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Research Reports and Memoranda

Research Reports and Memoranda June, 1942 AIRCRAFT ENGINEERIN G 161 aircraft, particularly at the leading edges of main FRANCE Report No. 23. Perpendicular Axes Con­ planes. The apparatus consists essentially of a trol Surface Binary Flutter. April, 1941. PUBLICATIONS SCIENTIFIQUES ET cylinder turning at a uniform slow rate about an axis perpendicular to the wind responsible for the TECHNIQUES DU SECRETARIAT This report outlines methods by which not only ice formation. The par t towards th e wind becomes th e critical flutter speeds of control surfaces for the D'ETAT A L'AVIATION covered with ice whereas th e rear part is cleared by flexure control surface binary case can be very rapid­ mean s of an internal heating element. The thick­ ly computed but also the minimum necessary (Blondcl la Rougery and Gauthier-Villars, Paris) ness of ice which forms during one revolution, at a amount s of dynamic balancing can be estimated to constan t speed enables an estimate to be made of obtai n the desired degree of flutter prevention. This B.S.T. No. 94. La Determination de la th e rate of ice formation. The methods are based is accomplished by the use of a series of engineering Duree d'Exposition en Photographic Aerienne. on the measurement of the thickness of the ice chart s which give a " flutter speed factor " as a layer on the cylinder. One is an optical method, function of the main variables affecting the critical Owing t o th e number of variables t o be take n into measuring the quantity of light received by a speed, namely : accoun t in calculating the exposure time in aerial photo-electric cell from a light beam arranged paral­ photography , an attempt was made to devise Surface weight, lel to the cylinder in such a manner that any ice apparatu s t o determine the optimum exposure time Chord ratio. formed, results in a reduction of th e light received. automatically . It was found that ordinary, com­ Control surface centre of gravit y location, Brief reference is mad e t o experiments carried out at mercial photo-electric exposure indicators gave Flexural and aerodynamic damping, —10 deg. C. and at an air speed of 20 m/s—and results favourable only for oblique views from less Frequenc y ratio. several improvements are suggested. The second tha n 2,000 m. A series of tests was carried out to is an electrical method based on the variation in the After the lluttcr speed factor has been obtained determin e th e optimum exposure tim e as a function capacit y of a condenser caused by the formation of from these charts th e critical flutter speed can b e de­ of all th e conditions : emulsion sensitivity, aperture, ice between its two plates, the variation depending termined by very simple numerical calculations. A altitude , light and atmospheric conditions. Four on the ice thickness and area. The plates are correlation between two-dimensional flutter theory Lcica cameras, mounted in one unit so tha t any hollow discs containing a heating clement at the an d three-dimensional dynamic balancing is de­ factor could be varied, were used to collect dat a over rear and arc mounte d and rotated in th e sam e wa y as veloped theoretically. a period of twelve months. Based on this ex­ th e cylinder mentioned earlier. Details of the Th e limits within which this report is applicable perience, a simple but robust, rotating indicator of electrical circuit are given and the need for careful are given. th e card type, constructed of two metal discs, was calibration is indicated. mad e an d its construction , graduation and metho d of use arc described. Even with this indicator, suc­ ENGINEERING SECTION cessful photography is still too much dependent on th e accuracy of th e photographer's estimation of the U.S.A. light value, atmospheric purity, mist intensity, etc., Report No. 24. Parallel Axes Control- CIVIL AERONAUTICS ADMINISTRA­ and a more reliable exposure meter is described, Surface Binary Flutter. September, 1941. consisting of a photo-electric cell, galvanometer, TIO N : DEPARTMENT OF COMMERCE variable resistance and a system of disc indicators This report outlines methods by which th e critical Th e principle is as follows: the photo-electric cell, flutter speeds of wings an d tail configurations for the AIRCRAFT AIRWORTHINESS of which the field is limited to that of the photo­ parallel-axes binary modes can be rapidly estimated. graphic lens emits a current which is a function of The means employed to achieve this end arc a series SECTION th e luminosity of the subject to be photographed. of engineering charts which determine a "flutter This current causes the galvanometer needle to be speed factor " as a function of the principal para­ Report No. 22. Flexure-Torsion Binary deflected. The needle is brought back t o a suitably meter s affecting the critical speed, namely: Flutter. January, 1941. selected graduation by turning one of th e indicator (1) Surface weight. discs which turns th e cursor of th e variable resist­ Thi s repor t