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The footnote regarding classified documents on the unclassified sections of Research Abstracts Kbs, 29 and 30 should be deleted. There were no documents described therein that came within this category; this note was inadvertently included. Digitized by the Internel Archive in 2011 with funding Iroin University oa Florida, George A. Smalhers Libraries with suLpport from LYRASIS and the Sloan Foundation http://www.archive.org/details/researchabstract3219527 National Advisory Committee For Aeronautics Research Abstracts NO.32 NOVEMBER 7, 1952 CURRENT NACA REPORTS NACA Reut. 1062 INVESTIGATION OF WEAR AND FRICTION PROP ERTIES UNDER SLIDING CONDITIONS OF SOME MATERIALS SUITABLE FOR CAGES OF ROLLING CONTACT BEARINGS. Robert L. Johnson, Max A. Swikert and Edmond E. Bisson. 1952. ii, 12p diagrs., photos., tab. (NACA Rept. 1062 Form erly TN 2384) The wear and the friction of brass, bronze, beryl c lium copper, monel, Nichrome V. 24ST alummum, nodular iron, and gray cast iron sliding against hardened SAE 52100 steel were studied. , 9 j NACA Rept. 1064 I LUBRICATION AND COOLING STUDIES CYLINDRICALROLLER BEARINGS AT HIGl SPEEDS. E. Fred Macks and Zolton N Nem th. 1952. li, 15p. diagrs., 2 tabs. (NACA Rept. 1064.  Formerly TN 2420) Oil inlet distribution (5 methods were investigated) and oil inlet temperature (1000 to 2050 F) were found to be significant factors in the cooling effec tiveness of a given quantity of oil. Dimensional analysis was used to generalize the testrig results so that it is possible to predict the inner or outer race temperatures above oil inlet temperature from a single curve regardless of whether speed, load, oil flow, oil inlet temperature, oiljet diameter or any combination of the parameters is varied. NACA Rept. 1068 AUTOMATIC CONTROL SYSTEMS SATISFYING CER TAIN GENERAL CRITERIONS ON TRANSIENT BE HAVIOR. Aaron S. Boksenbom and Richard Hood. 1952. ii, 13p. diagrs. (NACA Rep. 1068. Form erly TN 2378) An analytical method is presented for the design of automatic controls that starts from certain arbitrary criterions on the behavior of the controlled system and gives those physically realizable equations that the control system can follow in order to realize this behavior. The criterions used are in the form of certain time integrals. General results are shown for systems of second order and of any number of degrees of freedom. Detailed examples for several cases in the control of a turbojet engine are present ed. NACA TN 2779 EFFECTS OF MODERATE BIAXIAL STRETCH FORMING ON TENSILE AND CRAZING PROPERTIES OF ACRYLIC PLASTIC GLAZING. B. M. Axilrod, M. A Sherman, V. Cohen and I: Wolock, National Bureau of Standards. October 1952. 42p. photos., diagrs.,. 4 tabs (NACA TN 2779) Effects of approximately 50percent biaxial stretch forming on the tensile and crazing properties of polymethyl methacrylate were determined. Speci mens from formed and unformed pieces of the same r'; sheets were subjected to standard tensile tests, '*. C tresssolvent crazing with benzene, longtime ten a s\le loading, and accelerated weathering. Results 3 indicate that biaxial stretchforming does not affect thp tensile strength or modulus of elasticity but does / significantly increase the total elongation and strain S and stress at the onset of crazing. NACA TN 2781 THE EFFECTS OF DYNAMIC LATERAL STABILITY AND CONTROL OF LARGE ARTIFICIAL VARIA TIONS IN THE ROTARY STABILITY DERIVATIVES. Robert 0. Schade and James L. Hassell, Jr October 1952. 56p. diagrs. photo 2 tabs. (NACA TN 2781) The results of an experimental and theoretical in vestigation of mthe effects of large artificial variations of four rotary stability derivatives on the dynamic lateral stability and control of a 450 sweptbackwing airplane model are presented. The experimental results are presented mainly in the form of flight ratings for stability, control, and general flight be havior. Calculations of period and damping and of the response to rolling and yawing disturbances are also presented. NACA TN 2799 SIMPLE GRAPHICAL SOLUTION OF HEAT TRANS FER AND EVAPORATION FROM SURFACE HEATED TO PREVENT ICING. Vernon H. Gray. October 1952 19p. diagrs. (NACA TN 2799) Equations expressing the heat transfer and evapora tion from wetted surfaces during ice prevention have been simplified and regrouped to permit solutions by simple graphical means. Working charts for quick and accurate antiicing calculations are also included. *AVAILABLE ON LOAN ONLY. ADDRESS REQUESTS FOR DOCUMENTS TO NACA, 1724 F ST., NW., WASHINGTON 2s, D. C.. CITING CODE NUMBER ABOVE EACH TITLE THE REPORT TITLE AND AUTHOR 6 z fy./ 0  uSor 2 NACA TN 2805 AN ENGINEERING METHOD FOR ESTIMATING NOTCHSIZE EFFECT IN FATIGUE TESTS ON STEEL Paul Kuhn and Herbert F Hardrath. October 1952. 35p. diagrs. 