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Aviation History
1929
1929 - 1135.PDF
MA* 30, THE AIRCRAFT ENGINEER SUPPLEMENT TO FLIGHT fix the most convenient size and number of rivets with respect to bearing and shear. Use of Chart 3 Required : Tube to transmit a B.M. of 9.000 lbs. ins. (bending stress = 30 tons per sq. in.) 9,000Constant = —r— = 3,000 o 3,000 lbs. on chart 3 shows we may use either of the following: 1% X 11 S.W.G., 1| X 14S.W.G., If x 16S.W.C, 1' x 17 S.W.G., 2 in. X 18 S.W.G., 2£ x 20S.W.G. or2£ x 22 S.W.G. Chart No. 3 may be conveniently plotted for any family of standard sections which are likely to be manufactured in a variety of metals and S.W.G's. Should it be found necessary to design for loads greater than the scope of charts 1 and 2, it will be convenient, as the user will readily see, to halve the load and double the required* number of rivets. TECHNICAL LITERATURE SUMMARIES OF AERONAUTICAL RESEARCH COMMITTEE REPORTS These Reports are published by His Majesty's Stationery Offioe, London, and may be purchased directly from H.M. Stationery Office at the following addresses : Adastral House, Kingsway, W.C. 2; 28, Abingdon Street, London, S.W.I ; York Street, Manchester ; 1, St. Andrew's Crescent, Cardiff ; or 120, George Street, Edinburgh ; or through any book- seller. EXPERIMENTS ON A MODEL OF THI AIRSHIP R.101. By E. Jones, M.A., D.Sc; and A. H. Bell.) R. & M. No. 1168 (Ae. 332). (27 pages and 7 figures.) September, 1926. Price Is. 3d. net. Experiments are described which were undertaken to determine theaerodynamic characteristics of alternative forms of hull and flcs suggested lor the Government airship B..101. In the first place, experiments were madeon a model resembling the shape (V. 721)* whose head resistance was the lowest ever determined at the N.l'.J-., aDd on a second model which was thesame as the former from the nose to the maximum diameter, but whose tail was an oval in cross-section such that the vertical dimension was greater thanthe horizontal dimension. Such a form would not necessitate so great an area of vertical tin for lateral stability as the normal form. The drag of themodel with the oval tail was found to be slightly higher than that of the other, which itself was slightly higher than that of T7.721. It, wa^ decided,therefore, to abandon the shape with the modified tail in favour of the more normal design. "Experiments were then carried out on various types of flufor the selected shape, and a highly satisfactory type was ultimately developed. * K. <t M. 607. Experiments in a wind channel on elongated bodies ofapproximately streamline form. Part III. Effect of form on resistance.— Pannell and Jones. INSTRUMENTAL RECORDS OF THE LATERAL MOTIONS OF a STALLED BRISTOL FIGHTER AEROPLANE. By Prof. B. Melvill Jones, A.F.C., M.A., F.R.Ae.S., and Flt.-Lieut. C. E. Maitland, D.F.C., R.A.F. R. & M. Xo. 1181 (Ae. 345). (11 pages and 42 diagrams.) September, 1928. Price Is. net. This report represents a practical contribution to knowledge on theimportant question of the control of aeroplanes at high angles of incidence. The object of these experiments was to olrtain a series of instrumentalrecords which would display the behaviour of an aeroplane under the action of its control when flying at high incidences. A standard HrMol FighterWa;- chosen as the aeroplane because it is a type for which many accidents have been attributed to stalling. Model experiments at high incidencesrelating to the action of the controls and the effects of rotation, and free flight, experiments giving lift and drag up to about 23' incidence, have previouslybt'ii made on this aeroplane ; these provide data which can be used in the •aiwlvsis and explanation of the results to be described.The Instruments.—-These were designed and made at the Royal Aircraft I^'itblishment and lent to the Cambridge University Air .Squadron for theseexperiments. They consist of three recording gyroscopic rate of turn indicators, which give continuous photographic records of the angularTt-"'-itiei? of the aeroplane about three mutually perpendicular axes. Three otli'.-r instruments give continuous records of the movements of the controls—el«ators, ailerons, and rudder. All six records are synchronised from a •sir.irle clock *I'isctuiion of Results.—In all, something over 100 experiments were r«"rded, but. owing to the difficulty of ensuring the correct initial to"'iitions, some of these were repeats, and in some the initial conditions were too complicated for the results to IK- of much value. The it record*chosen for reproduction arc representative of the whole, and form n fairlv complete aeries, in which the progressive deterioration (if the control, froiiinormal flight to severely stalled tlisilit. can tic traced. Th.