FOE OFFICIAL USE.

AERONAUTICS

TECHNICAL REPORTOF THE

AERONAUTICAL RESEARCH

FOR THE YEAR 1928-1929(With APPENDICES).

VOL. I.Aerodynamics.

LONDON,PRINTED AND PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE

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1929.

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23-9003-1-29

Ill

CONTENTS.

VOLUME I.PAGE

Members o f t h e Committee - - - - - - - - i xReport o f t h e Committee f o r t h e year 1928-29 - - - - - 1

APPENDICES TO THE REPORT.Aerodynamics :—

(a) Fluid Motion :—(i) The characteristics of a Karman Vortex Street in a channel of

finite breadth. By H. Glauert, M.A. (R. & M. 1151) - 62(ii) On the flow of a compressible fluid past an obstacle. By

Dr. H. Lamb, F.R.S. (R. & M. 1156) - 76(iii) The effect of the static pressure gradient on the drag of a

body tested in a wind tunnel. By H. Glauert, M.A.,F.R.Ae.S. ( R . & M . 1158)- - - - - - 81

(iv) A theoretical estimate of the pressure gradient in a windtunnel. By H. Glauert, M.A., F.R.Ae.S. (R. &M. 1159) - 93

(v) The force acting on a body placed in a curved and convergingstream of fluid. By Professor G. I. Taylor, F.R.S.( R . &M. 1166) - - - - - - - - 1 0 4

(vi) Note on the forces experienced by ellipsoidal bodies placedunsymmetrically in a converging or diverging stream.By Dr. H. Lamb, F.R.S. (R. &M. 1164) - - - 114

(vii) The accelerated motion of a cylindrical body through afluid. By H. Glauert, M.A. (R. &M. 1215) - - - 118

(viii) The boundary layer of the front portion of a cylinder.By A. Thorn, B.Sc., Ph. D. (R. &M. 1176) - - - 128

(ix) The airflow around a circular cylinder in the region wherethe boundary layer separates from the surface. By A.Fage, A.R.C.Sc. ( R . & M . 1179) - - - - - 1 4 8

(x) An investigation of fluid flow in two dimensions. ByA. Thorn, D.Sc., Ph.D., A.R.T.C. (R. &M. 1194) - - 166

(xi) The hydrodynamic forces on a cylinder moving in twodimensions. By H. Lamb, F.R.S. (R. & M. 1218) - - 184

(xii) The skin friction on a circular cylinder. By A. Fage,A.RC.Sc. (R. & M. 1231) - - - - - 189 -

(xiii) A mechanical method for solving problems of flow incompressible fluids. By G. I. Taylor, F.R.S. and C. F.Sharman, Ph.D. ( R . & M . 1195) - - - - - 1 9 8

(xiv) Report on progress during 1927-28 in calculation of flow ofcompressible fluid, and suggestions for further work.By Professor G. I. Taylor, F.R.S. With an Appendix byC. F. Sharrnan, Ph.D. (R. &M. 1196) - - - - 220

(xv) On the effect ot air compression on drag and pressuredistribution in cylinders of infinite aspect ratio ByT. E. Stanton. (R. & M. 1210) 23h

(88956)—I Wt. 14750/68S/H34 375 1/30 Hurow G;7 A 2

IV

PAGE(6) Aerofoils and Wing Sections :—

(i) The theoretical relationships for an aerofoil with a multiplyhinged flap system. By W. G. A. Perring, R.N.C.,A.M.I.N.A. ( R . & M . 1171) - - - - - 2 4 3

(ii) An analysis of a rectangular monoplane with hinged tips.By S. B. Gates, M.A. (R. & M. 1175) - - - 2 5 7

(iii) The characteristics of a tapered and twisted wing withsweep-back. By H. Glauert, M. A. and S. B. Gates, M.A.( R . & M . 1226) - - - - - - - - 2 6 7

(iv) Wind tunnel experiments with infinite cascades of aerofoils.By R. G. Harris, D.Sc., F.R.S.E. and R. A. Fairthorne.( R . & M . 1206) - - - - - - - - 2 8 6

(v) Preliminary tests on the effect on the lift of a wing of theposition of the airscrews relative to it. By F. B. Bradfleld,Math. & Nat. Sci. Triposes. (R. &M. 1212) - - - 304

(vi) On the two-dimensional flow past a body of symmetricalcross-section mounted in a channel of finite breadth.By A. Page, A.R.C.Sc. (R. &M. 1223) - - - - 314

(vii) On the flow of air adjacent to the surface of an aerofoil.By N. A. V. Piercy, D.Sc. and E. G. Richardson, B.A.,D.Sc. ( R . & M . 1224) - - - - - - 3 2 6

(c) Airscrews :—(i) The change in airscrew characteristics with height. By

A. E. Woodward Nutt, B.A. (R. & M. 1178)- - - 349(ii) Experiments with the family of airscrews in. free air at zero

advance. By H. C. H. Townend, B.Sc., W. S. Walker andJ. H. Warsap. (R. & M. 1153) - - - - - 359

(iii) Photographs of streamers illustrating the flow around anairscrew in the vortex ring sbate. By C. N. H. Lock, M.A.( R . &M. 1167) - - - - - - - - 3 6 9

(iv) Full scale determination of the effect of high tip speeds onthe performance of an airscrew. By W. G. Jennings,B.Sc. ( R . & M . 1173) - - - - - - 3 7 3

(v) Wind tunnel tests with high tip speed airscrews. Someexperiments iipon an airscrew of conventional bladesection, aerofoil R. & M. 322, No. 3, at high speeds.By G. P. Douglas, D.Sc. and W. G. A. Perring, R.N.C.( R . &M. 1174) - - - - - - - - 3 8 3

(vi) Wind tunnel tests with high tip speed airscrews. Thecharacteristics of a conventional airscrew section, 0 • 082 c.thick, and of R.A.F. 27 and R.A.F. 28. By G. P. Douglas,D.Sc. and W. G. A. Perring, R.N.C. (R. & M. 1198) - 391

(d) Performance :—(i) The effect of wind, weight and atmospheric conditions

(including semi-tropical conditions) on the distance totake-off and land an aircraft. By Flight Sergt. B. H.Rolles and H. L. Stevens, B.A. (R. & M. 1172) - - 395

(ii) The inclusion of partial glides in routine performance tests.By A. E. Woodward Nutt, B.A. (R. & M. 1180) - - 409

(iii) Determination of the twist of a wing of an aeroplane inflight. By W. G. Jennings; B.Sc. (R. & M. 1202) - - 412

(iv) Pressure plotting a streamline body with tractor airscrewrunning. By C. N. H. Lock, M.A. and F. C. Johansen,B.Sc., A.M.I.Mech.E. (R. & M. 1230) - - - - 417

(v) Skin friction and the drag of streamline bodies. ByProfessor B. M. Jones. (R. &M. 1199)- - - - 439

PAGE(e) Wing flutter :—

(i) Wing flutter experiments upon a model of a single seaterbiplane. By W. G. A. Perring, R.N.C. (R. & M. 1197) - 451

(/) Airships :—(i) The resistance of the International airship models measured

in the wind tunnel of the Royal College of Science, SouthKensington, S.W.7. By Professor F. T. Hill and T.Tanner, A.C.G.I., D.I.C. (R. &M. 1160) - - - 471

(ii) Experiments on a model of the airship R.101. By R. Jones,M.A., D.Sc. and A. H. Bell. (R. & M. 1168)- - - 480

(iii) The distribution of pressure over the hull and fins of amodel of the rigid airship R. 101, and a determination of thehinge moments on the control surfaces. By R. Jones,M.A., D.Sc. and A. H. Bell. (R. & M. 1169)- - - 507

(iv) Tests on airship models at large Reynolds numbers. ByL. F. G. Simmons, M.A., A.R.C.Sc. (R. & M. 1234) - - 544

(g) Gyroplanes :—(i) Wind tunnel experiments on a model autogyro at small

angles of incidence. By C. N. H. Lock, M.A. and H. C. H.Townend, B. Sc. (R. & M. 1154) - - - - 551

(ii) On the horizontal flight of a helicopter. By H. Glauert,M.A. ( R . &M. 1157) - - - - - - 6 1 2

(iii) A summary of the experimental and theoretical investiga-tions of the characteristics of an autogyro. By H.Glauert, M.A. and C. N. H. Lock, M.A. (R. & M. 1162) - 624

VOLUME II.Stability and Control :—

(a) Stability :—(i) Notes on longitudinal stability at stalling in gliding flight.

By S. B. Gates, M.A. (R. &M. 1189) - - - - 629(ii) The lift and pitching moment of an aerofoil due to a uniform

angular velocity of pitch. By H. Glauert, M.A. (R. & M.1216) - - - - - - - - - 6 3 6

(b) Control :—(i) Instrumental records of the lateral motions of a stalled

Bristol Fighter aeroplane. By Professor B. Melvill Jones,A.F.C., M.A., F.R.Ae.S. and Flight Lieut. C. E. Maitland,D.F.C., R.A.F. (R. &M. 1181)- - - - - 645

(ii) Full scale control tests on Fokker F. VII 3M monoplane.ByJ.K. Hardy, B.A. (R. &M. 1228) - - - - 656

(iii) The control of the Fokker F. VII 3M aeroplane. InterimReport by the Stability and Control Panel, with anAppendix giving precis of polits' reports. (R. & M. 1236) 664

(iv) Wind tunnel tests of various servo rudder systems. ByK. V. Wright, B.A. (R. & M. 1186) - - - - 669

(v) On the use of a follow up mechanism in aerodynamic servocontrol systems. By H. M. Garner, M.A. and K. V.Wright, B.A. ( R . & M . 1187) - - - - - 6 8 6

VI

PAGE(vi) The longitudinal control of an aeroplane beyond the stall.

