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Aviation History
1909
1909 - 0136.PDF
MARCH 6, 1909. Fig, 4,-The French dirigible, " La Ville de Paris." ,case of war or emergency. When the " Patrie " was lost in November, 1907, the military authorities immediately took over the Deutsch airship, Gas-Bag,—The gas-bag is 200 ft. long for a maximum diameter of 34J ft-> g'V'ng a length of abcut 6 diameters, as in the " France " and the "Patrie." Volume 112,847 cub. ft. maximum diameter at about three-eighths of the distance from the front approximately, as in the " Patrie." The middle section is cylindrical, with conical sections in front and rear. At the extreme rear is a cylindrical section with eight smaller cylinders attached to it. The ballonette has a volume of 21,192 cub. ft., or about one-fifth of the whole volume, the same proportion found in the " Patrie." The ballonette is divided into three compartments from front to rear. The division walls are of permeable cloth, and are not fastened to the bottom, so that when the middle compartment fills with air, and the ballonette rises, the division walls are lifted up from the bottom of the gas-bag, and there is free communication between the three compartments. The gas-bag is made up of a series of strips perpendicular to a meridian line. These strips run around the bag, their ends meeting on the ,under meridian. This is known as the " brachistode " method of , cutting out the material, and has the advantage of bringing the seams parallel to the line of greatest tension. They are therefore more likely to remain tight and not allow the escape of gas. The disadvantage lies in the fact that there is a loss of 33-J per cent, of material in cutting. The material was furnished by the Continental Tyre Company, and has approximately the same tensile strength and,weight as that used in the " Patrie." It differs from the other in one important feature—it is diagonal thread ; that is, the warp of ithe outer layer of cotton cloth makes an angle of 45 degrees with the warp of the inner layer of cotton cloth. The result is to localise a rip or tear in the material. A tear in the straight thread material will continue along the warp, or the weave, until it reaches a seam. Valves.—There are five in all, made of steel, about 14 ins. in diameter ; one on the top connected to the car by a cord, operated by hand only ; two near the rear underneath. These are automatic but can be operated by hand from the car. Two ballonette valves directly under the middle are automatic and are also operated from the car by hand. The balloriette valves open automatically at a pressure of f in. of water, the gas valves open at a higher pressure. Suspension.—This airship has the "long" suspension. That is, the weight is distributed along practically the entire length of the gas-bag. A doubled band of heavy canvas is sewn with six rows of stitches along the side of the gas-bag. Hemp ropes running into steel cables transmit most of the weight of the car to these two canvas bands and thus to the gas-bag. Ofi both sides and bdow these first bands are two more. Lines run from these to points half ,way between the gas-bag and the car, then radiate from these points to different points of attachment on the car. This gives the tri- angular or non-deformable system of suspension, which is necessary in order to have the car and gas-bag rigidly attached to each other. •With this " long " suspension, the "Ville de Paris " does not have the deformation so noticeable in the gas-bag of the " Patrie." The Car.—This is in the forrn of a trestle. It is built of wood ..with aluminium joints and O'I2 in. wire tension members. It is 115 ft. long, nearly 7 ft. high at the middle, and a lit tie over 55 ft. wide .at the middle. It weighs.660 lbs., and is considered unnecessarily large and heavy. The engine and engineer are well to the front, ,the aeronaut with steering wheels is about at the centre of gravity. Motor.—The motor is a 70-h.p. to 75-h.p. "Argus," and is .exceptionally heavy. Propeller.—The propeller is placed at the front end of the car. It thus has the advantage of working in undisturbed air ; the dis- advantage is the long transmission and difficulty in attaching the propeller rigidly. It has two blades and is I9'68 ft. long with a jpitch of 26'24 ft. Th,e blades are of cedar with a steel arm. The Fig. 5.—The German "Zeppelin," with its floating shed. propeller makes a maximum of 250 turns per minute when the engine is making 900 revs. Its great diameter and width compensate for its small speed. Stability.—This is maintained entirely by the cylinders at the rear. Counting the larger one, to which the smaller ones are attached, there are five, arranged side by side, corresponding to the horizontal planes of the " Patrie," and five vertical ones corresponding to the " Patrie's " vertical planes. The volume of the small cylinders is so calculated that-the gas in them is just sufficient to lift their weight, so they neither increase nor decrease the ascensional force of the whole. The horizontal projection of these cylinders is 1,076 sq. ft. The centre of this projection is 72 ft. from the centre of gravity of the gas. The great objection to this method of obtaining stability is the air resistance due to these cylinders., and consequent loss of speed. The stability of the " Ville de Paris " in a vertical plane is said to be superior to that of the " Patrie," due to the fact that the stability planes of the latter do not always remain rigid. The in- dependent velocity of the '' Ville de Paris " probably never exceeded 25 miles an hour. The Rudder.—The rudder has a double surface of 150 sq. ft,, placed at the rear end of the car, 72 ft. from the centre of gravity. It is not balanced, but is inclined slightly to the rear so that its weight would make it point directly to the rear if the steering-gear should break. Two pairs of movable horizontal planes, one at the rear of the car having 43 sq. ft., and one at the centre of gravity (as on the " Patrie ") having 86 sq. ft., serve to drive the airship up or down without losing gas or ballast. Guide Ropes.—A 400 ft. guide rope is attached at front end of car. A 230 ft. guide rope is attached to car at the centre of gravity. About thirty men are required to manoeuvre the " Ville de Paris " on the ground. The pilot has three steering wheels, one for the rudder and two for the movable horizontal planes. The instru- ments used are an aneroid barometer, a registering barometer giving heights up to 1,600 ft., and an ordinary dynamometer which can be connected either with the gas-bag or ballonette by turning a valve. A double column of water is also connected to the tube to act as a check on the dynamometer. Due to the vibration of the car caused by the motor, these instruments are suspended by rubber attach- ments. Even with this arrangement, it is necessary to steady the aneroid barometer with the hand in order to read it. The vibration prevents the use of the statoscope. (To be continued.) FLIGHT. 44, ST. MARTIN'S LANE. LONDON, W.C. Telegraphic address : Truditur, London. Telephone: 1828 Gerrard. SUBSCRIPTION RATES. FLIGHT will be forwarded, post free, to any irart of the world at the following rates: — UNITED KINGDOM. 3 Months, Post Free ... i 6 „ „ ... 3 12 ,, ,, ... 6 ABROAD. 3 Months, Post Free . 6 „ . 12 ,, „ s. d. 2 6 5 ° IO oCheques and Post Office Orders should be made payable to the Proprietors of FLIGHT, 44, St. Martin's Lane, W. C., and crossed London atid County Bank ; otherwise no responsibility will be accepted. NOTICE.—Advertisement instructions should reach theoffice, 44, St. Martin's Lane, W.C., by first post, Thursday. The latest time for receiving small alterations for Advertise-ments is 12 noon, Thursday. No alterations can be made after that hour. 138
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