Access the full text.
Sign up today, get DeepDyve free for 14 days.
References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.
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
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Nov 1, 1930
You can share this free article with as many people as you like with the url below! We hope you enjoy this feature!
Read and print from thousands of top scholarly journals.
Already have an account? Log in
Bookmark this article. You can see your Bookmarks on your DeepDyve Library.
To save an article, log in first, or sign up for a DeepDyve account if you don’t already have one.
Copy and paste the desired citation format or use the link below to download a file formatted for EndNote
Access the full text.
Sign up today, get DeepDyve free for 14 days.
All DeepDyve websites use cookies to improve your online experience. They were placed on your computer when you launched this website. You can change your cookie settings through your browser.