- Email: [email protected]
Report No. 614, Pressure distribution over an N.A.C.A. 23012 airfoil with an N.A.C.A. 23012 external-airfoil flap
March, 1938.]
BOOK R E V I E W S .
367
may be had b y first calling to mind the solution of triangles. In a triangle there are six p a r t s - - t h r e e sides and three angles. When three parts, of which a t least one is a side, are known, the trigonometric functions offer a means of computing the other three unknown parts. Likewise, in a segment t h e r e are essentially five p a r t s - - t h e arc, the chord, the radius, the central angle subtended by the arc, and the height or the middle ordinate referred to the chord as abscissa. When any two parts are known, the other three, and also the area, may be determined by means of the segmental functions introduced in this volume. But since work of t h a t kind is simplified and shortened by the use of logarithms, the author preferred to use the logarithms of the segmental functions instead of the functions themselves and has evolved a set of formulas which are well adapted for logarithmic work, so t h a t the solutions are handled by means of additions and subtractions. The tables in this volume are divided into two groups. Group I contains a table of logarithms of the seven segmental functions for angles from 0 to I80 deg. and others which take care of corrections for seconds. Also in this group is a table which gives the natural value of function A, and a table containing logarithms of segments for radius i. In Group 2 there is a table of logarithms of numbers from o to I0,O00, the decimal as well as the English system of linear measure extended to 200 feet. The book should come in very handy to those whose work requires such computations. R. H. OPPERMANN. NATIONAL RESEARCH COUNCIL: Transactions of the American Geophysical Union, Eighteenth Annual Meeting, April 28, 29, 5o, I937, Washington, D. C. Part I, 264 pages, illustrations, tables. Part II, 597 pages, illustrations, tables, I7 X 25 cms. Washington, National Research Council, I937. This volume, in two parts, is a miscellaneous publication of the Council. It includes the transactions of the eighteenth annual meeting held in Washington, D. C., and Denver, Colo., of the American Geophysical Union. The first part contains reports and papers presented before the general assembly and sections of geodesy, seismology, meteorology , terrestrial magnetism and electricity, oceanography, and volcanology. Part two covers the section of hydrology and South Continental Divide Snow-Survey Conference. R. H, OPPERMANN. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS. Report No. 614, Pressure Distribution over an N.A.C.A. 23oi2 Airfoil with an N.A.C.A. 23oI2 External-Airfoil Flap, by Carl J. Wenzinger. I5 pages, illustrations, 23 X 29 cms. Washington, Government Printing Office, I938. Price IO cents. Pressure-distribution tests of an N.A.C.A. 23oI~ airfoil with an N.A.C.A. 23oI2 - external-airfoil flap were made in the 7- by Io-foot wind tunnel. The pressures were measured on the upper and lower surfaces at one chord section on both the main airfoil and on the flap for several different flap deflections and at several angles of attack. A test installation was used in which the airfoil was mounted horizontally in the wind tunnel between vertical end planes so t h a t twodimensional flow was approximated. The data are presented in the form of pressure-distrlbutlon diagrams and as
368
BOOK R E V I E W S .
[J. F. I.
