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Aviation History
1932
1932 - 0273.PDF
FLIGHT, MARCH 25, 1932 joints being made by welding the strut ends to the longerons, and the few bracing wires used being looped over tubular quadrants welded into the corners. The welded construc tion has facilitated the dropping of the top longerons to give deeper cockpit doors without making these a part of the primary structure. The outside form of the fuselage is given by spruce stringers carried on light skeleton wooden formers attached to the primary structure by simple clips. The fuselage covering is fabric, and in order to facilitate inspection the fabric is secured in appropriate places by " Zipp " fasteners. Normally the tags of the fasteners are locked by a small length of thin wire, but when this is removed the fasteners can, of course, be un done in a few seconds, and the interior structure examined. The Armstrong-Siddeley 7-cylinder " Genet Major " engine is mounted on a circular plate, which is in turn supported on four steel tube vees, the apices of which are secured to the forward ends of the longerons. This type of mounting has been found to resist torque reaction very well, and has the further advantage of making the back of the engine very accessible. By placing the petrol tank (capacity 28 gallons) in the deck fairing forward, the top centre section is kept thin, a fact which adds to the clean appearance of the machine. The oil tank is slung on straps on the fireproof bulkhead behind the engine. A very neat Townend ring has been designed for the " Cadet." As it promises to be very successful, it may be assumed that a similar principle will be applied to other v Avro types. The ring is built in two halves, held together by quick-release devices. The ring is supported on the engine by fitting brackets on top of the cylinders, these brackets corresponding with other brackets on the cowling ring. The brackets serve merely to locate the ring, which is not bolted or otherwise attached to the engine direct. By interposing a felt pad between the engine brackets and their corresponding cowl brackets, rattle is eliminated, and the amount of vibration transmitted from the engine to the ring is negligible. The arrangement has the very great advantage that the time taken in removing or replacing the cowl is a few minutes only, and the engine is for practical purposes as accessible as an uncowled engine. The main data of the Avro " Cadet " are given in the table on page 254. From this it emerges that the ratio of gross weight to tare weight is 1.62. At first this may appear to be a somewhat low value, but it should be realised that the ratio is based on the gross weight corre sponding to " Aerobatics " Certificate of Airworthiness. A considerably greater load could be carried for " Normal C. of A., when the ratio becomes rather higher than the average. Aerodynamically the " Cadet " appears to be very efficient, the Everling " High-speed Figure " IJ; 2ktl being THE ENGINE MOUNTING : The ring supporting the " Genet Major " engine is carried on four steel tube vees, the apices of which pick up the ends of the four longerons. The curved tube on the ring, shown in the inset, locates the cowl-securing cable. (FLIGHT Sketch.) no less than 21.7, which points to a low minimum drag co efficient. The speed range is from 45 to 118 m.p.h., a ratio of 2.62 to 1, and the initial rate of climb is 750 ft./min., all of which point to efficient aerodynamic design in pro portion to the wing loading and power loading. Altogether the Avro " Cadet " is to be regarded as a very attractive training aircraft, and in spite of its rela tively low power (135 h.p.) and sturdy construction, it has a performance which should make it suitable for full flying training, without the need for further training on high-power types. THE AVRO 631 " CADET " : The front view shows the simple and clean design. (FLIGHT Photo.) *£> Avro " Cadets " for Ireland THE Irish Free State paid A. V. Roe & Co., Ltd., a handsome compliment by ordering a batch of six Avro " Cadets " " from the drawings," i.e., before the machines were built. The first machine came fully up to expec tations, and Mr. Dobson is now busy turning out the production models in record time. The experimental machine, shown in the photographs above, is fitted with Handley Page slots, but the Irish machines will be without these. The first two were flown across to Ireland recently. 257
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