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Aviation History
1911
1911 - 0832.PDF
JQGHT SEPTEMBER 23, 1911. CORRESPONDENCE. •#* TTu name and address of the writer (not necessarily for publication) MOST in all cases accompany letters intended fot insertion, or containing queries. Correspondents communicating with regard to letters which they have read in FLIGHT, would much facilitate ready reference by quoting the number of each such letter. Dr. Hankln's Study of Bird Flight. [1363] I want very much to congratulate you on the Hankin papers: there is not the smallest doubt that they will become classical. They remind one of Langley, and reading them makes one realise to what a piciably poor level the general run of aero nautical literature has sunk since the bigger men died or dropped out, and the theory became the special care of the host of third-rate engineers and tenth-rate mathematicians who swarm over everything nowadays, men who could never have got a hearing in any better- understood branch of science. What a difference there is between the tone of these Hankin papers and that of the mass of pseudo- scientific rubbish, hastily conceived and aggressively trumpeted, with a pyramid of premature theory balanced on a pebble of fact, which we are told constitutes "modern aeronautical theory." Every line of the Doctor's papers show the true, trained scientist, the genuine disciple of Bacon, the man who is content to observe facts, facts, and nothing but facts, with mechanical impartiality and perfect restraint until he has enough ground upon which to venture a conjecture. Xot even an asserted theory, for in real science a theory is an almost sacred thing. It is, so to speak, the canonization of a conjecture, an event that frequently requires fifty years for its consummation. That Dr. Hankin is a man of science is evident and, apparently, he also has that rarer trait—a clear mind that is able to perceive some very broad, simple, and fundamental thing clearly indicated beneath all those individual complexities which ordinarily arrest and retain the attention. In the concluding paragraphs of the last published article, where the Doctor rules out for the nonce certain hypotheses as to ascending currents, the succeeding inference as to the " fine-grained heterogenity " of the air is a most beautiful piece of clear thinking. I am inclined to think, however, that the ascending current hypotheses cannot be ruled out thus, and think that there is a great deal in Huffaker's theory (I believe it is Huffaker), that the heated air is in a state of unstable equilibrium with regard to the colder layers above it, and that flapping round in a circle creates the required ascending current. I have seen vultures, disturbed while feeding and apparently heavily gorged, flap slowly and laboriously round in a circle of perhaps 120 yards diameter, not all on one side of the circle, but spread out round the circumference, wings almost touching the ground, gradually exhibiting increasing buoyancy, and (if I can trust my memory), increasing speed until at about twelve or fifteen feet up they suddenly unanimously started soaring and then rose rapidly. I have seen cranes soaring at about 500 feet circling about a point in the middle of the group, which group was so compact that the birds appeared fitted into one another so that no one could revolve on a vertical axis without fouling the next. Probably an effect of perspective, some being higher than others. There were about a dozen birds, and the diameter of the group may have been as much as twenty-five feet and was certainly not more than thirty. They were obviously in one of the narrow ascending columns which are common in those parts. These columns have clearly defined bases of some times as little as three feet across. I write, of course, from general memory, and not from estimations made at the moment. My bird work has, as you know, been mostly done among sea birds, and my attention entirely devoted to such birds as were what Dr. Hankin calls " flex-gliding," and which I used to call in my notes " travelling," because it was the form of gliding adopted by the bird when it wished to go from one point to another, and not merely to move lazily along searching the water for food. I have a number of photogiaphs of birds " flex-gliding," some of which might form excellent confirmatory evidence of the Doctor's notes. I have several of ospreys " flap-gliding," but only one showing " flex-gliding," and that so small that it might be a crow from all one can see. I can bear out Dr. Hankin's remarks about the non- directive effect of head movements, having often seen gliding ospreys eating fish held in their claws. They seem, however, to lower the head very gingerly, bringing the claws forward at the same time equally gingerly, as if afraid of disturbing