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Research Reports and Memoranda

Research Reports and Memoranda Report V. 1543. Drawing Sphere for Analysis of Flight Test Results. By Ir S. Wynia and Ir L. R. Lucassen. A drawing sphere, an octant gauge and a great- circle gauge are described. These tools have been Under this heading arc published regularly abstracts of all Reports and Memoranda of the Aeronautical designed and constructed to facilitate and accelerate the analysis of flight test results. An example of their Research Council, Reports and Technical Memoranda of the United States National Advisory Com­ application is included. mittee for Aeronautics and publications of other similar Research Bodies as issued SWEDEN AUSTRALIA No. 233. La Fonderie des Alliages Légers et Ultra- ROYAL INSTITUTE OF TECHNOLOGY Leuers. (Foundry Practice for Light and Ultra-Light DIVISION OF AERONAUTICS COUNCIL FOR SCIENTIFIC AND INDUSTRIAL Alloys.) By M. Caillon. RESEARCH Stockholm A report of more than 200 pages, liberally illus­ 314 Albert Street, East Melbourne, C.2, Victoria TECHNICAL NOTES trated, and concerning in particular the casting of AERONAUTICAL RESEARCH REPORTS magnesium alloys, much of which is also applicable KTH-AERO TN 7. An Approximate Method for to the aluminium alloys. Chapters deal with the melt­ Determining the Incompressible Irrotational Flow ACA-43. January 1949. The Stresses in Certain ing of magnesium, casting equipment, moulding Around a Symmetrical Wing Section. By Sune B. Cylindrical Swept Tubes Under Torsion and Bending. sands, defects in casting, casting practice and repairs Berndt. (In English.) By J . J. Thompson and W. H. Wittrick. by welding. Considerable space is devoted to the Starting from the Theodorsen method of mapping In Part 1 a method is presented of calculating the study of a new casting under ideal conditions, the conformally an arbitrary wing section upon a circle, stress distribution in a singly symmetrical swept tube importance of design, and the final production of the an approximate expression is obtained for the singu­ of constant trapezoidal section, with booms and casting. larity distribution on the axis of a symmetrical wing stringers, under constant bending and torque. Only section in incompressible, irrotational flow. A method simple bending theory and the resolution of simple NETHERLANDS for computing the stream function and the velocity stress systems is involved. Expressions are derived field around the wing section by expanding the singu­ from which the complete stress distribution can be NATIONAAL LUCHTVAARTLABORATORIUM larity distribution into a series is suggested and the determined. As an example the stresses in a rec­ Sloterweg 145, Amsterdam functions necessary are tabulated. A numerical tangular tube swept at 45 dcg. arc calculated, and Report F.35. A One Parameter Method for the example is given. graphs arc presented showing the variation of the Calculation of Laminar Boundary Layers. By Dr R. direct and shear stresses in all walls, with variation KTH-AERO TN 10. Comparison between Theoreti­ Timman. (In English.) of the stress bearing area. cal and Experimental Lift Distributions of Plane Delta Based on Von Kármán's momentum equation for In Part 2, the stress function solution for a doubly Wings at Low Speeds and Zero Yaw. By Sune B. boundary layer flow a new assumption for the velocity symmetrical rectangular tube with booms only, under Bcrndt and Kazimierz Orlik-Rückemann. (In English.) profile is made, taking account of as many boundary an exponentially varying torque is obtained. This in­ A calculation has been made of the lift distribution conditions at the wall as is possible and of the volves six constants, and expressions for these con­ at zero yaw and low speeds on six plane delta wings asymptotic behaviour at the outer edge of the bound­ stants are derived in analytical form. of aspect ratio between 0·5 and 2·5. The plan form of ary layer. all wings was basically triangular; three wings had The results are checked with known exact calcula­ their tips cut off to give a taper ratio of 0·303. The CANADA tions and show a definite improvement over those method of calculation, due to Falkncr, involves a obtained from the well-known Pohlhausen method, NATIONAL RESEARCH COUNCIL layout with 126 vortices and six control points, and particularly in the region of retarded flow. DIVISION OF MECHANICAL ENGINEERING allowance is made for the discontinuity in the direc­ Report F.43. Mathematical Principles of Flutter tion of the leading edge at the wing centre. A parabolic FLIGHT RESEARCH SECTION Analysis. By Dr J . H. Greidanus and Ir. A. I. van de basic distribution of vorticity is assumed for pre­ Ottawa Vooren. (In English.) liminary calculations on the triangular wings, whereas The basic equations