- complete series in' records fully explain the great dltneultv of controllinga stalled aeroplane. The view which has been put forward by the Aeronautical Research Com-mittee, that it is important to provide adequate rudder power to alleviate the dangers of accidental stalling, but that no rudder, however powerful, canalone provide satisfactory control, is conilniied. The view, derived mainly from the study of wind-tunnel data, that the rudder of the Bristol Fighterwas inadequate for stalled flight, is also continued. The report is purely descriptive, being a record of the result* obtained,with « brief discussion which does no more than point out their principal teatures. The correlation of these experiments, with the result* of experi-ments on models involves rather computation, and Is not yet completed. FULL SCALE EXPERIMENTS WITH A BRISTOL FIGHTER FITTED WITH SLOTS AND FLAPS AND SLOT AND AILERON CONTROL. By K. V. Wright, B.A. Presented by the Director of Scientific Research. Air Ministry. R. & M. No. 1188 (Ae. 350). (6 pages and (i diagrams.) June, 1928. Price 9d. net. The present report describes an investigation of the lift and drag and ofthe control at low speeds, of a Bristol Fighter fitted with slotw and flaps and slot and aileron control, described in It. * M. 1088.*The lift and drag have been measured with the slots and flaps in three positions, the latter being set at 0°, 1M)° and IS". In the first two positionsthe mean position of the ailerons wa,s the same as that of the flaps, whereas with the flaps at 15' the ailerons remained at 10 . Experiment* were madeto determine the relative effectiveness of the slot and aileron control lu stalled flight with the flaps and ailerons set for maximum and minimumcamber. The maximum lift coefficients with the flaps at 0" (nlot closed) and at 11-9°and 15° (slots open) were 0-5:S, 0-77 and ()•»:! respectively. The drag with the Haps at 0°, in which position the wing was of normal R.A.F. 15 sectiou,was found to be high. The slot and aileron control was found to he equally effective at all flap settings. Quantitative observations of the effectiveness of the control* will be madein accordance with a programme drawn up by the Stability and Control Panel. . * it.AM. »42. The R.A.E. Control Movement Recorder Mark III.— *•'• •'•- Jones and H. L. Stevens. * E. & M. 1088. Preliminary report on the fitting of slots and flapsand slot and aileron control to a Bristol Fighter, by H. L. Stevens, B.A. WIND TUNNEL EXPERIMENTS ON THE DESIGN OF AN AUTOMATIC SLOT FOR R.A.F.31 SECTION.—By F. B. BRAD- field, Math. & Nat. Sci. Triposes, and F. W. G. Greener, B.Sc. Presented by the Director of Scientific Research, Air Ministry. R. & M. No. 1190 (Ae. 352). (11 pages and 5 diagrams.) August, 1928. Price 9d. net. These tests form part of a wind tunnel investigation of autoslots on wingsof various sections. An aerofoil of R.A.F. !!1 section has been tested with an auxiliary aerofoilwhose chord is 15 per cent. of the main chord. A range of linkages was tested. The free position of the auxiliary and the lift of the whig with the slot havebeen measured. The auxiliary cannot be brought far enough forward to produce the beatresults, unless extremely long links are used, and some other form of opening mechanism is desirable. The maximum lift coeflicient with the links testedis 0-8; the effect on lift of small slot openings limy be large, and may be objectionable if the aeroplane is rolled so that one slot opens and not theother. It is proposed to carry out similar tests on n uing of It.A.I1'. 34 section. WIND-TUNNEL TESTS FOR DESIGN OF AN AUTOMATIC SLOT FOR AVRO 504 N. By E. T. Jones, M.Eng., and K. W. Clark, B.Sc, D.I.C. Presented by the Director of Scientific Research, Air Ministry. R'. & M. No. 1192 (Ae. 354). (11 pages and 5 diagrams.) May, 1928. Price \)d. net. Wind-tunnel tests were required to provide data for the design of anautomatic slot for the Avro 504 N aeroplane. The maximum lift of the slotted wing has been measured in a wind speedof till ft./sec. on an aerofoil of 0-43 in. chord and 36 in. span, with a fixed auxiliary aerofoil of equal span over a range of auxiliary aerofoil positions,and at 40, 50 and 00 ft./sec. with the auxiliary aerofoil set In one position. A link mechanism was designed to allow the auxiliary aerofoil to reach theoptimum position, and measurements of slot opening against wing incidence were made on a 2-ft. chord aerofoil. The maximum lift coefficient of the sWted wing with the auxiliary aerofoilin the optimum position is 0-80 at 22" incidence, while thut of the unslotted winu is 0 55 at 15°--0 incidence, measured in a wind speed of «0 ft./sec. Theleusrths of the links necessary to allow the auxiliary aerofoil to reach the optimum position are 3-5 in. and 2-75 in. fur front and rear links, respec-tively, for a wing of 2 ft. chord. The auxiliary aerofoil bet'ins to move forward at 7° incidence, and the slot is fully open at 20° incidence. THE LONGITUDINAL CONTROL OF AN AEROPLANE BEYOTO THE STALL. By H. M. Garner, M.A., and K. V. Wright, B.A. Presented by the Director of Scientific Research, Air Ministry. R. & M. No. 1193 (Ae. 355). (6 pages.) May, 1928. Prioe 4rf. net. It is a matter of experience that the control of an aeroplane beyond th«stall is much more difficult than at normal incidences. Until the advent of slot control it was impossible to say how much the failure of the controlwas lateral and how much longitudinal. A good deal of experience has now been obtained in flying aeroplanes with slot control at large angles of incidence 44%
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