outlines methods by which th e critical (2) Elastic axis location. ance in the photo-electric cell—galvanometer lluttc r speed of wings for th e flexure-torsion binary (3) Centre of gravit y location circuit. The combinations of exposure period and case can be very rapidly computed. Tin's is accom­ (4) Control-surface chord ratio. apertur e can then be read off. This apparatu s and plished by the use of a scries of engineering charts (5) Control-surface dynamic balance. its components are described in detail, together which give a " flutter speed factor " as a function of (6) Structural damping. with their graduation and method of use. A th e main variables affecting the critical speed, (7) Frequency ratio. variation is also discussed for the case when it is namely : surface weight, elastic axis location, centre desired to mount the indicator directly on the of gravity location, and frequency ratio. After the Th e use of this flutter speed factor in a simple camera . A table gives correction factors for flutter speed factor has been obtained from these numerical equation to determine the flutter speed atmospheric conditions and altitude. chart s the critical flutter speed can be determined ha s already been illustrated in the preceding b y very simple numerical calculations. reports. Although the theory on which this method is Although th e theory by means of which th e flutter B.S.T. No. 95. Indicateurs de Vitesse de based strictly applies only to the case of a wing speed factor charts have been developed is based Givrage. withou t control surfaces, the limits within which upo n an infinite span aerofoil, th e application of the th e method can be applied to a wing having control chart s to aerodynamic surfaces of finite span is This report describes two methods for the con­ surfaces are given. shown by means of parametric correlation. tinuous measurement of th e rate of ice formation on Althoug h prepared primarily to meet the tackled . The contents of the book are com­ Book Review domesti c U.S.A. need for rapidly educating plete d by a chapter on the photographic re­ Aircraf t Templat e Development . Compiled aeroplan e template makers from unskilled productio n of templates , a shor t glossary an d a an d Edited by the publishers. [Aero member s of the aviation industry, or from ver y complete set of data sheets and bend- Publisher s Ltd., New York. 4 dollars.] completel y new material, this excellent book allowanc e tables. contain s muc h information tha t would be useful t o be discursive or develop a " style, " the Wit h regard to the layout of the book it is t o th e junio r draughtsma n in thi s country. possibl e to make several comments. The informatio n is presented compactly, without printin g and reproduction of illustrations is I t has been compiled by th e Publishers from trimming s and largely pictorially. excellent . The drawing s ar e of a hig h standard materia l placed a t thei r disposa l b y th e majority Startin g with an elementary section covering an d well reproduced—wit h one exception . This of the large aeroplane manufacturers in the th e types and uses of templates the book goes sole ba d example is unfortunate , as it is a very U.S.A . This method of preparing a technical o n to a description of the workshop processes practica l bend-allowance char t tha t should have textboo k has much to commend it, for it en­ connecte d with the manufacture and use of bee n reproduced quite twice the size that it sure s a wide view of the subject without the them . After these introductory chapters, appears . The drawings of the examples have almos t inevitable bias in favour of th e author's th e various subjects required for template de­ bee n printed in blue in reverse—presumably in "pet " ideas. In this instance, at any rate, sig n are covered fully, but concisely ; mathe­ orde r t o familiarize th e novice wit h th e appear­ th e result has been admirable. Although the matics , drawing and geometry, engineering anc e of blu e prints . In on e respec t it is lacking : book , of necessity, starts with somewhat ele­ drawing , principles of mathematical develop­ th e indexing is poo r an d full advantag e has no t mentar y details, the whole field of template men t and the tools used in template making bee n take n of a n ingenious syste m of paragraph desig n and manufacture has been so well ar e all described. The nex t section of th e book an d figure numbering. covere d tha t there should be some information comprise s 147 practica l examples. These exer­ of use to any draughtsman interested in the cises each consist of a drawing of a detail part, Despit e its relatively high price this volume subject . One particularly good point about it followed by the developed template drawing certainl y deserves a place in an y drawing office is that , a s ther e is n o individua l autho r anxious an d a short description of how the job was library. J. H. S. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Research Reports and Memoranda

Aircraft Engineering and Aerospace Technology , Volume 14 (6): 1 – Jun 1, 1942

