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Aviation History
1927
1927 - 0294.PDF
34 SUPPLEMENT TO FLIGHT APRIL 28, 1927 THE AIRCRAFT ENGINEER Nos. 737,f 790,$ 791§. 819,1] and 821.H TOther experience has been gained bv him in co-operation with the Cardington StafF during the designing of R. 101. In the main the methods outlined by the Airship Stressing Panel have been substantiated, but certain additional matters have needed treatment, some of which have been met by what is called by the author " The Device of the Separate Panel." This device and methods of stressing a complete ring are described in the present report, which also briefly sum- marises the conclusions reached by other workers. tK.4M 737. On the determination of the stresses in braced frameworks.Part I. The effects of axial loading, flexure and torsion upon a framework of uniform rectangular cross section.—It. V. Southwell. t R. & M. 790. On the determination of the stresses in braced frameworks.Part II. The effect of shear upon a framework of uniform rectangular cross- section. - R. V. Southwell,§ R. & M. 791. On the determination of the stresses in braced frameworks. Part III. The effect of axial loading, torsion, flexure and shear upon abraced tube of any uniform cross-section.—R. V. Southwell. II R. &M. 819. On the determination of the stresses in braced frameworks.Part IV. The eflects of axial loading, flexure, torsion and shear upon a tubular framework with taper.—R. V. Southwell." B,. & M. 821. On Castigliano's theorem of least work, and the principle of St. Tenant.—R. V. Southwell. D. M. SMITH'S METHOD FOR THE DETERMINATION OF THE TRANSVERSE FREQUENCIES OF VIBRA TION OF UNIFORM BEAMS. By T. W. K. CLARKE, B.A., AND V. M. FAULKNER, B.SC. Presented by the Director of Scientific Research. R. & M. No. 1058 (Ae. 240) (9 pages and 3 diagrams). April, 1926. Price 9d. net. The nomographic method described (reproduced from an article in Engineering, December 25, 1925, page 808. by David M. Smith, B.Sc.) can be used for finding, by a simple tabular process, the frequencies of vibration of uniform beams of any number of spans, and under any conditions of support ranging from simple to rigid and with or without overhanging ends. The formulae and several illustrative examples are given in the present paper. FLYING POSITIONS OF CONTROL SURFACES OF BRISTOL FIGHTER. By Oapt. G. T. R. HILL, M.C., M.Sc, A.F.R.A.S. R. & M. No. 1060 (Ae. 243) (6 pages and 8 diagrams). May, 1926. Price Qd. net. The object of the experiments described in this report was to determine the positions of the control surfaces of a Bristol Fighter under varying conditions of flight, as this aeroplane has been taken as a standard for research purposes. At a height of 6,000 ft., the positions of the control surfaces have been measured throughout the whole range of speed for three different settings of the throttle, both in straight flight and on steady turns up to 30° bank. The various control positions for the different flights are shown in the number of curves for the same airspeed. The aeroplane is longitudinally unstable throughout most of its speed range whatever the power output of the engine. Except near the stalling point, the variation of control posi- tion with engine power is greater than the variation with speed, while the positions required when on a 30° bank are not greatly different from those observed in straight flight at the same speed and engine power. ON THE CONTRACTION OF THE SLIPSTREAM OF AN AIRSCREW. By H. GLAUKRT, M.A. Presented by the Director of Scientific- Research. R. & M. No. 1067. (Ae. 249) (11 pages and 3 diagrams). February, 1926. Price 6d. net. The development of aircsrew theory depends on the deter- mination of the induced velocity of the trailing vortex system which forms the slipstream and in the vortex theory this induced velocity is calculated on the assumption that the contraction of the slipstream can be neglected. An attempt has been made to extend the theory by taking account of the contraction of the slipstream, which is repre- sented by a close succession of vortex rings. By a method of successive approximation a modified theory has been deve- loped which is represented by the characteristic curve of Fig. 3. The form of