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Aviation History
1920
1920 - 0750.PDF
putting-ofi the evil day. It is not an easy matter to turn out a satisfactory all-metal machine, but the problem will have to be tackled sooner or later, and the sooner a firm begins to tackle it the sooner, obviously, will it pass through the difficult initial stages which always attend attempts at breaking new ground and arrive at the metal machine which is a commercial proposition. In the way of actual all-metal machines there is one machine, and one only, at the show. This is the Short, wfiich is of metal throughout, even to the wing covering. This is the first time in the history of aviation that a British machine entirely without wood or fabric in its construction has been exhibited, and Messrs. Short Brothers are to be congratulated, not only on a very fine p^sce of work, but also on having had the courage and fore- sight to launch out along entirely original constructional lines. Whether the machine as it actually stands yet represents a commercial proposition, or whether it should merely be regarded as a step on the way to finality in design, does not detract in the slightest from the merits of the task tackled, and we can only express the hope that the lead given by this firm will be followed by many others, so that at the next Olympia show there will be a great number of all-metal aeroplanes. The task is a difficult one, but it is one. which can only be put off for a time. The Question of Unit Construction The time was when a machine was so designed that all its parts were so interconnected that if one part failed nearly all the rest of the machine collapsed. We have distinct recollections of one particular machine which on a certain occasion broke a chassis strut after taxying across the aerodrome. For several minutes afterward sounds con- tinued to issue from various portions of the machine. Ping went a wire, crack—Crack said the struts, Pong went another wire, and so until the machine gradually settled in a heap on the ground. The days when this happened are over long ago, and designers now aim at making the various units of a machine as self-contained as possible, so that damage to one part does not affect the rest of the machine. In several of the machines shown one finds, for example, the fuselage built in three sections, the front one being formed by the engine housing, the middle one by the passenger cabin, and the aft portion by the tail end of the fuselage. Thus in case of damage to one of the sections the whole body need not be scrapped or re-built. A new section is put in in place of the damaged one, and the machine is ready again. While this is a healthy sign, we do think that it could and should be carried much farther. Thus we were informed on the stand of one firm that it only took 24 hours to change the engine. We submit that if the engine with its housing had been designed as an independent unit, the change of engine should not have taken 24 hours, but more likely 24 minutes. It should not be very difficult so to design the nose of a machine that the whole engine housing with engine complete came adrift after undoing some 6 or 8 bolts. There is no doubt that on a commercial air service engine trouble is the most frequent cause of a machine being laid up. If the machines are so designed that the engine can be changed in a very short time, the faulty engine can be replaced and taken to the engine- JUJLY 15, IQ2O shop, where the necessary repairs can be effected under the most favourable conditions. In twin-engined machines the problem is complicated by the fact that the engine struts are also interplane struts. It should, however, be possible so to design the arrangement of the engine struts and engine bearers that, when the wings are folded, the engine unit can be slipped out sideways after undoing a few bolts and turnbuckles. A travelling crane would then be used for removing one engine unit and sub- stituting another. On Economy of Flight s A study of the table which we published last week discloses the fact that the average loading per horse-power is gradually growing. This is, we think, a healthy sign. For War purposes it was performance which counted, and the price at which this performance was bought was, comparatively speaking, immaterial. The call for performance led to lighter and lighter engine loading until 10 lbs./h.p. was considered a fairly heaving loading. The resulting speed and climb improved out of all recognition, but the load which could be carried was small, and the duration of the flight was but short. Now, for commercial work performance is not of such—vital importance—except in some relatively few instances. What is of great importance, however, is the economy of flight. Power loadings of 10 lbs./h.p. may result in spectular performances, but they are not a commercial proposition. The value of the saving in time between a machine doing 150 m.p.h., and carrying a load of only between 6 and 7 lbs./h.p. and one which does, say, 100 m.p.h., but carries close on 20 lbs./h.p., is not sufficient to make the extra speed worth the cost. Except, as we have already said, in a few isolated cases. Our table shows that quite a good proportion of the machines exhibited carry loadings of round about 20 lbs./h.p., and having maximum speeds of in the neighbourhood of 100 m.p.h. Compared with the speeds of some of the later War machines this is a crawl, we admit, but then they should not be compared with these weapons of War any more than a barge should be compared with a destroyer, or a submarine chaser. A much sounder basis for comparison with the commercial aeroplane is the train, the steamer, and the motor- vehicle. Compared with any of these an aeroplane which is capable of 100 m.p.h., or a cruising speed of 80-85 m.p.h., is fast—very fast. So much faster than the others that the slight extra cost of this form of transport is worth while. The " Popular " Aeroplane Even at the present day there are those who refuse to see any future for the little low-powered single-seater sporting machine. It is, they say, a toy of no practical value. This contention has been refuted in the best possible manner by Mr. Bert Hinkler's recent non-stop flight from London to Turin, a distance of close on 700 miles, accomplished for a fuel expenditure of 20 gallons of petrol. As a matter of fact the 35 h.p. of the Avro " Baby " and 45 h.p. of the Austin " Whippet " (both exhibited) does not represent the minimum with which it is possible to fly, but merely the minimum power of engine which is at present obtainable. Another firm has just announced its intention of putting on the market a machine with 45 h.p. engine, to be sold at ^250. "Flight" Copyright THE AUSTIN " WHIPPET " AT^OLYMPIA : This little machine has folding wings and occupies a very small space 750
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