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- Publisher
- Emerald Publishing
- Copyright
- Copyright © Emerald Group Publishing Limited
- ISSN
- 0002-2667
- DOI
- 10.1108/eb032485
- Publisher site
- See Article on Publisher Site
Abstract
arc also introduced for the shear flow in the trape- zodial root panels. The calculated stresses are com Research Reports and Memoranda pared to the test results from a glued aluminium alloy model wing and the longitudinal normal stress distri bution is shown to agree very well with the experi Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical mental values, while there is a certain discrepancy for the shear stresses. The model tests are described in Research Council, Reports and Technical Memoranda of the United States National Advisory Com F.F.A. Report No. 53. mittee for Aeronautics and publications of other similar Research Bodies as issued. U.S.A. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS GREAT BRITAIN R. & M. No. 2793. Determination of Reversal TECHNICAL REPORTS Speed of a Wing with a Partial-Span Flap and Inset AERONAUTICAL RESEARCH COUNCIL Government Printing Office, Washington, D.C. Aileron. By W. G. Molyneux and E. G. Broadbent. REPORTS AND MEMORANDA (Foreign Annual Subscription Rate: 11·0 dollars) February, 1950. (3s.) 1120. Relative Importance of Various Sources of H.M. Stationery Office, London Control reversal due to deformation of a wing with Defect-Producing Hydrogen Introduced into Steel a partial-span flap and inset aileron is considered R. & M. No. 2757. A Survey of Performance Reduc During Application of Vitreous Coatings. By Dwight G. theoretically for the particular case of a flap held at tion, with Particular Reference to Turbo-Propeller Moore, Mary A. Mason and William N. Harrison. the root end. The semi-rigid method is used. Aircraft. By K. J . Lush. January, 1950. (2s. 6d.) An investigation is made for a particular aircraft. The purpose of this investigation was to study and Performance reduction methods will soon be The calculated reversal speed is found to be con to determine experimentally the relative importance required for routine tests of turbo-propeller aircraft. siderably lower than for the straight-forward wing- of various sources of defect-producing hydrogen intro A survey of the types of methods available has there aileron case. The effect of variation of the degrees duced into steel during the application of vitreous-type fore been made to find which type seemed likely to of wing and flap constraint is also considered. It is ceramic coatings. Under the conditions investigated, be most useful. concluded that an increase in reversal speed is best the principal source of defect-producing hydrogen The purpose of performance reduction is briefly obtained by an increase in flap root stiffness. was the dissolved water present in the enamel frit of examined. Methods in use are classified into experi the coating. Acid pickling, milling water, chemically mental methods, which require no advance numerical combined water in the clay, and quenching water data, and analytical methods, which require such data. SWEDEN were all minor sources. Test results indicated that The latter class is sub-divided into methods based fishscaling, reboil, and possibly primary boil may be FLYGTEKNISKA FÖRSÖKSANSTALTEN (F.F.A.) on small corrections and methods based on per eliminated by using a coating prepared with a water- (THE AERONAUTICAL RESEARCH INSTITUTE formance analyses. The suitability of each class free frit. OF SWEDEN) of method is discussed. Ulsvunda 1, Stockholm Experimental methods are only practicable if any 1123. A Study of Inviscid Flow About Aerofoils at engine control linkage scheme is such as to impose F.F.A. REPORTS] High Supersonic Speeds. By A. J. Eggers, Jnr., dimensionally correct relations between the linked Report 52. An Electronic Apparatus for Automatic Clarence A. Syvertson and Samuel Kraus. variables. They are convenient if data are required Recording of the Logarithmic Decrement and Frequency Steady flow about curved aerofoils is investigated over a range of all variables or if, of the non-dimen of Oscillations in the Audio and Subaudio Frequency analytically, first assuming air behaves as an ideal sional groups which result from dimensional analysis, Range. By C. O. Olsson and K. Orlik-Rückemann. gas, and then assuming it behaves as a thermally all or most are susceptible to precise control. If such An electronic apparatus for automatic evaluation perfect, calorically imperfect gas. Conclusions are methods are practicable and reasonably convenient of the damping of a harmonic oscillation has been drawn from the study. they are very attractive and probably the best to use designed and constructed. The apparatus is based on on turbo-propeller aircraft, particularly at high altitude the idea of representing