FOB OFFICIAL USE.

AERONAUTICS

TECHNICAL REPORTOF THE

AERONAUTICAL RESEARCHCOMMITTEE

FOR THE YEAR 1924-25.

(With APPENDICES.)

VOL. I.

Aeroplanes (Model and Full scale.)

L O N D O N :PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE.

To lie purchased directly from H.M. STATIONERY OFFICE at the following addresses:Adastral House, Kingsway, London, W.C. 2; 28, Ablngdon Street, London, S.W. 1;

York Street, Manchester; 1, St. Andrew's Crescent, Cardiff;or 120, George Street, Edinburgh;

or through any Bookseller.

1926.Price 17s. 6<2. Net,

CONTENTS.

VOLUME I.

AEROPLANES (MODEL AND FULL-SCALE).PAGE

Members of the Committee . . . . . . . . viiiHeport of the Committee for the year 1924-25 1

APPENDICES TO THE REPORT,Aerofoils and Wing Sections:—

(a) Aerofoil Theory :—(i) A theory of thin aerofoils.—By H. Glauert, of the Royal

Aircraft Establishment. Presented by the Directoro f Research - - - - - - - - - 4 3

(ii) The theory of the design of aerofoils, with an analysis ofthe experimental results for the aerofoils, R.A.F. 25,26, 30 to 33.—By H. Olauert, M.A. Presented by theDirector o f Scientific Research - - - - - 5 2

(iii) The characteristics of thick aerofoils.—By H.Glaxiert, M.A.,Royal Aircraft Establishment - - - - - 5 9

(iv) Note on the application of the vortex theory of aerofoilsto the prediction of downwash.—By L. F. G. Simmons,B.A., A.R C.Sc., and E. Ower, B.Sc., A.C.G.I. - - 63

(v) The performance of tandem systems.—By H. Glauert, M.A.Presented by the Director of Research 66

(vi) A generalised type of Joukowski aerofoil.—By H. Glauert,of the Royal Aircraft Establishment. Presented by theDirector of Research - - - - - - - 7 7

(6) Wind Tunnel Tests :—(i) The interference of wind channel walls on the downwash

angle and the tail-setting to trim.—By H. Glauert, M.A.,and A. S. Hartshorn, B.Sc. Presented by the Directoro f Scientific Research - - - - - - - 8 3

(ii) Test of a thin low drag aerofoil, R.A.F. 25.—By the Aero-dynamics Staff of the Royal Aircraft Establishment.Presented by the Director of Scientific Research - - 92

(iii) Test of three aerofoils suitable for high speed. A.D. 1,Sloane, and R.A.F. 26.—By F. B. Bradfield and A. S.Hartshorn, B.Sc., of the Royal Aircraft Establishment.Presented by the Director of Scientific Research - - 95

(iv) Test of four thick aerofoils, R.A.F. 30, 31, 32, and 33.—By F. B. Bradfield, Math, and Nat. Sci. Trip., andA. S. Hartshorn, B.Sc., of the Royal Aircraft Estab-lishment. Presented by the Director of Scientific Re-search - - - - - - - - - - 1 0 1

(v) Experiments to measure the variation, with speed andsize, of the forces on an aerofoil of thick section (GermanAerofoil No. 420). By A. Fage, A.R.C.Sc., andW . L . Cowley, A.R.C.Sc. - - - - - - 1 0 8

(vi) Some experiments on a slotted aerofoil.—By H. B Irving,B.Sc., a n d A . S . Batson, B.So. - - - - - 1 2 1

(vii) Summary of data on slotted wings obtained in the windtunnel of Messrs. Handley Page, Ltd.—By H. B. Irving,B.Sc., a n d A . S . Batson, B.Sc. - - - - - 1 3 5

Ill

(viii) Lift and drag of two aerofoils measured over 360° range ofincidence.— By C. N. H. Lock, M.A., and H. C. H.Townend, B.Sc. - - - - - - - - 160

(ix) A note on the Katzrnayr effect ; that is, the effect on thecharacteristics of an aerofoil produced by an oscillatingairstream. — By W. L. Owley, A.R.C.Sc. - - - 165

Stability and Control : —(a) Full-scale : —

(i) Notes on stalled flying. — By Squadron Leader R. M. Hill,M.C., A.F.C., and H. L. Stevens, B.A., of the RoyalAircraft Establishment. Presented by the Director ofResearch . . . . . . . . . 1 7 0

(ii) The control of a stalled aeroplane as affected by the useof differential ailerons. — By H. L. Stevens, B.A.Presented by the Director of Scientific Research - - 179

(iii) Full-scale tests of a new slot-and-aileron lateral control. —By H. L. Stevens, B.A., of the Royal Aircraft Estab-lishment. Presented by the Director of ScientificResearch . . . - - . . . - 1 8 4

(iv) Full-scale tests of different ailerons on Bristol Fighteraeroplane. — By H. M. Garner, M.A., and. E. T. Jones,B.Eng. Presented by the Director of Scientific Re-search - - - - - - - - - - 1 8 7

(v) Experiments with rudders on two twin-engine aeroplanes. —By F. W. Meredith, Aerodynamics Department, RoyalAircraft Establishment. Presented by the Director ofResearch . . . . - - . . . 1 9 4

(vi) A theory of the full-scale determination of damping inroll.- — By S. B. Gates and H. M. Garner, of the RoyalAircraft Establishment. Presented by Director ofScientific Research . . . . . . . 2 0 2

(vii) On the effect of inertia on the lateral motion of an aeroplaneunder the influence of gusts and control movements. —By L. W. Bryant, B.Sc., A.R.C.Sc., and D. H. Williams,B.Sc. - - - - - - - - - - 2 1 0

(viii) Automatic landing of aeroplanes. — By F. W. Meredith,of the Royal Aircraft Establishment. Presented bythe Director of Research - - - - - - 219

(6) Model:—(i) Slot control on an Avro with standard and balanced

ailerons, — By F. B. Bradfield, of the Royal AircraftEstablishment. Presented by the Director of ScientificResearch . . . . . - - - . 2 2 8

(ii) Lateral force and moments on Avro model. — By R. G.Harris and A. S. Hartshorn, of the Royal AircraftEstablishment. Presented by the Director of ScientificResearch . . . . . . . . . 2 4 4

(iii) Measurement of pitching moments due to roll on wings ofAvro 504K.— By F. B. Bradfield, Math, and Nat. Sci.Tripos. Presented by the Director of Scientific Research. 250

(iv) Pitching and yawing moments with sideslip on a modelaeroplane with zero stagger. — By F. B. Bradfield,of the Royal Aircraft Establishment. Presented bythe Director of Scientific Research . . . . 256

(c) Instruments : —(i) The Royal Aircraft Establishment control movement

recorder, Mark III. — By D. A. Jones and H. L. Stevens,of the R.A.E. Presented by the Director of ScientificResearch . . . - - - - - - 2 7 0

* (5)25173—1 Wt 18968—12455/1058 375 4/26 a 2

IV

PAGD(ii) A continuous rotation balance for the measurement of

pitching and yawing moments due to angular velocityof roU (Mp and Nv). — By T. Lavender - - - - 2 7 3

Experiments on complete models : —(a) Aeroplanes : —

(i) Experiments on a model of a Bristol Fighter aeroplanescale) . . . . . . . . . 276

Section 1.Force and moment measurements at various angles of

yaw.— By H. B. Irving, B.Sc., and A. S. Batson, B.Sc. - 277

Section 2.Lateral derivatives by the forced oscillation method. —

By R. A. Frazer, B.A., B.Sc., A. S. Batson, B.Sc., andA . G . Gadd - - - - - - - . - 2 8 7

(ii) Measurements of lift, drag and pitching moment on the^th scale model of the Bristol Fighter with airscrewrunning. By E. F. Relf, A.R.C.Sc., and L. J. Jones - 316

(iii) Lift and drag of Junker monoplane. Comparison ofmodel with full-scale results. — By B. D. Clark,B.Sc., L. P. Coombes, B.Sc., H. Glauert, M.A., andA. S. Hartshorn, B.Sc. Presented by the Director ofScientific Research . . . . . . . 33(5

(iv) Forces and moments (including those due to controls)on a model Fairey " N. 4 " flying boat " Atalanta," atvarious angles of yaw. — By H. B. Irving, B.Sc., andA. S. Batson, B.Sc. - - - . . . . 34(5

Full-scale Experiments on Seaplanes : —(i) P.5 flying boat N. 86, impact tests (Experiments with full

size machines, third series). — By the William FroudeNational Tank in conjunction with the Marine andArmament Experimental Establishment, Royal AirForce, Felixstowe, Suffolk - - - - - - 3 6 0

VOLUME II.

