, swung froin the upper panel andsteadied from the engine bed, has a frontal area' of 620 sq. ins. A full face shutter control, operated from the pilot's cockpit,regulates the air flow. Two 50-gal. 35. alloy welded petrol tanks mounted in thecentre panel and one 70-gal. reserve tank in the hull constitute the petrol system, the 70-gal. tank being used for long flightsonly and is separated from the main system by a shut-off valve. A visible petrol gauge, located in the hull, fihows theamount of fuel in the lower tank ; separate gauges in the upper tanks indicate their condition. All three tanks weigh but60 lbs. for a petrol capacity of 170 gals. One-inch 3s. alloy piping connects the tanks. The petrol is fed by gravity fromthe main tanks to the carburettor, which eliminates the head resistance of a fuel pump and assures reliability under alloperating conditions. ' The hull, which is the •first all-metal hull to be constructed) 711
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