By H. M. Garner, M.A. and K. V. Wright, B.A. (R. & M.1193) - - - - - - - - - 6 9 4

(vii) On the stability of controlled motion. By W. L. Cowley,A.R.C.Sc., D.I.C. (R. &M. 1235) - - - - 700

(c) Slots and Pilot Planes :—(i) Wind tunnel tests for design of an automatic slot for Avro

504N. By E. T. Jones, M.Eng. and K. W, Clark, B.Sc.,D.I.C. ( R . & M . 1192) - - - - - - 7 0 9

(ii) Wind tunnel experiments on the design of an automaticslot for R.A.F. 34 section. By F. B. Bradfield, Math. &Nat. Sci. Triposes, and F. W. G. Greener, B.Sc. (R. & M.1204) - - - - - - - - - 7 2 0

{iii) Wind tunnel experiments on the design of an automaticslot for R.A.F. 31 section. By F. B. Bradfield, Math, andNat. Sci. Triposes, and F. W. G. Greener, B.Sc. (R. & M.1190) - - - - - - - - - 7 3 1

(iv) Wind tunnel experiments on the design of an automaticslot for R.A.F. 28 section, and on interconnection withailerons. By F. B. Bradfield, Math, and Nat. Sci. Triposes,and K. W. Clark, B.Sc., D.I.C. (R. & M. 1165) - - 742

(v) On a method of delaying the opening of an autoslot (windtunnel experiments). By F. B. Bradfield, Math, andNat. Sci. Triposes, and R. A. Fairthorne. (R. & M. 1214) - 762

(vi) Wind tunnel tests of a R.A.F. 30 wing fitted with a self-setting slotted wing (pilot plane). By F. B. Bradfield,Math, and Nat. Sci. Triposes, and S. Scott Hall, M.Sc.( R . & M . 1225) - - - - - - - 7 6 8

(vii) Wind tunnel tests of aerofoils with pilot planes. By F. B.Bradfield, Math, and Nat. Sci. Triposes, and K. W. Clark,B.Sc. ( R . & M . 1213). - - - - - - 7 8 0

(viii) Full scale test of Bristol Fighter aeroplane with R.A.F. 30wings, fitted with " pilot planes " at the wing tips.By W. G. Jennings, B.Sc. (R. &M. 1205) - - - 806

(ix) Full scale tests of a standard Bristol Fighter aeroplane fittedwith " pilot planes " at the wing tips. By W. G. Jennings,B.Sc. ( R . & M . 1191)- - - - - - - 8 1 0

(x) Full scale experiments with a Bristol Fighter fitted withslots and flaps and slot and aileron control. By K. V.Wright, B.A. ( R . & M . 1188) - - - - - 8 1 5

(xi) Wool-tufts. A direct method of discriminating betweensteady and turbulent airflow over the wing surfaces ofaircraft in flight ; applied to explore the region of effectof the slot on a Bristol Fighter wing. By Flight Lieut.J. A. G. Haslam, D.F.C., M.C. (R. & M. 1209) - - 821

{d) Spinning :—(i) Experiments on a model of a single seater fighter aeroplane

in connection with spinning. By H. B. Irving, B.Sc. andA. S. Batson, B.Sc. (R. & M. 1184) - - - - 827

(ii) Rolling experiments on an aerofoil of R.A.F. 32 section.By H. B. Irving, B.Sc. and A. S. Batson, B.Sc. (R. & M.1182) - - - - - - - - - 8 4 6

(iii) A dash-pot for use in spinning experiments on a modelaerofoil. By T. H. Fewster. (R. &M. 1208) - - - 854

Vll

PAGEStrength of Construction :—

(i) The graphical and analytical determination of stresses insingle span and continuous beams under end compressionand lateral load with variations in shear, distributed loadand moment of inertia. By H. B. Howard, B.A., B.Sc.(R. & M. 1233) . . . . . . . 856

(ii) Loads on the main planes and tail of an aeroplane whenrecovering from a dive. By H. Bolas, B.Sc,, A.M.LC.E.and G. A. Allward of Messrs. Geo. Parnall & Co. (R. & M.1229) . . . - - - . . . 8 8 6

(iii) On the maximum load in pulling out from vertical dives.By S. B. Gates, M.A. and H. B. Howard, B.A., B.Sc.( R . & M . 1232) - - - - - - - 9 1 0

(iv) Report of the Airworthiness of Semi-Rigid Airships Sub-committee. ( R . & M . 1170) - - - - - 9 1 9

Materials :—(i) The strength of tubular struts. By Professor Andrew

Robertson, D.Sc. (R. & M. 1185) - - - - 935(ii) The behaviour of a single crystal of zinc subjected to

alternating torsional stresses. By H. J. Gough, M.B.E.,D.Sc., Ph.D. and H. L. Cox, B.A. (R. & M. 1183)- - 959

(iii) The effect of stress upon the X-ray reflections fromtungsten wire at air temperature. By H. L. Cox, B.A. andI. Backhurst, M.Sc. (R. &M. 1221) - - - - 982

(iv) Report on the drop of stress at yield in Armco iron. ByA. Robertson, D.Sc. and A. J. Newport, B.Sc. (R. & M.1161) - - - - - - - - - 9 8 6

(v) The age-hardening of some aluminium alloys. By MarieL. V. Gayler, D.Sc. and G. D. Preston, B.A. (R. & M.1220) - - - - - - - - - 9 9 3

(vi) Investigation into the proposed use of a sand cast test barfor specification purposes for aluminium alloys. By W.Rosenhain, D.Sc., F.R.S. and S. L. Archbutt, F.I.C.( R . & M . 1219) - - - - - - - - 1026

Engines :—(i) On the stiffness of crankshafts. By H. Constant, B.A.

( R . & M . 1201) - - - - - - - 1035(ii) The effective torsional rigidity of a crank. By R. V.

Southwell, F.R.S. (R. & M. 1211) - - - -1052

General :—(i) On the convection of heat from the surface of an aerofoil

in a wind current. By L. W. Bryant, B.Sc., A.R.C.Sc.,E. Ower, B.Sc., A.C.G.I., A. S. Halliday, B.Sc., D.I.C.,V.M.Falkner,B.Sc. (R.&M. 1163) - - - -"1069

vm

Index to Serial Numbers of the Technical Reports.

Report No. PAGE Report No. PAGER. &M. 1151 - 62 R. &M. 1192 - - - 709

1153 - - - 359 „ 1193 - - - 6941154 - - - 551 „ 1194 - - - 1661156 - - - 76 „ 1195 - - - 1981157 - - - 612 „ 1196 - - - 2201158 - 81 „ 1197 - - - 4511159 - 93 „ 1198 - - - 3911160 - - - 471 „ 1199 - - - 4391161 - - - 986 „ 1201 - - - 10351162 - - - 624 „ 1202 - - - 4121163 - - - 1069 „ 1204 - - - 7201164 - - - 114 „ 1205 - - - 8061165 - - - 742 „ 1206 - - - 2861166 - - - 104 „ 1208 - - - 8541167 - - - 369 „ 1209 - - - 8211168 - - - 480 „ 1210 - - - 2381169 - - - 507 „ 1211 - - - 10521170 - - - 919 „ 1212 - - - 3041171 - - - 243 „ 1213 - - - 7801172 - - - 395 „ 1214 - - - 7621173 - - - 373 „ 1215 - - - 1181174 - - - 383 „ 1216 - - - 6361175 - - - 257 „ 1218 - - - 1841176 - - - 128 „ 1219 - - - 10261178 - - - 349 „ 1220 - - - 9931179 - - - 148 „ 1221 - - - 9821180 - - - 409 „ 1223 - - - 3141181 - - - 645 „ 1224 - - - 3261182 - - - 846 „ 1225 - - - 7681183 - - - 959 „ 1226 - - - 2671184 - - - 827 „ 1228 - - - 6561185 - - - 935 „ 1229 - - - 8861186 - - - 669 „ 1230 - - - 4171187 - - - 686 „ 1231 - - - 1891188 - - - 815 „ 1232 - - - 9101189 - - - 629 „ 1233 - - - 8561190 - - - 731 „ 1234 - - - 5441191 - - - 810 „ 1235 - - - 700

1236 - - - 664

IX

MEMBERS OF THE COMMITTEE.

March, 1929.

Sir RICHARD GLAZEBBOOK, K.O.B., F.R.S. (Chairman).Sir JOSEPH PETAVEL, K.B.E., F.R.S. (Vice-Chairman)*

Professor L. BAIBSTOW, C.B.E., F.R.S.

Dr. R. FEEGiisoisr, D.Se.fMr. A. H. HALL, C.B.E., M.I.C.E., M.I.M.E.

Professor B. M. JOWES, M.A., A.F.C.

Professor F. A. LDSTDEMANN, F.R.S.

Lieut.-Colonel M. O'GOBMAN, C.B., D.Sc.

Dr. G. C. SIMPSON, C.B., C.B.E., F.R.S.

Dr. F. E. SMITH, C.B., C.B.E., F.R.S.J

Mr. R. V. SOUTHWELL, F.R.S.

Professor G. I. TAYLOE, F.R.S.

Mr. H. T. TIZABD, C.B., F.R.S.*

Mr. H. E. WIMPEKIS, C.B.E., F.R.Ae.S., M.I.E.E.

Secretary : Mr. J. L. NAYLEE.

Assistant Secretary : Mr. E. OWEB.

National Physical Laboratory,Teddington, Middlesex.

* Representing the Department of Scientific and Industrial Research,t Representing the War Office. J Representing the Admiralty.

AERONAUTICAL RESEARCHCOMMITTEE.

Report for the year 1928-29.

General Rt. Hon. The Lord Thomson, C.B.E., D.S.O.,Secretary of State for Air.

May, 1929.MY LOBD,

The Aeronautical Research Committee beg to submit their reportfor the year 1928-29.

One of the problems that has received much attention during thepast year is that of the improvement of aeroplane performance. Apublished paper (R. & M. 1199) by Professor B. M. Jones hasdrawn attention to the wide disparity between the total headresistance of an ideal aeroplane whose drag is due entirely to skinfriction and that of conventional aeroplanes of present design.Attempts to reduce this large difference constitute the object ofresearches that have already been initiated, and it is anticipated'that much of the work of the Committee in the immediate futurewill be concerned with this problem. Already a simple means hasbeen devised for decreasing the drag of aeroplanes fitted with air-cooled engines ; other experiments, although so far only of apreliminary character, have shown that it should be possible toreduce the drag resulting from the interference of different parts ofthe machine. The whole question is complicated and involves aconsideration of many collateral problems, but the Committee feelthat there is considerable scope for research in this field, and theresults already obtained justify their belief that steady pursuit ofthis line of work will have valuable consequences.

Other matters dealt with in previous Annual Reports havereached an advanced stage. Amongst these may be mentioned thelateral control of aeroplanes at low speeds ; autoslots have, forexample, been fitted to a large number of service aircraft, and arebeing fitted in increasing numbers to civil aircraft; pilot planes arein use on experimental aircraft; and various means of " spoiling "*a slot when used in conjunction with an aileron are under trial. Animportant monograph (R. & M. 1155) describing researches onflutter has been completed and is now in the press. Researches onsleeve valve engines, on engines when highly supercharged and

* By " spoiling " is implied the putting out of action of a slot which wouldotherwise be operative, thus reducing the extra stability given by an openslot and retaining a certain amount of additional control given by the freedomto open or close the slot with the aileron, as desired by the pilot.

on compression-ignition engines, have progressed favourably. TheCommittee have also to report on several researches initiated atUniversities while attention is drawn elsewhere to the considerablehelp received from individual investigators.

Equipment for Experimental Work at various Establishments.—Visits have been paid to Air Ministry establishments as follows :—

The Aeronautical Research Committee, Accidents Investiga-tion Sub-Committee, and the Stability and Control Sub-Com-mittee have visited the Royal Aircraft Establishment and theStability and Control Sub-Committee have also held a meetingat the Aeroplane and Armament Experimental Establishment,Martlesham.

Full use has been made of the experimental equipment at thevarious establishments where the researches under the care of theCommittee arc in progress, and to meet the requirements of futureresearches a need is now strongly felt for the additional apparatusmentioned below. The programme of work has been more thansufficient to keep the staffs fully occupied, but the new equipmentalready authorised is necessary to attack certain problems whicheither cannot be investigated with existing means or for which theuse of available methods is too costly.

