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Aerodynamic Theory of Today

Aerodynamic Theory of Today 284 AIRCRAF T ENGINEERING November, 1932 A Comprehensive Italian Work for Advanced Students and a More Elementary American Book H E science of aerodynamics has made rapid t o some special problems, of which the most im­ enhanced by its excellent bibliography. If any progress during the last ten or twenty portan t are Wagner's theory of accelerated motion criticism is to be raised, it is tha t at times a surfeit years, and the rate of advance shows an d Munk's analysis for a wing with a uniform of good things may lead to mental indigestion, little sign of abating. Text books, however, are angula r pitching velocity. The next chapter deals tha t the explanation in succession of five or six in the same comprehensive manner with the theory a s yet few in number, and these two books, though different methods of attacking the same problem, of wings of finite span. The fundamental basis of differing widely in character, are both welcome thoug h giving the book its comprehensive character th e theory of induced drag is clearly explained, addition s to our literature. Prof. Pistolesi's a s a book of reference, inevitably leads to some lack "Aerodinamic a " is a comprehensive account of the several proofs of the minimum drag theorem are of unity of thought and continuity of treatment. presen t state of aerodynamic theory, which will be given, and the use of Fourier series to determine Thi s may seem exacting criticism, but Prof. of great value to advanced students of the subject th e characteristics of a wing of any shape is de­ Pistolesi has set himself, and has undoubtedly and , more generally, as a standar d book of reference. veloped in detail. In this section, however, occurs attained , an exactingly high standard. I t includes full accounts of th e modern aerodynamic one of the few omissions of an important analytical theories of wings and airscrews and of the progress method , since no mention is made of the analysis, Prof. Reid's Elementary Book in the analyses of the motion of viscous and com­ developed by Lotz, in which the angle of incidence pressible fluids, together with detailed references an d the inverse of the chord are expressed as Prof. Reid's "Applied Wing Theory " is essentially t o original papers on these subjects. Prof. Reid's Fourie r series. The determination of the rolling a n elementary tex t book. After a brief introductory momen t of an asymmetric wing is, however, dis­ aim is more modest in scope, but no easier of chapter , the autho r gives a clear and simple account cussed in detail, and brief accounts are also given execution. He has endeavoured to provide an of the fundamental concepts underlying the theory of Blenk's analysis of the effect of sideslip and of accoun t of modern wing theory suitable for en­ of fluid motion, but it is rather regrettable that gineering students and aeroplane designers of Wieselsberger's analysis for a wing in curved n o proof of Bernoulli's theorem is given, whilst limited mathematical knowledge, and he has flight. The theory of biplane interference is treated th e approach to the velocity potential and stream fulfilled his object by combining a detailed develop­ ver y fully, but the brief notes about infinite series function from their mathematical definitions, fol- men t of the more elementary parts of the subject of aerofoils might be elaborated with advantage. lowed by their physical interpretations, is rather wit h a descriptive and critical account of the more Th e chapter also contains discussions of various surprising, since it will be less illuminating to the complex parts. miscellaneous problems, of which the most in­ studen t than the alternative method of developing terestin g is perhap s th e determination of th e position thes e functions from the basis of the physical of the vortex line which may be used to replace Prof. Pistolesi's Advanced Work conceptions. The third chapter is devoted to a wing in approximate calculations. The discussion establishing the Kutta-Joukowski relationship A detailed account of the contents of Prof of wind-tunnel interference is clearly developed, between lift and circulation, first in detail for a Pistolesi's book would be a catalogue of the manifold bu t omits some of the latest developments of the circular cylinder, and then more generally for any problems of theoretical aerodynamics, and it must subject and, in particular, the interference on the cylinder by considering the conditions at infinity. suffice to indicate the trend of the analysis and angle of downwash. Thi s chapter also contains a brief account of the it s most important features. The first two chapters criterion which is used to determine the circulation ar e of an introductory character and are devoted Th e fifth chapter is devoted to the subject of round an aerofoil, but omits any explanation of drag , and opens with a discussion of discontinuous t o the development of those aspects of the theory th e origin of the circulation. flow problems, including Levi Civita's generalisation of fluid motion which are required subsequently. of th e analysis initiated by Helmholtz and Kirchhoff. After describing briefly the nature of the aero­ Th e next two chapters deal respectively with This is followed by the theory of vortex streets dynami c problems to be considered and the ex­ monoplanes and multiplanes, and the author has an d of the drag associated with this type of wake. perimenta l methods available for their study, the here fulfilled his purpose very efficiently by ex­ The author next deals very fully with the various autho r develops in turn the equations of motion plaining clearly the conceptions of trailing vortices method s which have