governing small oscillations Report No. MR-7. June 16, 1949. Flight Tests on Falkner's elliptic distribution is used for the final of the wing or tail-plane system of a conventional Undercarriage Loads for a Single-Engined Aircraft calculations. Comparison between results obtained aeroplane arc given in the form of differential and Equipped with Skis. By A. D. Wood. from experiments and calculations shows fairly good integral equations. Though these equations arc written Results are presented of a series of tests to deter­ agreement at small angles of attack. The most im­ down in detail for a fuselage-wing-aileron system (the mine the loads experienced by a ski undercarriage portant deviation can be attributed to the influence fuselage being rigid), they can easily be generalized while landing and during other ground manoeuvres. of the finite thickness of the wing, which is neglected to other systems. In contrast to the results of other Tests cover a wide range of snow conditions. in the present theory. applications of the theory of small oscillations, the Comparison is made between skis of different plan set of basic equations in flutter analysis is not self- form and area. Occasional very severe vertical loads GREAT BRITAIN adjoint due to lack of symmetry of the matrix of are found to result from landings made on undulating AERONAUTICAL RESEARCH COUNCIL aerodynamic coefficients. These coefficients arc taken snow surfaces encountered north of the tree-line. The H.M. Stationery Office, London from theoretical results applying to two-dimensional highest torque load on a ski may be produced by incompressible and inviscid flow about a thin aero­ R.& M. No. 2427. The Solution of the Equations of external manipulation of the aircraft unless the nature foil with control surface. the Laminar Boundary Layer for Schubauer's Observed of such ground handling is restricted. Pressure Distribution for an Elliptic Cylinder. By The derivation of the integral form of the basic D. R. Hartree. April 4, 1939. (5s. 6d.) equations by way of influence functions involves a FRANCE The solution of the equations of the laminar bound­ slight difficulty since the original system as a whole is PUBLICATIONS SCIENTIFIQUES ET TECHNI­ ary layer has been carried out for the pressure dis­ elastically unrestrained. Therefore, the integral equa­ QUES DU MINISTERS DE L'AIR tribution for an elliptic cylinder of axial ratio 2.96: 1 tions arc derived at first for the case that the motion Magasin C.T.O., 2 Rue de la Porte d'Issy, Paris (XVe) of the complete system is opposed by linear springs with its major axis in the* direction of the incident linking the system with an immobile body (e.g. the stream. The solution has been obtained by the method BULLETINS ground). By aid of first integrals of the differential of Hartree and Womcrsley. In applying this method No. 111. Le Point Astronomique à Terre, sans equations these springs may be eliminated, yielding the derivatives parallel to the boundary arc replaced Instrument. (Astronomical Position-Finding from the equations which express the deformations in the by finite differences, so that the partial differential Ground, without Instruments.) By R. Genty. system as integrals containing the displacements. equation of the boundary layer is replaced by an This report is a mathematical analysis of a method ordinary equation relating the velocity distribution These equations alone are not sufficient for calculating by which airmen who have been forced to land in through the boundary layer at one section to that at the displacements, but have to be completed by first desert country can describe, by radio, observations another, at an interval upstream. By two independent integrals. Another possibility, leading to self-support­ of shadows made with two improvised plumb-lines integrations covering the same range by finite intervals ing integral equations, is to relax the artificial springs in such a way as to enable receiving stations to of different sizes, it is possible to estimate the errors and to remove the characteristic roots v 2 = 0 with their determine their position within a rectangle of dimen­ involved in replacing the derivatives by finite differ­ vectors in the same way as when the characteristic sions 2.5 km. in longitude by 15 km. in latitude. The root is unequal to zero (Art. 9.8 or 11.8). The kernel ences, and so to correct for these errors. method is most satisfactory between the 20 deg. and of the integral equations, thus obtained, is un- The process of solution requires the values of the 30 deg. latitudes but is not applicable to the arctic or symmetrical. pressure gradient along the solid boundary, and there antarctic regions. is a certain tolerance in the derivation of the pressure Report S. 341. Experimental Investigation of the