AIRSCREWS, ENGINES, MATERIALS, &e.Airscrews : —

(i) The effect of wind tunnel interference on a combinationof airscrew and tractor body. — By C. N. H. Lock, M.A.,a n d H , Bateman, D.I.C., B.Sc. - - - - - 3 6 7

(ii) The effect of gap between an airscrew and a tractor body. —By C. K. H. Lock, M.A., and H. Bateman, D.I.C., B.Sc. 373

(iii) An analysis of the pressure distribution on a modelairscrew by means of the vortex theory. — By A. Fage,A.R.C.SC. . - - - . . . . - 3 7 5

(iv) Experiments to verify the independence of the elementsof an airscrew blade. — By C. N. H. Lock, M.A., H. Bate-man, B.Sc., D.I.C., and H. C. H. Townend, B.Sc. - 381

(v) The measurement of airflow round an airscrew. — ByC. N. H. Lock, M.A., and H. Bateman, B.Sc., D.I.C. - 385

(vi) The airflow round a body as affecting airscrew performance.—By C. N. H. Lock, M.A., H. Bateman, B.So., D.I.C.,and H. C. H. Townend, B.Sc. - - - - - 400

Radiators : —(i) Wind channel tests on radiators. — By R. G. Harris, M.A.,

D.Sc., and W. K, Alford, of the Aerodynamics Depart-ment of the Royal Aircraft Establishment. Presentedby the Director of Scientific Research - 422

PAGE(ii) Further experiments on honeycomb radiators. By

R. G. Harris,, M.A., D.Sc., and L. E. Caygill, B.Sc.Presented by the Director of Scientific Research - - 438

Engines:—(i) Variation of engine power with height.—By H. L. Stevens,

of the Royal Aircraft Establishment. Presented by theDirector o f Scientific Research - - - - - 453

(ii) The variation of engine power with height.—ByH. M. Garner, M.A., and W. G. Jemiings, B.Sc.,of the Royal Aircraft Establishment. Presented bythe Director of Scientific Research - 466

(iii) The friction of pistons and piston riiia:^.- By T. E. Stantoii,D.Sc., F.R.S. - - - " -" - - - 469

(iv) An improved model of optical indicator.— By W. J. Stern,B.Sc., A.R.C.S., D.I.C., and H. Moss. TXSe.. A.R.C.S..D.I.O., of the Air Ministry Laboratory. Presented bythe Director of Scientific Research . . . . 473

Materials:—(a) Fatigue and Impact Tests :--

(i) The effect of keyways upon the strengrh and stiffness ofshafts subjected to torsional stresses.—By H. J. Gough,M.B.E., B.Sc. - - - - - ' - - - 488

(ii) The failure of a nickel chrome steel under repeatedstresses of various ranges.—Bv Professor F. C. Lea,D.Sc., M.Inst. C.E., and H. P. Budgen, M.Sc. - - 508

(iii) Cold work and fatigue.—Bj* L. Aitcinsoii, D.Met., B.Sc.,F.I.C. - - - - " - - - - - - 5 1 2

(iv) Notched bar impact tests at low temperatures.—By Dr.L. Aitehison and the Staff of the Engineering Depart-ment of the National Physical Laboratory - - - 518

(b) Light Alloys :—(i) A method of improving the properties of aluminium alloy

castings.—By S. L. Archbutt, F.I.C., of the NationalPhysical Laboratory. Presented by Dr. W. Rosenhain,F.R.S. Work performed for the Engineering ResearchBoard of the Department of Scientific and IndustrialResearch . . . . . . . . . 5 3 7

(e) Fabrics and Chemistry :—•(i) Report on further investigations of the effect of sunlight

on aeroplane fabric (Part 2).—By W. G. Glendinning,B.A., B.Sc., and J. E. Bamsbottom, D.Sc., Ph.D., of theRoyal Aircraft Establishment. Presented by the Directoro f Research - - - - - - - - - 5 4 9

(ii) The measurement of viscosity by means of capillary tubes.—By G u y Barr, B.A., D.Sc. - - - - - - 5 5 8

Strength of Structures:—(i) Stresses in a stiff-jointed polygonal frame under a system of

parallel loads. Part II.—By Professor A. J. ButtonPippard, M.B.E., D.Sc. -" - - - - 581

(ii) The distortion of a stiff-jointed plane polygonal frameunder loads applied in its plane.—By ProfessorA. J. Sutton Pippard, M.B.E., D.Sc., and P. FieldFoster, B.Sc., A.M.I.Mech.E. . . . . . 597

(iii) An experimental investigation into the properties ofcertain framed structures having redundant bracingmembers.—By Professor A. J. Sutton Pippard, M.B.E.,D.Sc., a n d J/F. Baker, B.A. - - - - - Oil

VI

PAGEAirworthiness of Airships:—

(i) Report of the Airworthiness of Airships Panel - - - 636General Problems :—

(i) An electrical method of tracing stream lines for thetwo-dimensional motion of a perfect fluid.—BvE. F. Relf, A.R.C.Sc. - - - - - "- 655

(ii) The frequency of the eddies generated by the motion of cir-cular cylinders through a fluid. —By E. F. Relf, A.R.O.Sc.,and L. F. G-. Simmons, B.A., A.R.C.Sc. - - - 658

(iii) Experiments on the transmission of air waves throughpipes.—By L. F. G. Simmons, B.A., A.R.C.Sc., andF . C . Johanseii, B.Sc. - - - - - - - 6 6 1

(iv) Discontinuous flow around the edge of a bluff obstacle.—By L. W. Bryant, B.Sc., A.R.C.Sc., and D. H. Williams,B.Sc. - '- - - - - - - - - 6 7 4

(v) Measurement of vertical currents in the lowest layers ofthe atmosphere during sea-breezes.—By J. Durward,Meteorological Office. Presented by the Director oft h e Meteorological Office . . . . . . 6 7 8

VII

INDEX TO SERIAL NUMBERS or THE TECHNICAL REPOBTS.

Report No.R. & M. 864

904905906

„ 908909910911912913

., 914915916

„ 917919920921922923924925

„ 926927928

» 929930

,, 931932933934935

PAGE

4885496555581942194377581587639222865836750837351851224447336059101121135469276346422108

Report Xo.R. & M. 936 -

937 -938 -939 -

„ 940 -„ 941 -

942 -„ 943 -

944 -945 -946 -947 -948 -949 -952 -953 -

,, 955 -956 -957 -958 -959 -960 -961 -962 -983 -964 -965 -966 -968 -969 -970 -

PAGE

- 273- 316- 202- 216- 375- 678- 270- 95- 250- 336- 52- 83- 611- 66- 438- 381- 385- 400- 661- 160- 537- 458- 466- 674- 170- 179- 256- 187- 184- 165- 636

Vlll

MEMBERS OF THE COMMITTEE.

March 1925.

Professor Sir RICHARD GLAZEBROOK, K.C.B., F.R.S. (Chairman).Sir JOSEPH PETAVEL, K.B.E.. D.Sa, F.R.S.f (Vice-Chairman).Professor L. BAIRSTOW, O.B.E., F.R.S.Air Vice-Marshal Sir W. SEFTON BRADTCKER, K.C.B., A.F.C.Professor J. D. CORMACK, C.M.G., C.B.E., D.Sc., M.Inst.C.E.Professor W. E. DALBY, M.A., B.Sc., F.R.S.Mr. C. R. FAIREY, M.B.E., F.R.Ae.S.Lieut.-Colonel E. GOLD, D.S.O., F.R.S.Professor B. M. JONES, M.A.Dr. H. LAMB, M.A., F.R.S.Lieut.-Colonel M. O'GoRMAN, C.B.Mr. A. OGILVIE, C.B.E., M.I.Mech.E.*Air Vice-Marshal Sir W. H. GEOFFREY SALMOSD, K.C.M.G.,

C.B., D.S.O.Mr. F. E. SMITH, C.B.E., F.R.S.§Sir HESRY WHITE-SMITH, K.B.E.*Professor G. I. TAYLOR, M.A., F.R.S.Mr. H. T. TIZABD, M.A.tMr. H. E. WIMPERIS, O.B.E., M.A., F.R.A.E., M.T.E.E.