been used to obtain solutions of a perfect and of a viscous fluid, using concise an d induced velocities, by developing the analysis of the equations of motion of a viscous fluid, in­ vecto r notation, and then proceeds to a detailed for elliptic lift distribution, and by summarising cluding finally Prandtl's boundary layer theory. discussion of Bernoulli's equation and its appli­ th e results for more complex conditions. The Th e conception of turbulent motion is introduced cation, and to an account of vortex motion, in­ discussion of multiplane interference is treated b y discussing the flow in pipes, and this leads to cluding the estimation of induced velocities and ver y fully, and constitutes the best section of the a n explanation of Prandtl's conception of a th e conception of bound vortices. The second whole book. The sixth chapter is devoted to Mischungsweg and Karman's law of resistance chapte r is devoted to the development of some various miscellaneous problems, including wind- derived from dimensional considerations. The aspect s of potential flow, and its main feature is tunne l interference, the rolling an d yawing moments chapte r concludes with brief descriptions of the a very full treatment of the use of the analytical of asymmetric wings, and the angle of downwash scale effect on bodies of different shape, of device of sources and sinks, both in two and in behind a wing, and in a brief concluding chapter th e origin of circulation, and of the control thre e dimensions, including an account of Fuhr- th e author summarises the formula; for calculating of the boundary layer by suction mann' s airship shapes and a comparison of the th e lift and pitching moment of an aerofoil in two- theoretical and experimental pressure distribution dimensional motion. I n the sixth and final chapter the author con­ round them. The chapter concludes with a dis­ siders the development of airscrew theory. The Th e author is to be congratulated on his choice cussion of th e conception of virtual mass an d of some accoun t of the momentum theory, including the of material and on the discrimination which he problems of motion in a curved path. The analysis effect of tunnel constraint and body interference, ha s used in deciding which parts of the work of these two chapters is ably presented, and forms omit s nothing of importance, and special mention should be developed analytically and which should a n excellent introduction to the main theme of ma y be made of the author's clear exposition of be treated descriptively. Unfortunately the book th e book. th e difficulties associated with applying the suffers in places from a certain looseness of ex­ momentu m theory to an elementary annulus of pression, degenerating occasionally into inexacti­ Th e theory of the lift of a wing of infinite span a n airscrew. The vortex and blade element theories tude , which must be confusing to the student; is developed in th e third chapter. After establishing ar e also explained in detail, and include two little- as , for example, on page 22, where " integral " is th e fundamental Kutta-Joukowski theorem, the know n features—the representation of the inter­ autho r passes to the use of complex co-ordinates used in the sense of "increment." The author ference flow by use of an effective aspect ratio of an d conformal transformation to obtain the flow also falls into serious error when explaining the th e blade elements, and the inclusion of Prandtl's pas t any aerofoil. This analysis, which is presented wind-tunne l interference on the angle of downwash approximat e formula for ti p losses in th e momentum clearly and in great detail, falls naturally into an d tailsetting. He confesses (page 185) his equation s for thrus t and torque. Finally, th e autho r thre e stages. First comes the development of inabilit y to justify the assumption of neglecting considers briefly the different working states of an expressions for the lift and pitching moment of th e induced velocity of the transverse vortex, which airscrew, the effect of body interference, and the a n aerofoil in term s of the conformal transformation is, in fact, quite unjustifiable ; he establishes, mutua l interference of tandem airscrews. b y which the aerofoil is related to a circle. This on the basis of this assumption, a formula for a is followed by the consideration of a few special circular tunnel which is incorrect; and he then These six lengthy chapters are followed by two type s of aerofoil which can be derived by simple quote s the formula for a rectangular tunnel which shorte r appendices, dealing, first, with the dis­ does not involve this false assumption. In spite transformations , and lastly the author explains continuou s potential theory of wing lift developed of these occasional lapses, however, Prof. Reid th e various methods which have been developed b y Witoszinski and Dupont, and, secondly, with has provided us with a very useful elementary t o determine the characteristics of any given th e influence of the compressibility of the air on aerofoil. The remainder of the chapter is devoted introductio n to the theory of lifting surfaces. th e characteristics of an aerofoil. A lengthy H . G. bibliography and an adequate index conclude * E. Pistolesi . Aerodinamica (Unione Tipogra- a book full of valuable information. Little has fico, Editric e Torinese, Turin. Price SO lire) been omitted that could usefully have been in­ [Either of these boohs can be obtained from AIR- E . G. Reid. Applied Wing Theory (McGraw- cluded, the author's explanations are invariably CRAF T ENGINEERING, 6 Norfolk Street, Strand, Hill. Price 18s.) clear and precise, and the value of the book is London, W.C.2.] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Aerodynamic Theory of Today