gradient distribution from a limited number of RAPPORTS Post-Buckling Behaviour of Flat Plates Loaded in observed values of pressure. An analysis of Schubaucr's No. 232. Souffleries à Eau. Etude Theorique et Shear and Compression. By Professor Dr Ir A. Van pressure distribution is outlined, and the results were Avant-Projct. (Water Tunnels. Theoretical Study and dcr Neut and Ir W. K. G. Floor. (In English.) used for the main solution calculated. It is found that Preliminary Project.) By L. A. Sackmann. Full version of a paper presented at the 7th Inter­ the solution, for the distribution of pressure gradient A short report setting out the advantages of a national Congress of Applied Mechanics, September so derived, does not give separation of the boundary 'water-tunnel' (by analogy with a wind-tunnel) in 1948. An abbreviated version is published in the layer from the solid boundary, whereas the actual which the test-model is held stationary at the surface Proceedings of the Congress. flow docs separate. of or immersed in a closed water circuit. Contents It is found that the calculated solution is very A table shows comparative data relating to the 1. Introduction sensitive to the pressure distribution, and a com­ most important towing tanks and notes arc given on 2. The parameters of the phenomenon paratively small modification of the pressure dis­ the compromise required by the Froudc and Reynolds 3. The quantities to be measured tribution gives a solution which docs indicate separa­ laws of similitude. The author discusses the velocity- 4. The test specimen and the measuring apparatus tion close to the point at which separation is observed dimensions relationships for water tunnels and defines 5. The results of the tests to occur. The solution with this pressure distribution two distinct operating conditions for model tests and 6. Discussion of results and comparison with theory also gives very good agreement with the observed hydrodynamic research. A proposed programme 7. Conclusions velocity distribution through the boundary layer at illustrates the possible uses of water tunnels and an 8. Notations points upstream from separation. outline is given of a projected tunnel. 9. References February 1950 57 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 22 (2): 1 – Feb 1, 1950

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Emerald Publishing
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0002-2667
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10.1108/eb031865
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Abstract

Report V. 1543. Drawing Sphere for Analysis of Flight Test Results. By Ir S. Wynia and Ir L. R. Lucassen. A drawing sphere, an octant gauge and a great- circle gauge are described. These tools have been Under this heading arc published regularly abstracts of all Reports and Memoranda of the Aeronautical designed and constructed to facilitate and accelerate the analysis of flight test results. An example of their Research Council, Reports and Technical Memoranda of the United States National Advisory Com­ application is included. mittee for Aeronautics and publications of other similar Research Bodies as issued SWEDEN AUSTRALIA No. 233. La Fonderie des Alliages Légers et Ultra- ROYAL INSTITUTE OF TECHNOLOGY Leuers. (Foundry Practice for Light and Ultra-Light DIVISION OF AERONAUTICS COUNCIL FOR SCIENTIFIC AND INDUSTRIAL Alloys.) By M. Caillon. RESEARCH Stockholm A report of more than 200 pages, liberally illus­ 314 Albert Street, East Melbourne, C.2, Victoria TECHNICAL NOTES trated, and concerning in particular the casting of AERONAUTICAL RESEARCH REPORTS magnesium alloys, much of which is also applicable KTH-AERO TN 7. An Approximate Method for to the aluminium alloys. Chapters deal with the melt­ Determining the Incompressible Irrotational Flow ACA-43. January 1949. The Stresses in Certain ing of magnesium, casting equipment, moulding Around a Symmetrical Wing Section. By Sune B. Cylindrical Swept Tubes Under Torsion and Bending. sands, defects in casting, casting practice and repairs Berndt. (In English.) By J . J. Thompson and W. H. Wittrick. by welding. Considerable space is devoted to the Starting from the Theodorsen method of mapping In Part 1 a method is presented of calculating the study of a new casting under ideal conditions, the conformally an arbitrary wing section upon a circle, stress distribution in a singly symmetrical swept tube importance of design, and the final production of the an approximate expression is obtained for the singu­ of constant trapezoidal section, with booms and casting. larity distribution on the axis of a symmetrical wing stringers, under constant bending and torque. Only section in incompressible, irrotational flow. A method simple bending theory and the resolution of simple