FOOTNOTES.[37]“The Flying Machine”McClure’s Magazine, June, 1897.[38]One noted astronomer and mathematician re-affirmed this opinion as late as 1900 and even stated that man could not hope to construct a flying machine capable of sustaining a weight as great as our largest birds, knowing that even at that time the model Aerodromes Nos. 5 and 6 had already done more than this.[39]These wings are described in Chapter VI, pp.191.[40]See “Experiments in Aerodynamics.” It will be recalled that in the experiments with the “plane-dropper” there was a greatly reduced lifting power with superposed planes when their distance apart was one-half the width the planes, unless a speed of about 42.5 feet a second was obtained. In the above tests with the superposed wings, the speed was only from twenty to twenty-two feet a second at the time of launching, and as the distance between the surfaces was only one-half as great as their width, it is not surprising that the lifting power should not be as great as with the “single-tier” wings.[41]In fact the setting of the tail at a negative angle and fastening it to the frame by an elastic or spring connection was only begun in 1896, and while it proved to be the key to the solution of the problem of automatic longitudinal stability, yet it was not at that time so recognized, although the first real test of the aerodromes after the elastic connection and negative angle of the tail were adopted resulted in the epoch-making flight of No. 5 on May 6. By comparing the angle of the tail on No. 5 in Plate27A, Part I, with the angle of the tail on No. 6 in Plate27B, Part I, it will be seen that while the first had an angle of much less than 5 degrees, the latter had an angle of about 15 degrees. But the wooden springs changed so that it was not accurately known what the angle really was at the time at either flight in 1896.[42]The drawings, Plate55, which illustrate many of the fittings used on the frame, show the guy-wires as attached by means of loops twisted in their ends, these drawings having been made before the final plan of attaching the wires had been devised.[43]See explanation of system of locating points in Part I, Chap. II, p. 15.[44]See Balancing of Engines, by Archibald Sharpe.[45]Except for a ten minute stop to renew the supply of lubricating oil and change the sparking batteries.[46]See foot-note, page249.[47]The weight was afterwards increased to 850 pounds due to repairing the wings and adding more sparking batteries.[48]See Experiments in Aerodynamics, Smithsonian Contributions to Knowledge, Vol. 27, Washington 1891.[49]Researches and Experiments in Aerial Navigation, Smithsonian Publication No. 1809, Washington, 1908.[50]All these minimum permissible conditions are connected by the tacit assumption that the supporting area is not greatly over 2 ft. to the pound of weight. If for instance the weight were increased by larger wings or more wings, furnishing a much greater supporting area per pound, these conditions would not necessarily apply.[51]These tables were later designated as “Data Sheets.” Several copies, with the data duly entered on them, are given in this appendix, and the form which Mr. Langley included in this letter is therefore not repeated here.—EDITOR.
[37]“The Flying Machine”McClure’s Magazine, June, 1897.
[37]“The Flying Machine”McClure’s Magazine, June, 1897.
[38]One noted astronomer and mathematician re-affirmed this opinion as late as 1900 and even stated that man could not hope to construct a flying machine capable of sustaining a weight as great as our largest birds, knowing that even at that time the model Aerodromes Nos. 5 and 6 had already done more than this.
[38]One noted astronomer and mathematician re-affirmed this opinion as late as 1900 and even stated that man could not hope to construct a flying machine capable of sustaining a weight as great as our largest birds, knowing that even at that time the model Aerodromes Nos. 5 and 6 had already done more than this.
[39]These wings are described in Chapter VI, pp.191.
[39]These wings are described in Chapter VI, pp.191.
[40]See “Experiments in Aerodynamics.” It will be recalled that in the experiments with the “plane-dropper” there was a greatly reduced lifting power with superposed planes when their distance apart was one-half the width the planes, unless a speed of about 42.5 feet a second was obtained. In the above tests with the superposed wings, the speed was only from twenty to twenty-two feet a second at the time of launching, and as the distance between the surfaces was only one-half as great as their width, it is not surprising that the lifting power should not be as great as with the “single-tier” wings.
