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Aviation History
1926
1926 - 0207.PDF
MARCH 25, 1926 33 THE AIRCRAFT ENGINEER SUPPLEMENT TO FLIGHT a certain fixed angle. This strut is made in the form of a large turnbuckle with a right- and left-handed screw and is lengthened and shortened by turning the hand wheel in the centre. The buoyancy of the wheels is easily sufficient to keep afloat the whole chassis. Each half of the chassis is attached to the hull at two points, these being the bases of the wing root struts. The inner end of the axle forms one point of attachment and the end of the rear chassis strut. the other attachment. These attachments are made with very slack fitting pins in a horizontal plane, thus enabling the chassis to swing up and down. The upper end of the adjustable strut is attached to the front spar of the lower plane at its point of attachment to the front wing root strut. It will be seen that by lengthening and shortening the adjust- able strut by means of its central control wheel the chassis is lowered and raised and swings about its two points of attachment on the hull. The chassis can be attached to the flying-boat when afloat. This can be done at its moorings by means of a boat, or from the slipway by bringing the flying-boat in to the slipway stern first. The two attachments on the hull are first made. The following are some of the advantages claimed for this type of handling chassis over the beach cradle :— Liability to Damage Due to Handling. The beach cradle takes the weight of the flying-boat through a portion of the bottom of the hull, and thus places on the hull loads of a different nature from those experienced in other ways. The bottom of the hull forms a very narrow base for support in comparison with the span, and this causes rocking of the flying-boat on its beach cradle during handling, or when resting in even a light breeze. This, in turn, causes "working" of the hull and liability to subsequent leakage. When launching a flying-boat or bringing it ash >re by means of a beach cradle, there occurs a very critical period during which serious damage may very easily be done. This period occurs during the change over from the flying-boat being water borne and cradle borne. ]f the sea is a little rough, or is affected by the swells from passing steamers, the hull is very liable to be hammered on to its cradle by a series of heavy blows. This usually happens when the BEACHING CHASSIS OF SUPERMARINE " SOUTHAMPTON." On the left the chassis is shown in the down position, while on the right it is shown at the top of its travel. . The attachment pins are a very slack fit and the joints have a big lead into their sockets, so that the attachments are very easily made. The chassis will now float so that the upper end of the adjustable strut, which is shortened to its limit, can be conveniently attached to its socket on the lower plane in a similar manner. The adjustable strut is now lengthened and the chassis forced down into its lowest position. By the use of a light tail trolley the flying-boat can now be drawn out of the water and handled on the ground in exactly the same manner as a normal type of land machine. Owing to the necessity of packing flying-boats as closely as possible in their hangars, in order to economise hangar space, it has been found necessary to be able to move them in any direction, especially sideways, without the usual backward and forward manoeuvring. This requirement is analogous to that of motor-cars in a closely-packed garage and can be satisfied in an exactly similar manner by the use of skates with swivelling rollers. The flying-boat can be wheeled on to a pair of these skates, made to fit the chassis wheels, and can then be side-tracked or moved in any direction. cradle is not in its proper place, with the result that the bottom of the hull receives these blows on projecting parts of the cradle. The handling chassis carries the main weight of the flying- boat from points on the wing structure, and the hull is suspended from these points in a similar manner to when the machine is in the air. The loads due to handling are thus taken through the structure in a manner analogous to the flying loads. No additional strengthening of the hull or structure is. therefore, necessary, and the flying-boat can be roughly handled or left out in the open in rough weather without fear of damage. The use of the handling chassis eliminates the causes of damage attributable to the beach cradle, as when the chassis is attached and lowered into position the flying-boat can alternate between its chassis- borne and water-borne conditions without the least harm. Ease of Operation. The operations of launching and bringing ashore by means of a beach cradle require the use of a large crew, specially trained to the job, and who can be relied upon to use great care and very considerable skill. 178*
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