7 tabs. (NACA TN 2805) Neuoer's proposed method of calculating a practical factor of stress concentration for parts containing notches of arbitrary size depends on the knowledge of a "new material constant" which can be established only indirectly. In this paper, the new constant has been evaluated for a large variety of steels from fatigue tests reported in the literature, attention being confined to stresses near the endurance limit; reasonably satisfactory results were obtained with the assumption that the constant depends only on the tensile strength of the steel. Even in cases where the notches were cracks of which only the depth was known, reasonably satisfactory agreement was found between calculated and experimental factors. It is also shown that the material constant can be used in an empirical formula to estimate the size effect on unnotched specimens tested in bending fatigue. NACA TN 2806 COMPARISON OF TWO AND THREEDIMENSIONAL POTENTIALFLOW SOLUTIONS IN A ROTATING IMPELLER PASSAGE. Gaylord 0. Ellis and John D. Stanitz. October 1952. 61p diagrs. (NACA TN 2806) A solution is presented for inreedimensional, in compressible, nonviscous, potential flow in a rotat ing impeller passage with zero through flow. The solution is obtained for a conventional impeller with straight blades but witn the inducer vanes removed and the impeller blades extended upstream parallel to the axis of the impeller. By superposition of so lutions two additional examples are obtained for dif ferent ratios of compressor flow rate to impeller Lip speed. The threedimensional solutions are com pared with corresponding twodimensional solutions and it is concluded that, at least for the type of im peller geometry investigated, twodimensional solu tions can be combined to describe the three dimensional flow in rotating impellers with sufficient accuracy for engineering analyses. NACA TN 2811 ON THE CALCULATION OF FLOW ABOUT OBJECTS TRAVELING AT HIGH SUPERSONIC SPEEDS A. J. Eggers, Jr. October 1952 25p. diagrs. (NACA TN 2811) A procedure for calculating threedimensional steady and nonsteady supersonic flows with the method of characteristics is developed and discussed An approximate method is deduced from the character istics method and shown to be of practical value at high supersonic speeds. NACA RESEARCH ABSTRACTS NO.32 NACA TN 2812 a._. I, EFFECTS OF CYCLIC LOADING ON MECHANICAL BEHAVIOR OF 24ST4 AND 755T6 ALUMINUM ALLOYS AND SAE 4130 STEEL. C W MacGregor and N Grossman Massachusetts Institute of Technology. October 1952. 53p. diagrs., photos., 4 tabs. (NACA TN 2812) An investigation was conducted to determine the ef fects of cyclic loading on the mechanical behavior of 24ST4 and 75ST6 aluminum alloys and SAE 4130 steel. Specimens of the three materials were sub jectea to various numbers of prior fatigue cycles both below and above the fatigue limits. Special slow bend tests were employed to show the effects of prior cycles of fatigue stressing on the transition tempera ture to brittle fracture for SAE 4130 steel and on the energyabsorption capacity of the aluminum alloys. Micrographic studies were made to observe ana measure crack formation and propagation and addi tional special tests were conducted to supplement the results of the slowbend tests. These included Charpy impact tests, microhardness surveys, tension tests, and frettingcorrosion studies. NACA TN 2814 THE APPLICATION OF PLANING CHARACTER ISTICS TO THE CALCULATION OF THE WATER LANDING LOADS AND MOTIONS OF SEAPLANES OF ARBITRARY CONSTANT CROSS SECTION. Robert F. Smiley. November 1952. 37p. diagrs. (NACA TN 2814) The general equations governing the fixedtrim water landing of a straightkeel seaplane of arbitrary con stant cross section are presented in such a form that the landing motions and loads are expressed In terms of the steadyplaning characteristics of the seaplane. In order to verify the general validity of these equa tions, solutions are made for the water landing of a rectangular flat plate and are compared with experi mental impact data. Calculated and experimental time histories of draft, velocity, and load are In good agreement. A survey is made of the available infor mation on seaplane planing characteristics which is suitable for use with the analysis of the paper. NACA TN 2818 SECOND APPROXIMATION TO LAMINAR COM PRESSIBLE BOUNDARY LAYER ON FLAT PLATE IN SLIP FLOW. Stephen H. Maslen. November 1952. 38p. diagr.. tab. (NACA TN 2818) The firstorder solution for the laminar compressi ble boundarylayer flow over a flat plate at constant wall temperature is given. The effect of slip at the wall as well as the interaction between the boundary layer flow and the outer stream flow is taken into consideration. The solution is obtained explicitly in terms of the known zero order, or continuum, solu tion. No assumptions regarding the Prandtl number or viscositytemperature law need be made. It is found that the firstorder solution gives a decrease in NACA RESEARCH ABSTRACTS NO.32 heat transfer and, for supersonic flow, an increase in skin friction. For subsonic flow there is no first order shear effect. The change in heat transfer is due to slip and the change in friction is due to the interaction of the zero and firstorder velocities at the outer edge of the boundary layer. NACA RM 52109 A METER FOR TIMING THE FLOW OF VERY SMALL VOLUMES OF A GAS. J. C. Westmoreland, National Bureau of Standards. October 1952. 