NETHERLANDS for computing the stream function and the velocity stress systems is involved. Expressions are derived field around the wing section by expanding the singu­ from which the complete stress distribution can be NATIONAAL LUCHTVAARTLABORATORIUM larity distribution into a series is suggested and the determined. As an example the stresses in a rec­ Sloterweg 145, Amsterdam functions necessary are tabulated. A numerical tangular tube swept at 45 dcg. arc calculated, and Report F.35. A One Parameter Method for the example is given. graphs arc presented showing the variation of the Calculation of Laminar Boundary Layers. By Dr R. direct and shear stresses in all walls, with variation KTH-AERO TN 10. Comparison between Theoreti­ Timman. (In English.) of the stress bearing area. cal and Experimental Lift Distributions of Plane Delta Based on Von Kármán's momentum equation for In Part 2, the stress function solution for a doubly Wings at Low Speeds and Zero Yaw. By Sune B. boundary layer flow a new assumption for the velocity symmetrical rectangular tube with booms only, under Bcrndt and Kazimierz Orlik-Rückemann. (In English.) profile is made, taking account of as many boundary an exponentially varying torque is obtained. This in­ A calculation has been made of the lift distribution conditions at the wall as is possible and of the volves six constants, and expressions for these con­ at zero yaw and low speeds on six plane delta wings asymptotic behaviour at the outer edge of the bound­ stants are derived in analytical form. of aspect ratio between 0·5 and 2·5. The plan form of ary layer. all wings was basically triangular; three wings had The results are checked with known exact calcula­ their tips cut off to give a taper ratio of 0·303. The CANADA tions and show a definite improvement over those method of calculation, due to Falkncr, involves a obtained from the well-known Pohlhausen method, NATIONAL RESEARCH COUNCIL layout with 126 vortices and six control points, and particularly in the region of retarded flow. DIVISION OF MECHANICAL ENGINEERING allowance is made for the discontinuity in the direc­ Report F.43. Mathematical Principles of Flutter tion of the leading edge at the wing centre. A parabolic FLIGHT RESEARCH SECTION Analysis. By Dr J . H. Greidanus and Ir. A. I. van de basic distribution of vorticity is assumed for pre­ Ottawa Vooren. (In English.) liminary calculations on the triangular wings, whereas The basic equations governing small oscillations Report No. MR-7. June 16, 1949. Flight Tests on Falkner's elliptic distribution is used for the final of the wing or tail-plane system of a conventional Undercarriage Loads for a Single-Engined Aircraft calculations. Comparison between results obtained aeroplane arc given in the form of differential and Equipped with Skis. By A. D. Wood. from experiments and calculations shows fairly good integral equations. Though these equations arc written Results are presented of a series of tests to deter­ agreement at small angles of attack. The most im­ down in detail for a fuselage-wing-aileron system (the mine the loads experienced by a ski undercarriage portant deviation can be attributed to the influence fuselage being rigid), they can easily be generalized while landing and during other ground manoeuvres. of the finite thickness of the wing, which is neglected to other systems. In contrast to the results of other Tests cover a wide range of snow conditions. in the present theory. applications of the theory of small oscillations, the Comparison is made between skis of different plan set of basic equations in flutter analysis is not self- form and area. Occasional very severe vertical loads GREAT BRITAIN adjoint due to lack of symmetry of the matrix of are found to result from landings made on undulating AERONAUTICAL RESEARCH COUNCIL aerodynamic coefficients. These coefficients arc taken snow surfaces encountered north of the tree-line. The H.M. Stationery Office, London from theoretical results applying to two-dimensional highest torque load on a ski may be produced by incompressible and inviscid flow about a thin aero­ R.