Approval has been given for the construction of a compressedair tunnel at the National Physical Laboratory and it is expectedthat the erection of the shell to contain this tunnel will commenceduring 1929. The shell is to be 17 ft. in diameter, and will becapable of withstanding a pressure of 25 atmospheres. The modelexperiments that have been in progress at the N.P.L. show that asatisfactory tunnel 6 ft. in diameter can be constructed in the spacewithin the shell.

Further consideration has been paid to the provision of a highspeed tank at the Royal Aircraft Establishment, and it is understoodthat the details of its construction are now satisfactorily settled.

An increasing need is being felt for a large wind tunnel of about24 ft. diameter, in which can be placed a complete aeroplane bodyand engine. A study of the cooling of aeroplane engines can best bemade in such a tunnel which provides a quicker and cheaper meansthan that of flight experiment; further, many researches on im-provement of performance can only be undertaken if facilities areavailable such that small variations in shape of body, wing roots,etc., can be made on the full scale and separately measured.

Aerodynamics.—In the earlier history of the Committee allresearches on aerodynamics were co-ordinated by one Sub-Committee,but with the growth of the work some modification of this procedurebecame desirable. Special Sub-Committees are now appointed todeal with new aspects of the subject and the main work of theAerodynamics Sub-Committee during the past year has been directed

almost solely towards problems of fluid motion and to the improve-ment of performance. Some work on the latter subject has beendiscussed by the Interference Sub-Committee and mention of this ismade later. Problems on stability and control, and the flutter ofaeroplanes have been dealt with by separate Sub-Committees.

Considerable interest has been aroused by a paper by ProfessorB. M. Jones (R. & M. 1199), to which reference has already beenmade. Attention is drawn to the relation between the resistance ofstreamline bodies and the skin friction on flat surfaces both forlaminar and turbulent flow. Recognition of this relation suggests anew method of attack upon the general problem of improvement ofperformance. It has been well-known that the resistance of a modelof good aerodynamic shape is not determinable accurately at lowReynolds numbers and that, according to the tunnel in which theexperiments are made or the conditions of the water medium throughwhich the model is towed, the value of the resistance varies appreci-ably. The work of Froude, Prandtl, Burgers and Baker, on thedetermination of skin friction on flat plates indicates similar effectsat slow speeds. Some years ago the Committee published a paper,R. & M. 597, showing that the measured resistance of a model of anairship could be altered by placing in front of it a mesh of cords soas to produce artificial turbulence. It would appear that within acertain range of Reynolds number the resistance of a streamline bodyin any tunnel with a uniform velocity and direction over the experi-mental portion may vary with turbulence between the valuescalculable from laminar conditions and turbulent conditions respec-tively. Under certain conditions it is possible to obtain a curve ofresistance which, for a low Reynolds number, agrees with the resist-ance calculable on the assumption that the flow in the boundarylayer is laminar, but which rises with increasing Reynolds numberuntil the resistance is the same as if the flow were wholly turbulent.

It seems probable that " scale effect," for which an allowance hasto be made in the prediction of full scale resistance from model dataon good streamline bodies, is often due to the fact that the flow withthe model was not wholly turbulent whereas that with the full scalebody was. If this be so, it follows that predictions of this kind willbe less liable to error if the flow past the model in the wind tunnelcan be rendered sufficiently turbulent. This question of turbulence,including both the mechanism of its origin and its general effect onperformance, is considered by the Committee to be a matter ofprimary importance and to show promise of throwing new light onscale effect.

A research, whose ultimate aim is the reduction of the headresistance of aeroplanes, has been initiated on the drag of streamlinebodies as affected by the interference of a protuberance such asanother small body or a wing root attached to the surface. Prelim-inary results show that under some conditions, as, for example,when a wing is in contact with a body of circular section either at

the top or bottom surface the interference may be large ; further,the effect of a protuberance on a body is less when it is aft of themaximum section. All the experiments on these lines have up tothe present been largely of a tentative nature : a report describingthe work will be issued when the research has reached some definitepoint.

Another matter bearing on performance has been the subject ofan extensive research by Mr. L. W. Bryant and Mr. E. Ower onwing radiators, R. & M. 1163. A radiator was represented on aR.A.F.26 aerofoil by means of platinum strips, electrically heated,,extending over the central portion of the span. Each strip formedpart of a separate electrical circuit so that it was possible to findthe distribution of heat dissipation around the entire surface whenall the strips were maintained at the same temperature. Goodagreement in the overall cooling was found with the results of testsmade at the R.A.E. on the Supermarine and Gloster wing radiators.Later work shows that the portion of the wing ahead of the frontspar gives cooling per unit surface appreciably greater than for thewhole wing area ; this fact may have application for a radiator to-condense steam generated by the engine.

The improvement of performance of aeroplanes fitted withair-cooled engines has also been the subject of experiment.By placing streamline rings in front of a body with radial air-cooled cylinders it has been found possible to obtain an importantreduction in total resistance. Further researches are contemplated onthis device, which has been put forward by Mr. H. C. H. Townend(T.2670)*. At the time that this device was being perfected, adescription of another plan for reducing resistance was publishedby the U.S. National Advisory Committee of Aeronautics.f

Forms of cowling suitable for air-cooled engines will also betested in a wind tunnel and on engines on a test bed. Considerableimprovement was found possible by the use of cowling on theCrusader seaplane which was constructed to compete for theSchneider Trophy in 1927. The results of these experiments on theCrusader model will be published at a later date. It appears that theoverall drag can be greatly reduced by the use of suitable helmetsover the heads of air-cooled cylinders, and it is considered possible tobring the performance of an aeroplane with an air-cooled engine towithin a few m.p.h. of that obtained with a water-cooled engine.

Airscrews.—The mutual interference of an airscrew and a bodyhas been dealt with by Mr. C. N. H. Lock and Mr. F. C. Johansen.In one paper, R. & M. 1218, are given the results of pressure dis-tribution measurements and their connection with the mutualinterference of a tractor airscrew on a body. Good agreement i&shown with a theory outlined by one of the authors in a report,

* To be published hereafter. f N.A.C.A. Reports No. 313 and 314.

published in the previous year (see R. & M. 1120). Other papersdeal with various efficiency factors for the airscrew, and estimateshave been made of the skin friction of the body.

Further experiments have been made during the year on air-screws running at high tip speeds and the results have been published.The symmetrical section, R.A.F.27, tested at speeds of 0-8 and 0-9of the velocity of sound was found to be superior to other sections.In general, it seems that the sections should be as thin as possibleto minimise loss at high speeds. An observed increase of the slopeof the lift curve with speed can be explained on theoretical grounds(see R. & M. 1135). The ratio of lift/drag for aerofoil sections atspeeds greater than 0 • 8 of the velocity of sound has in every casebeen considerably less than at lower speeds. There still remainsoutstanding a discrepancy between the model results and thoserealised in flight, but it is hoped to clear up this matter in due course,

In parallel with this work, Professor Taylor has made experimentsemploying an electrical tank (B. & M. 1195) by means of which theirrotational flow of a compressible fluid, for which the density variesin a known manner, can be determined experimentally by the aidof the analogy with the flow of electricity in a conductor of variablethickness. The experiments, described in another paper, R. & M.1196, corresponded with speeds for which n= 0-4, 0-5, and 0-6,where n is the ratio of the velocity of the body (relative to the distantfluid) to the velocity of sound in the undisturbed fluid. The correctdistribution is sought by a process of continual trial, each determina-tion suggesting a new approximation. The successive approxima-tions were found to converge for the smallest value of n, but theprocess was divergent in the case of the B.A.F.31A wing sectionwhen n was between 0 • 5 and 0 • 65. Further experiments are con-templated to determine the nature of the flow which correspondswith the region of failure of the electrical method ; it is hoped thateither visual experiments or pressure measurements in Sir ThomasStanton's 3 in. high speed tunnel may help.

International Trials.—A report has been received from the U.S.A.on their tests in four wind tunnels of the International R.A.F.15aerofoil section. There is some variation in technique in the methodof testing models in the American tunnels and the results differ,possibly on this account. The agreement between the results obtainedwith the various U.S. tunnels is of the same order as that obtainedbetween the various N.P.L. and R.A.E. tunnels.

Fluid Motion.—Attention has been directed to the flow of fluidsnear models both from the theoretical and experimental standpoints.Several papers have been communicated on the effect of pressuredrop in a wind tunnel and this has been calculated for a flat plate,a cylinder and a streamline body. The method of correction hithertoadopted is satisfactory for the streamline body but the theoreticalarguments advanced by Professor G. I. Taylor (R. & M. 1166) suggestappreciable errors in the case of tests on forms with a bluffer shape.

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Mr. H. Glauert has shown, in R. & M. 1215, how to calculate theaccelerated motion of a cylindrical body through a fluid on theassumption that the motion is represented by a suitable distributionof vorticity over the surface. Dr. H. Lamb, in another paper, R. & M.1217, has calculated the same motion by direct methods employingonly equations of potential flow without recourse to the conceptionof a vortex.

In R. & M. 1223, Mr. A. Fage has discussed the interferenceof the walls of a two-dimensional channel on a Rankine oval placedin the stream and has, from experimental work, obtained sufficientdata for the estimation of the empirical constants used in hisanalysis.

Mr. A. Fage has also investigated the boundary layer around acircular cylinder from observations of the total head taken nearthe surface with the aid of an exceedingly small pitot tube, R. & M.1179. The distinctive characteristics of the boundary layer arefound to resemble those in the layer along a plane surface, thecritical value of the Reynolds number is of the same order as thatfound by van der Hegge Zijnen for a plane surface and there appearsto be a determinable critical point on the cylinder where a transitionfrom a laminar to a turbulent state of flow begins. From theseexperiments it would appear that the'intensity of skin friction arounda cylinder differs appreciably in value from that on a flat plate ofthe same area.

Dr. A. Thorn of Glasgow University has investigated theboundary layer on the front portion of a cylinder moving at rightangles to its axis and has compared his experimental results with asolution of certain simplified equations of the boundary layer laiddown by Professor Prandtl. He has used a method of approximationin which the mean values at the centre of the rectangles formed bystreamlines and equipotential lines are adopted for trial as a newestimate of the correct distribution and his method appears to beconvergent for the problem attacked. The agreement shown inDr. Thorn's paper between theory and experiment is satisfactory(see R. & M. 1176), and has been partly confirmed by other experi-mental results obtained at the N.P.L.

Dr. Piercy at East London College has measured the flow of airadjacent to the surface of an aerofoil at very low wind speeds (seeR. & M. 1224). Using a hot wire instrument, he has found thethickness of the boundary layer and observed the occurrence ofvorticity under a variety of conditions near the upper and lowersurfaces of the aerofoil at different angles of incidence. The conditionsunder the lower surface appeared to approximate to those of Burgersand Zijnen for a flat surface, but a region of remarkably high velocity,not yet explained, was found just under the trailing edge.

Gyroplanes.—No systematic wind tunnel or theoretical researchhas been carried out during the year on gyroplanes except in relation

to incidental matters. The construction of a gyroplane having amore rigid type of wing construction with single articulation hasbeen completed, but so far the flying tests with this craft have notbeen fully successful. The performance of the doubly articulatedgyroplane (Cierva Autogyro) has been measured, but, except forspecial purposes, it is not anticipated that this type of aircraft willprovide a serious competitor with the ordinary aeroplane owing tothe smaller rate of climb.