17p. diagrs., photos. (NACA RM 52109) A flowmeter has been developed which combines a volumetime measurement of the flow, regulation of the rate, and a determination or presetting of the pressure head producing the flow. This meter is capable of accurately metering and controlling very small rates of gas flow within a closed system such as those required in a small capillary tube.gas vis cosimeter. NACA RM E52H26 EFFECT OF GEOMETRY ON SECONDARY FLOWS IN BLADE ROWS. A. G. Hansen, G. R. Costello and H. Z. Herzig. October 1952. 38p. pnotos. (NACA RM E52H26) The influence of bladerow geometry on secondary flows in a twodimensional cascade was investigated qualitatively by varying independently the stagger angle, aspect ratio, solianty, angle of attack, anu by providing blade fillets. The influence of tip clear ance and relative motion between blades and wall was also studied. Stagger angle and aspect ratio had no appreciable effect on this secondary flow, whereas solidity and angle of attack did affect the flow patterns indicating the turning as a major parameter. Blade tip clearance induced a vortex produced by flow under the blade enu which rotated opposite to the original seconaaryflow passage vortex. The clearance vor tex displaced but did not reduce the secondaryflow vortex When the wall was moved relative to the blades, the blade leading surfaces "scraped" up entrained fluid near the wall and Imparted a roll up motion to the air in this region. On the tradiling surface the fluid was pulled off the blade onto the wall. The magnitude of the scraping effect was so large that it masked completely the secondaryflow and tipclearance phenomena. NACA TM 1351 ON THE DESIGN OF AIRFOILS IN WHICH THE TRANSITION OF THE BOUNDARY LAYER IS DELAYED. (Kyokaiso no Sen'i o okuraseru Yokugata no tuite). Itiro Tani. October 1952. 74p. diagrs., 8 tabs (NACA TM 1351. Trans. from Aeronautical Research Institute, Tokyo Imperial Univ., Rept 250, v. 19, no. 1, January 1943). A method is presented for designing suitable thick ness distributions ana mean camber lines for airfoils permitting extensive chordwise laminar flow. Wind tunnel and flight tests confirming the existence of laminar flow; possible maintenance of laminar flow 3 by area suction; and the effects of wind tunnel turbu lence and surface roughness on the promotion of premature boundarylayer transition are discussed. In addition, estimates of profile drag and scale effect on maximum lift of the derived airfoils are made BRITISH REPORTS N17215' Aeronautical Research Council (Gt. Brit.) TWODIMENSIONAL COMPRESSIBLE FLOW PAST A SOLID BODY SYMMETRICALLY PLACED IN A CHANNEL. P. V. Abdurahiman. 1952. 6p. (ARC R & M 2443. Formerly ARC 11,243; FM 1205) Goldstein and Lighthill have given a method of finding the effect of compressibility on the potential flow past a symmetrical body, either in unlimited fluid or symmetrically placed in a channel, when the irrota tional incompressible flow is known. The object of this paper is to use this method to find the effect of compressibility on the velocity at the point C of an oval placed symmetrically in a channel of breadth h. N17216 Aeronautical Research Council (Gt. Brit.) NOTE ON SIR GEOFFREY TAYLOR'S CRITERION FOR THE RATE OF BOUNDARYLAYER SUCTION AT A VELOCITY DISCONTINUITY. N. Gregory. 1952. 12p. diagrs., photo. (ARC R r M 2496. For merly ARC 10,630; Pert. 326; FM 1112) Sir Geoffrey Taylor's criterion for the rate of boundarylayer suction at a velocity discontinuity is described, and is compared with experimental results obtained from boundarylayer explorations. It is found that, despite neglect of the pressure gradient due to the curvature of the flow, the criterion gives reasonable estimates of the suction quantity. On the other hand, close agreement with velocity profiles is only obtained when the pressure gradient is taken into account. N17217l Aeronautical Research Council (Gt. Brit.) POSSIO'S SUBSONIC DERIVATIVE THEORY AND ITS APPLICATION TO FLEXURALTORSIONAL WING FLUTTER. PART I. POSSIO'S DERIVATIVE THEORY FOR AN INFINITE AEROFOIL MOVING AT SUBSONIC SPEEDS. R. A. Frazer. PART 11. IN FLUENCE OF COMPRESSIBILITY ON THE FLEXURALTORSIONAL FLUTTER OF A TAPERED CANTILEVER WING MOVING AT SUBSONIC SPEED. R. A. Frazer and Sylvia W. Skan. 1951. 22p. diagrs., 5 tabs. (ARC R 5 M 2553. Formerly ARC 4932; ARC 0.205; ARC 5916; ARC 0.274) The derivative theory due to C. Possio for an infinite airfoil moving at subsonic speeds is reviewed, and certain modifications are proposed. Derivative values are calculated for a Mach number of 0.7 and for values of the frequency parameter A ranging from 0 to 5.0. For A < I the derivative values based on a threepoint collocation method are in fair 4 agreement with those given by Possto. For the range 1.0 < A < 2.0 fivepoint collocation is necessary, while for A = 5.0 even sevenpoint collocation may prove unsatisfactory. The numerical results obtained are applied in Part II to estimate the influence of compressibility and flying height on the critical speed for flutter of a tapered cantilever wing. N17218* Aeronautical Research Council (Gt. Brit.) BOUNDARYLAYER AND WAKE INVESTIGATION IN SUPERSONIC FLOW. J. Lukasiewicz and J. K. Royle. 1952. 