[40]See “Experiments in Aerodynamics.” It will be recalled that in the experiments with the “plane-dropper” there was a greatly reduced lifting power with superposed planes when their distance apart was one-half the width the planes, unless a speed of about 42.5 feet a second was obtained. In the above tests with the superposed wings, the speed was only from twenty to twenty-two feet a second at the time of launching, and as the distance between the surfaces was only one-half as great as their width, it is not surprising that the lifting power should not be as great as with the “single-tier” wings.
[41]In fact the setting of the tail at a negative angle and fastening it to the frame by an elastic or spring connection was only begun in 1896, and while it proved to be the key to the solution of the problem of automatic longitudinal stability, yet it was not at that time so recognized, although the first real test of the aerodromes after the elastic connection and negative angle of the tail were adopted resulted in the epoch-making flight of No. 5 on May 6. By comparing the angle of the tail on No. 5 in Plate27A, Part I, with the angle of the tail on No. 6 in Plate27B, Part I, it will be seen that while the first had an angle of much less than 5 degrees, the latter had an angle of about 15 degrees. But the wooden springs changed so that it was not accurately known what the angle really was at the time at either flight in 1896.
[41]In fact the setting of the tail at a negative angle and fastening it to the frame by an elastic or spring connection was only begun in 1896, and while it proved to be the key to the solution of the problem of automatic longitudinal stability, yet it was not at that time so recognized, although the first real test of the aerodromes after the elastic connection and negative angle of the tail were adopted resulted in the epoch-making flight of No. 5 on May 6. By comparing the angle of the tail on No. 5 in Plate27A, Part I, with the angle of the tail on No. 6 in Plate27B, Part I, it will be seen that while the first had an angle of much less than 5 degrees, the latter had an angle of about 15 degrees. But the wooden springs changed so that it was not accurately known what the angle really was at the time at either flight in 1896.
[42]The drawings, Plate55, which illustrate many of the fittings used on the frame, show the guy-wires as attached by means of loops twisted in their ends, these drawings having been made before the final plan of attaching the wires had been devised.
[42]The drawings, Plate55, which illustrate many of the fittings used on the frame, show the guy-wires as attached by means of loops twisted in their ends, these drawings having been made before the final plan of attaching the wires had been devised.
[43]See explanation of system of locating points in Part I, Chap. II, p. 15.
[43]See explanation of system of locating points in Part I, Chap. II, p. 15.
[44]See Balancing of Engines, by Archibald Sharpe.
[44]See Balancing of Engines, by Archibald Sharpe.
[45]Except for a ten minute stop to renew the supply of lubricating oil and change the sparking batteries.
[45]Except for a ten minute stop to renew the supply of lubricating oil and change the sparking batteries.
[46]See foot-note, page249.
[46]See foot-note, page249.
[47]The weight was afterwards increased to 850 pounds due to repairing the wings and adding more sparking batteries.
[47]The weight was afterwards increased to 850 pounds due to repairing the wings and adding more sparking batteries.
[48]See Experiments in Aerodynamics, Smithsonian Contributions to Knowledge, Vol. 27, Washington 1891.
[48]See Experiments in Aerodynamics, Smithsonian Contributions to Knowledge, Vol. 27, Washington 1891.
[49]Researches and Experiments in Aerial Navigation, Smithsonian Publication No. 1809, Washington, 1908.
[49]Researches and Experiments in Aerial Navigation, Smithsonian Publication No. 1809, Washington, 1908.
[50]All these minimum permissible conditions are connected by the tacit assumption that the supporting area is not greatly over 2 ft. to the pound of weight. If for instance the weight were increased by larger wings or more wings, furnishing a much greater supporting area per pound, these conditions would not necessarily apply.
[50]All these minimum permissible conditions are connected by the tacit assumption that the supporting area is not greatly over 2 ft. to the pound of weight. If for instance the weight were increased by larger wings or more wings, furnishing a much greater supporting area per pound, these conditions would not necessarily apply.
[51]These tables were later designated as “Data Sheets.” Several copies, with the data duly entered on them, are given in this appendix, and the form which Mr. Langley included in this letter is therefore not repeated here.—EDITOR.
[51]These tables were later designated as “Data Sheets.” Several copies, with the data duly entered on them, are given in this appendix, and the form which Mr. Langley included in this letter is therefore not repeated here.—EDITOR.