Secretary, Mr. J. L. NAYLEE.

Assistant Secretary, Mr. E. OWEB.

National Physical Laboratory,Teddington.

* Representing the Society of British Aircraft Constructors.f Representing the Royal Aeronautical Society.J Representing the Department of Scientific and Industrial Research.§ The Director of Scientific Research, Admiralty.|| Mr. H. B. Irving was Assistant Secretary during 1924,

AERONAUTICAL RESEARCHCOMMITTEE.

Report for the Year 1934r-S5.

April, 192,3.

Lieut.-Colonel The Rt. Hon. Sir SAMUEL J. HOARE, Bart..C.M.G., M.P., Secretary of State for Air.

SIB,The Aeronautical Research Committee* submit their

report for the year 1924-25.In presenting this, their fifth annual report, the Committee

complete a period during which they have had the assistance ofthe representatives from the Society of British Aircraft Con-structors and of a representative from the Royal AeronauticalSociety; at the end of the financial year, a reconstitution tookplace.

Reconstitution.—The Air Council have informed the Com-mittee of a change in the Committee's Terms of Reference andconstitution.

The new Terms of Reference are as follows :—(1) To advise the Secretary of State on scientific problems

relating to Aeronautics.(2) -To make from time to time recommendations to the

Air Council as to any researches which the Committeeconsider it desirable to initiate, and as to any mattersreferred to them, by the Council.

(3) To supervise the aeronautical researches at theNational Physical Laboratory initiated by them, and, ifrequested to do so by the Air Council, any other researchesconnected with Aeronautics.

(4) To make an annual report to the Air Council of theresearch work which the Committee consider should beundertaken at the National Physical Laboratory, or else-where, together with an estimate of expenditure at theNational Physical Laboratory.

(5) To investigate the causes of such accidents as maybe referred to them by the Air Council, and to make

* For membership, SKK page 19.

recommendations as to the prevention of accidents in. thefuture.

(6) To promote education in Aeronautics by co-operatingwith the Governors of the Imperial College and in anyother way within their power.

(7) To assist with advice any research carried out byor on behali of the Aeronautical Industry, and to makeavailable any information of value to the Industry so faras is compatible with public interests.

(8) To make an annual report to the Secretary of Statefor Air.

In the previous Terms of Reference, the Committee wereinstructed to advise on scientific and technical problems relatingto the construction and navigation of aircraft; in future, theywill advise the Secretary of State on scientific problems relatingto aeronautics. This change has been made possible by there-organisation at the Air Ministry of that Department whichformally dealt with Technical Development and Research. As afurther consequence, the Council have decided that future member-ship shall be confined solely to members appointed in virtue oftheir scientific standing rather than as representatives of definiteinterests. With the conclusion of the present arrangements, theCommittee desire to express their thanks to the representativesof the Society of British Aircraft Constructors and of the RoyalAeronautical Society, who have helped them in a great numberof ways during the last five years.

Contact between the Committee and the Aircraft Industrywill still be retained by the following arrangements :—

(a) Annually, before the programme of research for theensuing year is decided upon, a joint meeting of the Aero-nautical Research Committee and the industry will takeplace, at which the carrying out of particular researchesduring the ensuing year will be freely discussed. Afterthis joint meeting has been held, the Aeronautical ResearchCommittee and the Society of British Aircraft Constructorswill forward their respective proposals for research to theAir Council, who will decide upon the programme for theensuing year. A copy of the decisions will then be forwardedto the Aeronautical Research Committee and the Society ofBritish Aircraft Constructors.

(b) Six months after the programme has been decidedupon—probably in July—a second joint meeting of theAeronautical Research Committee and the Society ofBritish Aircraft Constructors will take place, at which theprogress of the last six months will be reported and a dis-cussion will ensue. As a result of this second meeting theAir Council will decide if any modifications of the annualprogramme are necessary.

The first meeting at which the above arrangements willbecome effective will be held in July, 1925, when the AeronauticalResearch Committee will welcome the co-operation of the Societyof British Aircraft Constructors to discuss the urgency of thevarious proposals for research contained in their own and in theSociety's programmes.

In respects other than those mentioned above, the Terms ofReference for the Committee are not widely different from thoseunder which they previously served.

Personnel.—The personnel of the Committee has remainedunchanged during the year 1924-25, as the three members dueto retire by a rota at the end of the previous year were re-appointed for a further term of three years, and the representa-tives of the Industry and of the Royal Aeronautical Societypreviously nominated, continued to serve for a further year.

Some changes have been made in the personnel of the Sub-Committees and Panels and a list of members of the activebodies is appended. Where possible, the rota of service forprevious years will be continued during the next and subsequentyears. A special Panel was appointed during the year to con-sider and report on the Airworthiness of Airships.

Grants to Individual Research Workers.—By arrangementwith the Air Ministry a sum of 1,500Z. was made available to theCommittee for the purpose of grants to individual researchworkers during the year. The amount of this grant exceeded by50GZ. that allowed in the previous year in order that funds mightbe made available for special experiments on light aeroplanes.Grants have also been made for work on

(1) Experimental research on redundant structures.(2) Wind tunnel and theoretical research on skin

friction.(3) Theoretical research on the problem of control at

low speeds.The whole of the sum available has been spent during the

year.The Committee welcome the use of this grant, as it enables

them to finance certain research work carried out by independentworkers; approval has been given for a sum of 1,OOOZ. for ardmilar purpose during the year 1925-26.

Researches at Universities.—In addition to the provision ofthe above grants, some work financed by the Department ofScientific and Industrial Research has been carried out onelasticity and fatigue at Oxford University, and a programmeof investigation on single cylinder internal combustion unitsis in hand at the Universities of Cambridge, Durham andManchester.

A 2

Finance.—The financia1 arrangement^ for the work of theCommittee remained the same as in the previous year. Allresearch work having a direct application to aeronautic i- isfinanced by the Air Ministry; and the cost of the remainder,having a more general application, is met by the Department ofScientific and Industrial Research.

Sub-Committees.—The scheme of the Sub-Committees andPanels directing the work in detail is, at the request of the Ail-Ministry, under consideration by the reconstituted Committee.During the past year no new problems have been referred to theMeteorology Sub-Committee and the Fire Prevention Sub-Committee and these Sub-Committees have consequently notmet. Certain urgent meteorological questions were discussed bya small body of experts, called together for that specific purposeonly, and it is not proposed to retain a special MeteorologicalSub-Committee. No new questions on fire prevention havearisen since the last meeting of that Sub-Committee, and it i«not proposed that the}^ shall continue to function; should thenecessity arise, they can be called together again. Under the ne'uterms of reference the Air Inventions Sub-Committee will nolonger exist, the work being carired out entirely by the Air Inven-tions Department of the Air Ministry, as has actually been thecase during the past five years. Xo special questions relating toengine reliability have been brought forward, and the .ReliabilityPanel of the Engine Sub-Committee have accordingly not met.The Big End Bearings Panel have not met during the past year,but the work for this Panel has gone forward under the directionof Dr. Stanton at the National Physical Laboratory • whc-nnecessary, reference on specific points has been made to member^-by letter.

Airship Co-ordinating Sub-Committee.—The Air Council haveinvited the Aeronautical Research Committee to appoint anAirship Co-ordinating Sub-Committee who will consider andreport to the Air Council on any design, research and experi-mental questions that may be referred to them, whether arisingat the Royal Airship Works or in connection with the AirshipGuarantee Company's contract. Arrangements are being madeby the Air Ministry for information as to the experimental andresearch work initiated by the Director of Airship Developmentto be communicated as required to the Sub-Committee, and arequest for similar information is being sent to the AirshipGuarantee Company.