22p. diagrs., photos., 2 tabs. (ARC R& M 2613, ARC 12,130. Formerly RAE Aero 2292; SD 31) The report describes the results of traverses of the boundary layer and wake encountered in a small supersonic tunnel at a Mach number of 2.5. The tunnel was arranged with two throats in parallel formed by two shaped walls enclosing a shaped central element. Both the laminar and turbulent boundary layers were encountered and compared with existing experimental and theoretical results. The frictional drag of the central element as deduced from the wake traverses is in close agreement with that calculated from considerations of laminar boundarylayer growth over the surface of the ele ment. The tests also provide information relating to the design of nozzle profiles, particularly at the point of inflexion, where the changes of pressure gradient may have a serious effect on the boundary layer and on the velocity distribution. N17219* Aeronautical Research Council (Gt. Brit.) THE NUMERICAL METHOD OF CHARACTERISTICS FOR HYPERBOLIC PROBLEMS IN THREE INDE PENDENT VARIABLES. C. K. Thornhill. 1952. 13p. diagrs. (ARC R & M 2615; ARC 11,767. Formerly Armament Research Establishment Rept. 29 48; Theoretical Research Rept. 4/48) Recent advances in electronic computing devices suggest that it may soon be feasible to attempt nu merical solutions of problems involving three inde pendent variables. In this paper, preliminary con sideration is given to the extension of the numerical method of characteristics for hyperbolic equations to the case of three independent variables. A general quasilinear secondorder partial differential equa tion in three variables is first considered, and the characteristic surfaces and curves are derived, together with the differential relations which hold along them. It is shown that numerical integration should be possible along the faces or edges of a hexahedral grid. The equations are developed in more detail for two special cases of compressible flow, namely steady isentropic supersonic flow in threedimensional space, and unsteady flow in two dimensions. N17227* Aeronautical Research Council (Gt. Brit.) TESTS ON A 'GLAUERT' NOSESUCTION AERO FOIL IN THE N.P.L. 4FT. NO. 2 WIND TUNNEL. F.. Cheers and Ola Douglas. 1952. 5p. diagrs. (ARC R & M 2356. Formerly ARC 10,507; FM 1096; Perf. 302) NACA RESEARCH ABSTRACTS NO.32 Tests on an 8.65percentthick nosesuction airfoil designed by Glauert have been made in theloot No. 2 wind tunnel at the National Physical Laora tory at Reynolds numbers 0.385 and 0.577 x 106. The results show that the section stalls at a lift coeffi cient of 1.13 without suction. With suction quantities of 0.003, 0.0045, 0.006, and (with a wider slot) 0.012, the values of CLmax were respectively 1.32, 1.34, max 1.36, and 1.57. N17228* Aeronautical Research Council (Gt. Brit.) THE FLOW IN AN AXIALLYSYMMETRIC SUPER SONIC JET FROM A NEARLYSONIC ORIFICE INTO A VACUUM. P. L. Owen and C. K. Thornhill. 1952. 8p. diagrs. (ARC R b M 2616; ARC 11,768. Formerly Armament Research Establishment Rept. 30, 48; Theoretical Research Rept. 5 48) The numerical method of characteristics is used to calculate the flow in a steady supersonic jet of air issuing from a slightly supersonic circular orifice into a vacuum. The calculations are entirely numer ical, and no recourse is made to graphical methods. The characteristic equations for steady supersonic flow with rotational symmetry are first derived, and then special consideration is given to the flow near the axis of symmetry, where the normal stepbystep numerical process breaks down. In the calculation, the Mach angle in the plane of the orifice is taken as 850 to obviate the difficulties of a sonic orifice at which the initial characteristics would be perpendic ular to the flow, and the potential equation parabolic. The results should be practically the same as for a sonic orifice. An alternative method of dealing with a sonic boundary plane would have been the use of analytical solutions for the initial flow in this region The results of the calculations are presented in diagrams. The solution is a universal solution insofar that it applies to any similar jet, flowing into any external pressure, in that region bounded by the orifice and the first wave front which registers the existence of an external pressure outside the jet This fact allows the calculated pressure distribution along the axis of symmetry to be compared with experimental measurements in air jets with finite pressure ratios, and good agreement is obtained. N17229* Aeronautical Research Council (Gt. Brit.) PRESSURE DISTRIBUTIONS AT HIGH SPEED ON EC 1250 (DATA REPORT). J. A. Beavan and G. A. M. Hyde. 1952. 12p. diagrs. (ARC R & M 2625. Formerly ARC 10,729; Perf. 331; FM 1132) This report puts on record, as data, pressure distri butions measured on a 5in. chord airfoil of EC 1250 section in the 20 by 8inch rectangular highspeed tunnel at the National Physical Laboratory. NACA RESEARCH ABSTRACTS NO.32 N17230* Aeronautical Research Council (Gt. Brit.) FOUR AND EIGHTCHANNEL DESYNN GRAPHICAL RECORDERS. F. R. J. Spearman. 1952. 6p. photos. (ARC R& M 2636; ARC 11,495. Formerly RAE Tech. Note Instn. 