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Aviation History
1918
1918 - 1281.PDF
NOVEMBER 14, 1918 The spars possess several points of interest, and their dimen- sions and method of construction are presented in Figs. 2 and 3, from which it will be seen that they differ from the practice adopted in other German designs. The I Section main members are of spruce. The three-ply walls, applied to them by glueing and tacking, are principally birch, and are 4 mm. thick. - The spars are wrapped with fabric throughout. In the earlier Gotha designs the sweep back of the wings was 10 deg. In the present design it is 4 deg., due probably to the fact that other means have been successfully adopted to get the centre of gravity sufficiently forward. It will be seen from the scale drawings that whereas the upper wing surface consists of two portions which unite at the centre line of the machine, the lower plane on each side consists of the centre section attached to the base of the fuselage, and an outward extension, between which is inter- posed a short span of plane forming, with the engi ne bearers and their struts, and the landing carriages on each side, a completely independent and separate unit. These small sections of planes are covered in with three-ply, both top and bottom, and the same material is used for the upper surface of the centre section of the lower plane. At the junction of the two upper wings, a rather unusual joint is employed; this is illustrated in Fig. 4, and consists of a series of rectangular staples which are held together by a steel wedge. The joints used in the lower plane are of a > different character, and embody the usual pin principle, giving the spars, when not braced by the wiring, a hingeing action in the vertical plane. This joint is shown in Fig. 5, which also illustrates the manner in which the wings are braced against drag stresses by means of very light steel compression tubes and cables. Another view of the box joint on the spar end is given in Fig. 5a, which shows its internal construction. Joints of the above design are used on either side of the engine bearer section. Struts. Apart from the struts which separate the engine eggs and brace them to the fuselage, there are three pairs of interplane struts on each wing. These struts are composed of steel tubing to which is attached a three-ply fairing. The design of the strut joint is shown in Fig. 6. The wire bracing throughout is by multi-strand steel cable, the fitting of which, however, presents no features of interest. Ailerons. Only the upper ailerons are balanced, the upper and lower ailerons being connected by a single strut on each side. The operating lever is fitted on the top aileron, and works in a slot cut in, the upper main plane. From this lever wires are taken over pulleys on the leading spar of the lower plane, and thence to the fuselage through the space between the leading edge and the forward spar. Where the wires pass through the small sections of lower plane under the engines, they are provided with detachable connections which can be inspected through hinged flaps. The framework of the ailerms is of steel tube throughout, involving a welded-up one-piece construction. Propeller Accommodation. In order to permit the engine eggs to be placed sufficiently far forward to allow of the centre of gravity being correct, considerable inroads have had to be made in the trailing edge of both upper and lower planes in order to give scope for the propellers. In front of the screws, the chord of the planes is reduced to 5 ft. 9 in., and at this point the trailing edge is very blunt. Empennage. The whole of the empennage construction is of steel tubing, and the various components are rigidly braced together by inclined streamline struts, which, as in the case of the main struts, are of circular section steel tubing, to which a hree- ply fairing has been added. These external struts give the Gotha tail a somewhat clumsy appearance, and would seem furthermore to exercise a notable masking effect upon the rear gun. Only the rudder is balanced, and it will be noticed that the area of this organ, compared with that of the fin, is very large. _-. . ' - Fuselage. The fuselage is in one piece from nose to rudder post,[and is an entirely wooden construction, consisting of the usual longerons and wooden transverse members. It is covered in with three-ply throughout its length on the top, bottom and sides, but whereas in most German aeroplanes the three- ply lining is relied upon for solidifying the structure, in this machine it is extensively reinforced by diagonal wire bracings, especially in the forward portion of the fuselage at the point at which the main planes are attached. In the extreme front is placed the front gunner's cockpit. Immediately behind him, and on the left-hand side of the machine, sits the pilot ; beside him is a folding seat for another passenger. Between the pilot's seat and the rear gunner's cockpit are placed the two main petrol tanks, which occupy the full widthof the,fuselage. The original intention of the designer was evidently to fit tanks of smaller capacity, shaped in such a way as to provide a communication tunnel between the pilot's seat and the rear gunner's cockpit. For this purpose the wooden bulk- heads on each end of the tank space are deeply cut away on the left-hand side. With the existing arrangement of tanks, however, no interchange of personnel is possible. Another small point of interest is the inclination of the back of the pilot's seat ; for this purpose careful consideration of space has resulted in a wedge-shaped piece being let into the forward tank, indicating again that all possible means have been adopted to get the C.G. sufficiently forward. The rear tank is of identical construction, and also possesses this wedge-shaped arrangement. In this case, however, the wedge-shaped piece represents waste of space. The rear gunner's cockpit is roomy and provided with a folding seat. Abaft of it, the fuselage is furnished with an elaborate gun tunnel, which, however, differs very markedly from that which was incorporated in the earlier Gotha designs, in which tine fuselage was completely covered in as to its top surface, and the tunnel was only used for a gun mounted on the floor of the cockpit. In the present design, the tunnel is furnished with a V-shaped opening in the upper surface, so that the gun mounted on the top of the fuselage can fire back- wards and downwards through an arc of about 25 deg. laterally and about 60 deg. vertically. This is shown in Fig. 7. The inside of this tunnel is lined with three-ply wood, and its arrangement is clearly shown in Fig. 8. On the floor of the fuselage, in the rear gunner's cockpit, a mount is provided for a second gun, but in none of the Gotha machines brought down was a gun fitted at this point. It is noted that to give the rear gunner a greater feeling of security, and to prevent any loose articles from falling out, wooden cross pieces are fitted up immediately in front of the tunnel opening. At the forward end of the tunnel the fuselage is evidently weak, as it was at this point that breakage occurred in most of the machines brought down. Fig. 9 illustrates one of the brackets by means of which the fuselage is secured to the upper main plane ; it carries a short stream-lined strut. It will be noticed that the char- acteristic German dome-shaped clip is used, but that in this case the usual welded joint is replaced by rivets. This bracket occurs at the after bulkhead immediately behind the rear petrol tank ; the dotted lines proceeding from the small clip indicate how this bulkhead is cut away so as to provide, in the original scheme, an opening through which the personnel could squeeze in order to change places if necessary. To be continued.) Fighting: in the Air. ' THE winter session of the Royal Aeronautical Society was opened at the Central Hall, Westminster, on November 8th, when Maj. Cochrane Patrick, D.S.O., R.A.F., lectured on " Fighting in the Air." As this lecture was of the popular order, it was somewhat elementary, Maj. Patrick explaining in an interesting manner some of the problems which have to be mastered in connection with modern air-fighting. He traced the progress of air fighting and the development of special machines to meet the continually changing condi- tions, and then went on to enlarge upon the various aspects of such questions as camouflage, the effect of the sun, mist clouds, &c, the various methods of approach from below, above, in front and from the east, then going on to speak of formation flying in several kinds of work. Not the least interesting part of the lecture was the series of diagrams by the aid of which Maj. Patrick made clear such technical questions as the deflection of the machine gun, sighting, &c. •.•..,.•. ,'i -,, / 1282
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