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Fifth International Air Congress

Fifth International Air Congress November, 1930 AIRCRAFT ENGINEERING 281 Summaries of Some of the Important Papers read at the Recent Meetings at the Hague O n the Motion of a Fluid under the Action can be quickly estimated by a simple graphical "discontinuou s potential" proposed by Witoszyn- method . of Exterior Forces. By J. M . Burgess. ski. A brief discussion of the basis on which the Proof load tests to determine elastic stiffness use of this function is justified is given, and a Hydrodynami c theory is usually occupied with can be made without injury to the aircraft. Special correction is introduced in order to avoid the th e problem of motion of a fluid round a body, or method s can be employed to find the torsional negativ e value of the resistance obtained with the a system of bodies, immersed in it : in other words, flexural axis and the principal axis of inertia at origina l theory a t certain angles of attack. Because on seeking to ascertain a motion fulfilling certain a wing tip. of the complexity of the formulas developed for condition s at the wall of the field of flow. The Satisfactor y tests of oleo struts can be made th e lift and drag, an approximate method, using a problem of motion of a fluid in an infinite field on wit h a dropping weight, bu t it is necessary to repre­ "potentia l of three vortices," is given by means whic h external forces are acting has received sent not only the elastic effect of the tyre and axle, of which the numerical values of these quantities littl e attention. The latter problem, however, bu t also the mass of the parts which lie between ma y be obtained with much greater facility. thoug h difficult on account of the terms of second th e tyre and the oleo strut. degree tha t enter into the hydrodynamic equations, Th e New High-Speed Wind Tunnel at the is much more simple than the problem of the walls. Ai r Ministry's Laboratory in Rome . By A . Eula. Althoug h in the majority of cases which arise a O n the Equilibrium of Steady Spinning of A new high-speed wind tunnel has just been force only acts on a fluid (liquid or gas) through Aeroplanes . By Ryozo Fukatsu. installed at the Aerodynamic Laboratory of the th e intermediary of a body of appropriate form, A new form of diagram representing the state Ministero del Aeronautic a in Rome, th e only existing i t is sometimes advantageous to consider first the of equilibrium of steady spinning of an aeroplane tunne l being one installed b y General Crocco in 1913. actio n of a force, or system of forces acting directly was developed . In this diagram the equilibrium I t is not large—the testing chamber has a diameter on the fluid. It then becomes possible to obtain curves for the rolling, yawing, and pitching of only 1.60 metres (5 ft. 3 in.), bu t the installation a general idea of motion while at the same time moments , including the conditions of equilibrium possesses certain unusual features. The return of an advantageou s approach t o problems of technique, of forces, are represented by curves with rates th e air is no t effected through passages, but within i n which the magnitude of the forces play the th e room housing the tunnel, the corners of which most important part, is obtained. At the same tim e the form of the body, through the inter­ are rounded off to prevent the formation of eddies mediar y of which the force acts on the fluid (e.g., and irregularities of flow. The maximum wind- th e supporting surface) is no t laid down in advance, speed obtainable is 80 metres/sec. (262 ft./sec. or 180 m.p.h.) with an absorbed power of 470 h.p. bu t is subject to the condition of ensuring an effect A t this speed the fluctuations are only 1·5 per cent. compatibl e with the least possible loss of energy. in intensit y and 0·5 per cent. in direction. Thi s point of view is not new. Resort has been A t first the speed scarcely reached 68 metres/sec . had, in order to indicate the method, to the reso­ (223 ft./sec.) and the flow was subject to highly lution of the hydrodynamic equations given by accentuate d pulsations owing to the insufficient M. Oseen for the case of forces, acting on a fluid, dimensions of the room. The speed was increased given a general motion in a determined direction and satisfactory regularity of flow obtained by a t a constant speed, which enables the principal makin g the following modifications: the corners features of the turbulences caused by the forces of the room were rounded off; the room was divided t o be deduced in a simple manner. M. Oseen's longitudinally by a