Structures Sub-Committee.—There have been a number ofpapers communicated dealing vsitli the theorjr of structure,-- andits applications. These papers were referred to a special Sub-Committee* for consideration. The same body Iw c dealt withthe work on redundant structure* in hand under the direction

For membership. s<v page l ft.

of Professor Pippard at Cardiff University, and have prepared aprogramme for further researches during the year 1925-26.The work of this Sub-Committee is now at an end.

Publication s —The Committee wish to report that thearrangements to which reference was made last year haveresulted in the publication^ of the Committee being issued morerapidly and brought up to date. Not only are the individualReport^ and Memoranda issued within a few weeks of theirapproval by the Aeronautical Research Committee, but theAnnual Volumes of collected technical papers for past years arenow on sale.

Several papers communicated by the staff of the NationalPhysical Laboratory, working under the direction of the Committee. have been offered to and accepted by the Royal Society;other papers have been communicated to the Royal AeronauticalSociety and to Scientific Journals.

A complete list of papers approved for publication both inthe Reports and Memoranda series and elsewhere is appended tothis report.

Equipment for Experimental Work at the National PhysicalLaboratory the Royal Aircraft Establishment, and elsewhere.—Fulluse has been made during the past year of the experimentalequipment at the various establishments where the aeronauticalresearch co-ordinated by the Committee is in progress. Thestaffs at the National Physical Laboratory, the Royal AircraftEstablishment, and the Air Ministry Laboratory, have sufficientlylengthy programmes to keep them fully occupied for some years.Special mention is made elsewhere of the more importantresearches completed or in hand during the past year.

The Committee do not make any new proposals this year forincreasing staff or equipment at the National Physical Laboratoryexcept in connection with certain proposals for a new high-speedtank. In the opinion of the Committee it is important thatapproval for the construction at the N.P.L. of this tank shouldbe given, as with the progress in seaplane development it isimperative that apparatus and equipment should exist by meansof which comparative tests can be carried out at speeds con-siderably greater than those now possible with the existingequipment at the William Fimide Tank : better progress in^eaplane development will result therefrom, as no means existat present for making model experiments on a high-speed sea-plane. It is further desirable that both test and research work-houlcl be carried out by the same staff.

Progress of Research.—The progress of research during thepaM; year has been satisfactory. The field of enquiry is wide,and the Committee have concentrated on certain lines ofinvestigation directed in detail by various Sub-Committees.In two directions a substantial stage in progress has beenreached.

6

During the last few years in which the Committee have beenstudying the problem of stalled flight they have been occupiedin accumulating data and investigating the general principles ofthe problem, but with the completion of the first flight experi-ments on the slot-and-aileron control the research is nowemerging from this pioneer stage. This new form of lateralcontrol shows a very marked improvement on the normal typeof aileron in use on most aeroplanes up to the present date,and with it the danger, when in flight at low speeds, near theground, should be greatly decreased since the aeroplane can becontrolled even when it has lost flying ^peed.

The other promising advance has been made in the coui^e ofinvestigations on elasticity and fatigue In a similar mannerto the research on stalled flight, data have been accumulatedfrom a large variety of experiments carried out by investigatorsat the N.P.L., at the K.A.E., and at various universities underthe direction of a Panel specially appointed for the purpose.New methods of ascertaining the fatigue of materials have beenreported in previous years and attention has been directed duringthe past year to work on single crystals; in particular, the N.P.L.staff have now established certain facts regarding slip bandswhich, it is hoped, will assist substantially in the future progressof this work. The problems of fatigue which have thus beenstudied are of special importance to aviation, because of thenecessity for working at a lower factor of safety than in other andheavier structures.

Aerodynamics.—Research upon the control of stalled aero-planes has gone steadily forward throughout the year, the cause^leading to defective lateral control in these circumstances havingbeen thoroughly investigated by the Stability and Control Panel.the characteristics required in an aeroplane to make it con-trollable when stalled are now understood, and it has beendemonstrated that these characteristics can be given by mean^of practicable modifications to the organs of control.

It appears from the investigations that conventional aero-planes, when stalled, are defective in two respects; they haveinsufficient rudder power, and the ailerons when applied causethe aeroplane to turn and by so doing neutralise their directeffect on roll. It has been found by analysis, and proved byexperiment, that either an increase of rudder power, or the useof an aileron which does not turn the aeroplane, wTould give thepilot power to regain an even keel from any position and «oprevent the fatal spinning dive. Estimates of the increase inrudder power required to do this without using the aileron^have been made and communicated to designers to provide animmediate cure for the worst forms of loss of control, but sinceno rudder—however powerful—can of itself provide satisfactorylateral control in the absence of effective ailerons, efforts havebeen made to find more satisfactory forms of wing tip controlFor this purpose several devices have been tried with varying

success, both on the model and full scale, the most successfulto date being a combination of a Handley Page slot on theleading edge, operated by a simple cam mechanism in conjunctionwith a balanced aileron of the Bristol-Frise type. The attentionof the Committee was first drawn to the advantage of using awing slot combined with normal ailerons by the jXLP.L., andexperiments carried out there having proved encouraging, asrecorded in the Annual Report for 1922-23, the matter waspassed to the R.A.E. for development and trial in flight. Windtunnel experiments there carried out have shown that still furtherimprovements resulted from the use of an aileron of the Bristol-Frise type in combination with the ^lot, and this combinationhas been fitted to a standard Avro •« ith the result that it« controlin the stalled state is greatly improved: the combination has thevaluable property that the actions required from the pilot aresimilar to those in normal flight. In particular, it is found thatthe spin, either in its initial stages or when fully developed,can be stopped by the ailerons without using rudder. Thisdevice is now being fitted to other aeroplanes, and a generalaccount of the researches which have been carried out uponlateral control is being prepared for publication.

The fore-and-aft control of stalled aeroplanes has not beenso thoroughly studied; it does not present problems of suchcomplication as the lateral control and statistics show that ithas not so great a bearing on the safety of flight: it requires,however, more study than it has yet received and it will beinvestigated further.

Although the behaviour of stalled aeroplanes is now under-stood in general outline, much data have yet to be accumulatedand analysed before the prediction of their controllability can beput upon a quantitative basis compaiable, for example, withthe prediction of performance. This further study should bemuch facilitated by the use of the three special research aero-planes, of "which mention was made in the previous Annual Report.It is expected that the first of these craft will be ready in thesummer and a programme of experiments on them ha* beenalready prepared.

For use with these special aeroplanes and for other researcheson aeroplanes in flight it is essential that an adequate supply ofinstruments should be forthcoming for the use of the R.A.E.and other experimental staffs. Many satisfactory instrumentshave been developed at the R.A.E. for aerodynamic research,but hardly more than one complete set to include every instru-ment that might be needed on an experimental aeroplane hasyet been constructed. The Committee recommend that the AirMinistry should take steps at once to increase largely the numberof such instruments available, for example, by introducing aprocedure \v hereby all instruments are placed in an instrumentmaker's hands, for development on a production basis &< soona& each has passed through the experimental stage. The

resulting benefit to the progress of research would be mostmarked and some such step is very necessary.

Mention must also be made of other work on the subject ofstability and control. Experiments in normal flight have beencontinued mainly in the direction of obtaining further full scaleand model data to evaluate the various derivatives involved inthe quantitative study of these problems.

The subject of recovery from spins has been discussed in somedetail. Some experiences in the past with easily controllablescout aeroplanes have shown that there is often danger that suchmachines cannot be brought out of a spin, and it has been pointedout that even without using special ailerons this danger canprobably be obviated by the increase in size of one of the controls(e.g , rudder or tail plane) or by the alteration of some charac-teristics of design such as gap or stagger.

In connection with the work of the same Panel, a specialinvestigator has been appointed to calculate, under the directionof Professor B. M. Jones, the initial movements of an aeroplanefor a variety of conditions. These calculations have been madeon a basis of wind tunnel results and have brought out from atheoretical standpoint, and explained, many manoeuvres of anaeroplane as yet incompletely understood. A report of this workwill shortly be published. Assistance in tabulating data for alarge variety of machines has been rendered by the AirworthinessDepartment of the Air Ministry.

