464 



THE INDIA RUBBER WORLD 



[June 1, 1916. 



the sustaining surfaces of the first aeroplanes, but the rubber 

 industry had been taken unawares and the rubberized fabrics 

 then obtainable were not well suited for the requirements of 

 aeroplane construction and they soon fell in disfavor because 

 the best of them absorbed a certain amount of humidity, strctclicd, 

 and thus lost their rigidity. Canvas, coated with acetate of cellu- 



Photograph from Unut 



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Army Aeropi..\nes Into Mexico 



lose, took the place of rubberized fabrics in the construction of 

 aeroplanes because such canvas is supple and at the same time 

 little afifected by the weather. The plain canvas was first 

 stretched and fastened tightly to the frame of the machine and 

 then coated with acetate of cellulose varnish. Acetate of cellu- 

 lose applied in the form of a collodion tightens cloth that is 

 stretched on a frame ; it makes the cloth waterproof without 

 making it stiff and brittle as nitrocellulose does; it does not 

 crack and it is not inflammable. Acetate of cellulose varnishes 

 used in the early days of aviation were diluted with chloroform, 

 but this solvent was soon dropped on' account of its high cost 

 and the danger in its use. At the present time two sorts 

 acetate of cellulose varnishes are used — varnishes that give a 

 rigid coating and those that give supple coatings. 



RUBBERIZED FABRICS. 



The use of rubberized fabrics in the construction of aero- 

 planes is not so extensive as it is generally believed to be. Aero- 

 plane manufacturers and aeroplane users are still under the in- 

 fluence of the prejudice developed in the early days of aviation 

 when proper rubberized fabrics for this purpose were not to be 

 obtained. The fabrics available in the pioneer days of aviation 

 were rubber-coated and not impregnated with rubber as tht\\ 

 are now. The result was that the rubber coating cracked and 

 peeled off, allowing moisture to penetrate the fibre of the fabric^, 

 causing them to alternately shrink and stretch. Modern rubber- 

 ized aeroplane fabrics present no such difficulties, and aeroplane 

 builders are now beginning to give them the consideration they 

 deserve. 



Rubberized balloon fabrics are made either of linen or of cot- 

 ton and they are thoroughly impregnated and saturated with 

 rubber applied gradually by a series of operations. Manufac- 

 turers have learned to make them absolutely weather-proof and 

 lasting. Besides being thoroughly saturated with rubber, modern 

 rubberized aeroplane fabrics are generally coated with rubber 

 solution on both of their surfaces. These coatings are so light 

 that rubberized aeroplane fabrics are no longer open to objec- 

 tions on the score of weight, as was formerly the case. The 

 process of preparing these fabrics is quite similar to that used 

 in the preparation of balloon fabrics already described in a pre- 

 ceding article on the subject. Aeroplane fabrics are made in all 

 colors or, like some of the balloon fabrics, are metallized with 

 aluminum. 



SHOCK ABSORBERS, 

 All aeroplanes are provided with a running gear which in- 

 variably includes a system of shock absorbers built to protect 



the machine as well as the aviator from too violent shocks when 

 leaving and when returning to earth. 



The Bleriot type of ruljber springs or shock absorbers was 

 at first built up of fine rubber strands bundled together, covered 

 with a cotton fabric, the ends of the strands being firmly held 

 in metallic clamps constructed in such a manner as to facilitate 

 the fastening of the spring to the landing gear of the aeroplane. 

 It was, however, discovered that the fine rubber strands soon 

 decayed from oxidation and their place was taken by molded 

 rubber vulcanized to give proper tensile strength and elasticity. 



The Farman type of aeroplane spring is used in attaching the 

 a.xle on which the wheels are mounted, to the skids of the 

 flying machine. Two or more rubber rings are hooked to one 

 side of the skid, then brought over the axle and fastened 

 to the other side of the skid. These rings are made of 

 either red or of bluish-gray stock compounded so as to be 

 strong enough to withstand heavy strain and with the exact 

 degree of elasticity to allow proper elongation and no more. 

 These types of rubber shock absorbers vary widely with the 

 type of machine and of landing gear used. For aeroplane 

 shock absorbers rubber is unrivalled on account of its light 

 weight and extraordinary elasticity. Metal springs, hydro- 

 pneumatic shock absorbers and the like are used but not nearly 

 to the extent that rubber is. 



EQUIPMENT OF THE AVIATOR. 



--Vviators. when flying, use rubber and rubberized fabric clothes 

 almost e.\clusi\ely. These are made in all colors and afl'ord per- 

 fect protection against weather. Aerial waves make riding in an 

 aeroplane comparable to riding a bucking bronco and aviators 

 are obliged to fasten themselves to their seats lest they be thrown 

 out by the violent bounding of their machine. 



Here again rubber is used in the shape of a rubber belt which 

 the aviator passes around his waist and fastens to the machine 

 with leather straps. Such a belt not only prevents the aviator 



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from being thrown out of his machine but, in case of accident 

 the elasticity of the rubber acts as a fall-breaker. This type of 

 rubber belt is generally composed of two pieces held together 

 by a miniature coupling pin. By pulling out the coupling pin 

 the flyer can immediately free himself from his machine. 



Many aviators use hard rubber helmets to guard their heads 

 in case of accident and rubberized gloves to protect their hands 

 and forearms from cold and rain. .As in dirigibles, the navi- 

 gating instruments used in aeroplanes are generally held in place 

 by soft, elastic ruljber attachments which prevent excessive vi- 

 bration and violent shocks reaching the delicate mechanism of 

 these instruments. The upholstering of aeroplane seats is often 

 made of rubberized fabric inflated with air. Aviation, like aero- 

 station, presents numerous and extensive applications of rubber 

 and offers an interesting field to the rubber manufacturer, and 

 one that may in the future grow into much larger proportions 

 and become of still greater importance. 