the characteristic curve obtained from the modified theory is in close agreement with the straight lines The solution is consistent with the momentum equation, but the ratio of the induced velocity in the wake to that in the airscrew disc no longer has the constant value 2. The ratio is less than 2 for a propeller and greater than 2 for a windmill. THE FULL SCALE DETERMINATION OF THE LATERAL RESISTANCE DERIVATIVES OF A BRISTOL FIGHTER AEROPLANE. PART II. -THE DETERMINATION OF THE RATE OF TURN DERIVATIVES. By H. M. GARNER, M.A. R. & M. No. 1068 (Ae. 250) (4 pages). September, 192ti. Price 3'/. net. The determination of the sideslip derivatives of a Bristol Fighter is described in R. & M. 987.* The present report deals with the determination of the rate of turn derivatives. Glides were carried out at an incidence of 10" with steady turns to the right and left, and measurements made of aileron angles, rudder angle, sideslip and rate of turn. From these measurements the rolling and yawing moments due to turn are calculated. The values of the rolling and yawing moments agree quite well with the model values determined in R. & M. 932. Section 2. A scheme has been devised for the determination of the rate of roll derivatives and is now proceeding. * R. & M. 987. The full scale determination of the lateral resistancederivatives of a Bristol Fighter aeroplane, by H. SI. Garner, SI.A., and S. h. Gates, B.A. These Reports are published by His Majesty's Stationery Office, London, and may be purchased directly from H.M. Stationery Office at the following addresses : Adastral House, Kingsway, W.C. 2; 28, Abingdon Street, London, S.W.I; York Street, Manchester; 1, St. Andrew's Crescent, Cardiff; or 120, George Street, Edinburgh ; or through any book- seller. SUMMARIES OF TECHNICAL REPORTS OF THE RIJKS STUDIEDIENST V00R DE LUCHTVAART, AMSTERDAM. REPORT A. 129. EXPERIMENTS ON THE VELOCITY DISTRI- BUTION IN THE BOUNDARY LAYER OF AN AEROFOIL WITH ROTARY CYLINDER. Earlier experiments have shown (Report* A. H6 and A. 105) that arotary cylinder accommodated in an aerofoil may have an important influence on the flow. To ciieck the explanation of tlus phenomenon giventhere, a closer investigation of the flow was made. The velocity in several points in the proximity of the surface of the moo''was measured with a hot-wire anemometer. Fig. 1 shows the general arrangement of the tests. The pressure distribution on the upper surfaceof the model has been measured in the ordinary way (Fig. 2). At all tests the angle of incidence was 0\ the air speed at a considerabledistance from the mode! 5-44 m. sec. (17-8 ft./sec.). The position of the measuring points is given in the sketches, which are joined to the figures.The distance tj between the anemometer and the aerofoil surface was 0 05 cm., gradually increased to 5 cm., measured along the normal to thechord. In all points measurements were made with the cylinder rotating (A) and stopped (if), and then in the point* III—VII, also with cylinder stopp*"and the gap between cylinder and fixed part filled tip and carefully smoothed The number of revolutions per minute of the cylinder was 9,600, so tin-ratio peripheral spc«d : air speed was 'AM. The pressure distribution on the upper surface has been determined aw>for the cases A, Is and C at an air speed of 6-44 ni./nec., the cylinder runnnU at 9.600 r.p.m. The results of the velocity measurements are given In Table I »»<'Figs. 3 to 8. In the Figs. 3 to f> they are plotted together for all measuring points on the upper surface for each arrangement of the model. Ii*?s- t>and 7 show a comparison of the model with cylinder rotating and at rest (A and C). and also that of the model with cylinder at rest and slot ope"or closed (B and C). Fig. 8 showg the results'for both points on the lo»< surface. The results of the pressure measurements are represented i"Table II and Fig. 9. In the latter the pressures have been divided by Me dynamic pressure before plotting. _fThe results confirm the surmise made in Report A. 105 that an important momentum is imparted by the cylinder to the air in the immediate proxinw>of the surface, but that the direct action is confined to a very thin layer- 262/
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