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb030912
Publisher site
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Abstract

June, 1942 AIRCRAFT ENGINEERIN G 161 aircraft, particularly at the leading edges of main FRANCE Report No. 23. Perpendicular Axes Con­ planes. The apparatus consists essentially of a trol Surface Binary Flutter. April, 1941. PUBLICATIONS SCIENTIFIQUES ET cylinder turning at a uniform slow rate about an axis perpendicular to the wind responsible for the TECHNIQUES DU SECRETARIAT This report outlines methods by which not only ice formation. The par t towards th e wind becomes th e critical flutter speeds of control surfaces for the D'ETAT A L'AVIATION covered with ice whereas th e rear part is cleared by flexure control surface binary case can be very rapid­ mean s of an internal heating element. The thick­ ly computed but also the minimum necessary (Blondcl la Rougery and Gauthier-Villars, Paris) ness of ice which forms during one revolution, at a amount s of dynamic balancing can be estimated to constan t speed enables an estimate to be made of obtai n the desired degree of flutter prevention. This B.S.T. No. 94. La Determination de la th e rate of ice formation. The methods are based is accomplished by the use of a series of engineering Duree d'Exposition en Photographic Aerienne. on the measurement of the thickness of the ice chart s which give a " flutter speed factor " as a layer on the cylinder. One is an optical method, function of the main variables affecting the critical Owing t o th e number of variables t o be take n into measuring the quantity of light received by a speed, namely : accoun t in calculating the exposure time in aerial photo-electric cell from a light beam arranged paral­ photography , an attempt was made to devise Surface weight, lel to the cylinder in such a manner that any ice apparatu s t o determine the optimum exposure time Chord ratio. formed, results in a reduction of th e light received. automatically . It was found that ordinary, com­ Control surface centre of gravit y location, Brief reference is mad e t o experiments carried out at mercial photo-electric exposure indicators gave Flexural and aerodynamic damping, —10 deg. C. and at an air speed of 20 m/s—and results favourable only for oblique views from less Frequenc y ratio. several improvements are suggested. The second tha n 2,000 m. A series of tests was carried out to is an electrical method based on the variation in the After the lluttcr speed factor has been obtained determin e th e optimum exposure tim e as a function capacit y of a condenser caused by the formation of from these charts th e critical flutter speed can b e de­ of all th e conditions : emulsion sensitivity, aperture, ice between its two plates, the variation depending termined by very simple numerical calculations. A altitude , light and atmospheric conditions. Four on the ice thickness and area. The plates are correlation between two-dimensional flutter theory Lcica cameras, mounted in one unit so tha t any hollow discs containing a heating clement at the an d three-dimensional dynamic balancing is de­ factor could be varied, were used to collect dat a over rear and arc mounte d and rotated in th e sam e wa y as veloped theoretically. a period of twelve months. Based on this ex­ th e cylinder mentioned earlier. Details of the Th e limits within which this report is applicable perience, a simple but robust, rotating indicator of electrical circuit are given and the need for careful are given. th e card type, constructed of two metal discs, was calibration is indicated. mad e an d its construction , graduation and metho d of use arc described. Even with this indicator, suc­ ENGINEERING SECTION cessful photography is still too much dependent on th e accuracy of th e photographer's estimation of the U.S.A. light value, atmospheric purity, mist intensity, etc., Report No. 24. Parallel Axes Control- CIVIL AERONAUTICS ADMINISTRA­ and a more reliable exposure meter is described, Surface Binary Flutter. September, 1941. consisting of a photo-electric cell, galvanometer, TIO N : DEPARTMENT OF COMMERCE variable resistance and a system of disc indicators This report outlines methods by which th e critical Th e principle is as follows: the photo-electric cell, flutter speeds of wings an d tail configurations for the AIRCRAFT AIRWORTHINESS of which the field is limited to that of the photo­ parallel-axes binary modes can be rapidly estimated. graphic lens emits a current which is a function of The means employed to achieve this end arc a series SECTION th e luminosity of the subject to be photographed. of engineering charts which determine a "flutter This current causes the galvanometer needle to be speed factor " as a function of the principal para­ Report No. 22. Flexure-Torsion Binary deflected. The needle is brought back t o a suitably meter s affecting the critical speed, namely: Flutter. January, 1941. selected graduation by turning one of th e indicator (1) Surface weight. discs which turns th e cursor of