partition; the airscrew boss equation s can be further simplified by neglecting was streamlined. The form of the curves to round of rotation plotted against incidence angles α th e influence of viscosity. In applying the expres­ off the corners of the room was obtaine d by following sions obtained to, for example, the theory of sup­ th e path taken by the air, which was made visible portin g surfaces, a formula can be obtained which, for the definite value of side slip. in the tunnel room itself by injecting smoke and for a prescribed distribution of the lift, gives Th e diagram was applied for the investigation i n a th scale mode l b y using titaniu m tetrachloride. directl y the induced vertical speed at all points of the mechanism of the steady spinning of aero­ of the field. planes. Th e Effect of Propellor Reduction Gearing on A type of dangerous state of equilibrium was Aircraft Performance. By R. K. Pierson Th e Uses and Limitations of Mechanical deduced, and in preventing an aeroplane entering Tests . By Wm . D . Douglas, F.R.C.Sc.I. Thi s paper deals seriatim with the effects of tha t state of equilibrium, contributions of various reductio n gearing on performance, weight, and noise characteristic s inherent of the design are clearly Stati c loading tests of aircraft structures can of aircraft. The disadvantages of gearing, namely, usually represent assumed conditions of loading expounded . loss of power in th e drive, extr a weight, unreliability, wit h considerable accuracy, whereas a simplified Special consideration was also paid to the equili­ an d cost, are considered first, after which the form of loading is frequently necessary for purposes briu m of the flat spin. counter-balancin g advantages are mentioned in of calculation. turn . The effect of pitch diameter ratio upon Th e failing load obtained on test will be affected Th e Effect of a Hinged Flap on the Aero­ efficiency is shown; the inter-relation of tip-speed b y the material strength of the part at which the dynami c Characteristics of an Airfoil. By M . J. an d gearing is developed; the gyroscopic effects failure originated. It is usual to make a material Thompson . are investigated. Reduction of slipstream drag tes t of the fractured member and to estimate the wit h gearing, and the effect upon the cooling of air- Th e work presented in this paper is an approxi­ load at which failure would have occurred if the cooled engines, are mentioned; a paragraph deals mat e solution of the problem of the determination materia l had had the minimum strength allowed wit h th e question of noise in passenger aircraft, with of the effect of a hinged flap on the aerodynamic b y the specification. This method of adjustment special reference to airscrew noise. The paper con­ characteristic s of an airfoil. Assuming that the of the results may be misleading in certain cases. cludes with comparative analyses of an aircraft airplan e wing provided with a flap is moving I n the test of a complete structure , i t is frequently fitted alternatively with geared and direct-drive throug h a perfect fluid, and that the motion of engines, showing the distribution of power, the of interest to determine the load at which the th e latter is two-dimensional, a complex function saving due to the reduction gear, and the effect deformatio n is such, that if it had occurred in is developed which transforms a circle into a so- upo n performance. The percentage gains resulting service it would be necessary to replace or repair called "bi-linear" profile, that is, a broken line som e member. from the use of a 525 b.h.p . engine geared down mad e up of two finite segments. The lift and from 1,800 to 1,100 r.p.m. in a single-engined freight momen t coefficients, as well as the moment about Limitatio n of damage at the time of failure is carrie r are given as:—Maximum speed at ground, th e hinge of the forces acting on the flap, are then a n essential part of the test, and suitable arrange­ 10 per cent ; rate of climb at ground, 48 per cent; calculated by means of the Jouhowsky potential ment s should be made for this, and also for the absolute ceiling, 45 per cent; range at cruising function. Then the drag in addition to these safety of th e personnel, by the provision of suitable speed, 14 per cent. othe r quantities, is calculated by means of the supports . I t is frequently advisable to use a system of levers rather than weights for the application of a distributed load. The dimensions of the levers http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Fifth International Air Congress

Aircraft Engineering and Aerospace Technology , Volume 2 (11): 1 – Nov 1, 1930