119) A fourchannel recorder, providing continuous traces against time on photographic film, has been developed for use with any instruments embodying Desynn transmitters. It is suitable for the measurement of quantities which vary with a maximum frequency of 3 cps. It is made from F.24 camera component parts, and uses the standard magazine and 5In. wide film. It has been successfully used for flight trials, manufacturing drawings are available. An eight channel version, of which two or three may be coupled together, is under development. N17231 Aeronautical Research Council (Gt. Brit.) A THEORETICAL INVESTIGATION INTO THE LATERAL STABILITY OF AN AEROPLANE CON TROLLED BY AN AUTOMATIC PILOT, WITH PARTICULAR REFERENCE TO THE EFFECT OF FLIGHT PATH ANGLE. T. W. Prescott. 1952. lip. diagrs. (ARC R & M 2640; ARC 11.409. Formerly RAE Tech. Note LAP 974) Several autopilots produce aileron deflection propor tional to the movement between the airplane and the outer gimbal of a vertical gyroscope. In nonlevel flight, this relative movement is not equal to the rotation of the airplane about its xaxis, and it was desirable to investigate the lateral stability for steep angles of climb and dive. Calculations show that instability does occur, but that stability can be restored either by making the rudder deflection dependent on aileron movement in order to counter act the aileron drag coefficient, or by adding a rate of yaw term to the rudder circuit. The addition of both aileron and rate terms to the rudder circuit is greatly superior to the addition of either term alone. The aileron drag coefficient can also have a detri mental effect at the start of an automatic turn, and response curves during entry into the turn have been calculated for various degrees of aileron drag com pensation. The bank angle and sideslip response curves are unaffected by the compensation. The rate of turn response is Improved during the first second but subsequently is little affected by aileron drag compensation. N17232* Aeronautical Research Council (Gi. Brit.) ON A THEORY OF SANDWICH CONSTRUCTION. W. S. Hemp. 1952. 9p. (ARC R & M 2672. ARC 11, 568. Formerly College of Aeronautics, Cranfield Rept. 15) The theory of sandwich construction developed in this paper proceeds from the simple assumption that the filling has only transverse direct and shear stiffnesses, corresponding to its function require ments. This supposition permits integration of the equilibrium equations for the filling. The resulting integrals are used to study the compression buckling 5 of a flat sandwich plate. The formulas obtained are complex, but may be simplified in practical cases. A second approach to sandwich problems is made in section 5, where a theory of "bending" of plates is outlined. This generalizes the usual theory, making allowance for flexibility in shear This approach is applied to overall compression buckling of a plate and agreement with the previous calculations is found. This suggests the possibility of calculating buckling loads for curved sandwich shells. A sim ple example, the symmetrical buckling of a circular cylinder in compression, is worked out. The theory developed would seem applicable to all cases of buckling of not too short a wave length. N17233' Aeronautical Research Council (Gt. Brit.) SERVICE FAILURES IN AIRCRAFT STRUCTURES ASSOCIATED WITH FATIGUE, REPEATED OR DYNAMIC LOADS. J. B. B. Owen. 1952. 13p. diagrs., photos. (ARC R & M 2688; ARC 9426. Formerly RAE SME 3384) This note gives examples and photographs of several structural defects which have occurred in service and shows that, although many failures may be due to fatigue or the application of excessive static loads, some are probably influenced by the repeated applica tion of loads of high intensity, and by loads of a dynamic character. It is suggested that changes in design aimed at (1) eliminating the loads causing failure, for example, reducing in one case tab back lash, and (2) alleviating stress concentrations are ways of reducing the incidence of defects due to repeated loading. N17535* Aeronautical Research Council (Gt. Brit.) NOTES ON HELICOPTER ROTOR BEHAVIOUR AFTER ENGINE FAILURE IN HOVERING FLIGHT. W. Stewart and G. J. Sisslngh. 1952. 6p. diagrs. (ARC R& M 2659; ARC 12,525. Formerly RAE Tech. Note Aero 1997) Calculations have been made of the changes in rotor speed following engine failure on a typical helicopter in hovering flight. Various time functions for the collective pitch operation are considered. The re sults are in excellent agreement with the one recorded case of an actual power failure In hovering flight. Rapid pilot action in reducing the collective pitch after engine failure is essential to prevent dangerously low rotational speed of the blades. The possibilities of automatic pitch reduction or of a power failure warning to the pilot are considered. N17536* Aeronautical Research Council (Gt. Brit.) NOTE ON THE APPLICATION OF THWAITES' NUMERICAL METHOD FOR THE DESIGN OF CAM BERED AEROFOILS. A. R. Curtis. 1952. 13p. 6 tabs. (ARC R & M 2665. Formerly ARC 12,154; FM 1336; Pert.531) Some minor developments in the technique of Thwaites' numerical method of airfoil design are 6 described. In particular, the process of obtaining the camberline ordinates from the Goldstein approximation I velocity distribution is discussed in detail, the relevant tables of constants are given. An opportunity is taken to include a complete set of 20 point tables of conjugation factors needed in any actual application of the numerical methods. The theory underlying these tables is given by Watson in R & M 2716. N17537* Aeronautical Research Council (Gt. Brit.I A THEORETICAL EXAMINATION OF THE EFFECT OF DEADRISE ON WETTED AREA AND ASSOCIATED MASS IN SEAPLANEWATER IMPACTS. R. J. Monaghan. 