th e variable resist­ Thi s repor t outlines methods by which th e critical (2) Elastic axis location. ance in the photo-electric cell—galvanometer lluttc r speed of wings for th e flexure-torsion binary (3) Centre of gravit y location circuit. The combinations of exposure period and case can be very rapidly computed. Tin's is accom­ (4) Control-surface chord ratio. apertur e can then be read off. This apparatu s and plished by the use of a scries of engineering charts (5) Control-surface dynamic balance. its components are described in detail, together which give a " flutter speed factor " as a function of (6) Structural damping. with their graduation and method of use. A th e main variables affecting the critical speed, (7) Frequency ratio. variation is also discussed for the case when it is namely : surface weight, elastic axis location, centre desired to mount the indicator directly on the of gravity location, and frequency ratio. After the Th e use of this flutter speed factor in a simple camera . A table gives correction factors for flutter speed factor has been obtained from these numerical equation to determine the flutter speed atmospheric conditions and altitude. chart s the critical flutter speed can be determined ha s already been illustrated in the preceding b y very simple numerical calculations. reports. Although the theory on which this method is Although th e theory by means of which th e flutter B.S.T. No. 95. Indicateurs de Vitesse de based strictly applies only to the case of a wing speed factor charts have been developed is based Givrage. withou t control surfaces, the limits within which upo n an infinite span aerofoil, th e application of the th e method can be applied to a wing having control chart s to aerodynamic surfaces of finite span is This report describes two methods for the con­ surfaces are given. shown by means of parametric correlation. tinuous measurement of th e rate of ice formation on Althoug h prepared primarily to meet the tackled . The contents of the book are com­ Book Review domesti c U.S.A. need for rapidly educating plete d by a chapter on the photographic re­ Aircraf t Templat e Development . Compiled aeroplan e template makers from unskilled productio n of templates , a shor t glossary an d a an d Edited by the publishers. [Aero member s of the aviation industry, or from ver y complete set of data sheets and bend- Publisher s Ltd., New York. 4 dollars.] completel y new material, this excellent book allowanc e tables. contain s muc h information tha t would be useful t o be discursive or develop a " style, " the Wit h regard to the layout of the book it is t o th e junio r draughtsma n in thi s country. possibl e to make several comments. The informatio n is presented compactly, without printin g and reproduction of illustrations is I t has been compiled by th e Publishers from trimming s and largely pictorially. excellent . The drawing s ar e of a hig h standard materia l placed a t thei r disposa l b y th e majority Startin g with an elementary section covering an d well reproduced—wit h one exception . This of the large aeroplane manufacturers in the th e types and uses of templates the book goes sole ba d example is unfortunate , as it is a very U.S.A . This method of preparing a technical o n to a description of the workshop processes practica l bend-allowance char t tha t should have textboo k has much to commend it, for it en­ connecte d with the manufacture and use of bee n reproduced quite twice the size that it sure s a wide view of the subject without the them . After these introductory chapters, appears . The drawings of the examples have almos t inevitable bias in favour of th e author's th e various subjects required for template de­ bee n printed in blue in reverse—presumably in "pet " ideas. In this instance, at any rate, sig n are covered fully, but concisely ; mathe­ orde r t o familiarize th e novice wit h th e appear­ th e result has been admirable. Although the matics , drawing and geometry, engineering anc e of blu e prints . In on e respec t it is lacking : book , of necessity, starts with somewhat ele­ drawing , principles of mathematical develop­ th e indexing is poo r an d full advantag e has no t mentar y details, the whole field of template men t and the tools used in template making bee n take n of a n ingenious syste m of paragraph desig n and manufacture has been so well ar e all described. The nex t section of th e book an d figure numbering. covere d tha t there should be some information comprise s 147 practica l examples. These exer­ of use to any draughtsman interested in the cises each consist of a drawing of a detail part, Despit e its relatively high price this volume subject . One particularly good point about it followed by the developed template drawing certainl y deserves a place in an y drawing office is that , a s ther e is n o individua l autho r anxious an d a short description of how the job was library. J. H. S.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Jun 1, 1942

There are no references for this article.