Artificial Flight Research Articles

Generating controlled gust perturbations using vortex rings.

To understand the locomotory mechanisms of flying and swimming animals, it is often necessary to develop assays that enable us to measure their responses to external gust perturbations. Typically, such measurements have been carried out using a variety of gusts which are difficult to control or characterize owing to their inherently turbulent nature. Here, we present a method of generating discrete gusts under controlled laboratory conditions in the form of a vortex rings which are well-characterized and highly controllable. We also provide the theoretical guidelines underlying the design of gust generators for specific applications. As a case study, we tested the efficacy of this method to study the flight response of freely-flying soldier flies Hermetia illucens. The vortex ring based method can be used to generate controlled gusts to study diverse phenomena ranging from a natural flight in insects to the artificial flight of insect-sized drones and micro-aerial vehicles.

Asynchronous and Self‐Adaptive Flight Assembly via Electrostatic Actuation of Flapping Wings

Biologically Inspired Robots Most of the artificial flying robots are based on the synchronous driving mechanism, while in article number 2100048, Liu Zhiwei, Yan Xiaojun, and co-workers demonstrate the feasibility of artificial flight muscle using the asynchronous driving by self-sustained electrostatic oscillations of metal beams to power flapping wings without any AC circuits, which exhibits takeoff along the guide rails and self-adaptive hovering features.

다중 사이클릭 헬리콥터 진동 제어

The vibration control performance of an active twist rotor using multicyclic control is evaluated and discussed. Artificial flight data for a descent flight with 6-degree flight path angle are generated using CAMRAD II. A linear, quasi-static, frequency domain system model with six multicyclic higher harmonic control inputs and 12 harmonic response outputs of nonrotating hub loads is identified offline by using the least squared error. The optimal control input for minimizing the quadratic performance function and the corresponding response to the optimal control are calculated. The open-loop control performance is simulated using CAMRAD II by applying the optimal control input. The nondimensionalized vibration index combining 12 nonrotating hub loads is reduced by 93 % using open-loop control. The gradient descent method is applied for closed-loop control, and MATLAB/CAMRAD II coupled analysis is performed to evaluate the closed-loop multicyclic control system. The closed-loop control using the gradient descent algorithm with the system model identified offline shows very good vibration reduction performance, and the reduced vibration level converges to the optimal solution.

A Data-Driven Approach to Identify Flight Test Data Suitable to Design Angle of Attack Synthetic Sensor for Flight Control Systems

Digital avionic solutions enable advanced flight control systems to be available also on smaller aircraft. One of the safety-critical segments is the air data system. Innovative architectures allow the use of synthetic sensors that can introduce significant technological and safety advances. The application to aerodynamic angles seems the most promising towards certified applications. In this area, the best procedures concerning the design of synthetic sensors are still an open question within the field. An example is given by the MIDAS project funded in the frame of Clean Sky 2. This paper proposes two data-driven methods that allow to improve performance over the entire flight envelope with particular attention to steady state flight conditions. The training set obtained is considerably undersized with consequent reduction of computational costs. These methods are validated with a real case and they will be used as part of the MIDAS life cycle. The first method, called Data-Driven Identification and Generation of Quasi-Steady States (DIGS), is based on the (i) identification of the lift curve of the aircraft; (ii) augmentation of the training set with artificial flight data points. DIGS’s main aim is to reduce the issue of unbalanced training set. The second method, called Similar Flight Test Data Pruning (SFDP), deals with data reduction based on the isolation of quasi-unique points. Results give an evidence of the validity of the methods for the MIDAS project that can be easily adopted for generic synthetic sensor design for flight control system applications.

