FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1922
1922 - 0651.PDF
NOVEMBER 2, 1922 supported, by very doubtful aerodynamic data and also forti fied by the same Order in Council. The loads in the members are then estimated by ignoring those members to take account of whose presence would seriously complicate the calculations and by making what are often the wildest assumptions as to the nature of the joints between the members. This brings us to that very data which we were regretting our inability to interpret in an accurate scientific manner. But the whole process works after a fashion because aeroplanes are not designed by science, but by art in spite of some pretence and humbug to the contrary. I do not mean to suggest for one moment that engineering can do without science—on the con trary, it stands on scientific foundations—but there is a big gap between scientific research and the engineering product which has to be bridged by the art of the engineer. Nevertheless, the technique of the design of thin metal members is progressing rapidly. To arrive analytically by measuring the frictional coefficient of the cloth, the resilience of the balls and cushions, -at the precise way to play a com plicated stroke at billiards is practically hopeless, but practice and a knowledge of principles deduced from scientific analysis of simple cases will produce surprising results. So it is that, over a wide range, light metal members can be designed with every confidence that they will fulfil their designer's expecta tions and realise the advantages in weight economy fore shadowed by the properties of the materials. Inspection and Manufacture It would be perhaps too much to say of light metal con struction that the material is half the battle, but there would be a strong element of truth in such an assertion. I am not suggesting that there is one particular class of steel or light alloy which will be found to be ideal for all purposes. On the contrary, I believe that the types of material used in a single metal aeroplane will increase as time goes on. What we require are materials that can be produced with the necessary degree of uniformity both as regards their elastic properties in the sense these have already been discussed, and as regards their plasticity, both absolute as ductility, and in relation to the true elastic properties. This last is required to be reasonably uniform in the state in which the strip is to be worked (sections formed from strip and riveted together are the most characteristic forms of light metal construction). The strip in forming through rolls or dies springs back from the profile of the tool by an amount dependent on its resilience. Reasonable limits are thus required if tools are to produce a satisfactorily uniform article. Control at present is limited to an upper and lower " proof " stress and a bend test. These tests, comparatively simple as they appear, seem somewhat to strain the capacities of commercial testing and inspection without giving as much information as is required. What is wanted is a stress/strain diagram from which the. properties of the materials can be deduced, and it is unfor tunate that there is no machine capable of producing them commercially and reliably. For that matter there is not even a standard extensometer which is commercially practical. It is possible that this class of testing apparatus may be improved in the near future. There is also the alternative" that research may show a connection between these elastic properties and some more easily measured feature of the material. It is a matter well worth the attention of metallurgists, testing engineers and physicists generally. A further mechanical uniformity in strip is required in thickness, flatness and straightness. The tolerances laid down in the B.E.S.A. specifications^seem satisfactory, and more than a slight departure from them often leads to manufacturing troubles. The problem of manufacture from the strip onwards has two phases which are novel and of special importance. Firstly, forming the strip. Secondly, riveting it. There is a simple formula for designing tools for forming strip. It is " live and learn." Direct attack on the resilience problem is probably hopeless, but one soon arrives at a few general principles of design, though when marked departure from experience comes along it often brings rude shocks in its train. There are broadly three methods of forming strip- rolling, drawing and pressing—and all have their uses and limitations ; but whatever method is used (all are really required), it is necessary in order to get the best results, to have machines of special design, and my own experience is that it is most satisfactory to design and make them on the spot. The commonest process in aircraft work is to form the strip in its final state of treatment, but although this has great advantages in assisting production by eliminating heat treat ment processes, 1 believe that a certain amount of soft forming with subsequent heat treatment or even hot forming will be in regular use, by reason of the wider scope of materials and forms opened up. With satisfactory tools and uniform material the production of formed sections makes