the harmonic damped oscil or Mach number, because of the lack of knowledge, lation by a rotating vector on the screen of a cathode- as yet, of aircraft and engine characteristics under ray tube in such a way, that the rate of decrease of these conditions. the length of the vector is a measure of the damping. If experimental methods are impracticable or very The results are obtained simultaneously with the inconvenient, analytical methods based on per oscillation test as two numbers in decimal digits, formance analyses are probably the best substitute, which are inversely proportional to the logarithmic at least for tests at high altitude or high Mach num decrement and the frequency, respectively. The ap ber, until such time as numerical data on engine and paratus, which is named the 'Dampometer', has been airframe behaviour are available and can be easily used for some time for free oscillation measurements used. of the dynamic stability derivatives of aeroplane models in wind tunnels, and has proved to be very R. & M . No. 2759. Notes on the Dynamic Response satisfactory. It gives results of usually higher accuracy of an Aircraft to Gusts and on the Variation of Gust than evaluation methods in common use, and permits Velocity along the Flight Path. By Anne Burns. Sep a most considerable saving of time. tember, 1949. (7s. 6d.) A collection of records showing the time histories Report 53. Stress and Deflexion Measurements on of strains and accelerations at various parts of a a Multicell Cantilever Box Beam with 30 deg. Sweep. Lancaster flying in turbulent air is presented and By S. Eggwcrtz and B. R. Noton. discussed. The records include specimens taken in cloud at moderate altitudes and in clear air at low An experimental investigation of the stress distribu altitudes. Two points of interest regarding the response tion and deflexion has been carried out on an idealized of the aircraft to gusts are brought to light: four-cell model wing with 30 deg. sweep. The model (i) The amount of fundamental oscillation excited consisted of two identical untapered cantilever beams by a gust appears to be affected to a marked joined together with a heavy root rib. The cover plates extent by the variation of gust velocity across extended unbroken between the tip ribs, while the the span. spars were built into the root rib. The specimen has (ii) The amount of oscillation excited docs not been manufactured in 24S-T aluminium alloy and appear to show any marked decrease as the the components have been joined by using Redux airspeed of the aircraft is increased. Some and Araldite structural adhesives. The stress distri decrease in the oscillation excited might be butions in the model and the deflexions of the outer expected due to increase in aerodynamic most spars have been determined for two symmetrical damping. loading cases. In the first case, two vertical forces were applied on each cantilever at the intersection of An attempt is made to deduce the variation of gust the front and rear spars with the tip ribs and in the velocity along the flight path from the measured second case, a vertical force was applied at the rear response of the aircraft. The results indicate that a spar and tip rib joints. To measure the strains on the large up-gust is often closely followed by a large structure, electrical strain gauges have been used and down-gust and vice versa. the reliability of the results has been determined by equilibrium calculations. The model wing is analysed R. & M. No. 2790. Records of Major Strength theoretically in FFA Report No. 54. Tests. By P . B. Walker. July, 1949. (2s.) The strength attained in major strength tests, made Report 54. Calculation of Stresses in a Swept over a period of ten years, is given for twenty-four Multicell Cantilever Box Beam with Ribs Perpendicular wing systems and ten fuselages. A preliminary analysis to the Spars and Comparison with Test Results. By is also presented from the standpoints of safety and S. Eggwertz. design efficiency. One-third of all the wing systems tested are found to be seriously understrength as An energy calculation is carried out on a 30 degrees originally designed, and it is concluded that wing and swept four-cell box beam which is entirely clamped at fuselage testing for all new types is essential for safety. the root. The beam has a constant section along its The majority of understrength aircraft, however, whole length and is provided with three outboard ribs were brought up to the required standard by local perpendicular to the spars. Different assumptions strengthening, and it is concluded that this has an are made as to the bending stiffness in the lateral important bearing on design efficiency. direction of the beam. Two different approximations 366 Aircraft Engineering
Journal
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Oct 1, 1954