graphs of calculated coefficients for the airfoil-and-flap combination and for the flap alone. The pressure-distribution tests showed that, as with other types of flap, the greater part of the increment of total maximum lift due to deflecting the external-airfoil flap downward arises from the increased load carried by the main airfoil The maximum normal-force coefficient of the external-airfoil flap was about the same as t h a t of a split flap. The hinge moments, however, were much lower because of the axis location used with the external-airfoil flap. The pressure diagrams showed that, when the plain airfoil and the flapped airfoil are compared at the same total lift, the flap reduces the adverse pressure gradients and the tendency of the main airfoil to stall. When the plain and flapped airfoils are compared at the same angle of attack, it is apparent t h a t the flap influences the air flow around the main airfoil so t h a t the airfoil carries a much greater load without stalling than is possible without the flap. No. 616, Interrelation of Exhaust-Gas Constitutents, by Harold C. Gerrish and Fred Voss. 8 pages, illustrations, 23 X 29 cms. Washington, Government Printing Office, I937. Price Io cents. An investigation was made to determine the interrelation of the constituents of the exhaust gases of internal-combustion engines and the effect of engine performance on these relations. Six single-cylinder, liquid-cooled test engines and one 9-cylinder radial air-cooled engine were tested. Various types of combustion chambers were used and the engines were operated at compression ratios from 5.I to 7.0 using spark ignition and from I3. 5 to I5.6 using compression ignition. The investigation covered a range of engine speeds from 1,5oo to 2,IOO r.p.m. The fuels used were two grades of aviation gasoline, Auto Diesel fuel, and Laboratory Diesel fuel. Power, friction, and fuel-consumption data were obtained from the single-cylinder engines at the same time t h a t the exhaust-gas samples were collected. Definite relations, which were independent of engine design and operating conditions, were found among the constltutents of exhaust gases, air-fuel ratio, water of combustion, and combustion efficiency. Combustion efficiency and amount of water of combustion increased approximately linearly with air-fuel ratio for rich mixtures and were independent of mixture strength for lean mixtures. These relations make it possible to obtain a complete exhaust-gas analysis simply by determining the air-fuel ratio or the CO2 and O, content. The results also showed t h a t compression-ignition engines may be operated at the same air-fuel ratio as spark-ignition engines without loss in combustion efficiency. ASSOCIATION OF CONSULTINGCHEMISTSAND CHEMICALENGINEERS, INC. DIRECTORY OF ASSOCIATION MEMBERS, JANUARYI, I938. Fourth edition. 22 X 28 cms., variously paged. New York, Association, I938. A new departure in membership directories. After a foreword and excerpts from the By-Laws, five pages are devoted to an alphabetical list of the members, this is followed by a list of members in numerical order of members' certificates. A geographical list is next in order and then a fist of organizations and firms with which the members are identified. One page is devoted to a detailed account of the officers, staff, scope and activities of each laboratory. There is a key sheet
BOOK R E V I E W S .
367
may be had b y first calling to mind the solution of triangles. In a triangle there are six p a r t s - - t h r e e sides and three angles. When three parts, of which a t least one is a side, are known, the trigonometric functions offer a means of computing the other three unknown parts. Likewise, in a segment t h e r e are essentially five p a r t s - - t h e arc, the chord, the radius, the central angle subtended by the arc, and the height or the middle ordinate referred to the chord as abscissa. When any two parts are known, the other three, and also the area, may be determined by means of the segmental functions introduced in this volume. But since work of t h a t kind is simplified and shortened by the use of logarithms, the author preferred to use the logarithms of the segmental functions instead of the functions themselves and has evolved a set of formulas which are well adapted for logarithmic work, so t h a t the solutions are handled by means of additions and subtractions. The tables in this volume are divided into two groups. Group I contains a table of logarithms of the seven segmental functions for angles from 0 to I80 deg. and others which take care of corrections for seconds. Also in this group is a table which gives the natural value of function A, and a table containing logarithms of segments for radius i. In Group 2 there is a table of logarithms of numbers from o to I0,O00, the decimal as well as the English system of linear measure extended to 200 feet. The book should come in very handy to those whose work requires such computations. R. H. OPPERMANN. NATIONAL RESEARCH COUNCIL: Transactions of the American Geophysical Union, Eighteenth Annual Meeting, April 28, 29, 5o, I937, Washington, D. C. Part I, 264 pages, illustrations, tables. Part II, 597 pages, illustrations, tables, I7 X 25 cms. Washington, National Research Council, I937. This volume, in two parts, is a miscellaneous publication of the Council. It includes the transactions of the eighteenth annual meeting held in Washington, D. C., and Denver, Colo., of the American Geophysical Union. The first part contains reports and papers presented before the general assembly and sections of geodesy, seismology, meteorology , terrestrial magnetism and electricity, oceanography, and volcanology. Part two covers the section of hydrology and South Continental Divide Snow-Survey Conference. R. H, OPPERMANN. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS. Report No. 614, Pressure Distribution over an N.A.C.A. 23oi2 Airfoil with an N.A.C.A. 23oI2 External-Airfoil Flap, by Carl J. Wenzinger. I5 pages, illustrations, 23 X 29 cms. Washington, Government Printing Office, I938. Price IO cents. Pressure-distribution tests of an N.A.C.A. 23oI~ airfoil with an N.A.C.A. 23oI2 - external-airfoil flap were made in the 7- by Io-foot wind tunnel. The pressures were measured on the upper and lower surfaces at one chord section on both the main airfoil and on the flap for several different flap deflections and at several angles of attack. A test installation was used in which the airfoil was mounted horizontally in the wind tunnel between vertical end planes so t h a t twodimensional flow was approximated. The data are presented in the form of pressure-distrlbutlon diagrams and as
368
BOOK R E V I E W S .
