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Aviation History
1921
1921 - 0778.PDF
NOVEMBER 24, 1921 drift, etc., the navigator need not expose his head to the wind. Altogether the cabin appears well thought-out. There is a trap door in the floor, leading to the " basement " below, from which another door leads to the., lower plane. Corresponding to this door is one in the inner wall of each engine nacelle, obviously for the engineer to crawl through so as to get at his engines. As exhibited, there is no provision on the wing for keeping the engineer from being blown into space, but one understands that it is intended to fit some form of guide rail with netting. The engines—four Hispano-Suizas—are placed on the wings tandem fashion. This is the feature one likes least of all on this machine. Past experience with tandem airscrews has not been such as to give any cause for optimism as regards efficiency, and we are quite certain that M. Herbemont would have been better advised to use two engines of greater landing wires run from the lower spars up to the sides of the body, at the foot of the centre-section struts. The spars are of the box type, and bound with fabric throughout. Ailerons are fitted to the lower planes only, and are operated in the usual Spad fashion by cranks and tubes inside the wings. As in the Spad Berline, the two petrol tanks are placed on top of the upper wing, with gravity feed direct to the engines. The undercarriage of the Bleriot four-engined machine. View inside the cabin of the Spad 45. power. He may have been influenced by the lack of French engines, suitable for the purpose, and possibly also by the somewhat problematical advantages of splitting the power up into four units, so that if one engine fails, the power is reduced by one-fourth only instead of by one-half. It is doubtful if this is so in practice. For instance, if the front engine stops, the propeller of the rear engine is deprived of the slip stream. Consequently, its propeller must be of too coarse pitch and the efficiency suffer correspondingly. The engine nacelles and their internal framework, engine- bearers, etc., rest on the lower plane, and appear to be sup- ported only on the struts which slope outwards at a fairly flat angle from the undercarriage. This looks somewhat insufficient, but as the wing bracing would probably help somewhat, although indirectly, owing to the pin-joint in the spars just outside the engines, the structure may be better than would appear at first sight. Perhaps the most daring feature of the design is the use of a single I-strut on each side. While this arrangement has proved quite satisfactory on the smaller Spads, it is somewhat staggering to see a four-engined machine with only one strut on each side. However, the wing brac- ing looks substantial, and the single strut may be sufficient. Two lift wires (streamline, in duplicate) run from two points on the side of the fuselage to the upper spars at the points of attachment of the I-strut cross-piece. Another two wires run from a single point on the front spar just outside the engine nacelle to the same points on the upper spars. The The undercarriage is shown in one of the accompanying sketches. There is a substantial Vee under the inner end of each wing root, and the axle carries two wheels in tandem on each side. The wheels are fitted with mud guards, after the fashion of the Curtiss " Eagle." As regards the usefulness for commercial purposes, it would appear that, except as a sort of passenger carrier de luxe the machine would be extravagant. Taking the total power as 1,200 h.p., and the number of passengers carried as 17, the power per passenger is over 70 h.p. This does not appear a particularly good commercial proposition. We have in this country machines with approximately the same speed, carrying one passenger for each 45 h.p. The main characteristics of the Spad 45 are as follows : Passengers, 17 ; engine power, 1,200 h.p. ; speed (estimated), 124 m.p.h. ; span, upper plane, 70 ft. 5 ins. ; lower plane, 64 ft. 10 ins. ; length o.a., 51 ft. 10 ins. ; height, 18 ft. 10 ins. Two more complete aeroplanes are exhibited on the Bleriot stand. One of these is a Berline, exactly similar to those used on the London-Paris route. As this type was fully described and illustrated in our issue of July 7, 1921, we need An aileron crank inside the wing of the four-engined Spad 45. THE SPAD 34 : This machine is a side-by-side, dual controlschool machine, with 80 h.p. Le Rhone engine.
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