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Report No. 315. Aerodynamic characteristics of airfoils—VI, by National Advisory Committee for Aeronautics. 38 pages, illustrations, quarto. Washington, Government Printing Office, 1929. Price, twenty cents
310
J~OOK REVIEWS.
[J. F. T.
Report No. 313. Drag and Cooling with Various Forms of Cowling for a “Whirlwind” Radial Air-Cooled Engine-I, by Fred E, Weick. 26 pages, illustrations, quarto. Washington, Government Printing Office, 1929. Price, fifteen cents. The Committee has undertaken an investigation in the Twenty-Foot Propeller Research Tunnel at Langley Field on the cowling of radial air-cooled engines. A portion of the investigation has been completed, in which several forms and degrees of cowling were tested on a Wright “Whirlwind” J-5 engine mounted in the nose of a cabin fuselage. The cowlings varied from the one extreme of an entirely exposed engine to the other in which the engine was entirely enclosed. Cooling tests were made and each cowling modified, if necessary, until the engine cooled approximately as satisfactorily as when it was entirely exposed. Drag tests were then made with each form of cowling, and the effect of the cowling on the propulsive efficiency determined with a metal propeller. The propulsive efficiency was found to be practically the same with all forms of cowling. The drag of the cabin fuselage with uncowled engine was found to be more than three times as great as the arag of the fuselage with the engine removed and nose rounded. The conventional forms of cowling, in which at least the tops of the cylinder heads and valve gear are exposed, reduce the drag somewhat, but the cowling entirely covering the engine reduces it 2.6 times as much as the best conventional one. The decrease in drag due to the use of spinners proved to be almost negligible. The use of the cowling completely covering the engine seems entirely practical as regards both cooling and maintenance under service conditions. It must be With cabin fuselages its use should carefully designed, however, to cool properly. result in a substantial increase in high speed over that obtained with present forms of cowling on engines similar in contour to the J-5. Report No. 315. Aerodynamic Characteristics of Airfoils-VI, by National Advisory Committee for Aeronautics. 38 pages, illustrations, quarto. Washington, Government Printing Office, 1929. Price, twenty cents. This collection of data on airfoils has been made from the published reports of a number of the leading aerodynamic laboratories of this country and Europe.* The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for the use of designing engineers and for purposes of general reference. It is a well-known fact that the results obtained in different laboratories, because of their individual methods of testing, are not strictly comparable even if proper scale corrections for size of model and speed of test are supplied. It is, therefore, unwise to compare too closely the coefficients of two wing sections Tests of different wing sections from the same tested in different laboratories. source, however, may be relied on to give true relative values. The absolute system of coefficients has been used, since it is thought by the * A previous collection of airfoil sections numbered I to 759 and Charts > 20 may be found in N. A. C. A. Reports Nos. 93, 1.24, 182, 244, and 286.
I
Aug..
~pg.]
PUBLIC:\TIONS
RECEIVED.
3x1
National Advisory Committee for Aeronautics that this system is the one most suited for international use and yet it is one from which a desired transformation For this purpose a set of transformation constants is given. can be easily made. Each airfoil section is given a reference number, and the test data are presented in the form of curves from which the coefficients can be read with The dimensions of the profile of sufficient accuracy for designing purposes. each section are given at various stations along the chord in per cent. of the The shape of the section chord length, the latter also serving as the datum line. is also shown with reasonable accuracy in order to enable one to more clearly visualize the section under consideration, the outside of the heavy line representing the profile. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, as explained under abbreviations, with the size of model, wind velocity, and year of test. Tables for Pressure of Air on Coming to Rest from Various Report No. 316. Washing8 pages, quarto. Speeds, by A. F. Zahm and F. A. Louden. Price, five cents. ton, Government Printing Office, 1929. In Technical Report No. 247 of the Committee theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from In that report, the various speeds, such as those of aircraft and propeller blades. table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per second, The pressure values knots per hour, kilometers per hour, and meters per second. in Table II are also more exact than the values given in the previous table. To furnish the aeronautical engineer with ready numerical formulas for finding the pressure of air on coming to rest, Table 1 has been derived for the standard values specified below it. This table first presents the theoretical pressure-speed formulas and their working forms in C.G.S. units as given in N. A. C. A. Technical Report No. 247, then furnishes additional working fomulas for several special units of speed. Ii.
PUBLICATIONS
RECEIVED.
Mechanism of Enzyme Action and Associated Cell Phenomena, by F. F. Nord. 78 pages, illustrations, 8~0. Baltimore, The Williams and Wilkins Company, 1929. Ondes et &ectrons, par Pierre Bricout. Collection Armand Colin. 215 illustrations. I6mo. Paris, Armand Colin, 1929, price nine francs. Structure de I’Atome, Tourbillon d’L?ther et Penstes Scientifiques Indkpendentes par L. Cugnin. 184 pages, 8~0. Sceaux, Marcel Bry, 1929. Professor Coker’s Photo-elastic Apparatus for Determining the Distribution of Stress in Structural and Machine Members. London, 28 pages, illustrations, 8~0. Adam Hilger, Ltd., 1929. pages,
J~OOK REVIEWS.