Aircraft Engineering and Aerospace Technology , Volume 4 (11): 1 – Nov 1, 1932
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Emerald Publishing
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Copyright © Emerald Group Publishing Limited
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0002-2667
DOI
10.1108/eb029617
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Abstract

284 AIRCRAF T ENGINEERING November, 1932 A Comprehensive Italian Work for Advanced Students and a More Elementary American Book H E science of aerodynamics has made rapid t o some special problems, of which the most im­ enhanced by its excellent bibliography. If any progress during the last ten or twenty portan t are Wagner's theory of accelerated motion criticism is to be raised, it is tha t at times a surfeit years, and the rate of advance shows an d Munk's analysis for a wing with a uniform of good things may lead to mental indigestion, little sign of abating. Text books, however, are angula r pitching velocity. The next chapter deals tha t the explanation in succession of five or six in the same comprehensive manner with the theory a s yet few in number, and these two books, though different methods of attacking the same problem, of wings of finite span. The fundamental basis of differing widely in character, are both welcome thoug h giving the book its comprehensive character th e theory of induced drag is clearly explained, addition s to our literature. Prof. Pistolesi's a s a book of reference, inevitably leads to some lack "Aerodinamic a " is a comprehensive account of the several proofs of the minimum drag theorem are of unity of thought and continuity of treatment. presen t state of aerodynamic theory, which will be given, and the use of Fourier series to determine Thi s may seem exacting criticism, but Prof. of great value to advanced students of the subject th e characteristics of a wing of any shape is de­ Pistolesi has set himself, and has undoubtedly and , more generally, as a standar d book of reference. veloped in detail. In this section, however, occurs attained , an exactingly high standard. I t includes full accounts of th e modern aerodynamic one of the few omissions of an important analytical theories of wings and airscrews and of the progress method , since no mention is made of the analysis, Prof. Reid's Elementary Book in the analyses of the motion of viscous and com­ developed by Lotz, in which the angle of incidence pressible fluids, together with detailed references an d the inverse of the chord are expressed as Prof. Reid's "Applied Wing Theory " is essentially t o original papers on these subjects. Prof. Reid's Fourie r series. The determination of the rolling a n elementary tex t book. After a brief introductory momen t of an asymmetric wing is, however, dis­ aim is more modest in scope, but no easier of chapter , the autho r gives a clear and simple account cussed in detail, and brief accounts are also given execution. He has endeavoured to provide an of the fundamental concepts underlying the theory of Blenk's analysis of the effect of sideslip and of accoun t of modern wing theory suitable for en­ of fluid motion, but it is rather regrettable that gineering students and aeroplane designers of Wieselsberger's analysis for a wing in curved n o proof of Bernoulli's theorem is given, whilst limited mathematical knowledge, and he has flight. The theory of biplane interference is treated th e approach to the velocity potential and stream fulfilled his object by combining a detailed develop­ ver y fully, but the brief notes about infinite series function from their mathematical definitions, fol- men t of the more elementary parts of the subject of aerofoils might be elaborated with advantage. lowed by their physical interpretations, is rather wit h a descriptive and critical account of the more Th e chapter also contains discussions of various surprising, since it will be less illuminating to the complex parts. miscellaneous problems, of which the most in­ studen t than the alternative method of developing terestin g is perhap s th e determination of th e position thes e functions from the basis of the physical of the vortex line which may be used to replace Prof. Pistolesi's Advanced Work conceptions. The third chapter is devoted to a wing in approximate calculations. The discussion establishing the Kutta-Joukowski relationship A detailed account of the contents of Prof of wind-tunnel interference is clearly developed, between lift and circulation, first in detail for a Pistolesi's book would be a catalogue of the manifold bu t omits some of the latest developments of the circular cylinder, and then more generally for any problems of theoretical aerodynamics, and it must subject and, in particular, the interference on the cylinder by considering the conditions at infinity. suffice to indicate the trend of the analysis and angle of downwash. Thi s chapter also contains a brief account of the it s most important features. The first two chapters criterion which is used to determine the circulation ar e of an introductory character and are devoted Th e fifth chapter is devoted to the subject of round an aerofoil, but omits any explanation of drag , and opens with a discussion of discontinuous t o the development of those aspects of the theory th e origin of the circulation. flow problems, including Levi Civita's generalisation of fluid motion which are required subsequently. of th e analysis initiated by Helmholtz and Kirchhoff. After describing briefly the nature of the aero­ Th e next two chapters deal respectively with This is followed by the theory of vortex streets dynami c problems to be considered and the ex­ monoplanes and multiplanes, and the author has an d of the drag associated with this type of wake. perimenta l methods available for their study, the here fulfilled his purpose very efficiently by ex­ The author next deals very fully with the various autho r