1952. 16p. diagrs. (ARC R & M 2681; ARC 12,395. Formerly RAE Tech. Note Aero 1989) A theoretical examination is made of the dead rise effect on associated mass and wetted area in the two dimensional impact case (vertical drop of an infinite ly long wedge at zero attitude). Available estimates are summarized and a new theoretical formula is developed by means of an expanding prism flow which gives results for associated mass in very close agreement with those given by Wagner's semi empirical formula (on which most of the estimates of threedimensional associated mass have so far been based). In addition, the new treatment gives a formu la for wetted area which is not available from Wagner's treatment except for very small values of dead rise angle. Comparison is made between these and other formulas in the light both of theory and experiment and a brief survey is made of the assump tions involved in applying associated mass methods to motions through a free surface. N17538* Aeronautical Research Council (Gt. Brit.) SYSTEMATIC WINDTUNNEL TESTS WITH SLATS ON A 10 PER CENT THICK SYMMETRICAL WING SECTION (EQ 1040 PROFILE). G. F. Moss. 1952. 22p. diagrs., 6 tabs. (ARC R & M 2705; ARC 12,068. Formerly RAE Aero 2294) It was thought that present rules for the design of Handley Page slats might be inadequate for modern highspeed airfoil sections. These tests were made on the EQ 1040 wing section to determine the optimum slat setting for this type of wing profile. Three slats were tested whose chords were 10 percent, 20 per cent, and 30 percent of the wing chord, over a wide range of positions. Lift coefficients were measured over the stall in each case. Some tests were made with a split flap. Best results for the 10percent chord slat are obtained with very small gap and large dip. Zero gap, that is, using the slat as a nose flap, may in fact give the optimum. Optimum positions for the larger chord slats are more conventional, but require larger forward extensions than are given by the old rules. NACA RESEARCH ABSTRACTS NO.32 N17539" Aeronautical Research Council (Gt. Brit.) ..  NOTE ON SEMIEXPERIMENTAL METHODS FOR THE DETERMINATION OF AERODYNAMIC DERIVA TIVES FOR AN OSCILLATING WINGAILERON SYSTEM. P. F. Jordan. 1952. 6p. diagrs., tab. (ARC R M 2706; ARC 12,042. Formerly RAE Tech. Note Structures 28) A brief survey is given of existing semiexperimental methods for the determination of twodimensional aerodynamic derivatives for unsteady motion of a wingaileron system (and, in particular, for aero dynamically balanced controls); a comparison with (partly unpublished) experimental data is made. The result is encouraging for further investigations. N 17540' Aeronautical Research Council (Gt. Brit.) TESTS ON A MODEL BODYWING COMBINATION AT SUPERSONIC SPEED. P. J. Wingham. 1951. 4p. diagrs. (ARC R i M 2711. Formerly ARC 8229; Ae. 2663; FM 759) The tests described in this report were made in the 1 foot circular tunnel at the National Physical Lab oratory at a Mach number of about 1.4. The main object was to determine the lift obtainable from wings of very short span and in particular to see whether the lilt curve departed much from a straight line at incidences up to about 120, it being already known that the lilt curve for a twodimensional air foil was sensibly straight up to 200 or so of inci dence. Unfortunately it was not possible to measure the drag load, so that only normalforce and pitching moment values are available. N17541' Aeronautical Research Council (Gt. Brit.) A METHOD FOR DETERMINING THE WATER STA BILITY OF A SEAPLANE IN TAKEOFF AND LANDING. H. G. White and A. G. Smith. 1952. 17p. diagrs. (ARC R M 2719; ARC 6834. Formerly MAEE Rept. H Res 163) A direct method of determining the water stability in takeoff and landing of fullscale seaplanes is de scribed. The customary method of measuring full scale stability is by steady runs over a range of speed and attitudes. This is tedious; it does not give the true takeoff stability and does not give the land ing stability. The steadyrun stability is assumed to correspond very closely to the takeoff stability but was originally used to obtain fullscale conditions comparable with model scale. This report gives a method of analysis of takeoil records of attitude against speed, and results obtained by this method are compared with the steadyrun results. Results on the Scion fitted with a I 2scale Sunderland hull and Saro with a 1 2.75scale Shetland hull are used to establish the method, but it has also been checked against the available date on the full scale Seal and Sunderland 1. The takeoff stability limits show remarkable agree ment with the corresponding steady run limits (to within I 20) of the Scion and Saro. Evidence on the Seal and Sunderland is insufficient for a definite con clusion in these cases, but there is no disagreement NACA RESEARCH ABSTRACTS NO.32 between the results obtained. The method is accurate and quick to use, but takes no account of the ampli tude of porpoising so that a few steady runs would still be necessary to establish this where required. By use of this method, the investigation of the sta bility characteristics of a seaplane under different conditions of weight, c.g., and flap angle can proceed quickly on the evidence of about eight takeoff records at each condition, these records covering the full attitude range. The method may also be applied to find landing stability from landing records. N17542' Aeronautical Research Council (Gt. Brit.) THE HULL LAUNCHING TANK (DESCRIPTIVE). A. G. Smith, G. C. Abel and W. Morris. 