The Design Panel are continuing their investigation into scaleeffect and two new sections have been chosen. E.A.F. 26 and 31,for further comparative work between model and full scale.Wind tunnel experiments on slotted aerofoils using E.A.F. 15 asa base have proceeded and others will shortly be put in hand onnew sections. Some full-scale experiments on slotted wings havebeen made and the results will shortly be compared with wind-tunnel results and then published. Other work on aerofoilsincludes a series of tests or sections designed by a theory outlinedin a published paper, E. & M. 946 : the experimental resultsobtained in a wind tunnel agree well with those deduced fromthe theory.

A new method for the measurement of aeroplane performancehas been developed by an independent investigator, CaptainG. T. E. Hill. The method adopted in analysing full-scaleexperiments on a Bristol Fighter is similar to that of Bairstow'sApplied Aerodynamics, and has been communicated to the AirMinistry. The whole subject is under discussion by the DesignPanel in conjunction with the analysis of te&ts by the TechnicalStaff at the Martlesham Experimental Establishment. It ishoped that an improvement in performance analysis will result.since by the use of this method no tests need be made withoutthe airscrew running.

The completion of the first stage of the model work on the1'oth «cale Bristol Fighter model in the JST.P.L. Duplex tunnel

deserves special mention, as it is the first time that a modelbeen tested with, the airscrew running under conditions comparablewith full-scale experiments. Some of the results have beenpublished and they will be compared shortly with the full-scaleflight tests in a further report.

Of increasing importance is the problem of wing flutterwhich has been discussed with representatives of a number offirms; a preliminary theoretical attack has been made on theproblem. It would appear that the subject may need a largeamount of experimental inquiry before a complete solution isobtained. Information on the rigidity of wings is being collectedby the Airworthiness Department of the Air Ministry, and aseries of accidents associated with nutter is being investigatedby t-he Accidents Sub-Committee.

Airscrews.—The most important work on airscrews during thepast year has been the measurement of airflow round an airscrewwith and without a body. An attempt has been made to find anempirical relation for predicting the interference effect of the bodyon the airscrew, but the experiments are not yet sufficientlyextensive to give a complete answer'.

Experiments have been made at the JR.A.E. to find the press-ure on the blades of an airscrew in flight; these are now completeand will shortly be published. It is intended that this investiga-tion should be continued at some later date, on an airscrew whosetip speed exceeds that of sound, but prior to attacking thisproblem more full-scale experiments are in hand to ascertainthe amount of twist of an airscrew blade in flight, while modelexperiments at very high speeds are being made to find thepressure on the blades. Various airscrew theories are also underconsideration, including that of Alexandrow and an extension ofthe Vortex Theory brought forward by the N.P.L.

The Committee have viewed with interest a film of a flyingappliance employing a rotating windmill, and the problemssiiggested by this new form of heavier-than-air craft are beingattacked. Another new matter brought before the Committeedeals with the aerodynamics of a rotating cylinder, and in orderto ascertain its possible usefulness on an aeroplane, experimentson a large scale and at a high speed are to be made in a windtunnel.

Seaplanes.—Important model experiments have been made atthe X.P.L. to ascertain the effect of moving the maximum beamof a seaplane to various fore and aft positions along the hull.The results show that it should be possible in some cases to movethe position of the maximum beam forward and shape the bodyof the seaplane aft so as to give a lighter tail and enable theamount of weight carried in the fore part of many seaplanes tobe reduced. Xo attempt has been made to define the bestposition of the maximum beam, but it is hoped that some prac-tical application may be made of some of the results by putting-rms in touch with the X.P.L. staff.

10

A crushing test has been made on a " Seagull " hull at theB.A.E.; the hull utlimately broke mid-way between the stringers.This agrees with a conclusion reached by certain theoretical workcarried out in the previous year by the N.P.L. to which referencewas then made. Further crushing tests on another hull are beingarranged.

The water absorption of seaplane hulls is attracting attentionand a lengthy programme of absorption experiments on paintedand unpainted specimens of wood is in hand at the N.P.L. Thesetests will be carried out in fresh and sea water, the specimensbeing alternately placed in fresh or salt water and then exposedagain in the atmosphere. Other specimens will be exposed in awind tunnel.

The programme of research work for the next year will include,in addition to the continuation of the above work, investigationson the effect of curvature, on the use of fins, on porpoising, onmulti-step bodies and on amphibians.

Airships.—Wind-tunnel work is in progress on airship modelsin connection with the design of new airships by the CardingtonStaff of the Air Ministry, and by the Airship Guarantee Company.Full-scale experiments have been put in hand by the Air Ministryto find the air pressures on the hull of B. 33 during certainmanoeuvres, and the staff of the N.P.L. are being consulted.These pressures are being measured as the result of recommenda-tions by the Committee in previous years. As the result of anotherrecommendation of the Committee, the lightning risks to an air-ship when moored to a mast are being considered by ProfessorC. T. B. Wilson.

In view of the recommencement of airship flying in thiscountry, the Air Ministry requested the Committee to discussthe question of airworthiness. A special Panel was appointedin April, 1924, for this purpose, and reported in the followingOctober, as to the various forces on the hull, the methods of calcu-lation of the stresses due to these forces, on the limiting con-ditions of loading, and on the appropriate factors of safety forcertain flight and other conditions. Other questions affectingairworthiness, such as possible deterioration of material and theprotection of airships from damage by electrical discharges werealso discussed by this body. Their report. B. & M. 970. willshortly be published.

Engines,—A large number of aeroplane engine problems areunder investigation. That of detonation is being steadily attackedat the N.P.L. in closed vessel experiments, and by engine tests atthe B.A.E., at the Air Ministry Laboratory and elsewhere.Owing to the urgency of the problem, the work on anti-detonationsubstances for fuels has been given preference at the Air MinistryLaboratory. The original N.P.L. experiments on air-petrolmixtures have been followed by .others on air-benzene, air-hexaneand air-methane mixtures. By raising the initial temperature.

11the rich, mixture knock in the case of benzene was entirely elimi-nated, and in other cases the addition of a small quantity of theproducts of combustion of the mixture was found to be quiteeffective. The influence of initial charge temperature andpressure has also been investigated on the normal fuel-air ratio.and both have been proved to be factors in the production ofdetonation.

The subject of mechanical efficiency has been raised by a reportfrom the 1ST.P.L. on piston friction. The N.P.L. work showedthat a large portion of a constantly maintained gas pressurereached the first two rings and that the ring friction was of asolid nature. Further work on the problem of mechanicalefficiency is in hand at the Air Ministry Laboratory as a continua-tion of that reported last year.

The thermal conductivity of a number of copper alloys ha,-been measured as a consequence of certain observed changes inpower output and efficiency, when substituting bronze for cast-iron cylinder heads. Following on this work the Department ofScientific and Industrial Research arranged for the N.P.L. tomake certain thermal conductivity tests; all the alloys testedfollowed Lorenz's law for the relation between thermal andelectrical conductivity and absolute temperature, and increasesin thermal conductivity with temperature were observed in allcases.

Certain experiments on the Ricardo variable compressionunits, following approved programmes of research, are in hand atCambridge and Durham Universities. Progress with this workhas not been rapid.

The Engine Sub-Committee are giving considerable attentionto the various problems in connection with increasing thepower/weight ratio of aircraft engines, particularly at greatheights. Pending the development of supercharged engines andother devices requiring further work before they can be broughtinto practice, the Committee have formed a high opinion of thebi-fuel system submitted by the Bristol Aircraft Company in.conjunction with a high compression engine; additional efficiencyat great heights can be obtained by the employment of a variablevalve timing gear.

Research on the design of connecting-rod big-end bearings-has been carried on at the N.P.L., but owing to the excessivevibration of the machine used for this research at 2.120 r.p.m..rapid deterioration of the working parts has set up. It hastherefore been decided to run future tests at a lower speed,retaining the same load factor for the duration tests, by addingmasses to the small end of the connecting rod. Three bearing*in all have been tested at the higher speed, and a report on thesewill be published.

