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Some episodes in the Manchester Association of Engineers
April, 1939.]
BOOK REVIEWS.
58I
Propeller-design c h a r t s - a n d methods of computing propeller thrust are included. Report No. 648, Design Charts for Predicting Downwash Angles and Wake Characteristics Behind Plain and Flapped Wings, by Abe Silverstein . and S. Katzoff. 25 pages, illustrations, 23 X 29 cms. Washington, G o v e r n m e n t Printing Office, 1939. Price 15 cents. Equations and design charts are given for predicting the downwash angles and the wake characteristics for power-off conditions behind plain and flapped wings of the types used in modern design practice. The downwash charts cover the cases of elliptical wings and wings of taper ratios I, 2, 3, and 5, with aspect ratios of 6, 9, and I 2 , having flaps covering o, 4 o, 7o, and Ioo per cent of the span. Curves of the span load distributions for all these cases are included. Data on the lift and the drag of flapped airfoil sections and curves for finding the contribution of the flap to the total wing lift for different types of flap and for the entire range of flap spans are also included. The wake width and the distribution of dynamic pressure across the wake are given in terms of the profile-drag coefficient and the distance behind the wing. A method of estimating the wake position is also given. The equations and the charts are based on theory t h a t has been shown in a previous report to be in agreement with experiment. SOME EPISODES IN THE MANCHESTER ASSOCIATION OF ENGINEERS, compiled by A. C. Dean. 139 pages, 14 )< 22 cms. Manchester, Association, 1938. The name of the Manchester Association of Engineers indicates a purely local body with local interests. It is well recognized however t h a t such a body will in time exert a wide influence and become known at considerable distances through the work of the members connected with it as well as the work of the association itself from which the members benefit. Still another, but no less important reason is the environment of the association. In the case of Manchester, all of these have so played a part, that, the association is not by a n y means unknown the world over. This little book will certainly do its share in this respect. It is composed of extracts from the early minute books which give an interesting picture of the manner in which the affairs were conducted and the interest and pride t h a t was taken in the engineering profession. A special feature is the recordings relative to the Manchester Ship Canal and reports of discussion meetings, the latter covering a great variety of subjects. R. H. OPPERMANN. TENSOR ANALYSIS OF NETWORKS, by Gabriel Kron. 635 pages, illustrations, 16 )< 24 eros. New York, John Wiley & Sons, Inc., 1939. Price $7.5 o. Almost every practicing electrical engineer is familiar with the mental and physical drudgery t h a t accompanies the solution of many types of problems. Along with this comes the ever present possibility of errors in calculations and manipulations of equations. It is therefore quite natural for those encountering such problems to be watchful for a tool t h a t will facilitate the work. The author here suggests the use of tensors which have been known also as hypercomplex numbers, polyadics, matrices, etc. The solution of problems with the aid of these
BOOK REVIEWS.
58I
Propeller-design c h a r t s - a n d methods of computing propeller thrust are included. Report No. 648, Design Charts for Predicting Downwash Angles and Wake Characteristics Behind Plain and Flapped Wings, by Abe Silverstein . and S. Katzoff. 25 pages, illustrations, 23 X 29 cms. Washington, G o v e r n m e n t Printing Office, 1939. Price 15 cents. Equations and design charts are given for predicting the downwash angles and the wake characteristics for power-off conditions behind plain and flapped wings of the types used in modern design practice. The downwash charts cover the cases of elliptical wings and wings of taper ratios I, 2, 3, and 5, with aspect ratios of 6, 9, and I 2 , having flaps covering o, 4 o, 7o, and Ioo per cent of the span. Curves of the span load distributions for all these cases are included. Data on the lift and the drag of flapped airfoil sections and curves for finding the contribution of the flap to the total wing lift for different types of flap and for the entire range of flap spans are also included. The wake width and the distribution of dynamic pressure across the wake are given in terms of the profile-drag coefficient and the distance behind the wing. A method of estimating the wake position is also given. The equations and the charts are based on theory t h a t has been shown in a previous report to be in agreement with experiment. SOME EPISODES IN THE MANCHESTER ASSOCIATION OF ENGINEERS, compiled by A. C. Dean. 139 pages, 14 )< 22 cms. Manchester, Association, 1938. The name of the Manchester Association of Engineers indicates a purely local body with local interests. It is well recognized however t h a t such a body will in time exert a wide influence and become known at considerable distances through the work of the members connected with it as well as the work of the association itself from which the members benefit. Still another, but no less important reason is the environment of the association. In the case of Manchester, all of these have so played a part, that, the association is not by a n y means unknown the world over. This little book will certainly do its share in this respect. It is composed of extracts from the early minute books which give an interesting picture of the manner in which the affairs were conducted and the interest and pride t h a t was taken in the engineering profession. A special feature is the recordings relative to the Manchester Ship Canal and reports of discussion meetings, the latter covering a great variety of subjects. R. H. OPPERMANN. TENSOR ANALYSIS OF NETWORKS, by Gabriel Kron. 635 pages, illustrations, 16 )< 24 eros. New York, John Wiley & Sons, Inc., 1939. Price $7.5 o. Almost every practicing electrical engineer is familiar with the mental and physical drudgery t h a t accompanies the solution of many types of problems. Along with this comes the ever present possibility of errors in calculations and manipulations of equations. It is therefore quite natural for those encountering such problems to be watchful for a tool t h a t will facilitate the work. The author here suggests the use of tensors which have been known also as hypercomplex numbers, polyadics, matrices, etc. The solution of problems with the aid of these