1952. 22p. diagrs., photos. (ARC R& M 2723; ARC 6804. Formerly MAEE Rept.H Res 161) The hull launching tank has been built in order that systematic measurements of impact pressures can be made on large model seaplane hulls to supple ment fullscale tests, and to cover conditions of im pact which would be dangerous full scale. The ob ject is to obtain generalized formulas for the maxi mum local pressures, the total impact load, and the simultaneous distribution of pressure on any hull form for any impact condition. The report describes the hull launching tank and apparatus, the range of impact conditions possible for test, and the methods developed for measuring the parameters which affect the Impact loads. Theoretical considerations, the results of tests and further developments, will be found in existing or in subsequent reports. N17543' Aeronautical Research Council (Gt. Brit.) SOME ELECTRICAL INTEGRATING CIRCUITS AND THEIR USE IN THE MEASUREMENT OF LOW FRE QUENCY VIBRATION AMPLITUDES. G. R. Richards. 1952. 18p. diagrs. (ARC R & M 2724; ARC 11,639. Formerly RAE Tech.Note lnstn.121) The note investigates the possibility of making low frequency vibration measurements by the use of electronic acceleration measuring equipment in con junction with electrical doubly integrating circuits. It is shown that by this method many of the disadvan tages associated with the use of seismic displacement units can be obviated particularly over the frequency range 2 to 40 cps. Three electrical integrating methods are discussed, the correct circuit conditions for the integration of periodic sinusoidal, rectangular and triangular waveforms are derived. A descrip tion is given of an existing acceleration measuring equipment incorporating two of the described inte gration networks; its sensitivity, frequency response, and methods of increasing these factors are dis cussed in detail. N17544' Aeronautical Research Council (Gt. Brit.) AN EXPERIMENTAL INVESTIGATION OF THE FLOW THROUGH A HELICOPTER ROTOR IN FOR WARD FLIGHT. P. Brotherhood and W. Stewart. 1952. 12p. diagrs., photos. (ARC R & M 2734; ARC 12,894. Formerly RAE Aero 2330) 7 Experiments have been made to determine the flow conditions through a helicopter rotor in forward flight using the smoke filament technique. This method consisted of flying the helicopter behind an aircraft from which smoke generators were suspended on a long wire. The smoke trails passed through the main rotor of the helicopter, and photographs were taken from another aircraft in a side position. Flow condi tions at the rotor disk over a narrow bend on the side of the advancing blade were investigated in this way. The range of speeds covered was from 44 mph to 60 mph corresponding to a range of tip speed ratios 0.138 to 0.188. An increase in induced velocity from front to rear of the rotor disk was obtained. The re sults are in reasonable agreement with theoretical predictions. N17545' Aeronautical Research Council (Gt. Brit.) EFFECT OF RATE AND DURATION OF LOADING ON THE STRENGTH OF AIRCRAFT STRUCTURES. K. D. Raithby. 1952. 13p. photos., diagrs., 5 tabs. (ARC R !i M 2736; ARC 12,600. Formerly RAE Structures 39) The effects of rate and duration of loading on the structural strength of aircraft have been investigated by comparing the failing loads of both wooden and metal tail planes when tested at different rates of loading, the duration of test varying from about 6 seconds to 33 4 hours. With wooden structures, differences in strength due to rate of loading were much less than those predicted from the results of American tests on wood. With metal structures, neither rate of loading nor sustained high loading had any appreciable effect on the failing load. N17546* Aeronautical Research Council (Gt. Brit.) A DISTANT READING MANOMETER WITH PAR TICULAR APPLICATION TO THE MEASUREMENT OF SMALL PRESSURES. A S. Halliday and H. Deacon. 1952. 5p. diagrs., photos. (ARC R & M 2744. Formerly ARC 11, 566; TP 247; S & C 2227; Perf. 457) The function of the manometer Is to enable small pressure differences to be measured at a distance. The instrument will measure either the difference of two pressures or a single pressure relative to atmosphere. N17547' Aeronautical Research Council (Gt. Brit.) FORCED FLOW AGAINST A ROTATING DISC. D. M. Hannah. 1952. 