Stability and Control.—The routine stability and control testson all new types of aeroplane to which reference was made in theprevious Annual Report have received extensive trial on anumber of aircraft at Martlesham. It is generally agreed thatthe tests for fore and aft stability and control are satisfactory butthey might well be reduced in length. The majority of the lateraltests have, on the other hand, proved unsuitable, since the indicationswhich they give cannot be made sufficiently definite and bear littlerelation to pilots' opinions as to the merits of the respectiveaeroplanes. The Stability and Control Sub-Committee, who areco-ordinating this work, have unanimously come to the opinion thatthe next step must be the design of greatly simplified recordingapparatus. The research instruments, including recording gyroturn indicators and control movement recorders, are too complicatedfor test purposes. It is proposed to go into the question of developingmore apparatus and of the possibility of obtaining records by simplemovements of the lateral controls.

Quantitative knowledge is being accumulated on the lateralmotions of aeroplanes. Instrumental records have been taken onthe Bristol Fighter attached for research purposes to the CambridgeUniversity Air Squadron. Professor Jones has measured the lateralmotions of a stalled and unstalled aeroplane for given movements ofthe controls and the report giving the instrumental records, whichis the first of its kind, has been published (R. & M. 1181). The changein behaviour of the aeroplane in response to the movement of theailerons and rudder, as the stalling angle is approached, is clearlyshown. Similar work has been carried out at the R.A.E. on a Fokkerand on an Avro. The Cambridge work will proceed on the BristolFighter with the R.A.E. large rudder and with slots on the tips ofall four wings.

The Committee welcome steps that are being taken toimprove the research facilities at Martlesham. The additions tothe experimental equipment will accelerate items in the programmeof investigations at that Establishment, such as the development ofroutine tests for stability and control, of which mention has beenmade above, the study of fore and aft control on stalled aeroplanes,and the behaviour of aeroplanes in prolonged spins. Little workhas yet been done on the fore and aft control problem but someexperiments, in addition to the work contemplated at Martlesham,

(38956)—I B

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will be carried out at the R.A.E. An experimental study of certainderivatives which are required to determine the longitudinalstability when the attitude of the aeroplane is near the stall, willalso be undertaken at the N.P.L. on models on the Whirling Armand in the wind tunnel.

The problem presented by the aeroplane which will not come outof a long spin is still not completely understood. Various character-istics which have from time to time been cited as affecting thematter, as, for example, C. G. position, wing stagger, unshielded finarea, etc., are undoubtedly important, but the further the matter isinvestigated the more varied appear to be the types of spin whichcause trouble on different machines. Some of the dangerous spinson aircraft do not take place at very large incidences as was previouslysupposed and the whole matter is being further examined, both byexperimental work on models and by theoretical research.

Work on lateral control at the stall has continued : some furtherresearch has been conducted, but the main development in this fieldhas consisted of practical trials of autoslots, of pilot planes, and ofthe slot-and-aileron control. Autoslots have provided a means ofobtaining stability and a certain amount of control on some aircraft,but this does not appear to be generally true for all machines. Thereare doubtless other ways of obtaining satisfactory control and itmay be that the shape of the curve of lift coefficient against incidencefor the wing section is important. In order to verify this possibilityexperiments are to be made on the properties of sections having flattopped Mft curves. In parallel with work on autoslots, experimentshave been made on " pilot planes " and some reports of model andfull scale experiments have been published. The ordinary slot hasnot, up to the present, given good results on some thick wing sections,but, an alteration in the design of the auto slot or its mechanism,or the pilot plane may possibly provide a solution in this case.

Among other matters discussed may be mentioned briefly the'stability of the Pterodactyl. A peculiarity of this type of aircraftappears to be unusual fore and aft liveliness in bumps, and, toinvestigate the cause, some measurements of derivatives are to beundertaken on models ; when modified, the Mark IA aircraft will besubjected to further experiment at the R.A.E.

Servo controls are now being more extensively used on variousaircraft, but precise information as to their aerodynamic behaviouris scanty ; it is proposed to measure the relative movements of theservo and of the rudder by the aid of control position indicators soas to provide facilities for checking, on the full scale, certain con-clusions reached in a theoretical paper, R. & M. 1187. An aeroplanewith all moving tail-plane has been designed and constructed byMessrs. Vickers, and presents features which warrant experiment.

Airships.—The airworthiness of non-rigid and semi-rigid airshipshas been considered in regard to (1) the specification of those con-ditions of flight and operation which govern the design of an airship,

(2) the determination of the loading systems which will act oncomponents of the airship under the specified conditions of flight,and (3) the calculation or estimation by test of the correspondingstresses in parts of the airship with a statement of the factors ofsafety considered to be necessary.

In the published report of a special Sub-Committee (see II. & M.1170), these matters are discussed in detail. The opinion is thereexpressed that the only satisfactory method of determining theinternal pressure necessary to maintain shape in semi-rigid andnon-rigid airships is to test a scale model inverted and filled withwater in accordance with a theory published in 1911.* The watermodel tests should be made to reproduce various representativeconditions of flight with the ballonets both full and empty, in orderto ensure that the system of suspension will result in wrinkling ofthe envelope. The strength of the envelope must be such as willwithstand a certain uniform " design pressure" calculated inaccordance with the rules given in the Sub-Committee's report.

Factors of safety are laid down including a figure of 4 for thefabric in tension. Other questions such as the minimum performancefor a given duty, the correct use of gas valves and ballonets, adequatestability and control, the carrying of ballast, protection from electri-cal discharges, matters of fire prevention, and inspection of materialsand workmanship are also discussed from the airworthiness pointof view.

The general research on structure of the wind, commenced lastyear, with reference to the mooring of airships, has been continuedat Cardington by the staff of the Meteorological Office. Muchinformation has been accumulated on the variation of wind forceand direction measured simultaneously at the four anemometer maststhere erected: it includes records taken during the passing of linesqualls. A brief account of the work was given to the BritishAssociation at their 1928 meeting and it is hoped to write a reportfor publication during the coming year.

Flutter of Aeroplanes.—The flutter of aeroplane wings has beenfurther studied by Dr. Douglas and Mr. Perring at the R.A.B. bymeans of cinematograph records of a model of reduced elasticity ina, wind tunnel. This method of experiment, as described in R. & M.1197, gives a satisfactory means of investigating the problem offlutter on models of aeroplanes actually in existence, but it is notyet possible to say with certainty that the method can be applied topredict the flutter speeds of a proposed design from drawings only.

A- •*-M1) S°-ISe theorems on stresses and deformation in the envelope of adingiblemth a suggested "model" method for their determination.—H. Booth, R. & M. No. 42, March 1911, also Advisory Committee for Aero-nautics Report 1910-1911, page 30.

(2) Les etudes d'acSrodynamique du laboratoire des a<§rostiers militairesitahens.—Capt. Crocoo. La Technique Aeronautique, Vol. 3, 1911, page 329.

36956)—IB2

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Further experiments on the same model to correlate theory andexperiment are in hand to verify the application of flutter methodsfor prevention purposes.

At the N.P.L. Messrs. R. A. Frazer and W. J. Duncan, since thecompletion of their monograph (R. & M. 1155) on wing flutter, haveadvanced their theory in some directions. A certain type of biplaneflutter has proved amenable to mathematical treatment; also allow-ance can now be made for the influence of the mobility of the fuselage.Problems associated with tail flutter are also receiving attention.Further papers describing this work will be published shortly.

Seaplanes.—Progress in full scale work at the Felixstowe AirStation has been slow owing to the number of other duties whichthis Station has had to undertake. It is, however, hoped thatin the future more research will be carried out, especially in co-operation with tests in the new high speed tank to be laid down atthe R.A.E.

Experiments have been made on a method of measuring thewater speed of seaplanes. There are some difficulties in takingsimultaneous bearings from two shore stations but as a first approxi-mation the method may be considered satisfactory. It has beenrecommended that, to measure taking-off speed when the accelerationmay be large, suitable photographic methods be developed forrecording both speed and acceleration. For measurement of thespeeds of racing craft camera guns have been successfully used.

A paper discussing the effect of wind on the take-off of seaplanesconcludes that heavily loaded seaplanes should not attempt totake-off except in a wind of a velocity greater than 0 • 2 of the take-offspeed ; a method for calculating the take-off in different winds islaid down.

Resistance and porpoising measurements have been made on aValentia model and satisfactory agreement has been obtainedbetween tests made at the N.P.L. and in the Vickers tank atSt. Albans.

The Fairey IIIF seaplane has been adopted as the standardmachine for seaplane research and one seaplane of this kind hasbeen allocated to the Felixstowe Station specially for researchwork. A model of this type will also be used for wind tunnelresearch for experiments on spinning. The research aircraft will bedevoted, in the first instance, to the development of research methodsand of instruments for future full scale work.

Engines.—The more important matters dealt with by the EngineSub-Committee have been the Torsional Vibration of Crankshafts,the Compression-Ignition Engine, Fuel Consumption and Air-cooled Cylinder and Cowling Research.

At Cambridge University a number of crankshafts have beensubjected by Mr. H. Constant to static torsional tests out of bearings,and a rational formula for the stiffness of a crankshaft in these

11circumstances has been based on the results. From torsion testson crankshafts in their crankcases an estimate of the ratio of stiffnessin bearings to stiffness out of bearings has also been obtained. Theformula for the crankshaft stiffness gives results which do not divergefrom experimental results by more than 7 per cent, for shapes ofreasonable proportions; the application of the formula to theestimation of resonance speeds is awaiting further experimentalconfirmation at the present time. The important conclusionsreached by this investigation have been published as R. & M. 1201.Experiments are being made as opportunity offers, by the staff of theRoyal Aircraft Establishment on the synchronous speeds of as manyengines as possible, in order to test the accuracy of the data now attheir disposal.

Many aspects of the compression-ignition engine have beendiscussed. Messrs. Ricardo have informed the Committee of progressof research on 4-cycle and 2-cycle units of this kind which employa sleeve-valve design of cylinder. The effect of rate of air swirl inthe cylinder upon ease of starting, smoothness of running, poweroutput, etc., have been investigated and satisfactory performanceis now being obtained with both types of experimental unit.It is considered that research on this type of compression-ignitionengine has now been carried to the point at which it can be said thatit shows good promise of successful development in the form of acomplete engine.

In regard to petrol operated sleeve-valve engines, Messrs. Ricardoare exploring the possibilities of small cylinders combined with veryhigh rotational speeds. It has been found possible to maintainhigh mean effective pressures up to 5,000 r.p.m. without super-charging. Further tests are to be made under supercharged conditions.

Squadron Leader Helmore has carried out a series of experimentsat Cambridge on a water cooled aero-engine using (1) a gas fueland (2) a combination of gas and liquid fuels and two reports havebeen received from him. These are supplementary to reports onearly work with the single cylinder variable compression engine.The Sub-Committee have been informed that preparations are in handfor further work on the use of combined gaseous and liquid fuels.

