Search results

The purpose of this paper is to study the correlation between the dynamic features of the running-in attractor and the wear particle group, so as to characterize the running-in attractor by means of the wear particle group.

Wear particles are collected in phased wear experiments, and their dynamic features are investigated by the equivalent mean chord length L. Then, the correlation between the equivalent mean chord length L and the correlation dimension D of the running-in attractor is studied.

In the wear process, the equivalent means chord length L first decreases, then remains steady, and finally increases, this process agrees with the increase, stabilization and decrease of the correlation dimension D. Therefore, the wear particle group has a dynamic nature, which characterizes the formation, stabilization, and disappearance of a running-in attractor. Consequently, the dynamic characteristics and evolution of a running-in attractor can be revealed by the wear particle group.

The intrinsic relationship between the wear particle group and the running-in attractor is proved, and this is advantageous for further revealing the dynamic features of the running-in attractor and identifying the wear states.

IN an earlier article dealing with the general aspects of clastic distortion phenomena, which appeared in an issue of Aeronautics, mention was made of the various factors which tend either to promote, or to damp out and eliminate the onset of the aerodynamic inertia elastic vibration phenomena known as flutter, and it was pointed out that in this respect the provision of an adequate measure of rigidity, both as regards to twisting and flexure of the wing or tail surface structure is one of the most effective safeguards against the occurrence of torsional‐flexural flutter.

WRITING an introduction to an article by Mr S. B. Gates on Trailing‐Edge Flaps, which appeared in these columns in 1937, the Editor felt constrained to admit his bewilderment over the number and variety of types of high‐lift aid which then existed. Without intending any disrespect, I imagine that the progress of years must have added to his embarrassment. It has certainly added to the number of devices in use and under test.

IN the earliest stages of the development of the aeroplane the speed range obtainable was small, flight occurred only at fairly high lift coefficients, and induced drag was the predominant component of total resistance, hence successful flight depended on the achievement rather of minimum weight, minimum wing loading and maximum engine power than on the achievement of minimum possible parasite resistance.

A comprehensive series of tests have been made on an experimental single‐stage turbine to determine the cooling characteristics and the overall stage performance of a set of air‐cooled turbine blades. These blades, which arc described fully in Part I of this paper had, internally, a multiplicity of passages of small diameter along which cool air was passed through the whole length of the blade. Analysis of the test data indicated that, when a quantity of cooling air amounting to 2 per cent, by weight, of the total gas‐flow through the turbine is fed to the row of rotor blades, an increase in gas temperature of about 270 dcg. C. (518 deg. F.) should be permissible above the maximum allowable value for a row of uncoolcd blades made from the same material. The degree of cooling achieved throughout each blade was far from uniform and large thermal stresses must result. It appears, however, that the consequences of this are not highly detrimental to the performance of the present type of blading, it being demonstrated that the main effect of the induced thermal stress isapparently to transfer the major tensile stresses to the cooler (and hence stronger) regions of the blade. The results obtained from the present investigations do not represent a limit to the potentialities of internal air‐cooling, but form merely a first exploratory step. At the same time the practical feasibility of air cooling is made apparent, and advances up to the present arc undoubtedly encouraging.

The purpose of this paper is to investigate the equivalent control authority of the conventional and circulation control (CC) wing of the aircraft and assess the energy expenditure and aerodynamic efficiency of the CC wing.

Four target cases with different flap deflection angles θ are set in advance for the conventional wing, and then a series of cases with different jet momentum coefficients Cμ are set for the CC wing. The lift, drag and momentum coefficient curves of the CC wing are compared to those of the four conventional wing cases. The curves with the best agreement are selected to establish the corresponding relation between θ and Cμ. The energy expenditure of the CC system is analyzed. The concept of equivalent lift-to-drag ratio for the CC wing is introduced to compare the aerodynamic efficiency with the conventional wing

The control authority of the conventional wing at θ = 0º, 10º, 20º, 30º are equivalent to the control authority of the CC wing with Cµ = 0.0, 0.005, 0.009 and 0.012. The CC system is more efficient at small Cµ than large Cµ.

This study could contribute to the application of the CC system on flapless aircrafts.

The corresponding relation between θ and Cµ is established by matching the equivalent control authority between the conventional wing and CC wing.

THIS article is intended, firstly, as a means to a quick approximate determination of the critical reversal speed of a wing, and secondly to give a clearer insight of why approximations can be given for the general formula for determining K, when the aileron chord and wing chord are of linear taper at least over the aileron portion.

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

IN applications of mathematics to aerodynamics, the biquadratic or quartic equation is of frequentoccurrence.Itarises forinstance in studies of aircraft stability as the characteristic equation which determines the frequencies and dampings of the lateral, or, alternatively, the longitudinal modes of motion of an aircraft with fixed controls, following a disturbance from steady flight; and in other cases, as, for example, in the study of the stability of an aircraft with free controls or of a towed glider, it may occur in the course of the solution of an equation of higher order.

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.