17p. diagrs., 7 tabs. (ARC R & M 2772. Formerly ARC 10,482; FM 1088) The steady motion of an incompressible viscous fluid due to an infinite rotating plane lamina has been con sidered by von Karman and by Cochran; the motion of fluid flowing with axial symmetry towards an infi nite stationary plane lamina has been dealt with by Homann. The present paper deals with the general UNIVERSITY OF FLORIDA 3 12 0 153 255 7 question of steady irrotational flow with axial symme try against an infinite rotating lamina, of which the above are two special cases. N17587' National Gas Turbine Establishment (Gt. Brit.) THE FOULING OF TURBINE BLADING BY THE PRODUCTS OF COMBUSTION OF PULVERISED FUEL. PART I. THE DESIGN AND DEVELOPMENT OF THE COMBUSTION SYSTEM. R. I. Hodge. June 1952. 35p. diagrs, photos. (NGTE Memo. M.154) This memorandum describes the construction of the pulverized fuel combustion chamber and the ancil lary equipment at present installed at the National Gas Turbine Establishment, Whetstone, to conduct an investigation into the effect on blading of the operation of an open cycle turbine fired with pulver ized fuel. The developments found necessary to give effective flame stability in this particular com bination of precombustlon and balanced vortex chambers are set forth. Both the conditions assumed in the design and those calculated to be obtaining at what was subsequently found to be the point of opti mum operation (based on combustion efficiency) are given. The analysis of the state of the exhaust prod ucts given at the end of this note is not complete but p *ovides some idea of the basic medium of the blade fouling test conditions. N17657' Forest Products Research Lab. (Gt. Brit.) REVISED MANUAL FOR CONDUCTING TRIALS OF TIMBERS FOR PLYWOOD MANUFACTURE. R. A. G. Knight. June 1952. 11, 14p. (Forest Products Research Lab. PRP 8. 1) The Composite Wood Section of the Forest Products Research Laboratory is completely equipped with machinery and plant for the manufacture of plywood of all types. The peeler will take billets up to 5 ft 6 in. long and 4 ft 6 in. diameter and the press will make boards up to 5 ft square. With equipment of this scale, an appraisal can be made of the value of a timber for plywood manufacture, and problems at any stage of the process can be investigated under conditions comparable with those in commercial factories but distinct from them in that the needs of continuous production are absent. These investi gations are made to a prescribed plan so as to apply uniform standards to all timbers, and the results are issued by the Laboratory as Progress Reports in the series "Trials of Timbersfor Plywood Manu facture.' The plan was originally prepared in collab oration with the Plywood Research Panel, and cir culated as Paper P. R. P. 5, 1, "Manual for Conduct  ing Trials of Timbers for Plywood Manufacture" in August 1950. After experience with the Manual in tests on 26 species, the Panel saw that improve ments could be made that would simplify the work and increase the practical value of the data obtained, so the present Revised Manual was then compiled. The original Paper P. R. P. 5, 1 is applicable to re porti up to No. 15, but for No. 16 and onwards, the methods of P. R P. 8 1 apply. The changes are not such as to nullify comparison between the earlier and later reports. NACA i RESEARCH ABSTRACTS NO.3S N17722* Royal Aircraft Establishment (Gt. Brit.) HEAT TRANSFER AND PRESSURE LOSSES IN COOLING DUCTS OF GENERATORS. Mary D. Wright. June 1952. 17p. diagrs., 3 tabs. (RAE Tech.Note EL.39) In connection with the cooling of aircraft generators an investigation has recently been made to determine the pressure drop and heat transfer in the cooling channels of an armature. In this note an attempt has been made to correlate the results with theoret ical and established empirical relationships. The description of the apparatus and experimental tech niques which were used will be described in a later report. N177231 Ministry of Supply (Gt. Brit.) DEVELOPMENT OF A PRESTALL DETECTOR FOR AIRCRAFT. R. T. Youngman. July 1952. 7p. diagre. (MOSS & TM 6/52) This report describes a stall warning detector which has been developed by the Ministry of Supply. It depends for its operation upon the pressure changes which occur on the undersurface of a wing. At cer tain points, the pressure increases at a fairly con stant rate with increase in angle of Incidence. A detector which operates on this principle has the advantage that there are no external parts. N17726* Royal Aircraft Establishment (Gt. Brit.) FATIGUE PROPERTIES AT LOW TEMPERATURE ON TRANSVERSE AND LONGITUDINAL NOTCHED SPECIMENS OF D. T.D. 363A ALUMINIUM ALLOY. N. J. F. Gunn. June 1952. 23p. diagrs., photo., 11 labs. (RAE Tech. Note Met. 163) Tests have been made to ascertain the effect of a specified subnormal temperature (400 C) on the notched and unnotched fatigue strength of the materi al. The test pieces were machined from a 5inch diameter, extruded D. T. D. 363A bar so that their axes coincided with.the longitudinal and transverse directions of the parent bar. The results of the tests showed that some increase in fatigue strength Is evident at 400 C for longitudinal specimens but no appreciable change for transverse specimens Is apparent. MISCELLANEOUS NACA ARR L4F26 Errata No. 1 on "DESIGN OF POWERPLANT INSTALLATIONS PRESSURELOSS CHARACTER ISTICS OF DUCT COMPONENTS". John R. Henry. June 1944. NACALangley 11752 4000 
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