Materials.—The general investigation in hand at severalestablishments on the subject of elasticity and fatigue of materialshas continued during the past year, but while data of great value

1-2

have been collected, there is still no clear understanding as tothe exact bearing that each of the various factors has on thephenomena observed. The N.P.L. have experimented on singlecrystals, which have disclosed characteristics in some respectsas complex as those of crystal aggregates. Several importantexperimental facts have been confirmed and it has further beendemonstrated that a slip band represents the trace of a crystallo-graphic plane on the surface of a specimen. These experimentson crystals are to be continued to ascertain the effects of thepresence of various chemicals. The B/.A.E. staff are extendingtheir researches into the nature of cleavage slipping, and theapplication of the phase rules to the general problems of plasticstrain and fatigue in metals; with the hope of obtaining furthersimplicity, liquids are being considered. Other work carried outat this establishment on the behaviour of undisturbed ironcrystals will shortly be published. High frequency fatigueexperiments are being continued at Oxford University.

Good progress has been made at the N.P.L. in severalinvestigations on light alloys. It has been found that aluminiumalloy castings, particularly sand castings of " Y " alloy, can begreatly improved by permitting the melt to cool and then reheating it before casting. By this method a large portion of thedissolved gas is expelled, and to a considerable extent pinholingis removed. A similar method has been simultaneously usedelsewhere on copper castings. Other methods of obtaining thesame effect, such as the passing of nitrogen through the melt,are being investigated.

The constitutional work on light alloy systems has beencontinued, and a report will be published 011 silicon-aluminiumalloys. The development of alloys, particularly " Y," inconnection with their use as materials for parts of aeroplaneengines, is continuing, and a study of magnesium alloys hascommenced.

In connection with the examination of the various structuralcomponents of airships, work has been carried out on corrosionproblems. Intererystal corrosion has been observed in duraluminstored under a variety of conditions, including ageing in an indooratmosphere, but it has only been found to occur concurrentlywith superficial corrosion. A wrapping test for rapidly detectingthe presence of intercrystal corrosion in thin sheet aluminiumalloy has been devised and successfully used.

The research at the N.P.L. into the action of light on fabricscontinues, and a report has been published showing that thedetermination of the viscosity of a solution of cotton fabricin copper ammonium hydroxide solvent affords an extremelysensitive method of following the deterioration of the fabric,particularly in the early stages of its exposure to the effect ofsunlight. The R.A.E. have in hand an important investigationon cellulose ether, a material soluble in mixtures of benzol andalcohol, whereas the present cellulose acetate dopes require

13

acetone in addition to methyl ethyl ketone. Other mattersunder discussion are the production of metallic gauzes and theuse of fire-proof dopes.

Accidents.—The Committee call attention to the need ofofficers with more technical knowledge, and to the hopeexpressed in their last report that it will not be impossibleto provide for highly-skilled persons to make a direct technicaldiagnosis of each power plant failure immediately it occurs, andto report it in a manner which will enable the Ministry to takemeasures to prevent recurrence. They consider it desirable toxitilise to the full the knowledge of such officers as possess thenecessary technical qualifications.

Two problems have been referred by the Air Ministry tothe Accidents Investigation Sub-Committee during the pastyear. These related to certain accidents in connection with theinvoluntary continuation of spins voluntarily started, a matterreferred to in the previous Annual Report; and to an occurrenceof flutter in a series of accidents to a high-speed fighting aero-plane.

The investigation on the nutter accidents has not yet beencompleted. There has been considerable delay at the R.A.E.in commencing certain investigations requested by the AccidentsSub-Committee, and the Committee wish to emphasise theimportance of giving adequate priority to this type of experimentin order that the risks to personnel from the repetition of certaintypes of accident may be reduced to a minimum.

The Sub-Committee have, however, issued an interim reporton the problem of spinning. The full investigation into theprecise nature of the numerous types of spin known to occurhas not yet been completed. The matter has been referred tothe Stability and Control Panel, who have prepared a reportdealing with the tendencies in design which may lead to dangerin this respect. Conventional ailerons appear to be practicallyinoperative in a spin, but the '' slot-and-aileron " combinationpreviously mentioned has been found to stop the spin of theAvro, even when the other controls are held hard over to causethe spin to continue. Although this new control may afford acomplete solution of the problem of stopping a spin, it is con-sidered that the whole subject of spinning should be thoroughlyinvestigated, and full scale experiments using recording instru-ments to give accurate information of the nature of the spin areproceeding vigorously.

Meteorology.—Measurements of vertical currents in the lowestlayers of the atmosphere during sea breezes have been made bythe Meteorological Office at the suggestion of the Committee. Itwould appear that in the neighbourhood of the station chosenfor convenience—viz., Calshot—large up and down currents dooccur. It has accordingly been decided to publish the resultsof this investigation, showing by certain diagrams the horizontal

14

and vertical trajectories of the individual balloons. The presenceof up and down currents at aerodromes is important, especiallywhere flying is frequent or performance trials of aeroplanes areearned out, and the published method of observation is applicablefor the use of trained observers.

Air Transport.—By the kind invitation of the Imperial Air-ways, Limited, a visit was made during the course of the year toCroydon Aerodrome, and a cordial discussion took place betweenthe Company and the Committee on various matters affectingthe reliability and economy of air transport. The arrangementsmade by the Company to ensure engine reliability were carefullyexplained, and the Committee visited the shops where the over-hauls take place. As a result of this meeting attention was drawnto the importance of three-engined aeroplanes to ensure relia-bility of service, and it is understood that the Air Ministry havenow ordered a civil type of machine for trial out in this con-nection. Also arising from the Committee's visit, it wouldappear that little is known of the life of an aeroplane enginein the air, running continuously at speeds greater or less thanthe normal, which corresponds to about 80 per cent, of' thatr.p.m. at which maximum, power is developed. The Committeehave accordingly recommended, and the Air Ministry are puttingin hand, certain running tests which will ultimately determinethe " commercial rating " of one aeroplane engine. It is hopedto maintain a close contact between the Committee and theImperial Airways, Limited.

The problem of economical flight has been the subject ofcontinued investigation by one of the staff at the N.P.L. Anumber of problems are being attacked, including the mosteconomical design of a three-engined aeroplane for a givenstrength when carrying a load distributed in a variety of ways.The questions of head wind, the economic length of stage, and theoptimum flight speed for freight machines, are other mattersunder investigation; and various subjects, including the lightingof aeroplanes, the need for acoustical research from the pas-sengers' point of view, the question of ventilation and the bestheight of flight, are being discussed with the Air Ministry.

Signed on behalf of the Committee,

R. T. GLAZEBROOK,Chairman.

15

The following reports have been approved for publicationduring the year and can be obtained from H.M. Stationeryoffice :—

B. AM.No, Title. Author.

911914

915927928

929930

935

943

946

949968

908

916

924936

938

939

942

944

947

963

AERODYNAMICS.

AEROFOILS AND WING SECTIONS.A theory of thin aerofoils . . .A generalised type of Joukowski aerofoil -Note on the application of the vortex

theory of aerofoils to the prediction ofdownwash.

Test of a thin, low drag aerofoil, B. A.F. 25.The characteristics of thick aerofoilsTest of four thick aerofoils, R.A.F. 30, 31,

32 and 33.Some experiments on a slotted aerofoil -Summary of data on slotted wings obtained

in the wind tunnel of Messrs. HandleyPage, Ltd.

Experiments to measure the variationwith speed and size, of the forces on anaerofoil of thick section (German Aero-foil No. 420).

Test of three aerofoils suitable for highspeed, A.D.I, Sloane and R.A.F. 26.

The theory of the design of aerofoils, withan analysis of the experimental resultsfor the aerofoils R.A.F. 25, 26, 30 to 33.

The performance of tandem systemsLift and drag of two aerofoils measured

over 360° range of incidence.

STABILITY AND CONTROL.Experiments with rudders on two twin-

engine aeroplanes.Slot control on an Avro with standard and

balanced ailerons.Lateral force and moments on Avro model.A contimiotis rotation balance for the

measurement of M.p and Np.A theory of the full scale determination of

damping in roll.On the effect of inertia on the lateral

motion of an aeroplane under the influ-ence of gusts and control movements.

The R.A.E. control movement recorder,Mark III.

Measurement of pitching moments due toroll of wings of Avro 504K.