develops in turn the equations of motion plaining clearly the conceptions of trailing vortices method s which have been used to obtain solutions of a perfect and of a viscous fluid, using concise an d induced velocities, by developing the analysis of the equations of motion of a viscous fluid, in­ vecto r notation, and then proceeds to a detailed for elliptic lift distribution, and by summarising cluding finally Prandtl's boundary layer theory. discussion of Bernoulli's equation and its appli­ th e results for more complex conditions. The Th e conception of turbulent motion is introduced cation, and to an account of vortex motion, in­ discussion of multiplane interference is treated b y discussing the flow in pipes, and this leads to cluding the estimation of induced velocities and ver y fully, and constitutes the best section of the a n explanation of Prandtl's conception of a th e conception of bound vortices. The second whole book. The sixth chapter is devoted to Mischungsweg and Karman's law of resistance chapte r is devoted to the development of some various miscellaneous problems, including wind- derived from dimensional considerations. The aspect s of potential flow, and its main feature is tunne l interference, the rolling an d yawing moments chapte r concludes with brief descriptions of the a very full treatment of the use of the analytical of asymmetric wings, and the angle of downwash scale effect on bodies of different shape, of device of sources and sinks, both in two and in behind a wing, and in a brief concluding chapter th e origin of circulation, and of the control thre e dimensions, including an account of Fuhr- th e author summarises the formula; for calculating of the boundary layer by suction mann' s airship shapes and a comparison of the th e lift and pitching moment of an aerofoil in two- theoretical and experimental pressure distribution dimensional motion. I n the sixth and final chapter the author con­ round them. The chapter concludes with a dis­ siders the development of airscrew theory. The Th e author is to be congratulated on his choice cussion of th e conception of virtual mass an d of some accoun t of the momentum theory, including the of material and on the discrimination which he problems of motion in a curved path. The analysis effect of tunnel constraint and body interference, ha s used in deciding which parts of the work of these two chapters is ably presented, and forms omit s nothing of importance, and special mention should be developed analytically and which should a n excellent introduction to the main theme of ma y be made of the author's clear exposition of be treated descriptively. Unfortunately the book th e book. th e difficulties associated with applying the suffers in places from a certain looseness of ex­ momentu m theory to an elementary annulus of pression, degenerating occasionally into inexacti­ Th e theory of the lift of a wing of infinite span a n airscrew. The vortex and blade element theories tude , which must be confusing to the student; is developed in th e third chapter. After establishing ar e also explained in detail, and include two little- as , for example, on page 22, where " integral " is th e fundamental Kutta-Joukowski theorem, the know n features—the representation of the inter­ autho r passes to the use of complex co-ordinates used in the sense of "increment." The author ference flow by use of an effective aspect ratio of an d conformal transformation to obtain the flow also falls into serious error when explaining the th e blade elements, and the inclusion of Prandtl's pas t any aerofoil. This analysis, which is presented wind-tunne l interference on the angle of downwash approximat e formula for ti p losses in th e momentum clearly and in great detail, falls naturally into an d tailsetting. He confesses (page 185) his equation s for thrus t and torque. Finally, th e autho r thre e stages. First comes the development of inabilit y to justify the assumption of neglecting considers briefly the different working states of an expressions for the lift and pitching moment of th e induced velocity of the transverse vortex, which airscrew, the effect of body interference, and the a n aerofoil in term s of the conformal transformation is, in fact, quite unjustifiable ; he establishes, mutua l interference of tandem airscrews. b y which the aerofoil is related to a circle. This on the basis of this assumption, a formula for a is followed by the consideration of a few special circular tunnel which is incorrect; and he then These six lengthy chapters are followed by two type s of aerofoil which can be derived by simple quote s the formula for a rectangular tunnel which shorte r appendices, dealing, first, with the dis­ does not involve this false assumption. In spite transformations , and lastly the author explains continuou s potential theory of wing lift developed of these occasional lapses, however, Prof. Reid th e various methods which have been developed b y Witoszinski and Dupont, and, secondly, with has provided us with a very useful elementary t o determine the characteristics of any given th e influence of the compressibility of the air on aerofoil. The remainder of the chapter is devoted introductio n to the theory of lifting surfaces. th e characteristics of an aerofoil. A lengthy H . G. bibliography and an adequate index conclude * E. Pistolesi . Aerodinamica (Unione Tipogra- a book full of valuable information. Little has fico, Editric e Torinese, Turin. Price SO lire) been omitted that could usefully have been in­ [Either of these boohs can be obtained from AIR- E . G. Reid. Applied Wing Theory (McGraw- cluded, the author's explanations are invariably CRAF T ENGINEERING, 6 Norfolk Street, Strand, Hill. Price 18s.) clear and precise, and the value of the book is London, W.C.2.]

Journal

Aircraft Engineering and Aerospace Technology – Emerald Publishing

Published: Nov 1, 1932

There are no references for this article.