[J. F. I.
graphs of calculated coefficients for the airfoil-and-flap combination and for the flap alone. The pressure-distribution tests showed that, as with other types of flap, the greater part of the increment of total maximum lift due to deflecting the external-airfoil flap downward arises from the increased load carried by the main airfoil The maximum normal-force coefficient of the external-airfoil flap was about the same as t h a t of a split flap. The hinge moments, however, were much lower because of the axis location used with the external-airfoil flap. The pressure diagrams showed that, when the plain airfoil and the flapped airfoil are compared at the same total lift, the flap reduces the adverse pressure gradients and the tendency of the main airfoil to stall. When the plain and flapped airfoils are compared at the same angle of attack, it is apparent t h a t the flap influences the air flow around the main airfoil so t h a t the airfoil carries a much greater load without stalling than is possible without the flap. No. 616, Interrelation of Exhaust-Gas Constitutents, by Harold C. Gerrish and Fred Voss. 8 pages, illustrations, 23 X 29 cms. Washington, Government Printing Office, I937. Price Io cents. An investigation was made to determine the interrelation of the constituents of the exhaust gases of internal-combustion engines and the effect of engine performance on these relations. Six single-cylinder, liquid-cooled test engines and one 9-cylinder radial air-cooled engine were tested. Various types of combustion chambers were used and the engines were operated at compression ratios from 5.I to 7.0 using spark ignition and from I3. 5 to I5.6 using compression ignition. The investigation covered a range of engine speeds from 1,5oo to 2,IOO r.p.m. The fuels used were two grades of aviation gasoline, Auto Diesel fuel, and Laboratory Diesel fuel. Power, friction, and fuel-consumption data were obtained from the single-cylinder engines at the same time t h a t the exhaust-gas samples were collected. Definite relations, which were independent of engine design and operating conditions, were found among the constltutents of exhaust gases, air-fuel ratio, water of combustion, and combustion efficiency. Combustion efficiency and amount of water of combustion increased approximately linearly with air-fuel ratio for rich mixtures and were independent of mixture strength for lean mixtures. These relations make it possible to obtain a complete exhaust-gas analysis simply by determining the air-fuel ratio or the CO2 and O, content. The results also showed t h a t compression-ignition engines may be operated at the same air-fuel ratio as spark-ignition engines without loss in combustion efficiency. ASSOCIATION OF CONSULTINGCHEMISTSAND CHEMICALENGINEERS, INC. DIRECTORY OF ASSOCIATION MEMBERS, JANUARYI, I938. Fourth edition. 22 X 28 cms., variously paged. New York, Association, I938. A new departure in membership directories. After a foreword and excerpts from the By-Laws, five pages are devoted to an alphabetical list of the members, this is followed by a list of members in numerical order of members' certificates. A geographical list is next in order and then a fist of organizations and firms with which the members are identified. One page is devoted to a detailed account of the officers, staff, scope and activities of each laboratory. There is a key sheet