Bob Gates, Colin Griffiths, Paul Keenan, Sandra Fleming, Carmel Doyle, Helen L. Atherton, Su McAnelly, Michelle Cleary and Paul Sutton
The third term has been expressed as but in wind tunnel work it is often more convenient to measure were the omission of the dash signifies that the moment is now measured about a…
Abstract
The third term has been expressed as but in wind tunnel work it is often more convenient to measure were the omission of the dash signifies that the moment is now measured about a wind axis. The two quantities are very closely related and the measurement of one tells us almost as much as if the two were known. The latter, however, tells us either directly or indirectly what effect the addition of fin and rudder will have on the autorotation properties of the wings alone. The damping of fin and rudder being due essentially to the air flow meeting them at an angle on account of the rotation it should theoretically be possible to deduce this dynamic quantity from a simple static test of moment due to yaw angle. An experiment to test this was carried out several years ago but the static test did not give any approximation to the truth. This was ascribed at the time to the shielding of fin and rudder by the tail plane in the rotative experiment and subsequent work has amply confirmed this view. It is now known that shielding by the tail plane is by far the most important factor in determining the efficiency of the vertical surfaces at high angles of attack.
IN a series of articles entitled “Tailless Aircraft and Flying Wings”, concluded last month, the evolution of the tailless aeroplane and the flying wing was treated. The different…
Abstract
IN a series of articles entitled “Tailless Aircraft and Flying Wings”, concluded last month, the evolution of the tailless aeroplane and the flying wing was treated. The different trends of the development were classified, and a short discussion of the difficulties which had been experienced during experimental work given.
IN these notes I have attempted to describe the main features of longitudinal stability and control in the simplest possible terms, omitting the mathematical apparatus which makes…
Abstract
IN these notes I have attempted to describe the main features of longitudinal stability and control in the simplest possible terms, omitting the mathematical apparatus which makes this subject so formidable to those who are not constantly using it. Designers are certainly justified in complaining that most analyses of this subject contain, so to speak, so much XYZ that the ABC of the matter (if indeed there is one) is successfully hidden from them. In making a drastic attempt to return to ABC it must be realised that such a statement can be neither strictly accurate nor complete. Something will be gained, however, if it helps some designers to be clearer about what they are supposed to be doing in this part of their task, and why. The XYZ of the subject is, of course, indispensable to the working out of any particular problem of design A classified list of some useful recent British reports will be found in the Appendix.
THE purpose of this paper is to give some account of the work on spinning and the progress which has been made since S. B. Gates and L. W. Bryant presented their paper to the…
Abstract
THE purpose of this paper is to give some account of the work on spinning and the progress which has been made since S. B. Gates and L. W. Bryant presented their paper to the Society, which was published in more comprehensive form by the Aeronautical Research Committee as R. & M. 1001.
A.D. Young and S. Neumark
Detailed step by step calculations have been made of the recovery with fixed elevator from a high speed dive for three different aircraft; for these calculations measured wind…
Abstract
Detailed step by step calculations have been made of the recovery with fixed elevator from a high speed dive for three different aircraft; for these calculations measured wind tunnel data were used. The aircraft differed markedly in the behaviour of their restoring margin Km=− (∂Cm/∂CL)M. The calculations demonstrated in all cases an initial, rapidly damped, short period oscillatory phase, a nearly constant value of ρV2 throughout the recovery, and subsequent to the initial oscillatory phase Cm was small. These results enable three different approximate methods for calculating the recovery after the initial oscillatory phase to be developed. The first is applicable where only a rough estimate of the recovery characteristics is required and the value of Km is about 0·3 or greater; it is very simple and quick to apply. The second is only a little more complicated and is found to give reliable results where Km is of the order of 0·1 or greater. The third method is the most complicated of the three but is still fairly simple and quick and it can be expected to give reliable results in all cases except where Km is appreciably negative for a considerable portion of the recovery. In the latter case, however, the aircraft is liable to be unstable and detailed step by step calculations or simulator studies are essential for an accurate assessment of the recovery. The main features of the initial oscillatory phase are satisfactorily predicted by Gates' manoeuvrability theory if the restoring margin Km is adequately positive (that is, greater than about 0·005) and if this factor docs not vary rapidly with Mach number at that stage. No detailed investigation has been made for aircraft diving at supersonic speeds; however, it seems likely that the general results of this investigation will still apply in such cases.
THIS report gives a general solution of the problem of the calculation of the Glauert loading of wings with discontinuities of incidence. The three existing variations of the…
Abstract
THIS report gives a general solution of the problem of the calculation of the Glauert loading of wings with discontinuities of incidence. The three existing variations of the original theory, the Glauert solution, the Gates' least squares solution, and the Lotz' solution, are not entirely satisfactory and may involve a considerable amount of labour. The present solution divides the Fourier series representing the circulation into two parts: (a) a standard solution representing the discontinuities, which includes the slowly convergent part of the solution, and which is expressible as a precise infinite series dependent only upon the position of discontinuities along the span, and (b) a secondary solution due to plan form, aspect ratio, slope of section lift curve, and so on, which is the quickly convergent part of the solution and usually requires a terminated scries of only from four to six terms. Once the standard solution has been computed, the remaining work is little more than for the standard Glauert solution for a flat wing.
IN dealing last month with developments since the inception of AIRCRAFT ENGINEERING in March, 1929, one of the features we mentioned was flaps. It is, therefore, apropos that wc…
Abstract
IN dealing last month with developments since the inception of AIRCRAFT ENGINEERING in March, 1929, one of the features we mentioned was flaps. It is, therefore, apropos that wc should this month publish an article by MR. S. B. GATES on this subject. Actually, this article had been promised us for some time and it is by a coincidence pure and simple that it should appear so appropriately now.
WITH tailless aeroplanes, all known aerodynamic control devices possess the peculiarity of not only producing moments about one axis, but of also causing secondary moments about…
Abstract
WITH tailless aeroplanes, all known aerodynamic control devices possess the peculiarity of not only producing moments about one axis, but of also causing secondary moments about one or both of the other axes. Horizontal controllers forming part of the wing near the tips in wings having sweep‐back or sweep‐forward, for instance, do not produce rolling moments alone, when differ‐entially deflected; they also cause yawing and pitching moments. Similarly, wing‐tip disk rudders operated on such wings not only produce yawing moments, but may cause rolling and even pitching moments.
IN high‐speed level flight in the compressibility region an entirely new factor makes its appearance, viz: small variations of atmospheric density and speed of sound with height…
Abstract
IN high‐speed level flight in the compressibility region an entirely new factor makes its appearance, viz: small variations of atmospheric density and speed of sound with height. This factor affects dynamic stability due to continuous changes of height during longitudinal disturbances; there is no effect in lateral disturbances. The affects are very small in low‐speed flight but they increase steadily with Mach number. The short‐period oscillations are not affected but the corrections to phugoid motion become appreciable in high subcritical flight, larger in supercritical (transonic) range, and very important in supersonic flight. The effects of compressibility are of paramount significance but they should be considered in conjunction with varying height effects. Another result of the investigation is the appearance of a new mode of disturbance, due to the stability quartic being converted into a quintic. The fifth (real) root is often small, it may vary in sign according to aerodynamic properties of the aircraft and characteristics of the power unit. The new mode is a subsidence or a divergence, and it determines height stability or instability, hence it may show to what extent an aircraft is able to keep constant altitude over long stretches of time.