The difficult problem of designing a petrol flowmeter which willbe sufficiently accurate under all conditions of temperature andaltitude has been successfully solved by the staff at the R.A.E., andaccurate measurement of fuel consumption in the air is now possible.The use of flowmeters in a R.A.F. Squadron flying in formation hasshown that it is possible to effect a large reduction in the averagerate of petrol consumption and at the same time reduce very muchthe wide differences in consumption between aircraft flying in thesame formation, which had previously been observed. Attention isnow being directed towards a means of providing automatic com-pensation of fuel-air mixture strength under all conditions of heightand throttle setting.

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The question of detonation has been briefly discussed in connectionwith work at the N.P.L. and the Air Ministry Laboratory. Someresearch work at the latter establishment has had as its object aroutine method of standardising aero-engine fuels with respect totheir anti-knock values.

Engine cooling has been discussed mainly in relation to thefact that the use of air-cooled cylinders involves a large amount ofaerodynamic drag, and mention of work bearing on this problemwill be found elsewhere. A series of experiments is included in theresearch programme at the R.A.E. in which wind tunnel experimentsupon models of engine cowling designed to reduce drag will becorrelated with engine cooling experiments on the test bed, and laterwith the engine in flight with a view to providing a form ofcowling which gives low drag combined with adequate cooling.

Elasticity and Fatigue.—Previous work carried out by Dr. H. J.Gough at the N.P.L. on the fatigue properties of single crystals ofmetals including aluminium and iron, has been concerned with metalsconforming to the face centred and to the body centred cubic latticestructure. The next stage in the research has been on a crystal ofzinc representing a hexagonal lattice and a report, R. & M. 1183,describing this work has been offered to and published by the RoyalSociety. The work was critical in that German investigators hadshown that the most important slip plane in zinc is the basal plane,i.e., that of maximum atomic density, and had suggested that theprismatic planes were slip planes. Dr. Gough applied stress to thezinc specimen so that it was greater on a prismatic plane than onthe basal plane and he showed definitely that under the fatiguestressing of the type investigated the only slip plane operative wasthe basal plane. The twinning plane of zinc has also been identifiedand a considerable amount of evidence has been accumulated re-garding the mode of formation of such twins. It seems possible thattwinning is a possible mode of mechanical deformation related to thefundamental problems of fatigue to which the Committee have beenpaying attention ; the subject will be further investigated.

At the R.A.E. some progress has been made by Dr. A. A. Griffithand Mr. B. Lockspeiser on their theory of the polyphasic structure ofmetals. As a result of a discussion on the phase theory of theseworkers, the nature of the X-ray reflections obtained from a singlecrystal under elastic straining has been investigated at the N.P.L.and the report R. & M. 1221 describing the experiments has beenoffered to and published in the Philosophical Magazine. The experi-ments failed to detect any broadening of the X-ray pattern due toelastic straining.

The Committee attach great importance to the investigation ofthe causes of fatigue in the presence of corrosive agents. Dr. D. J.McAdam of the United States Naval Experimental Station has beencarrying out much experimental work on this subject during the

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past three years and the Committee are in touch with him. Thereare certain aspects of corrosion fatigue which still need investigation,such as the exclusion of oxygen from the specimen, the variation ofturbulence of the water stream, etc.

Under the direction of Professor C. F. Jenkin at Oxford University,Mr. Lehmann has carried out an interesting research on the effect offrequency of alteration of stress on the fatigue limit of various metals,and his important paper, R, & M. 1222, dealing with this work hasbeen offered to the Royal Society, The experiments were made withthe aid of a blower and resonating chambers giving an air blast whichvibrated a small specimen and imposed in this way stresses atfrequencies up to 20,000 per second. A similar method of inducingalternating stress has been in use at the Bureau of Standards,Washington, but the frequency was appreciably less. The fatiguelimit was found to increase with the frequency, the increasereached a maximum of about 60 per cent, rather before the highestfrequency was attained, after which the limit began to decrease. Upto the present no method has been devised, except that of an airblast, for producing stresses at such high frequencies.

A new problem has recently been raised by the Aircraft Industryas to the strength of panel bracings for the fuselages, etc., of aircraftand the conditions under which failure occurs. It is proposed tocommence experiments on the conditions and manner of failure ofrectangular duralumin panels clamped in a pin-jointed frame andsubjected to shearing forces, the object of the tests being to deter-mine, in the first place, the manner of failure ; and, if failure byinstability is encountered, to investigate the conditions governingthis instability.

Alloys—It is now a matter of common knowledge that testresults from chill cast test bars of aluminium alloys are high com-pared with the mechanical properties of castings formed in a sandmould, and preliminary experiments have been made at the N.P.L.on the use of sand cast test bars for aluminium alloys. The first resultsof this work (R. & M. 1219) are being published and it is now proposedto carry out sufficient work to enable the British EngineeringStandards Association to adopt sand cast test bars as a standard inplace of the chill cast test bars at present used.

The period of soaking chill cast test bars of Y-alloy to get increasedtensile strength has been the subject of experiments at the N.P.L.It was hoped that if this period of soaking could be shortenedwithout loss of strength to the material, the cost of productionwould be cheapened, but the general conclusion reached is that it isnot desirable to shorten the period at present employed (A.41).*

The age-hardening of some aluminium alloys has been fullystudied by Dr. Marie Gayler at the JST.P.L., and a paper (R. & M.1220) which is being published represents a definite advance in the

* Unpublished.

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study of this subject by co-ordination of results from mechanicaltests, from physical properties, and from X-ray analysis. Thetheories agree in showing that during ageing precipitation from thesolid solution is taking place, and afford confirmation that hardeningis due to the precipitation of widely dispersed particles in the formof minute crystallites.

In work described in the'previous Annual Report the beneficialeffect of tempering Y-alloy at low temperatures had been demon-strated (E. & M. 1038) : this tempering was limited to 150° C.Further work shows that tempering at 200° C. produces superiortensile strength and hardening accompanied by slightly diminishedductility, but still higher tempering temperature results in a seriousreduction of the elongation.

The variation of elastic modulus by heat-treatment has beeninvestigated for a 3 per cent, copper beryllium alloy. In a report(T.2733)* on this matter, it is shown that the variation claimed inthe value of the rigidity modulus caused by heat-treatment, issubstantially confirmed; it appears probable that the cause of thevariation is the separation of a phase in the alloy.

Much attention has been paid to the possible use of magnesiumand its alloys in aircraft and aircraft engines. The Committee havebeen in close toiich with the Society of British Aircraft Constructorson this matter, and it would appear that, provided the question ofcorrosion can be overcome, the use of these alloys in place ofduralumin (even on the assumption that their strength in castingsis not more than two-thirds that of duralumin) would still result in anappreciable decrease in weight of the whole aircraft and a consequentimprovement in performance. The Committee are of opinion thatin addition to the prevention of corrosion, work is needed on themechanical properties of magnesium alloys, and a special programmeof work on these alloys will be put in hand at the N.P.L. during thenext year with the approval of the Department of Scientific andIndustrial Research.

Air Transport.—The Committee welcome the policy of theDirector of Civil Aviation in issuing to designing firms draftspecifications of different types of aircraft considered desirable forfuture development. The encouragement thus provided to designersmay result in important developments. A number of suchspecifications has been communicated to the Committee anddiscussed by them during the year ; amongst others one relating toa high speed aircraft intended to carry mails and to be capable offlying without a stop from the home aerodrome to most of theEuropean Capitals. Discussion of the amenities for travel in variousaeroplanes and the disturbance caused to the population nearaerodromes has led to the formation of a Sub-Committee to discussaircraft noise.

* Not published.

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Aircraft Noise.—In view of the importance of the matter of noise,researches are contemplated which will be directed towards itsreduction both to the passengers in the cabin of a civil aircraft•and to persons living in the neighbourhood of aerodromes. Thenoise given out by an aeroplane may be due to a variety of causesincluding the airscrew, engine exhaust, engine clatter, stay wires,etc. There is some evidence that certain types of civil aircraft aremore silent than others, but the views of individual observers differgreatly except in agreeing that most noise is experienced in theplane of the airscrew disc ; there is some evidence that, as might beexpected, the airscrew tip speed may be a factor.

The Committee have in mind the carrying out at an early dateof measures of noise reduction by the use of airscrews of differentdiameter but absorbing the same power and having widely differenttip speeds. Other experiments are being begun on the ground withairscrews designed hi accordance with the existing theories. Effectiveexhaust silencers though easily constructed for engine test bedexperiments, are not readily adapted for aeroplanes in normal use ;attention is accordingly being directed to the best form of diminishingthe noise from the exhaust. Engine clatter and stray noises fromstruts and wires and reflections from wings may be important, butit is not possible at the present time to say how far this can becontrolled or minimised. The Committee will also consider meansof making the cabins as silent as possible wi bh the least increment ofweight.

Progress on the above lines of attack involves the preparation ofinstruments to measure the noise given out by the aeroplane. Inco-operation with the Air Defence Experimental Establishment ofthe War Office and with a member of the staff of the BritishBroadcasting Corporation, the N.P.L. hope to develop certain typesof instruments for noise measurement. These will later be used onactual aircraft and in various flying and other experiments by theRoyal Aircraft Establishment, and by both staffs in relation tocivil aircraft.

Personnel.—The Secretary of State for Air attended the Decembermeeting of the Committee and the Air Member for Supply andResearch, Air Marshal Sir John Higgins, K.C.B., K.B.E., D.S.O.,A.F.C., has usually been present and has assisted the Committee.The personnel of the Aeronautical Research Committee has remained^altered, as the two unofficial members due to retire in 1928 were

re-nominated by the Air Ministry for a further term of threeyears.

After consultation with the Aeronautical Research Committee,the Air Council have expressed their intention of arranging nextvear that the retiring unofficial members shall not, except in special•ircumstances, be re-nominated until after a period of one year

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has elapsed. The Committee have welcomed this procedure as ameans of introducing a wider circle of scientific men to aeronauticalproblems.

One change has been made in official representation by theadditional nomination of Mr. A. H. Hall, C.B.E., M.I.C.E., M.I.M.E.,Chief Superintendent of the Royal Aircraft Establishment, Farn-borough, as a member of the Committee.

Changes have been made in the personnel of Sub-Committees andPanels and a list of members of bodies which have been activeduring the year is appended. The general procedure to whichreference was made last year has been continued.

Sub-Committees.—The following Sub-Committees and Panelshave met during the year :—Accidents Investigation, Aerodynamics,Aircraft Noise, Airscrew, Alloys, Air Transport, Airworthiness ofSemi-Rigid Airships, Compressed Air Tunnel, Elasticity and Fatigue,Engine, Flutter, Interference, Kite Balloon Accident, Large WindTunnel, Load Factors, Relations with Industry, Royal AircraftTank, Seaplane, Stability and Control, Torsional Vibration ofCrankshafts, University Research, Vortex.

Amongst the work of the new bodies may be mentioned thefollowing:—The Airworthiness of Semi-Rigid Airships Sub-Committee appointed at the request of the Air Council have discussedthe general question of airworthiness of both semi-rigid and non-rigid airships, and their report, R. & M. 1170, follows the generallines of an earlier report on the airworthiness of rigid airships (seeR. & M. 970). The Sub-Committee completed their work duringthe year and have been dissolved.

