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Aviation History
1922
1922 - 0206.PDF
given by the lecturer as between 15,000 and 20,000 miles, which compared with any type of motor transport. The chief items of expense as regards maintenance were given as renewal of control cables, replacement of rubber shock absorbers, replacement of wearing parts of petrol pumps, tail skids, and landing-wheel tyres. The lecturer thought that, with the exception of the' last named, these troubles had been eliminated, and the use of solid tyres was now, he said, receiving attention. Capt. de Havilland concluded his very interesting paper by stating that " if we leave out of consideration anv aerodynamic or structural improvements that will probably appear in the near future, the result of steady development on normal lines gives every reason for an optimistic outlook. With the appearance of larger and lighter engines the cost of passenger or ton mileage will further decrease, and owing to greater reliability the dangers of forced landings will be practically non existent." The Discussion Major F. M. Green said that he would now take the opportunity of replying to Capt. de Havilland, as this opportunity was not afforded at the Air Conference recently. He did not agree on the question of metal construction. It was now possible to build machines of metal which weighed less than wood machines, while probably the cost would not be any higher, might even soon be somewhat lower. He agreed with the lecturer in the matter of twin-engined machines, but thought that three-engined machines would have an advantage, as in case of one engine stopping only about one-third of the power would be lost. He referred to what he termed the " multi-unit " type of engine, on which he was, he said, now working. It consisted in mounting three engines on a common crank case, and gave some promise of good results. Mr. W. O. Manning did not agree with the lecturer on the question of landing speeds. He thought that experience had shown that low landing speeds formed a sort of insurance against excessive damage, and quoted as proof the old Bleriot 28-30 h.p. machines, which landed very slowly, and in which, in spite of many crashes, pilots hardly ever were seriously injured. As soon as the higher-speed 50 h.p. machines came along, which had wings with a smaller camber, crashes began to result in injury, sometimes fatal, to the pilots. Squadron-Leader Roderic Hill put in a good word for the twin-engined machine, saying that it would enable a pilot to make a flat glide to a landing ground, even if the machine were not capable, of flying on one engine. He could not, he said, view with equanimity landing speeds of 62 m.p.h., and thought that, as Mr. Manning had said, low landing speed was an insurance "against too much danger. With regard to petrol systems, he pleaded for greater simplicity, saying that it was time we got away from the necessity of a pilot sitting in the cockpit of a machine for three hours, trying to get acquainted with all the different cocks. Mr. F. Handley Page said he was told that insurance premiums would be considerably lower if landing speeds were kept below 50 m.p.h. He caused much amusement by admitting that to him it seemed that there was only one way to keep down the landing speed (referring, of course, to the H.P. slotted wing), but as this was a scientific society, and not a self-advertising one, he would say no more about that. He agreed with the lecturer that at present wood construction was most suitable. Later on, when we came to build very large machines, metal might be used for preference, much in the same manner, and for similar reasons, that large liners were now built of steel, but small craft, such as motor boats, were nearly always built of wood. Wood machines appeared to stand up well, and he quoted as an example the Fokkers used in Turkey during the War. He understood that the way in which the Fokkers stood up was due to -a special secret process of treating the wood, but did not know how much there was in this claim. As regards petrol systems, Mr. Handley H H Improving the Air Port Services THE Postmaster-General announces that from April 4 a new dispatch of Air Mail letters was inaugurated by the Post Office between London and Paris. The aeroplane is due to leave Croydon aerodrome at 9.30 a.m. daily. This dispatch is additional to the present service from Croydon at 12.30 p.m., for which letters are accepted at the General Post Office up to 11.10 a.m. daily. By the use of the new service/letters posted in London too late for the ordinary night mail dispatch to Paris, but in time for the last night collection, will normally be delivered in Paris on the following afternoon, and if they are addressed to places near Paris delivery may be expected in the evening instead of APRIL 6, 1922 Page again amused the audience by saying that what we really wanted was placing the tank very high above the machine, so as to get gravity feed, and then lead the petrol to the engine through 5-inch pipes. There would then be no danger of them choking up. Unfortunately one had to have some form of sky hook to support the tanks, which complicated matters. Colonel Mayo said that Capt. de Havilland was the pioneer of high landing speed machines, pointing out the big jump in performance which was attained with the introduction of the heavily-loaded " D.H.4." 'For military machines, that was good, as one was prepared to face the high landing speed for the sake of the better performance. For commercial machines, however, he did not think that the high landing speed was to be accepted. He was surprised at the lecturer's statement about the high landing speed machine having had no accident which could have been avoided had the landing speed been lower. He would like to know how many journeys had to be cancelled owing to the nnsuitability of the high speed machines for flying in fogs. As an example of the way in which the slow-landing machine could carry on, he men tioned the Farman " Goliath." This machine, he said, was without doubt fitted with the worst engine in the world, but in spite of this it had an excellent record. He mentioned several instances of this type of machine having made forced landings without serious damage. With regard to petrol systems, Col. Mayo stated that in France gravity feed was almost universal. Colonel Bristow offered a few criticisms of the inability of the pilot to see on more than one side on some machines, and said that this was very distressing in taking off from an aerodrome with obstacles. The placing of the compass where the pilot could see it easily was another point, and controls should be adjustable so as to be adaptable to different pilots. He thought that the present reliability of our air services and immunity from accidents were due to the extra ordinary skill and experience of the pilots employed, and that as it was becoming increasingly difficult to get good commercial pilots, we should not lose sight of the fact that it would be an advantage if machines could be so designed as to place a less sfevere tax on the skill of the pilot. He also referred to highly-loaded machines, and stated that recently one French heavily loaded machine had a forced landing and crashed. The Goliath also had to land, but did not crash. Colonel O'Gorman before asking the lecturer to reply, said that the discussion had brought out a pronounced differ ence of opinion as regards high loading versus low loading. He thought that high loading was quite all right if the engine was reliable. With regard to the Goliath, he was not speaking from knowledge of the facts, but he very much doubted whether the Goliath got a lower rate of insurance than did the high-load French machines. Capt. de Havilland stated that he thought that eventually metal construction would be adopted, but not at present, when, he was certain, a metal machine would take three times as long to build. Wood was easy to repair. Incidentally, he had heard of no reason why we should be building metal machines, except for the tropics. He was very glad to hear that Major Green was studying the "multi-unit" type of engine. He said there had been several forced landings with heavily loaded machines, but with a large ground angle they pulled up as quickly as the lightly loaded. In a bad fog, he thought, any machine was dangerous, and he did not think it made any difference whether one was coming into an aerodrone at 50 m.p.h. or at 62 m.p.h. Referring to the Goliath, Capt. de Havilland thought it was a pity that the one which forced-landed in Kent did not make a perfectly safe landing. As regards gravity petrol feed, he stated that it had been found that the effect of acceleration in taking off was to double the "head" necessary. Thus, if a certain carburettor was stated to function with a " head " of 2 ft., this was.increased to 4 ft. by acceleration. H a on the second morning following. Letters will be accepted for the 9.30 a.m. aeroplane dispatch at the counter of the General Post Office up to 7.15 a.m. Letters from the provinces, posted too late for the ordinary mails due for dispatch by the night boat, benefit by the new aeroplane service if they are posted in time for inclusion in mails due to reach the London train terminus by or before 6 a.m. As regards places at a considerable distance from London, that is, practically all localities except the south and south-east of England, the use of the air service enables the public to postpone the time of posting for France and beyond,, by the greater part of the business day. ,
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