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Aviation History
1913
1913 - 1104.PDF
OCTOBER II, 1913. Edited by V. E. How and Why I Built a Glider. By JOHN C. MORRISON. I UEGAN to study flight when I was about thirteen. I had no books on the subject, and conceived the idea of the kite to make a flying machine, and was quite disappointed to find in the Encyclopaedia that the principle had been already made use of. I also invented a helicopter, and was rather keen on the idea at first, but gave it after a time. When aeroplanes came into public notice, I read all I could about them, but was much troubled by the large amount of power required to make them fly. I often watched the seagulls on windy days, and saw how they could rise against the wind without being driven back by it, from which I argued that a machine built with wings similar to theirs ought to fly when diiven through the air at the speed necessary for flight. I read of aeroplanes having curved wings, and thought that the curve was an arc of a circle, which did not appear to me correct. I shot a seagull, and measured the curve of a cross-section of its wing, and found out afterwards that this was similar to Philip's curve. It never struck me that the upper curve had anything to do with the lift, and in the con struction of my glider I considered only the lower one. I read that automatic stability would of great advantage, and immediately thought of a pendulum suspended in such a manner that when the machine swayed to one side the pendulum remaining vertical would be made to work something in the nature of balancing ailerons. Then I decided to build a glider to test this idea, and also to see if it would rise against the wind, owing to the air lift of its arched surface. The main plane was 6ft. by I-5 ft., and the cross spars of light pailing wire, the camber being about 2-5 ins. Of the number and shapes of the tails I tried I would rather not speak, but at the present time the machine has a triangular tail, which has been broken and mended a good number of times. When I had nearly finished the pendulum balancing apparatus, it struck me that how ever excellent in theory it would be useless in practice, sol removed it straightaway. At first I made skids of pailing wire, but as they were unsatisfactory I made three light wheels, and used the skids as shock absorbers. The weight was 9 lbs., or 1 lb. to every square foot of surface, and it balanced perfectly about its centre of symmetry. I could not get it to glide very well, and found it rather risky to try it against the wind, although it did exhibit some of the symptoms of a seagull. After a time I got tired of being asked if the glider " went," so I determined to make a last grand attempt, and either succeed or smash it up. I took it to the top of a brae hill) on the road, and pulled it down after me on my bicycle. When I reached a speed of about 15 m.p.h. its wheels ceased their noise, and I knew it had risen. I couldn't very well look behind me, so I got several witnesses to view the experiment and establish the fact that the glider " went." My ambition now is to get an engine and make it fly " on its own." [The foregoing very naive account is not, we think, without interest, especially as a " reflection from the past," which it behoves us now and then to look at in order that we may the better appreciate where we stand to-day.] Dope for Full-sized Glider. Mr. H. F. McManus (Birmingham Aero Club), writing re "Canard's " recent query, says : " Your correspondent states it is his first machine." Well, in the light of our experience it is not worth while to use an expensive fabric or dope, as owing to lack of experience in handling such a machine it is likely to soon get smashed. We have found boiled linseed oil very satisfactory. Our last glider was proofed with it, and it has been left out in the open, exposed to all sorts of weather for several months, and the fabric is still in good condition. This last machine has had the longest life of any glider we have made, which proves that we are getting to know more about them. We have had to repair it several times, however, owing to bad landings. Last week we had a particularly bad smash, the machine side-slipping from a height of about 20 ft. Fortunately, the member who was piloting it was unhurt. We have at the pre sent time one club glider, and two in the possession of private members. One of the last-named was covered with Dunlop fabric, which came out rather expensive, costing about fourteen pounds." Some Interesting Experiments with a Large Power-Driven Model. " You may be interested," writes Mr. F. Mayer, " to know that JOHNSON. M.A. I have been away to fly a large and heavy model for a friend. The model weighs between 40 and 50 lbs. The first engine used being one of my make, which has seen over three years' service, this was not successful, and on the following day I installed an engine similar to the'Bonn-Mayer' one exhibited at Olympia ; with this engine and 3 ft. propeller of approximately 2 ft. pitch, the model flew at the first attempt and made five short flights in all. In initial trials of this kind I always use a stout kite]cord attached to the rear of the model. When the model is released I run after it paying out the line as I run. Then if the model gets up and misbehaves itself I just hang on to the cord and tug to the right or left and bring it back to earth, usually before it has had a chance to get sufficiently out of hand to smash. I have had some considerable experience at this game ; it is just like ' breaking in ' wild horses at a Wild West show." [Verily there are more things in . . . &c, &c. Mem. for 1914, " Aerial Model Chariot Races" in single and double harness. N.B.—No stunts permitted.] Some Experiments with Floats. By PHEROZE E. J. MINVALLA. I am sending you herewith the results of some experiments carried on by myself in floats, with comments thereon. You will see on plan A silhouettes of various float shapes towed under water. Not having the apparatus necessary for the use of coloured glycerine threads, I was compelled to use this substitute. However, I am led to believe that the actual merit of each type is shown equally as well in water as in air or glycerine. No. 1.—The form of this float is ichthyoid, except that the bottom surface is more curved than is the case usually. There was little disturbance bar that due to viscosity, but the liquid after leaving the trailing edge acquired an upward motion, thus causing the rear edge of the float to sink deeper into the water. This, I believe, was due to the fact that the bottom surface was more curved than usual ; consequently, the strata immediately touching the surface were deflected downwards, and when it did find space to rise clear of the float, came upwards with greater force, and so on account of the opposite force acting from the top surface, the trailing edge dropped ; the length of the partial vacuum formed by the lower strata of water rising from the middle of the float. No. 2.—This float has a conical body with a semi-spherical head. There were great disturbances in the water as this one was drawn through it. I attribute them to this : the semi-spherical head caused little resistance, consequently the water flowed over it in the usual waves ; the body of the float allows of no such natural flow since it is perfectly straight. Therefore as the concave part of the wave strikes the float the flow is broken and forms numerous eddies above and below. Thus it requires considerably greater force than No. 1 to draw it through the fluid. Mr. Minvalla's float sections. Flight " Copyright. No. 3.—The bottom surface of this float is of ichthyoid form, while the top is a gentle curve. There was little disturbance on the top and none on the bottom surface. The disturbance on the top surface I ascribe to the same cause as in No. 2. The trailing edge lifted very quickly, the reason, I suppose, being that the eddies on the top multiplied the downward sweep of the top strata of water, while the lower strata were allowed to have full scope and upward tendency, due to their being undisturbed by the form of the surface. No. 4.—Though the drawing of this model is somewhat crude, yet the salient features have been represented. It is a float combining 1130
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