A Sub-Committee appointed to consider matters in connectionwith the construction of a high speed tank at the R.A.E. have drawnattention to its more important scientific aspects. Questions affectingthis matter and the type of carriage for towing the model have beendiscussed with the Director of Scientific Research and with theDirector of Works and Buildings of the Air Ministry and theirstaffs.

A small body has been appointed to consider whether a largewind tunnel should be built to hold a full size body of an aeroplaneand what will be the advantages to be gained thereby. This bodyhas not yet reported.

Anew Load Factors Sub-Committee have been appointed to discussthe effects of the increasing speeds of aircraft on the stresses inducedduring certain manoeuvres, in particular, the pull out from a dive.Their attention will be mainly directed to service aircraft, althoughcertain matters affecting civil aeroplanes will be discussed. It isexpected that this Sub-Committee will bring up to date much of thematter given in the previous reports on load factors published bythe A.R.C.

17

A small body was appointed to discuss an accident to a specialform of kite balloon and, after the acceptance of the report of theSub-Committee by the Air Council, was dissolved.

During the year the Director of Civil Aviation brought to theattention of the Air Transport Sub-Committee the importance ofreducing the noise of civil aircraft and, as already mentioned, anAircraft Noise Sub-Committee have been specially appointed toi- onsider various matters.

At the request of the Air Council an Airship Stressing Sub-Com-mittee have been appointed to revise existing methods of stressing,i matter previously dealt with in the publication R. & M. 800,which is to be brought up to date in the light of further experiencegained in the design of airships.

The following bodies have completed their Terms of Referenceand have been dissolved during the year :—

Airworthiness of Semi-Rigid Airships Sub-Committee.Kite Balloon Accident Sub-Committee.Compression-Ignition Panel.Vortex Panel.

Finance.—The financial arrangements for the work of theCommittee have remained as in previous years. All research workhaving a direct application to aeronautics is financed by the AirMinistry. The cost of investigations which, in addition to theirimportance to aeronautics, have applications in a wider sphere ismet by the Department of Scientific and Industrial Research.

Researches at Universities and Grants to Individual ResearchWorkers.—The Committee have not previously drawn attention tothe foundation by the Armourers and Braziers Company of aFellowship in Aeronautics of £300 per annum tenable for two yearsat a university. The Company have invited the A.R.C. to nominatethree members to the Executive Committee controlling this fellow-ship and, in accepting, the A.R.C. have expressed their appreciationof the action thus taken to promote progress in aeronautical science ;the Secretary of State for Air has also expressed approval ofthe object in view. The first student, Mr. P. B. Walker, holding thefellowship is assisting Professor B. M. Jones at CambridgeUniversity.

The special fund available to the Committee for work by individualinvestigators has been used for a number of researches, some ofwhich have already been mentioned; the others are referred tobelow.

At Cambridge University, Mr. H. Constant has completed hiswork on the torsional rigidity of crankshafts. Professor B. M. Jonesand Mr. W. S. Farren are continuing their experiments in the smallwater tank and in the small wind tunnel now available.

18

Professor G. I. Taylor has completed the first stage of his workon the electrical tank to find the effect of the compressibility offlow past an aerofoil section corresponding to flow past airscrewsat high tip speeds.

Mr. R. V. Southwell has continued his work on the stability offluid motion and, with the assistance of Miss L. Chitty, has recentlycommunicated an important paper summarising the results he hasreached to date. (See R. & M. 1200.)

Squadron Leader Helmore has carried out further researches onthe use of gaseous fuels in airship engines and of safety devices inconnection therewith.

Professor L. Bairstow, at the Imperial College, South Kensington,is continuing researches on skin friction on a surface ; he has alsocompleted the construction of the water tank to which reference wasmade in the previous Annual Report.

Professor D. Hanson continues his work on fatigue at BirminghamUniversity in co-operation with the N.P.L.

Professor C. F. Jenkin at Oxford University is undertakingsome work on corrosion fatigue.

At the invitation of the Committee, Professor Andrew Robertsonwill commence, during the coming year, a research on the torsionof steel tubes as used in aeroplane construction.

Professor A. J. Sutton Pippard, at Bristol University, has nowreached a stage in his theoretical investigations in which he canhope to get useful experimental data from aeroplane wheels. Agrant has been made to him for apparatus.

Publications,—The procedure adopted in previous years for pub-lications has been continued and a list of the papers published bythe Committee is appended. Mention is made also of papers offeredto and published by the Royal Society.

Exchange of publications with several foreign aeronauticalinstitutions has been continued. The A.R.C. have invited co-opera-tion with workers abroad and several visits have been made to theN.P.L. to discuss researches of common interest.

Relations with Industry.—During the year the Committee haveheld two formal and two informal meetings with representatives ofthe Society of British Aircraft Constructors, at which the programmeof research as affecting the aircraft industry has been discussed. Toobtain closer contact with the technical side the Society have pro-posed that in future, in addition to their ordinary representatives,three members of their Technical Committee should attend jointmeetings. The A.R.C. in acceding to this request have expressedtheir pleasure in this further co-operation.

One of the pressing matters that have come forward is the needfor additional experimental facilities, and the Society have expressed

19

their desire for rapid progress in the construction of the CompressedAir Tunnel at the N.P.L. and the High Speed Tank at the R.A.E. :both these matters are proceeding. The Society are strongly infavour of the construction of a large wind tunnel in which completebodies of aeroplanes can be tested. The Committee hope that somearrangements may prove possible whereby, if such a tunnel beconstructed, the aircraft industry should assist towards the cost ofits maintenance and running.

A few visits to firms have been made by members of theCommittee. The Secretary of the Committee and various membersof the N.P.L. staff have from time to time discussed with firms'i epresentatives problems of interference, the reduction of the dragof air-cooled engines, fatigue problems, and model experiments onthe seaplanes that will compete for the Schneider Trophy in 1929.This co-operation is additional to the close contact maintained by theAir Ministry between its research staffs and aircraft designers.

U.S. National Advisory Committee for Aeronautics.—Many mem-ber's of the Committee welcomed the opportunity of meeting Dr.( ' . W. Lewis, Director of Aeronautical Research, during his visit toEngland in the autumn of 1928 and of discussing informally withhim a number of matters of interest to both countries. Cordialrelations continue between the National Advisory Committee forAeronautics and the Aeronautical Research Committee, and theA.R.C. have to thank the N.A.C.A. for assistance on certainsubjects on which there is available in U.S.A. a greater body ofinformation than in this country. For example, the effect ofaccelerations on a pilot is receiving close attention in Americaand accelerations much greater than those experienced in thiscountry have been measured, especially during pulling outfrom dives. Two exchanges of instruments have taken place : athree-axes linear accelerometer and an angular velocity recorderhave been sent from the N.A.C.A. in exchange for a force recordingrudder bar and a force recording control column. A R.A.F.31aerofoil and a model of the Hornbill with A.D.I wing section are tobe tested in the U.S. Variable Density Wind Tunnel in relation toproblems of control at and near the stalling angle. The experiencesin America with wheel brakes and the use of magnesium alloys inaircraft are also matters upon which correspondence has taken place.

Signed on behalf of the Committee,

R. T. GLAZEBROOK,Chairman.

20

The following reports have been approved for publication duringthe year and can be obtained from. ELM. Stationery Office :—

R. &M.No. Title. Author.

1165

1171

1175

1202

12031206

1209

1212

1216

1223

1224

1226

1153

1167

1173

1174

AERODYNAMICS.

AEBOEOILS AND WING SECTIONS.Wind tunnel experiments on the design of

an automatic slot for R.A.F.28 sectionand on interconnection with ailerons.

The theoretical relationships for an aerofoilwith a multiply hinged flap system.

An analysis of a rectangular monoplanewith hinged tips.

Determination of the twist of a wing of anaeroplane in flight.

Pressure distribution over a yawed aerofoilWind tunnel experiments with infinite

cascades of aerofoils.Wool-tufts. A direct method of discrimin-

ating between steady and turbulentairflow over the wing surfaces of aircraftin flight applied to explore the region ofeffect of the slot on a Bristol Fighter.

Preliminary tests on the effect on the liftof a wing of the position of the airscrewsrelative to it.

The lift and pitching moment of an aero-foil due to a uniform angular velocity ofpitch.

On the two dimensional flow past a bodyof symmetrical cross section mounted ina channel of finite breadth.

On the flow of air adjacent to the surfaceof an aerofoil.

The characteristics of a tapered andtwisted wing with sweep-back.

AIBSCBEWS.Experiments with the family of airscrews

in free air at zero advance.Photographs of streamers illustrating the

flow around an airscrew in the VortexRing State.

Full scale determination of the effect ofhigh tip speeds on the performance ofan airscrew.

Wind tunnel tests with high tip speed air-screws. Some experiments upon anairscrew of conventional blade sectionaerofoil R. & M. 322, No. 3 at high speeds,

Bradfield and Clark.

Perring.

Gates.

Jennings.

Williams.Harris and Fairthorne.

Haslam.

Bradfield.

Glauert.

Fage.

Piercy andRichardson.

Glauert and Gates.

Townend, Walker andWarsap.

Lock.

Jennings.

Douglas and Perring.

21

R. & M.Xo.

1178

1198

1172

1180

1199

1230

1154

11571162

1181

1182

1184

use11S7

11SS

lisa1190

Title.

AERODYNAMICS—continued.

AIRSCREWS—continued,

The change in airscrew characteristics withheight.

Wind tunnel tests with high tip speedairscrews. The characteristics of a con-ventional airscrew section 0.082C and ofB.A.F.27 and B.A.F.28.

PERFOBMANCE .The effect of wind, weight, and atmos-

pheric conditions, including semi-tropi-cal conditions, on the distance to takeoff and land an aircraft.

The inclusion of partial glides in routineperformance tests.

Skin friction and the drag of streamlinebodies.

Pressure plotting a streamline body withtractor airscrew running.

ATTTOGYBOS AND HBLICOPTBBS.Wind tunnel experiments on a model auto-

gyro at small angles of incidence.On the horizontal flight of a helicopter ...A summary of the experimental and

theoretical investigations of the charac-teristics of an autogyro.

STABILITY AND CONTBOL.Instrumental records of the lateral motions

of a stalled Bristol Fighter aeroplane.Boiling experiments on an aerofoil of

B.A.F.32 section.Experiments on a model of a single seater

fighter aeroplane in connection withspinning.

Wind tunnel tests of various servo ruddersystems.

On the use of a follow up mechanism inaerodynamic servo control systems.

Full scale experiments with a BristolFighter fitted with slots and flaps andslot and aileron control.

Notes on longitudinal stability at stallingin gliding flight.

Wind tunnel experiments on the design ofan automatic slot for B.A.F.31 section.

Author.

Nutt.

Douglas and Perring.

Bolles and Stevens.

Nutt.

Jones.

Lock and Johansen.

Lock and Townend.

Glauert.Glauert and Lock.

Jones and Maitland.

Irving and Batson.

Irving and Batson.

Wright.

Garner and Wright.

Wright.

Gates.