The interference of wind channel walls onthe downwash angle and the tail-settingto trim.

Notes on stalled flying -

Glauert.Glauert.Simmons and Owev.

R.AE.Glauert.Bradfield and Harts-

horn.Irving and Batson.Irving and Batson.

Fage and Cowley.

Bradfield and Harts-horn.

Glauert.

Glauert.Lock and Townend.

Meredith.

Bradfield.

Harris & Hartshorn.Lavender.

Gates and Gamer.

Bryant and Williams.

D. A. Jones andStevens.

Bradfield.

Glauert & Hartshorn.

Hill and Stevens.

16

R. & M.JSTo. Title. Author.

AEROD YX AMICS—continued.

STABILITY AND COXTHOL—continued.964 The control of a stalled aeroplane as

affected by the use of differentialailerons.

966 Full scale tests of different ailerons on.Bristol Fighter aeroplane.

AIRSCREWS,919 The effect of wind tunnel interference on

1 a combination of airscrew and tractorbody.

921 The effect of gap between an airscrew anda tractor body.

940 , An analysis of the pressure distribution ofa model airscrew by means of the vortextheory.

953 Experiments to verify the independenceof the elements of an airscrew blade.

955 The measurement of airflow round an air-screw.

956 The airflow round a body as affecting air-screw performance.

967 An experimental study of the vibrationsin the blades and shaft of an airscrew.

! GENERAL.909 I Automatic landing of aeroplanes926 P.5 flying boat 1ST. 86. Impact test.

(Experiments with full-size machines.Third Series.)

932 Experiments on a model of a BristolFighter, l/10th scale.—

Section 1.— Force and moments measure-ments at various angles of yaw.

Section 2.—Lateral derivative^ by theforced o&cillatioii method.

Forces and moments (including those dueto control) on a model Fairey "' N.4."Flying Boat " Atalanta" at variousangles of yaw.

934 Wind channel tests on radiators937 Measurements of lift, drag and pitching

moment on the l/5th scale model of the| Bristol Fighter with airscrew running.

945 I Lift and drag of Junker monoplane. Com-parison of model with full scale results.

I952 Further experiments on honeycomb radi-

1 a tors.965 | Pitching; and yawing moments with side-

slip on a model aeroplane with zeroi staaaer.

Stevens.

Gamer and Jones.

Lock and Bateman.

Lock and Bateman,

Fage.

Lock, Bateman andTownend.

Look and Bateman.

Lock, Bateman andTownend.

Fage.

Meredith.By the William

Froude NationalTank in conjunc-tion with M. &A.E.E., R.A.F.,Felixstowe.

Irving and Batson.

Frazer, Batson andftacld.

Irving and Batson.

Harris and Alford.Relf and L. J. Jone->.

Clark, Coombe.sGrlauerl and Harts-horn.

Harris and Cavgill.

R &M.v,No.

9U7925!»31'*60

9(16

912

913

Title.

ENGINES.i Exhaust manifold temperatures

An improved model of optical indicator -The friction of pistons and piston rings -

• Variation of engine power with heightI The variation of engine power w ith height.

, MATERIALS.1 Report on further investigations of the! effect of sunlight on aeroplane fabric.

Part 2.1 The measurement of viscosity by means1 of capillary tubes.I The failure of a nickel chrome steel underi repeated stresses of various ranges.

Notched bar impact tests at low tempera -, turps.

Cold work and fatigue -A method of improving the properties of

aluminium alloy castings.

STRENGTH OF STRUCTURES.

Author.

R.A.E.Stern and Moss.Stanton.Stevens.Garner and Jennings.

Glendinning andRamsbottom.

Barr.

Lea and Budgen.

Dr. L. Aitchisonand Staff of theEngineering Dept.,N.P.L.

Aitchison.Archbutt.

A. J. SuttonPippard.Stresses in a stiff jointed polygonal frameunder a system of parallel loads.—Part II.

The distortion of a i-tiff jointed plane poly-gonal frame under loads applied in itsplane.

The strength of strut-. : A review of pro- i R. V. Southwell.gress made m theory and experimentduring the war period.

An experimental investigation into theproperties of certain framed structureshaving redundant bracing members.

GENERAL.An electrical method for tracing stream

lines for the two-dimensional motion ofa perfect fluid.

The frequency of the eddies generated bythe motion of circular cylinders througha fluid.

Measurement of vertical currents in thelowest layers of the atmosphere duringsea breezes.

List of Reports and MemorandaOn the transmission of air waves through

pipes.Discontinuous flow around the edge of a

bluff obstacle.Report of the Airworthiness of Airships

Panel.

A. J. SuttonPippard.

A. J. Sutton Pippardand Baker.

Relf.

Relf and Simmons.

Durward.

Simmons and Jo-hansen.

Bryant and Williams.

18

MEMBERSHIP OF SUB-COMMITTEES AND PANELS.MAECH, 1925.

Aerodynamics Sub-Committee.—Professor L. BAIBSTOW, C.B.E..F.R.S. (Chairman); Mr. W. S. FABBES-, M.B.E.; Professor B. M.Jones, M.A.; Dr. EL LAM, M.A., F.R.S.; Mr. A. OGILVUE,C.B.E., M.LMech.E.: Lieut.-Colonel M. O'Gorman, C.B., Pro-fessor A. J. SUTTON PIPPABD, M.B.E., D.Sc.: Professor G 1.TAYLOB, M.A., F.R.S.; Dr. H. C. WATTS; Mr. J. D. NOBTH,Mr. F. HANDLEY PAGE and Sir H. WHITE-SMITH. K.B.E. (repre-senting the Society of British Aircraft Constructors); Mr. R. J.GOODMAS CROUCH and Mr. R. McKiraos WOOD (representingDirectorate of Scientific Research): Sir J. E. PBTAVEL. K.B.E.,D.Sc., F.R.S., Mr. E. F. RELE. A.R.C.Sc., and Mr. R. V. SOUTH-WELL, M.A. (representing National Physical Laboratory); withthe Chairman of the Aeronautical Research Committee (exofficio}.

Engine Sub-Committee.—Mr. H. T. TIZABD, M.A. (Chairman):Lieut.-Colonel W. A. BBISTOW, M.I.E.E., M.I.A.E.. F.R.A.S.;Professor H. L. CALLENDAB, F.R.S.: Lieut.-Colonel L. F. R.FELL, D.S.O., O.B.E.; Professor A. H. GIBSOX, D.Sc.: Mr. A.OGILVIE, C.B.E., M.I.Mech.E.: Lieut.-Colonel M. O'GoRMAir.C.B.; Mr. D.R. PYE; Mr. H. R. RICAEBO ; Mr. A. H. R. FEDDEW,Mr. A. J. ROWLEDGE, Mr. J. D. SIDDELEY, C.B.E.. and CaptainG. S. WILKINSOK (representing the Society of British AircraftConstructors); Wing Commander G. B. HYNES. D.S.O.. and Mr.H. E. WIMPEBIS, O.B.E. (representing Directorate of ScientificResearch); Major G. P. BULMAN (representing Directorate ofAeronautical Inspection); Dr. T. E. STANTOX, C.B.E., F.R.S.(representing Department of Scientific and Industrial Research);with the Chairman of the Aeronautical Research Committee(ex officio).

(Secretary : Mr. R. W. FENCING, M.B.E., B.Sc., D.I.C.)Materials and Chemistry Sub-Committee.—Dr. T. E. STAKTOK.

C.B.E., F.R.S. (Chairman); Professor L. BAIBSTOW, C.B.E.iF.R.S.; Professor W. E. DALBY, M.A., B.Sc., F.R.S.; ProfessorC. F. JENKIKT, C.B.E., M.A., M.Inst.C.E.; Professor A. J. SUTTOKPIPPABD, M.B.E., D.Sc.; Sir R. ROEEBTSON, F.R.S.; ProfessorG. I. TAYLOB, M.A., F.R.S.; Mr. J. D. NOBTH, Mr. J. D. SIDDELBY,C.B.E., Sir H. WHITE-SMITH, K.B.E., and Captain G. S. WILKIN-soisr (representing the Society of British Aircraft Constructors):Mr. R. F. McKAY (representing Department of Scientific andIndustrial Research); Mr. W. H. DYSOS and Lieut.-ColonelV. C. RICHMOND (representing Directorate of Scientific Research);Major G. P. BULMAN and Dr. G. RUDOBF (representing Directorateof Aeronautical Inspection): Dr. W. ROSEWHAIN, F.R.S., andMi1. R. V. SOUTHWELL, M.A. (representing National PhysicalLaboratory); with the Chairman of the Aeronautical ResearchCommittee (ex officio}.