little demand on skilled labour and can easily be brought to a large production standard. Riveting is a problem less easily tackled, it is so indefinite. The number of rivets in a steel aeroplane runs into many tens of thousands. The cost of riveting and all it implies is pro bably the critical factor in the cost of production, and the profit and loss scale will be turned by the drawing office and the planning department. This phase of technique is being slowly and painfully developed, and it is here to a large extent that the high cost of development appears. Metal construc tion is not inherently expensive. All our experience of the manufacture of details where the technique is in an advanced state confirms this. Money is spent on mistakes and errors of judgment, trial and error, the foundation stones of experience. (To be concluded.) London Gazette, October 20, 1922 General Duties Branch J. M. Darroch is granted short-service comnrn. as Pilot Offr. on probation, with effect from, and with seny. of, Sept. 2. Memorandum The permission granted to Sec. Lieut. E. S. Smyth to retain his rank is withdrawn on his joining the Army. London Gazette, October 24, 1922 General Duties Branch Fit. Cdt. C. Gupp'y, having successfully passed through the R.A.F. (Cdt.) Coll., is granted a permanent commu. as Pilot Offr., with effect from, and seny. of, Oct. 6. Flying Offr. G. H. Martingell, A.F.C., is granted a perma nent commn., retaining his present substantive rank and seny. ; Oct. 24, 1919 (Gazette, Oct. 24, 1919, appointing him to a short service commn. is cancelled). The seny. of Pilot Offr. E. A. Hodgson is antedated to Aug. 16, 1921. The follg. are granted short service commns. as Flying Offrs., with effect from, and seny. of, the dates indicated :—M. R. Banks ; Oct. 16. A. E. Evans, D.F.C. ; Oct. 12. C. Sutton; Oct. 16. The follg. officers are granted temp, cornmns. in ranks stated, on seconding for four years' duty with R.A.F". ; Oct. 16 :— Flying Offrs. (Hon. Flight Lieut s.).—Capt. E. L. O. Baddeley, Middlesex K. Capt. L. F. Marson, M.C., 4th Dragoon Gds. ROYAL AIR FORCE INTELLIGENCE Appointments.—The following appointments in the R.A.F. are notified :— Squadron-Leaders: A. H. S. Steele-Perkins, O.B.E., from Record Office (Inland Area) to Aircraft Depot, Egvpt (Middle East Area). 13.10.22. O. T. Boyd, O.B.E., M.C., A.F.C., from Air Ministry (Director of Operations and Intelligence) to command No. 24 Squadron (Inland Area). 23.10.22. E. P. Punch, from Aeroplane Experimental Establishment (Coastal Area) to No. 7 Group Headquarters (Inland Area). 26.10.22. Flight Lieutenants: N. P. Dixon, A.F.C., from R.A.F. Cadet College (Flying Wing) (Cranwell) to Bovs' Wing (Cranwell). 9.10.22. V. A. Albrecht, O.B.E., M.C., from Army (Manchester Regiment) to No. 4 Flying Training School (Middle East) ; on appointment to Temporary Commission in the Royal Air Force on being seconded from the Army. 25.9.22. R. G. J. McCullagh, to Research Laboratory and Medical Officers' School of Instruc tion ; on appointment to Short Service Commission. 4.io.22j J. J. Boyle, to Headquarters, R.A.F., Iraq, on appointment to Temporary Commission in the Royal Air Force on attachment for 4 vears from the Army Dental Corps. 1.10.22. O. R. Gayford from No. 1 Flying Training School (Inland Area) to Headquarters, Constantinople. For duty as Adjutant. 28.9.22. E. A. Fawcus, from No. r School of Technical Training (Boys) (Halton) to School of Photography. (Supernumerary.) 25.9.22. G. Bowen, from Iraq Group Headquarters (Middle East Area) to Aircraft Park (Middle East Area). 11.1.22 F E. Johnson, to Research Laboratory and Medical Officers' School of Instruction (Coastal Area) ; on appointment to Short Service Commission. 30,9.22. F. W. Trott, O.B.E., M.C., from No. 24 Squadron (Inland Area) to Headquarters, Constantinople Wing. 28.9.22. E. V. Longinotto, A.F.C., from Air Ministry (Director of Personnel) from R.A.F. Depot (Inland Area). (Supernumerary.) 9.10.22. A. W. Turner, from R.A.F'. Depot (Inland Area), from Headquarters, Constantinople Wing. 28.9.22. H. G. Crowe, M:C, from No. 39 Squadron (Inland Area) to School of Photography (Inland Area) (Supernumerary). 19.10.22. E. W. Longden, from Armament and Gunnery School (Inland Area) to R.A.F. Depot (Inland Area). 19.10.22. C. Y. Roberts, from Research Laboratory and Medical Officers' School of Instruction (Coastal Area) to Aeroplane Experimental Establishment (Coastal Area). 23.10.22. C. P. O. Bartlett, D.S.C., from No. 30 Squadron (Iraq) to R.A.F. Depot (Inland Area) (Supernumerary). 20.8.22. J. S. Goggin, from R.A.F. Base, Gosport (Coastal Area), to Palestine Wing Headquarters (Middle East Area). 23.10.22. B. F. Beatson, D.T.M., from Indian Medical Service to Research Laboratory and Medical Officers' School of Instruction (Coastal Area) ; on appointment to Temporary Com mission in the Royal Air Force on being seconded for two years from the Indian Medical Service. 13.10.22. J. Duminy: the notification which appeared in Royal Air Force Intelligence No. 82, dated 19.10.22, wherein this officer was posted from R.A.F. Depot to Headquarters, Coastal Area, with effect from 16.10.22, is hereby cancelled. 651
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