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb029335
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Abstract

November, 1930 AIRCRAFT ENGINEERING 281 Summaries of Some of the Important Papers read at the Recent Meetings at the Hague O n the Motion of a Fluid under the Action can be quickly estimated by a simple graphical "discontinuou s potential" proposed by Witoszyn- method . of Exterior Forces. By J. M . Burgess. ski. A brief discussion of the basis on which the Proof load tests to determine elastic stiffness use of this function is justified is given, and a Hydrodynami c theory is usually occupied with can be made without injury to the aircraft. Special correction is introduced in order to avoid the th e problem of motion of a fluid round a body, or method s can be employed to find the torsional negativ e value of the resistance obtained with the a system of bodies, immersed in it : in other words, flexural axis and the principal axis of inertia at origina l theory a t certain angles of attack. Because on seeking to ascertain a motion fulfilling certain a wing tip. of the complexity of the formulas developed for condition s at the wall of the field of flow. The Satisfactor y tests of oleo struts can be made th e lift and drag, an approximate method, using a problem of motion of a fluid in an infinite field on wit h a dropping weight, bu t it is necessary to repre­ "potentia l of three vortices," is given by means whic h external forces are acting has received sent not only the elastic effect of the tyre and axle, of which the numerical values of these quantities littl e attention. The latter problem, however, bu t also the mass of the parts which lie between ma y be obtained with much greater facility. thoug h difficult on account of the terms of second th e tyre and the oleo strut. degree tha t enter into the hydrodynamic equations, Th e New High-Speed Wind Tunnel at the is much more simple than the problem of the walls. Ai r Ministry's Laboratory in Rome . By A . Eula. Althoug h in the majority of cases which arise a O n the Equilibrium of Steady Spinning of A new high-speed wind tunnel has just been force only acts on a fluid (liquid or gas) through Aeroplanes . By Ryozo Fukatsu. installed at the Aerodynamic Laboratory of the th e intermediary of a body of appropriate form, A new form of diagram representing the state Ministero del Aeronautic a in Rome, th e only existing i t is sometimes advantageous to consider first the of equilibrium of steady spinning of an aeroplane tunne l being one installed b y General Crocco in 1913. actio n of a force, or system of forces acting directly was developed . In this diagram the equilibrium I t is not large—the testing chamber has a diameter on the fluid. It then becomes possible to obtain curves for the rolling, yawing, and pitching of only 1.60 metres (5 ft. 3 in.), bu t the installation a general idea of motion while at the same time moments , including the conditions of equilibrium possesses certain unusual features. The return of an advantageou s approach t o problems of technique, of forces, are represented by curves with rates th e air is no t effected through passages, but within i n which the magnitude of the forces play the th e room housing the tunnel, the corners of which most important part, is obtained. At the same tim e the form of the body, through the inter­ are rounded off to prevent the formation of eddies mediar y of which the force acts on the fluid (e.g., and irregularities of flow. The maximum wind- th e supporting surface) is no t laid down in advance, speed obtainable is 80 metres/sec. (262 ft./sec. or 180 m.p.h.) with an absorbed power of 470 h.p. bu t is subject to the condition of ensuring an effect A t this speed the fluctuations are only 1·5 per cent. compatibl e with the least possible loss of energy. in intensit y and 0·5 per cent. in direction. Thi s point of view is not new. Resort has been A t first the speed scarcely reached 68 metres/sec . had, in order to indicate the method, to the reso­ (223 ft./sec.) and the flow was subject to highly lution of the hydrodynamic equations given by accentuate d pulsations owing to the insufficient M. Oseen for the case of forces, acting on a fluid, dimensions of the room. The speed was increased given a general motion in a determined direction and satisfactory regularity of flow obtained by a t a constant speed, which enables the principal makin g the following modifications: the corners features of the turbulences caused by the forces of the room were rounded off; the room was divided t o be deduced in a simple manner. M. Oseen's