(Secretary : Mr. H. GOTJGH. M.B.E.. B.Sc.)Accidents Investigation Sub-Committee.—Lieut. -Colonel M.

O'GoBMAK, C.B. (Chairman): Professor L. BAEBSTOW. C.B.E..F.R.S.; Mr. G. B. COCKBUBN, O.B.E.. Professor W. E. DALBY.

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M.A., B.Sc., F.R.S.; Lieut.-Colonel E. GOLD, D.S.O., F.R.S.;Professor B. M. JOXES. M.A.; Major R. H. MAYO, O.B.E., M.A.,AssocJI.Inst.C.E., F.R.Ae.S.; Major J. P. C. COOPER (repre-senting the Air Ministry); Major C. H. NICHOLAS (representingDirectorate of Scientific Research); Sir J. E. PETAVEL, K.B.E.,D.Sc., F.R.S. (representing National Physical Laboratory); withthe Chairman of the Aeronautical Research Committee (exofficio).

(Secretary : Mr. H. B. TRYING, B.Sc.)Air Tratisport Sub-Committee,.—Lieut.-Colonel M. O'GoRMAX.

C.B. (Chairman); Professor L. BAIRSTOW, C.B.E., F.R.S.; AirVice-Marshal Sir W. SEFTOST BKASTCKER, K.C.B., A.F.C.; Mr.H. T. TIZARD, M.A.: Wing Commander H. M. CAVE-BROWTSTE-CAVE, D.S.O. (representing Directorate of Scientific Research);Sir J. E. PETAVEL, K.B.E., D.Sc., F.R.S. (representing NationalPhysical Laboratory); with the Chairman of the AeronauticalResearch Committee (ex officio),

(Secretary: Mr. E. OWER, B.Sc., A.R.C.Sc.)Temporary Structure Sub-Committee.—Dr. H. LAMB, M.A.,

F.R.S. (Chairman); Professor L. BAIRSTOW, C.B.E., F.R.S.;Mr. W. S. FARREN, M.B.E.; Professor A. J. BUTTON PIPPAK.D,M.B.E., D.Sc.; Lieut.-Colonel V. C. RICHMOND, O.B.E. (repre-senting Royal Airship Works); Mr. R. V. SOTJTHWELL, M.A.(representing National Physical Laboratory).

PANELS.AERODYNAMICS SUB-COMMITTEE.

Design Panel.—Mr. W. S. FARKEX, M.B.E. (Chairman);Professor H. LEVY, M.A., D.Sc.; Mr. A. OGILVIE, C.B.E.: Lieut.-Colonel M. O'GORMAX, C.B.; Professor A. J. STJTTON PLPPARD,M.B.E., D.Sc.; Captain F. S. BARXWELL and Mr. J. D. NORTH(representing Society of British Aircraft Constructors); Mr. R.McKrraoN WOOD (representing Directorate of Scientific Re-search) ; Mr. E. F. RELF, A.R.C.Sc. and Mr. R. V. SOTJTHWELLM.A. (representing National Physical Laboratory); with theChairman of the Aerodynamics Sub-Committee (ex-officio).

Stability and Control Panel.—Professor B. M. JOKES.. M.A.(Chairman); Professor L. BAIRSTOW, C.B.E.; F.R.S.. Dr. H.LAMB, M.A., F.R.S.; Lieut.-Colonel M. O'GoRMAN, C.B.; Mr.J. D. NORTH (representing Society of British Aircraft Con-structors) ; Mr. R. J. GOODMAS CROUCH and Major C. H. NICHOLAS(representing Directorate of Scientific Research): Mr L. W.BRYAXT, A.R.CJSc.. Mr. H. B. IRVIXG, B.Sc., A.F.K.Ae.S.. Mr.E. F. RELF, A.R.C.Sc.. and Mr. R. V. SOTJTHWELL, M.A. (repre-senting National Physical Laboratory); with the Chairman ofthe Aerodynamics Sub-Committee (ex-officio).

Airscrew Panel.—Dr. H. C. WATTS (Chairman): Mr. W. S.FARREN, M.B.E.; Dr. J. D. COALES and Mr. R. MoKivNONWOOD (representing Directorate of Scientific Research): Mr.A. FAGE, A.R.C.Sc.. and Mr. R. V. SOTJTHWELL. M.A. (repve--°nting National Physical Laboratory): with the Chairman ofthe Aerodynamics Sub-Committee (ex-officio).

IS 2

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Seaplane Panel.—Mr. F. E. SMITH, C.B.E. (Chairman);Mr. H. BOLAS (representing Society of British Aircraft Con-structors) ; Wing Commander H. M. CAVE-BROWN-CAVE, D.S.O.,and Squadron Leader H. E. A. WSIGHT (representing Directorateof Scientific Research): Mr. E. W. L. GAWW (representingAdmiralty); Mr. G. S. BAKER. O.B.E. (representing NationalPhysical Laboratory); with the Chairman of the AerodynamicsStill-Committee (ex-officio).

ENGINE SUB-COMMITTEE.Big End Bearings Panel.—Lieut.-Colonel T. M. HUTCHUTSOK .

D.S.O., O.B.E. (Chairman, at present abroad); Mr. H. R.RICARDO ; Mr. J. D. SIDDELEY (representing Society of BritishAircraft Constructors); Lieut.-Colonel H. N. FOSTEB (repre-senting War Office); Engineer Commander H. B. TOSTEVTN(representing Admiraltj7); Mr. W. L. TAYLOE (representingDirectorate of Scientific Research); Dr. T. E. STANTON, C.B.E.,F.R.S. (representing National Physical Laboratory); with theChairman of the Engine Sub-Committee (ex-officio).

MATERIALS AND CHEMISTRY SUB-COMMITTEE.Elasticity and Fatigue Panel.—Professor C. F. JBNKIK, C.B.E.,

M.A., M.Inst.C.E. (Chairman); Dr. F. S. GOUCHER; ProfessorB. P. HAIGH, D.Sc.; Professor F. C. LEA. D.Sc.; Mr. W. H.DYSON and Dr. A. A. GRIFFITH (representing Directorate ofScientific Research); Dr. W. ROSENHAEST, F.R.S., and Mr. R. V.SoTTTHWET/L. M.A. (representing National Physical Laboratory);with the Chairman of the Materials and Chemistry Stib-Committee(ex-officio).

Light Alloys Panel.—Dr. W. ROSENHAIN, F.R.S. (Chairman):Professor F. C. LEA, D.Sc.; Mr. W. H. DYSOIT (representingDirectorate of Scientific Research); Mr. W. A. THAEST (repre-senting Directorate of Aeronautical Inspection); with the Chair-man of the Materials and Chemistry Sub-Committee (ex-officio).

Fabrics and Dopes Panel.—Dr. G. RTTDORF (Chairman);Dr. W. H. GIBSOST; Mr. J. MACARTNEY; Sir R. ROBERTSOKT,F.R.S.; Dr. J. E. RAMSBOTTOM (representing Directorate ofScientific Research); Dr. G. BARE, D.Sc. (representing NationalPhysical Laboratory); with the Chairman of the Materials andChemistry Sub-Committee (ex-officio).

AIRWORTHINESS OF AIRSHIPS PANEL.October, 1924.

Professor L. BAIKSTOW, C.B.E., F.R.S. (Chairman); Pro-fessor C. F. JESKIX. C.B.E.,. M.A.. M.Inst.C.E.: Professor A. J.SUTTOX PIPPARD. M.B.E., D.Sc.: Mr. R. V. SOTTTHWELL. M.A.:Liettt.-Colonel V. C. RICHMOND, O.B.E.. and Major G. H. SCOTT(representing Directorate of Scientific Research).

(Secretarv : Mr. G. P. SroBE.)