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Aviation History
1909
1909 - 0303.PDF
MAY 22, 1909. APPENDIX No. 2. •_•;.; SIGNAL CORPS SPECIFICATION, NO. 4S3. Advertisement and Specification for a Dirigible Balloon. Bidders are requested to read carefully every paragraph of this specification and include in their proposal every detail called for. To the Public.—Scaled proposals, in duplicate, will be received at this office until 12 o'clock noon on February 15th, 1908, and no proposals will be considered which are received after that hour. Persons wishing to submit proposals under this specification can obtain the necessary forms and envelopes by application to the Chief Signal Ofiicer, United States Army, War Department, Washington, D.C. The United States reserves the right to reject any and all proposals. Unless the bidders are also the manufacturers of the dirigible balloon they must state the name and place of the maker. Preliminary.—This specification covers the construction of a dirigible balloon, to consist of a gas-bag supporting a suitable frame- work on which will be mounted the necessary propelling machinery. Inspection.—The Chief Signal Officer of the Army will reserve the right to inspect any and all processes of manufacture, and unsatisfactory material will be marked for rejection by the inspectors before assembling. Acceptance. —The dirigible balloon will be accepted only after a trial flight, during which it will comply with all requirements of this specification. General Requirements. The general dimensions of the dirigible balloon will be deter- mined by the manufacturer, subject to the following conditions:— 1. The gas-bag shall be designed for inflation with hydrogen. The material for the gas-bag shall be furnished by the bidder, and shall be subject to approval by the Chief Signal Officer of the Army, and must have a minimum breaking strength of not less than 62J lbs. per inch width, and must require no varnish. The dimen- sions and shape of the gas-bag will be as desired by the manu- facturer, except that the length must not exceed one hundred and twenty (120) feet. 2. Inside the gas-bag there will be either one or two ballonettes, having a total capacity of at least one-sixth the total volume of the gas-bag. Leading to the ballonettes there will be tubes of proper size, connected to a suitable centritugal blower for maintaining a constant air pressure in the ballonettes. The approved fabric for the ballonettes must have a minimum tensile strength of not less than 48A lbs. per inch width. 3. Valves.—In the lower part of the ballonette and gas-bag, or on the ballonette air tubes near the gas-bag, there will be an adjustable automatic valve designed to release air from the ballonette to the outside atmosphere. On the under side of the gas-bag there will be a second adjustable automatic valve of suitable size, so designed as to release hydrogen from the interior of the gas-bag to the outside atmosphere. This valve will also be arranged so that it may be opened at will by the pilot. 4. In the upper portion of the gas-bag there will be provided a ripping strip covering an opening five (5) inches wide by six (6) feet long, with a red rip cord attached in the usual manner, and brought down within reach of the pilot through a suitable gas-tight rubber plug inserted in a wooden ring socket. 5- The suspension system and frame must be designed to have a factor of safety of at least three, taking into account wind strains as well as the weight suspended. 6. A type of frame which can be quickly and easily assembled and taken apart will be considered an advantage. 7. The balloon must be designed to carry two persons having a combined weight of 350 lbs. ; also at least 100 lbs. of ballast, which may be used to compensate for increased weight of balloon when operating in rain. 8. The dirigible balloon should be designed to have a speed of twenty miles per hour in still air, but bidders must submit quotations in their proposals for cost depending upon the speed attained during the trial flight according to the following schedule :— 20 19 18 1716 m.p.h. >> • ft • 100 per cent. • 85 „ • 7O • 5540 21 22 i 23 24 m.p.h. »> i» ... 115 per cent ... 130 ... 145 ... 160 * Less than 16 m.p.h. rejected. 9. The speed accomplished during the trial flight will be deter- mined by taking an average of the time over a measured course of between two and five miles against and with the wind. The time will be taken by a flying start, passing the starting point at full speed at both ends of the course. This test subject to such addi- tional details as the Chief Signal Officer of the Army may prescribe at the time. 10. Provision must be made to carry sufficient fuel for continuous operation of the engine for at least two hours. This will be deter- mined by a trial endurance flight of two hours, during which time the airship will travel continuously at an average speed of at least 70 per cent, of that which the airship accomplishes during the trial flight for speed slated in paragraph 9 of this specification. The engine must have suitable cooling arrangements, so that excessive heating will not occur. 11. Three trials will be allowed for speed, as provided for in paragraph 9, and three trials for endurance, as provided for in paragraph 10, and both tests must be completed within a period of thirty days from the date of delivery, the expense of the tests to be borne by the manufacturer. The place of delivery to the Govern- ment and trial flights will be at Fort Myer, Virginia. 12. The scheme for ascending and descending and maintaining equilibrium must be regulated by shifting weights, movable planes, using two ballonettes or other approved method. Balancing by the aeronaut changing his position will not be accepted. 13. This dirigible balloon will be provided with a rudder of suit- able size, a manometer lor indicating the pressure within the gas-bag, and all other fittings and appurtenances which will be required for successful and continuous flights, according to this specification. 14. Bidders will be required to furnish with their proposal a certified check amounting to 15 per. cent, of the price stated for the 20-mile speed. Upon making the award for this airship these certified checks will be returned to bidders, and the successful bidder will be required to furnish a bond, according to Army Regulations, of the amount equal to the price stated for 20-mile speed. 15. Bidders must submit with their proposals drawings to scale showing the general dimensions and shape of the dirigible balloon which they propose to build under this specification ; the horse- power and description of the engine which will be used for the motive power ; the size, pitch, and number of revolutions of the propellers ; drawing illustrating the suspension system for attaching frame to gas-bag ; horse-power and description of blower for forcing air into ballonettes ; volume of gas-bag ; volume of ballonettes ; the material of which the frame will be constructed ; size of valves, &c. Plans received will not be shown to other bidders. 16. Bidders must furnish evidence that the Government of the United States has the lawful right to use all patented devices or appurtenances which may be part of the dirigible balloon, and that the manufacturers of the dirigible balloon are authorised to convey the same to the Government. This refers to the right of the Government to use this dirigible balloon without liability for infringe- ment of other inventors' patents. It does not contemplate the exclusive purchase of patent rights for duplicating the airship. 17. The prices quoted in proposals must be understood to include the instruction of two men in the handling and operation of this airship. No extra charge for this service will be allowed. JAMES ALLEN, Brigadier-General, Chief Signal Officer of the Army. Signal Office, Washington, D.C., January 2lst, 1908. Frankfort Exhibition Prizes. A PRIZE of 10,000 marks has been offered by the town of Wiesbaden for the dirigible which flies between Frankfort and that town, while a prize of 1,500 marks has been founded in Hamburg for the aeronaut who during the Exhibition makes the greatest number of flights over the city. The German Aerial League have promised a donation of 2,000 marks, and Mr. Henry Budge, of Hamburg, has offered to provide a prize of 1,000 marks. A sum of 6,500 marks will be used as a prize fund for a competition for hangars for dirigibles. BACK NUMBERS OF FLIGHT.' THE publishers have pleasure in announcing that they have secured a few of the back issues of FLIGHT, and any of our new readers who may wish to complete their sets may obtain the first twenty numbers for 2s. 6d. post free, from the Publishers, 44, St. Martin's Lane, W.C. 3OS
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