& M. No. 2427. The Solution of the Equations of external manipulation of the aircraft unless the nature foil with control surface. the Laminar Boundary Layer for Schubauer's Observed of such ground handling is restricted. Pressure Distribution for an Elliptic Cylinder. By The derivation of the integral form of the basic D. R. Hartree. April 4, 1939. (5s. 6d.) equations by way of influence functions involves a FRANCE The solution of the equations of the laminar bound­ slight difficulty since the original system as a whole is PUBLICATIONS SCIENTIFIQUES ET TECHNI­ ary layer has been carried out for the pressure dis­ elastically unrestrained. Therefore, the integral equa­ QUES DU MINISTERS DE L'AIR tribution for an elliptic cylinder of axial ratio 2.96: 1 tions arc derived at first for the case that the motion Magasin C.T.O., 2 Rue de la Porte d'Issy, Paris (XVe) of the complete system is opposed by linear springs with its major axis in the* direction of the incident linking the system with an immobile body (e.g. the stream. The solution has been obtained by the method BULLETINS ground). By aid of first integrals of the differential of Hartree and Womcrsley. In applying this method No. 111. Le Point Astronomique à Terre, sans equations these springs may be eliminated, yielding the derivatives parallel to the boundary arc replaced Instrument. (Astronomical Position-Finding from the equations which express the deformations in the by finite differences, so that the partial differential Ground, without Instruments.) By R. Genty. system as integrals containing the displacements. equation of the boundary layer is replaced by an This report is a mathematical analysis of a method ordinary equation relating the velocity distribution These equations alone are not sufficient for calculating by which airmen who have been forced to land in through the boundary layer at one section to that at the displacements, but have to be completed by first desert country can describe, by radio, observations another, at an interval upstream. By two independent integrals. Another possibility, leading to self-support­ of shadows made with two improvised plumb-lines integrations covering the same range by finite intervals ing integral equations, is to relax the artificial springs in such a way as to enable receiving stations to of different sizes, it is possible to estimate the errors and to remove the characteristic roots v 2 = 0 with their determine their position within a rectangle of dimen­ involved in replacing the derivatives by finite differ­ vectors in the same way as when the characteristic sions 2.5 km. in longitude by 15 km. in latitude. The root is unequal to zero (Art. 9.8 or 11.8). The kernel ences, and so to correct for these errors. method is most satisfactory between the 20 deg. and of the integral equations, thus obtained, is un- The process of solution requires the values of the 30 deg. latitudes but is not applicable to the arctic or symmetrical. pressure gradient along the solid boundary, and there antarctic regions. is a certain tolerance in the derivation of the pressure Report S. 341. Experimental Investigation of the gradient distribution from a limited number of RAPPORTS Post-Buckling Behaviour of Flat Plates Loaded in observed values of pressure. An analysis of Schubaucr's No. 232. Souffleries à Eau. Etude Theorique et Shear and Compression. By Professor Dr Ir A. Van pressure distribution is outlined, and the results were Avant-Projct. (Water Tunnels. Theoretical Study and dcr Neut and Ir W. K. G. Floor. (In English.) used for the main solution calculated. It is found that Preliminary Project.) By L. A. Sackmann. Full version of a paper presented at the 7th Inter­ the solution, for the distribution of pressure gradient A short report setting out the advantages of a national Congress of Applied Mechanics, September so derived, does not give separation of the boundary 'water-tunnel' (by analogy with a wind-tunnel) in 1948. An abbreviated version is published in the layer from the solid boundary, whereas the actual which the test-model is held stationary at the surface Proceedings of the Congress. flow docs separate. of or immersed in a closed water circuit. Contents It is found that the calculated solution is very A table shows comparative data relating to the 1. Introduction sensitive to the pressure distribution, and a com­ most important towing tanks and notes arc given on 2. The parameters of the phenomenon paratively small modification of the pressure dis­ the compromise required by the Froudc and Reynolds 3. The quantities to be measured tribution gives a solution which docs indicate separa­ laws of similitude. The author discusses the velocity- 4. The test specimen and the measuring apparatus tion close to the point at which separation is observed dimensions relationships for water tunnels and defines 5. The results of the tests to occur. The solution with this pressure distribution two distinct operating conditions for model tests and 6. Discussion of results and comparison with theory also gives very good agreement with the observed hydrodynamic research. A proposed programme 7. Conclusions velocity distribution through the boundary layer at illustrates the possible uses of water tunnels and an 8. Notations points upstream from separation. outline is given of a projected tunnel. 9. References February 1950 57

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Feb 1, 1950

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