[J. F. T.
Report No. 313. Drag and Cooling with Various Forms of Cowling for a “Whirlwind” Radial Air-Cooled Engine-I, by Fred E, Weick. 26 pages, illustrations, quarto. Washington, Government Printing Office, 1929. Price, fifteen cents. The Committee has undertaken an investigation in the Twenty-Foot Propeller Research Tunnel at Langley Field on the cowling of radial air-cooled engines. A portion of the investigation has been completed, in which several forms and degrees of cowling were tested on a Wright “Whirlwind” J-5 engine mounted in the nose of a cabin fuselage. The cowlings varied from the one extreme of an entirely exposed engine to the other in which the engine was entirely enclosed. Cooling tests were made and each cowling modified, if necessary, until the engine cooled approximately as satisfactorily as when it was entirely exposed. Drag tests were then made with each form of cowling, and the effect of the cowling on the propulsive efficiency determined with a metal propeller. The propulsive efficiency was found to be practically the same with all forms of cowling. The drag of the cabin fuselage with uncowled engine was found to be more than three times as great as the arag of the fuselage with the engine removed and nose rounded. The conventional forms of cowling, in which at least the tops of the cylinder heads and valve gear are exposed, reduce the drag somewhat, but the cowling entirely covering the engine reduces it 2.6 times as much as the best conventional one. The decrease in drag due to the use of spinners proved to be almost negligible. The use of the cowling completely covering the engine seems entirely practical as regards both cooling and maintenance under service conditions. It must be With cabin fuselages its use should carefully designed, however, to cool properly. result in a substantial increase in high speed over that obtained with present forms of cowling on engines similar in contour to the J-5. Report No. 315. Aerodynamic Characteristics of Airfoils-VI, by National Advisory Committee for Aeronautics. 38 pages, illustrations, quarto. Washington, Government Printing Office, 1929. Price, twenty cents. This collection of data on airfoils has been made from the published reports of a number of the leading aerodynamic laboratories of this country and Europe.* The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for the use of designing engineers and for purposes of general reference. It is a well-known fact that the results obtained in different laboratories, because of their individual methods of testing, are not strictly comparable even if proper scale corrections for size of model and speed of test are supplied. It is, therefore, unwise to compare too closely the coefficients of two wing sections Tests of different wing sections from the same tested in different laboratories. source, however, may be relied on to give true relative values. The absolute system of coefficients has been used, since it is thought by the * A previous collection of airfoil sections numbered I to 759 and Charts > 20 may be found in N. A. C. A. Reports Nos. 93, 1.24, 182, 244, and 286.
I
Aug..
~pg.]
PUBLIC:\TIONS
RECEIVED.
3x1
National Advisory Committee for Aeronautics that this system is the one most suited for international use and yet it is one from which a desired transformation For this purpose a set of transformation constants is given. can be easily made. Each airfoil section is given a reference number, and the test data are presented in the form of curves from which the coefficients can be read with The dimensions of the profile of sufficient accuracy for designing purposes. each section are given at various stations along the chord in per cent. of the The shape of the section chord length, the latter also serving as the datum line. is also shown with reasonable accuracy in order to enable one to more clearly visualize the section under consideration, the outside of the heavy line representing the profile. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, as explained under abbreviations, with the size of model, wind velocity, and year of test. Tables for Pressure of Air on Coming to Rest from Various Report No. 316. Washing8 pages, quarto. Speeds, by A. F. Zahm and F. A. Louden. Price, five cents. ton, Government Printing Office, 1929. In Technical Report No. 247 of the Committee theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from In that report, the various speeds, such as those of aircraft and propeller blades. table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per second, The pressure values knots per hour, kilometers per hour, and meters per second. in Table II are also more exact than the values given in the previous table. To furnish the aeronautical engineer with ready numerical formulas for finding the pressure of air on coming to rest, Table 1 has been derived for the standard values specified below it. This table first presents the theoretical pressure-speed formulas and their working forms in C.G.S. units as given in N. A. C. A. Technical Report No. 247, then furnishes additional working fomulas for several special units of speed. Ii.
PUBLICATIONS
RECEIVED.
Mechanism of Enzyme Action and Associated Cell Phenomena, by F. F. Nord. 78 pages, illustrations, 8~0. Baltimore, The Williams and Wilkins Company, 1929. Ondes et &ectrons, par Pierre Bricout. Collection Armand Colin. 215 illustrations. I6mo. Paris, Armand Colin, 1929, price nine francs. Structure de I’Atome, Tourbillon d’L?ther et Penstes Scientifiques Indkpendentes par L. Cugnin. 184 pages, 8~0. Sceaux, Marcel Bry, 1929. Professor Coker’s Photo-elastic Apparatus for Determining the Distribution of Stress in Structural and Machine Members. London, 28 pages, illustrations, 8~0. Adam Hilger, Ltd., 1929. pages,