their centre of gravity. I have seen a gull while " flex-gliding," plume the underside of his left wing with his beak without altering his mode of flight, though he may have made some unnoticed balancing adjustments. Gulls soaring over open sea invariably congregate together over one particular spot, which indicates a local ascending current. I have never seen the phenomena of general soarability throughou the whole atmosphere of which Dr. Hankin speaks, when I have been observing sea birds. Gulls "ease-gliding" over a definite ascending current such as is formed by the presence of a cliff on windy days, or such as exists over trie stern of a moving ship, generally adopt the " flex -gliding " position of the wings. Flex-gliding in still air always involves increase of speed, great increase of stability (which was what interested me), and loss of height. " Ease-gliding " in such an up current as I have described requires velocity to maintain headway against the strong wind, also the wind velocity renders the up current very powerlul, which two facts account for the necessity for, and the feasibility of, the adoption of the '' flex-gliding " attitude. What conclusions Dr. Hankin may have drawn from his observa tions—and one cannot discuss these until they are published—there is no doubt that the notes of his observations are priceless, and I hope they may eventually be published in full, together with the present series of papers, in book form. * J. W. DUNNE. [* It is the intention of Dr. Hankin to issue the work in volume form.—ED.] Cardiff Sportsmen and others—a Comparison by Mr. Hucks. [1364] Since my last visit to Cardiff by way of the air I am impressed by the different manner in which people receive the new science of aviation. Earlier in the year, whilst flying cross-country from Hendon, I had occasion to make an unexpected landing at an early hour in the morning in the private grounds of the rectory at Barton (Bedfordshire.) I was immediately received with the utmost cordiality by the rector, who at once had breakfast prepared for me and with whom I stayed for two days as his guest. He took the utmost pains to assist me, sent his gardeners to help me with the machine, and even went to the extent of having a long length of iron fencing removed entirely in order that I might fly my monoplane away with less risk. I was much impressed by his kindness and regarded him as a thorough sportsman as well as a rector. The other case, by way of comparison, was my descent at Whit church (Cardiff) polo ground last Sunday morning, which, I ought to mention, was in no way pre-arranged as I did not know my destination when 1 left Weston, but I told my manager there I would try to pick out a good field in the Cathays district. Several places were suggested to me, but I thought it best to decide after having had a bird's-eye view of them. To my great surprise to-day a letter reaches me indirectly from the assistant-secretary of the Cardiff and County Polo Club, the contents of which were roughly to this effect •.—" How dare you land on the polo ground, and who gave you permission?" Well, sir, I have replied to this letter, not without being impressed by the difference between my sporting friend, the rector, and the sporting (?) club whose ground I unfortunately chose as a landing place. Royal Hotel, Cardiff, September 12th. B. C. HUCKS. The Army Airships. [1365] In answer to Mr. Balfour's query No. 1,356, I have great pleasure in informing him and the public at large that the Clement and Lebaudy airships are both housed in " A " dirigible shed at S. Farnboreugh. As to the state of the ships in question, I may say that the Clement Bayard was taken to pieces in the latter part of last year at the Daily Mail garage, Wormwood Scrubbs, and was ungracefully and disgracefully brought down to Farnborough on steam lorries. Since then it has remained in its '' la pancake " condition, and no efforts whatsoever have been made to reconstruct it. As to the ill-fated Lebaudy dirigible, it was wrecked on May 4th, 1911, at S. Farnborough, the direct cause being due to the fact that a strong wind sprung up which evoked excitement and bad calculation on the part of the pilot. Since that time the airship (in pieces) has lain in the large dirigible shed untouched, no doubt the cause being due to the fact that the interested parties, viz., the Morning Post and Lebaudy Bros, had— well, complications regarding the same. S. Farnborough. " QuiCK-SNIFF." The Facts of the Plymouth Meeting. [1366] I think that possibly it would interest you and your readers to hear the experiences of an onlooker at the first aere meeting held at Plymouth. M. Blondeau and Mrs. Hewlett were engaged to fly at the Plym outh Race Course on Saturday, Monday and Tuesday ast at 834
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