Bradfield andGreener.

22

R. &M.No.

1191

1192

1193

1204

1205

1213

12H

1225

1228

12351236

1229

1232

1233

1151

1156

1158

1159

Title.

AERODYNAMICS—continued.

STABILITY AND CONTROL—continued.Full scale tests of a standard Bristol

Fighter aeroplane fitted with " pilotplanes " at the wing tips.

Wind tunnel tests for design of an auto-matic slot for Avro 504 N.

The longitudinal control of an aeroplanebeyond the stall.

Wind tunnel experiments on the design ofan automatic slot for R.A.F.34 section.

Full scale testa of Bristol Fighter aeroplanewith R.A.F.30 wings, fitted with ''pilotplanes " at the wing tips.

Wind tunnel tests of aerofoils with pilotplanes.

On a method of delaying the opening ofan autoslot (wind tunnel experiments).

Wind tunnel tests of a R.A.F.30 wingfitted with a self-setting slotted wing(Pilot plane).

Full scale control tests on Fokker F. VII-3 M monoplane.

On the stability of controlled motionThe control of the Fokker F. VII-

3 M aeroplane. Interim report by theStability and Control Panel withappendix.

LOAD FACTOBS.Loads on the main planes and tail of an

aeroplane when recovering from a dive.On the maximum load in pulling out from

vertical dives.The graphical and analytical determina-

tion of stresses in single span andcontinuous beams under end compres-sion and lateral load with variations inshear, distributed load and moment ofinertia.

FLUID MOTION.The characteristics of a Karman vortex

street in a channel of finite breadth.On the flow of a compressible fluid past an

obstacle.The effect of the static pressure gradient

on the drag of a body tested in a windtunnel.

A theoretical estimate of the pressuregradient in a wind tunnel.

Author.

Jennings.

Jones and Clark.

Garner and Wright.

Bradfield andGreener.

Jennings.

Bradfield.

Bradfield.

Bradfield andScott Hall,

Hardy.

Cowlev.S. & C. Panel.

Bolas.

Gates and Howard.

Howard.

Glauert.

Lamb.

Glauert.

Glauert.

23

R. &M.No. Title. Author.

1164

1166

1176

1179

1194

1195

1196

1210

1216

1218

1231

11551177

1197

1207

1160

1168

1169

AERODYNAMICS—continued.

FLUID MOTION—continued.Note on the forces experienced by

ellipsoidal bodies placed unsymmetri-cally in a converging or diverging stream.

The force acting on a body placed in acurved and converging stream of fluid.

The boundary layer of the front portion ofa cylinder.

The airflow around a circular cylinder inthe region where the boundary layerseparates from the surface.

An investigation of fluid in two dimen-sions.

A mechanical method for solving problemsof flow in compressible fluids.

Report on progress during 1927-28 in thecalculation of the flow of a compressiblefluid, and suggestions for further work.

On the effect of air compression on dragand pressure distribution in cylinders ofinfinite aspect ratio.

The accelerated motion of a cylindricalbody through a fluid.

The hydrodynamic forces on a cylindermoving in two dimensions.

The skin friction on a circular cylinder ...

WING FLUTTER.The flutter of aeroplane wingsA brief survey of wing flutter with an

abstract of design recommendations.Wing flutter experiments upon a model of

the Gloster Gamecock.The coupled longitudinal and wing oscilla-

tions of a monoplane.

AIRSHIPS.The resistance of the International Airship

models measured in the wind tunnel ofthe Royal College of Science, SouthKensington, S.W.7.

Experiments on a model of the airshipR.101.

The distribution of pressure over the hulland fins of a model of the rigid airshipR.101 and a determination of the hingemoments on the control surfaces.

Lamb.

Taylor.

Thorn.

Fage.

Thorn.

Taylor and Sharman.

Taylor and Sharman.

Stanton.

Glauert.

Lamb.

Fage.

Frazer and Duncan.Frazer and Duncan.

Perring.

Frazer and Duncan.

Hill and Tanner.

Jones and Bell.

Jones and Bell.

(38956)—I

R. & M.No.

1170

1234

12011211

1152

1161

1183

11851219

1220

1221

1222

1163

1208

Title.

AIRSHIPS — continued.Report of the Airworthiness of Semi-Rigid

Airships Sub-Committee.Tests on airship models at large Reynolds

numbers.

ENGINES.Report on the Stiffness of Crankshafts . . .The effective torsional rigidity of a crank

MATERIALS.Stresses in a plate bounded by a Hyper-

bolic cylinder.Report on the drop of stress at yield in

Armco Iron.The behaviour of a single crystal of zinc

subjected to alternating torsional stresses.The strength of tubular strutsInvestigation into the proposed use of a

sand cast test bar for specificationpurposes for aluminium alloys.

The age hardening of some aluminiumalloys.

The effect of stress upon the X-rayreflections from tungsten wire at airtemperature .

High Frequency Fatigue ...

GENERAL.On the convection of heat from the surface

of an aerofoil in a wind current.

A dash pot for use in spinning experimentson a model aerofoil.

Author.

_

Simmons.

Constant.Southwell.

Griffith.

Robertson andNewport.

Gough and Cox.

Robertson.Rosenhain and

Archbutt.

Gayler and Preston.

Cox and Backhurst.

Lehmann.

Bryant, Ower,Halliday andFalkner.

Fewster.

The following reports have been accepted by the Royal Society :—

Title. Author.

The behaviour of a single crystal of zinc subjected Gough.to alternating torsional stresses.

The strength of tubular struts ... ... ... Robertson.A mechanical method of solving problems of flow Taylor and

in compressible fluids. Sharman.High Frequency Fatigue ... ... ... ... Jenkin and

Lehmann.

•25

MEMBERSHIP OP SUB-COMMITTEES AND PANELS.

March, 1929.

Accidents Investigation Sub-Committee.—Lieut.-Colonel M.O'GORMAN, C.B., D.Sc. (Chairman) ; Professor L. BAIRSTOW,C.B.E., F.R.S. ; Mr. G. B. COCKBTJRN, O.B.E. ; Professor B. M.JONES, M.A., A.F.C. ; Professor A. J. STJTTON PIPPARD, M.B.E.,D.Sc. ; Major J. S. BUCHANAN, O.B.E., Major J. P. C. COOPER,M.C., O.B.E., and Captain F. ENTWISTLE (representing the AirMinistry) ; Squadron Leader J. NOAKES, A.F.C., M.M. (representingthe Directorate of Scientific Research) ; Sir J. E. PETAVEL, K.B.E.,F.R.S. (representing the National Physical Laboratory) ; withthe Chairman of the A.R.C. (ex officio).

Aerodynamics Sub-Committee.—Professor L. BAIRSTOW, C.B.E.,F.R.S. (Chairman); Mr. W. S. FARREN, M.A., M.B.E.; Professor B. M.JONES, M.A., A.F.C. ; Dr. H. LAMB, F.R.S. ; Lieut.-ColonelM. O'GORMAN, C.B., D.Sc. ; Professor A. J. STTTTON PIPPARD,M.B.E.. D.Sc. ; Mr. R. V. SOTJTHWELL, F.R.S. ; Professor G. I.TAYLOR, F.R.S. ; Dr. H. C. WATTS, D.Sc. ; Major J. S. BITCHANAN,O.B.E., Mr. R. S. CAPON, B.A., F.R.Ae.S., Mr. H. GLATJERT, M.A.,F.R.Ae.S., Mr. H. L. STEVENS, B.A., and Mr. R. McKiNNON WOOD,O.B.E., B.A., A.M.I.C.E., F.R.Ae.S. (representing the Directorateof Scientific Research) ; Sir J. E. PETAVEL, K.B.E., F.R.S.,Mr. E. F. RELF, A.R.C.Sc., and Mr. A. FAGE, A.R.C.Sc., D.I.C.(representing the National Physical Laboratory) ; with theChairman of the A.R.C. (ex officio).

Aircraft Noise Sub-Committee.—Lieut.-Colonel M. O'GoRMAN;C.B., D.Sc. (Chairman) ; Professor B. M. JONES, M.A., A.F.C. ;Major R. H. MAYO, O.B.E., M.A., A.M.I.C.E., F.R.Ae.S. ; CaptainA. G. D. WEST, M.A., B.Sc. ; Mr. R. S. CAPON, B.A., F.R.Ae.S.,and Mr. R. J. GOODMAN CROUCH, O.B.E., F.R.Ae.S., M.I.Ae.E.(representing Directorate of Scientific Research) ; Dr. A. H. DAVIS,D.Sc. ; and Dr. G. W. C. KAYE, O.B.E., D.Sc., F.Inst.P. (re-presenting the National Physical Laboratory); Dr. W. S. TUCKER,D.Sc. (representing the War Office) ; with the Chairman of theA.R.C. (ex officio).

(Secretary : Dr. A. H. DAVIS.)

Airship Co-ordinating Sub-Committee.*—Mr. H. T. TIZARD,C.B.. F.R.S. (Chairman) ; Professor L. BAIRSTOW, C.B.E., F.R.S. ;Mr. R. V. SOITTHWELL, F.R.S.

* This Sub-Committee has been dissolved.

26

Air Transport Sub-Committee.—Lieut.-Colonel M. O'GoRMAX,C.B., D.Sc. (Chairman) ; Professor L. BAIRSTOW, C.B.E., F.E.S.;Professor B. M. JONES, M.A., A.F.C. ; Major R. H. MAYO, O.B.E.,M.A., A.M.I.C.E., F.R.Ae.S. ; Rear-Admiral M. F. STJETER, R.N.,C.B., M.P. ; Air Vice-Marshal Sir W. SEFTON BRANCKER, K.C.B.,A.F.C., and Major J. S. BUCHANAN, O.B.E., F.R.Ae.S. (representingthe Air Ministry) ; Sir J. E. PETAVEL, K.B.E., F.R.S.(representing the National Physical Laboratory) ; with the Chairmanof the A.R.C. (ex officio).

(Secretary : Mr. E. OWEB.)

Alloys Sub-Committee.—Professor G. I. TAYLOR, F.R.S.(Chairman) ; Dr. L. AITCHISON, B.Sc., F.I.C. ; Sir H. C. CARPENTER,F.R.S. ; Dr. W. H. HATFIELD ; Dr. R. S. HTJTTON ; Mr. G.MORTIMER ; Commander G. H. H. BROWN and Mr. J. INNES(representing the Admiralty) ; Dr. W. ROSENHAIN, F.R.S. (re-presenting the National Physical Laboratory) ; Mr. D. R. PYE,M.A., and Mr. H. STJTTON (representing the Directorate of ScientificResearch) ; with the Chairman of the A.R.C. (ex officio).

(Secretary : Dr. H. GOTJGH.)

Compressed Air Tunnel Sub-Committee.—Sir R. T. GLAZEBROOK.K.C.B., F.R.S. (Chairman); Professor L. BAIRSTOW, C.B.E., F.R.S.;Mr. W. S. FARBEN, M.A., M.B.E. ; Mr. R. V. SOTITHWELL, F.R.S. ;Sir J. E. PETAVEL, K.B.E., F.R.S. and Mr. E. F. RELF,A.R.C.Sc. (representing the National Physical Laboratory) ;Mr. H. E. WIMPERIS, O.B.E., F.R.Ae.S., and Mr. R. McKiNNONWOOD, O.B.E., B.A., A.M.I.C.E., F.R.Ae.S. (representing theDirectorate of Scientific Research).

