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Aviation History
1925
1925 - 0391.PDF
JUNE 25, 1925 tion which was indicated by the preliminary test flights tobe correct. Without going into details regarding performance it may be said that the machine was designed to have acruising speed of over 100 m.p.h. and that probably the actual cruising speed with full load will be in the neighbour-hood of 103-104 m.p.h. In general design and construction the D.H.54 follows veryclosely standard De Havilland practice, and at first glance the '54 looks very much like the '34, but on a larger scale.There are however, several noticeable differences in general design as well as in details. One change in design is connected with the placing of the top plane in relation to the fuselage. Whereas in the '34 the top plane rests directly upon the fuselage, it is raised in the '54 a considerable distance above the top of the fuse- lage. This arrangement arises out of the fact that, with with fish-plates inside and out. Each portion forms acomplete structure in itself, and to keep out water in case of an emergency landing the small opening between thetwo sections is covered with fabric strip. To facilitate inspection of the rear portion of the fuselage large openingsare provided in the bottom, which are covered with fabric so that when the machine has been in use for some timeall that is necessary is to cut away a piece of the fabric when the interior structure can be inspected and after inspectionthe opening is again closed by doping a piece of fabric over it. The cabin portion of the fuselage is very large and room3Tand seating accommodation is provided f*-r fourteen passen- gers, the seats being arranged in three rows, two close togetheron one side and a single row on the othei with a narrow gang- way down between the two for the whole length of the cabin. SOME CONSTRUCTIONAL DETAILS OF THE D.H.54 : 1, The rear chassis strut is attached to the lower longeron by a fork-end and pin : when the pin is withdrawn, by means of the crank and rod shown, the leg is free to drop ; 2, shows details of the hook attachment of axle to front chassis strut ; while 3 and 4 are diagrammatic representations of the manner in which the undercarriage drops. The front struts remain on the machine, but swing free. 5, gives details of the rib construction, and 6, shows a spar root, with strut attachment and wiring lugs. the larger chord of the '54 wings, a larger cap was required, and as the fuselage is of approximately the same depth as that of the '34 the raising of the top plane resulted. In general design the D.H.54 is a normal two-bay tractor biplane with straight top plane and a fairly pronounced dihedral to the lower plane. A feature which impresses one both on looking at the machine and from an examina- sion of the accompanying general arrangement drawings, u the high aspect ratio of the wings which have a span of 68 ft. and a chord of 8 ft. giving an aspect ratio of 8-5. Aft of the cabin is a large lavatory with the usual fittings,the lavatory and the last two passenger seats being actually situated in the tail section of the fuselage. Access to thecabin is by a door on the starboard side, and in the design of the door provision has been made for making a water-tight joint bet.veen it and the dnor frame so that in case the machine should be forced to alight on the sea it will keepafloat for quite a long time. Provision has been made for heating and ventilating the cabin, the heating arrangementsbeing in the form of a muff around one of the exhaust pipes Constructionally also the D.H.54 follows normal De Havil- and admitting warm air to the cabin near the floor. Fresh land practice in that it has a flat-sided fuselage covered withply-wood and having a deeply cambered roof. In view of its size the fuselage has been built in two separate sections air is forced into the cabin from a scoop projecting out ofthe cabin rooi, just behind the pilot's cockpit, and louvres near the back of the cabin exhaust the air so that a fresh The joint in the fuselage occurs just aft of the cabin door, supply of air is constantly filtering through the cabin. The the joints being in the form of bolts through the longerons, rate at which the air can be changed is adjustable from within 391
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