longitudinally by a partition; the airscrew boss equation s can be further simplified by neglecting was streamlined. The form of the curves to round of rotation plotted against incidence angles α th e influence of viscosity. In applying the expres­ off the corners of the room was obtaine d by following sions obtained to, for example, the theory of sup­ th e path taken by the air, which was made visible portin g surfaces, a formula can be obtained which, for the definite value of side slip. in the tunnel room itself by injecting smoke and for a prescribed distribution of the lift, gives Th e diagram was applied for the investigation i n a th scale mode l b y using titaniu m tetrachloride. directl y the induced vertical speed at all points of the mechanism of the steady spinning of aero­ of the field. planes. Th e Effect of Propellor Reduction Gearing on A type of dangerous state of equilibrium was Aircraft Performance. By R. K. Pierson Th e Uses and Limitations of Mechanical deduced, and in preventing an aeroplane entering Tests . By Wm . D . Douglas, F.R.C.Sc.I. Thi s paper deals seriatim with the effects of tha t state of equilibrium, contributions of various reductio n gearing on performance, weight, and noise characteristic s inherent of the design are clearly Stati c loading tests of aircraft structures can of aircraft. The disadvantages of gearing, namely, usually represent assumed conditions of loading expounded . loss of power in th e drive, extr a weight, unreliability, wit h considerable accuracy, whereas a simplified Special consideration was also paid to the equili­ an d cost, are considered first, after which the form of loading is frequently necessary for purposes briu m of the flat spin. counter-balancin g advantages are mentioned in of calculation. turn . The effect of pitch diameter ratio upon Th e failing load obtained on test will be affected Th e Effect of a Hinged Flap on the Aero­ efficiency is shown; the inter-relation of tip-speed b y the material strength of the part at which the dynami c Characteristics of an Airfoil. By M . J. an d gearing is developed; the gyroscopic effects failure originated. It is usual to make a material Thompson . are investigated. Reduction of slipstream drag tes t of the fractured member and to estimate the wit h gearing, and the effect upon the cooling of air- Th e work presented in this paper is an approxi­ load at which failure would have occurred if the cooled engines, are mentioned; a paragraph deals mat e solution of the problem of the determination materia l had had the minimum strength allowed wit h th e question of noise in passenger aircraft, with of the effect of a hinged flap on the aerodynamic b y the specification. This method of adjustment special reference to airscrew noise. The paper con­ characteristic s of an airfoil. Assuming that the of the results may be misleading in certain cases. cludes with comparative analyses of an aircraft airplan e wing provided with a flap is moving I n the test of a complete structure , i t is frequently fitted alternatively with geared and direct-drive throug h a perfect fluid, and that the motion of engines, showing the distribution of power, the of interest to determine the load at which the th e latter is two-dimensional, a complex function saving due to the reduction gear, and the effect deformatio n is such, that if it had occurred in is developed which transforms a circle into a so- upo n performance. The percentage gains resulting service it would be necessary to replace or repair called "bi-linear" profile, that is, a broken line som e member. from the use of a 525 b.h.p . engine geared down mad e up of two finite segments. The lift and from 1,800 to 1,100 r.p.m. in a single-engined freight momen t coefficients, as well as the moment about Limitatio n of damage at the time of failure is carrie r are given as:—Maximum speed at ground, th e hinge of the forces acting on the flap, are then a n essential part of the test, and suitable arrange­ 10 per cent ; rate of climb at ground, 48 per cent; calculated by means of the Jouhowsky potential ment s should be made for this, and also for the absolute ceiling, 45 per cent; range at cruising function. Then the drag in addition to these safety of th e personnel, by the provision of suitable speed, 14 per cent. othe r quantities, is calculated by means of the supports . I t is frequently advisable to use a system of levers rather than weights for the application of a distributed load. The dimensions of the levers

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Nov 1, 1930

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