Elasticity and Fatigue Sub-Committee.—Professor C. F. JENKIN,C.B.E., M.I.C.E. (Chairman) ; Professor D. HANSON, D.Sc. ; Mr.R, V. SOTTTHWELL, F.R.S. ; Professor G. I. TAYLOR, F.R.S. ;Mr. D. R. PYE, M.A., Dr. A. A. GRIFFITHS, D.Eng., and Mr. H.SITTTON, B.Sc. (representing the Directorate of Scientific Research) ;Professor B. P. HAIGH, D.Sc. (representing the Admiralty) ; SirT. E. STANTON, C.B.E., F.R.S., Dr. W. ROSENHAIN, F.R.S., andDr. H. GOTJGH, M.B.E., D.Sc., Ph.D. (representing the NationalPhysical Laboratory) ; with the Chairman of the A.R.C. (ex officio).

(Secretary : Dr. H. GOFGH.)Engine Sub-Committee.—Mr. H. T. TIZARD, C.B., F.R.S.

(Chairman); Professor L. BAIRSTOW, C.B.E., F.R.S.; Professor H. L.CALLENDAB, F.R.S.; Mr. W. S. FARREN, M.A., M.B.E.; ProfessorA. H. GIBSON, D.Sc. ; Lieut.-Colonel M. O'GORMAN, C.B., D.Sc. ;Mr. H. R. RICARDO, M.A., F.R.S. ; Major G. P. BULMAN, O.B.E.,Major B. C. CARTER, D.I.C., A.M.I.M.E., Mr. D. R. PYE, M.A.,and Mr. A. SWAN, B.Sc. (representing the Directorate of ScientificResearch) ; Wing Commander G. B. HYNES, D.S.O. (representing

27

the Aeronautical Inspection Directorate) ; Sir T. E. STANTON,C.B.E., F.R.S. (representing the National Physical Laboratory) ;Engineer Commander G. C. MAIDEN (representing the Admiralty) ;with the Chairman of the A.R.C. (ex officio).

(Secretary : Mr. R. W. FENNIWG.)

Flutter Sub-Committee.—Professor L. BAIRSTOW, C.B.E., F.R.S.i Chairman); Mr. W. S. FARREN, M.A.,M.B.E.; Professor B. M. JONES,M.A., A.F.C. ; Dr. H. LAMB, F.R.S. ; Mr. R. V. SOUTHWELL,F.R.S. ; Professor G. I. TAYLOR, F.R.S. ; Mr. W. D. DOUGLAS,F.R.C.Sc., A.F.R.Ae.S., A.M.I.E.E., and Mr. R. McKiNNON WOOD,M.B.E., B.A., A.M.I.C.E., F.R.Ae.S. (representing the Directorateuf Scientific Research) ; Mr. R. A. FRAZER, B.A., B.Sc., and Mr.E. F. RELF, A.R.C.Sc. (representing the National PhysicalLaboratory); with the Chairman of the A.R.C. (ex officio),

(Secretary : Mr. E. OWER.)

Interference Sub-Committee.—Professor B. M. JONES, M.A.,A.F.C. (Chairman) ; Professor L. BAIRSTOW, C.B.E., F.R.S. ;Mr. W. S. FARREN, M.A., M.B.E. ; Mr. R.MoKiNNON WOOD, O.B.E.,B.A., A.M.I.C.E., F.R.Ae.S. (representing the Directorate ofScientific Research) ; Mr. E. F. RELF, A.R.C.Sc., and Mr. E. OWER,B.Sc., A.C.G.I, (representing the National Physical Laboratory) ;with Chairman of the A.R.C. (ex officio).

Kite Balloon Sub-Committee.—Mr. R. V. SOUTHWELL, F.R.S.(Chairman) ; Professor L. BAIRSTOW, C.B.E., F.R.S. ; Mr. G. M. B.DOBSON, M.A., F.R.S. ; Professor G. I. TAYLOR, F.R.S. ; Mr.H. BATEMAN, B.Sc., A.C.G.I., D.I.C., and Mr. E. F. RELF, A.R.C.Sc.(representing the National Physical Laboratory) ; Flying OfficerM. H. STEEP (representing the Director of Airship Development) ;Mr. H. E. WIMPERIS, C.B.E., M.A., F.R.Ae.S. (representing theDirectorate of Scientific Research) ; with the Chairman of theA.R.C. (ex officio).

(Secretary : Mr. E. OWER.)

Large Wind Tunnel Sub-Committee.—Professor L. BAIRSTOW,C.B.E., F.R.S. (Chairman); Mr. W. S. FARREN, M.A., M.B.E.; Lieut.-Colonel M. O'GoEMAN, C.B., D.Sc. ; Mr. R. V. SOUTHWELL, F.R.S. ;Mr. A. H. HALL, C.B.E., M.I.C.E., Mr. H. E. WIMPERIS, C.B.E.,M.A., F.R.Ae.S., M.I.E.E., and Mr. R. McKiNNON WOOD, O.B.E.,B. A., A.M.I.C.E., F.R.Ae.S. (representing the Directorate of ScientificResearch) ; with the Chairman of the A.R.C. (ex officio).

(Secretary : Mr. E. OWER.)

Load Factors Sub-Committee.—Sir J. E. PETAVEL, K.B.E.,D.Sc., F.R.S. (Chairman) ; Professor L. BAIRSTOW, C.B.E., F.R.S. ;Mr. W. S. FARREN, M.B.E. ; Professor A. J. SUTTON PIPPARD,M.B.E., D.Sc.; Mr. R. V. SOUTHWELL, F.R.S.; Mr. H. B. HOWARD,

28

B.A., B.Sc., A.F.R.Ae.S., and Mr. R. N. LIPTROT, B.A., A.F.R.Ae.S.(representing the Directorate of Scientific Research); with theChairman of the A.R.C. (ex officio).

Relations with Industry Sub-Committee.—Sir R. T. GLAZEBROOK,K.B.E., F.R.S. (Chairman) ; Professor L. BAIRSTOW, C.B.E.,F.R.S. ; Lieut. Colonel M. O'GoRMAX, C.B., D.Sc. ; Sir J. E.PETAVBL, K.B.E., F.R.S. (representing the D.S.I.R.) ;Mr. E. F. RELF (representing the National Physical Laboratory) ;and Mr. H. E. WIMPERIS, C.B.E., M.A., F.R.Ae.S. (representing theDirectorate of Scientific Research).

Royal Aircraft Tank Sub-Committee.—Sir R. T. GLAZEBROOK,K.C.B'., F.R.S. (Chairman); Professor L. BAIRSTOW, C.B.E.,F.R.S. ; Mr. G. S. BAKER, O.B.E., late R.C.N.C. (representingthe National Physical Laboratory); Major D. GOAD, O.B.E.,M.I.E.E. (representing the Air Ministry) ; Mr. R. McKiifsroNWOOD, O.B.E., B.A., A.M.I.C.E., F.R.Ae.S. (representing theDirectorate of Scientific Research).

Seaplane Sub-Committee.—Dr. F. E. SMITH, C.B., C.B.E., F.R.S.(Chairman) ; Professor L. BAIRSTOW, C.B.E., F.R.S. ; Mr. R. W. L.GAWN, R.C.N.C. (representing the Admiralty) ; Major J. H.LEDEBOER, M.B.E., and Mr. R. McKisnsroN WOOD, O.B.E., B.A.,A.M.I.C.E., F.R.Ae.S. (representing the Directorate of ScientificResearch) ; Major R. E. Penny, O.B.E. (representing the AirMinistry) ; Mr. G. S. BAKER, O.B.E., late R.C.N.C. (representingthe National Physical Laboratory) ; with the Chairman of the A.R.C.(ex officio).

Stability and Control Sub-Committee.—Professor B. M. JOSESIM.A., A.F.C. (Chairman); Professor L. BAIRSTOW, C.B.E., F.R.S.;Lieut. Colonel M. O'GORMAK, C.B., D.Sc. ; Mr. R. V. SOUTHWELL,F.R.S. ; Mr. L. W. BRYANT, A.R.C.Sc., Mr. H. B. IRVING, B.Sc.,and Mr. E. F. RELF, A.R.C.Sc. (representing the National PhysicalLaboratory) ; Mr. H. M. GARNER, M.A., Mr. H. B. HOWARD, B.A.,B.Sc., Mr. R. N. LIPTROT, B.A., A.F.R.Ae.S., Mr. H. L. STEVENS,B.A., and Mr. R. McKiKNON WOOD, M.B.E., B.A., A.M.I.C.E.,F.R.Ae.S. (representing the Directorate of Scientific Research) ;with the Chairman of the A.R.C. (ex officio).

Structure of the Wind Sub-Committee.—Dr. G. C. SIMPSON, C.B.,C.B.E., F.R.S. (Chairman) ; Professor L. BAIRSTOW, C.B.E.. F.R.S.,Professor G. I. TAYLOR, F.R.S. ; Lieut. Colonel M. O'GORMAN,C.B., D.Sc. ; with the Chairman of the A.R.C. (ex officio).

AERODYNAMICS SUB-COMMITTEE.Airscrew Panel.—Dr. H. C. Watts, D.Sc. (Chairman) ; Mr.

W. S. FARREX, M.B.E. ; Dr. H. LAMB, F.R.S. ; Professor G. I.TAYLOR, F.R.S. ; Sir T. E. STAXTON, C.B.E., F.R.S. (representingthe National Physical Laboratory) ; Dr. G. P. DOUGLAS, M.C., D.Sc.,Mr. H. GLACERT, M.A., F.R.Ae.S., Dr. A. A. GRIFFITH, D.Eng.,

29

and Mr. E. J. LYSTAM, A.R.C.Se., D.I.C., F.R.Ae.S. (representingthe Directorate of Scientific Research) ; with the Chairman of theAerodynamics Sub-Committee (ex officio),

ENGINE SUB-COMMITTEE.Torsional Vibration of Crankshafts Panel,—Mr. D. R. PYE, M.A.

! Chairman) ; Mr. E. B. MOTJLLIN, M.A. ; Mr. R. V. SOTJTHWELL,F.R.S. ; Dr. G. R. GOLDSBROTJGH, D.Sc., F.R.S.; Major B. C.CARTEB, D.I.C., A.M.I.Mech.E., and Mr. A. SWAN, B.So., A.M.I.C.E.i representing the Directorate of Scientific Research); with theChairman of the Engine Sub-Committee (ex officio).

University Research Panel—Mr. H. T. TIZAED, C.B., F.R.S.(Chairman) ; Professor H. !L. CALLEKDAK, F.R.S. ; Mr. S. J. DA VIES ;Professor A. H. GIBSON, D.Sc. ; Professor C. HAWKES ; Mr. S.LEES ; Mr. H. R. RICABDO, M.A., F.R.S.; Mr. D. R. PYE, M.A.representing the Directorate of Scientific Research).