BICUBIC SPLINE INTERPOLATION: A QUANTITATIVE TEST OF ACCURACY AND EFFICIENCY*

AbstractTwo different methods for the construction of an approximation to bicubic splines for interpolating irregularly spaced two‐dimensional data are described. These are referred to as the least squares line (LSL) and linear segment (LINSEG) construction procedures.A quantitative test is devised for investigating the absolute accuracy and efficiency of the two spline interpolation procedures. The test involves (i) laying of artificial flight lines on the analytically known field of a model, (ii) interpolation of field values along the flight lines and their subtraction from the original field values to compute the residuals. This test is applied on fields due to four models (three prism models and one dyke model) placed at different depths below the flight lines, and for each case the error estimates (the mean error, the maximum error and the standard deviation) are tabulated.An analysis of the error estimates shows in all cases the LSL interpolation to be more accurate than the LINSEG, although the latter is about 50% faster in computer time. The relative accuracy and efficiency of the LSL interpolation is also tested against a recent method based on harmonization procedure, which shows the latter to be more precise, though much slower in speed.

Thirty Years of Theoretical and Experimental Research in Fluid Mechanics

In the spring of 1904, when echoes of the Brothers Wright first flights began to be known in Europe, the author founded at Koutchino, near Moscow, on his family estate, the Aerodynamic Institute of Koutchino.Air is the fluid meant by the term “aerodynamic” and artificial flight was the most important of the applications included in the programme of the Institute; foreseeing, however, the importance of comparative researches in air and water, the author chose intentionally a location particularly suitable for hydraulic experiments. A small river, dammed so as to form a pond, afforded the possibility of regulating the speed of the current at will, and since 1905 parallel researches were carried on in the wind tunnel and in the stream of water.The idea of such an institute was very favourably received in the Russian scientific circles. When the author asked N. E. Joukovsky, V . V . Kouznetzoff and S. S. Nejdanovsky to participate in the organisation of this institution, they willingly gave their assent.

(1) Bases Théoriques de l'Aéronautique Aérodynamique (2) Dynamical Stability of Aeroplanes (3) Air Screws: an Introduction to the Aerofoil Theory of Screw Propulsion (4) Aérodonétique

(i) FOR tne French translation of Prof. Joukowski's work we are indebted to Dr. S. Drzewiecki. In a separate preface the latter writer emphasises the fact that the use of the principles of mathematical physics did not receive adequate attention in the early days of artificial flight, and he advocates the recognition of aerodynamics as a separate branch of theoretical science. We regret to find that whatever extraneous arguments may be and have been adduced for placing this subject on an independent footing, there is nothing, either in the translator's eloquent introduction or in the subject-matter of the book, to justify the present claim. (1) Bases Thoriques de l'Aeronautique. Aerodynamique. By Prof. N. Joukowski. Pp. xviii + 227. (Paris: Gauthier-Villars et Cie, 1916.) Price 11 francs. (2) Dynamical Stability of Aeroplanes. By Jerome C. Hunsaker, assisted by T. H. Huff, D. W. Douglas, H. K. Chow, and Capt. V. E. Clark. Pp. 78. (Smithsonian Miscellaneous Collections, lxii., 5; Hodgkins Fund.) (Washington: Smithsonian Institution, 1916.) (3) Air Screws: an Introduction to the Aerofoil Theory of Screw Propulsion. By M. A. S. Riach. Pp. viii + 128. (London: Crosby Lockwood and Son, 1916.) Price 10s. 6d. net. (4) Aerodonetique. Par F. W. Lanchester. Traduit de l'anglais sur la deuxime edition par le Commandant C. Beno®t. (Paris: Gauthier-Villars et Cie, 1916.) Pp. xvii + 478. Price 14 francs unbound.

The Evolution of an Aeroplane 1

READERS of the first two numbers of the twenty-seventh volume of “Smithsonian Contributions to Knowledge,” who have not forgotten the pleasure they derived from the study of Dr. S. P. Langley's work in aërodynamics, will welcome the publication of this third number, on mechanical flight. While experimental aerodynamics and the theoretical study of flight respectively may form the sole subject of an investigation, the successful flight of models and of full-scale machines cannot be attained without both the guide of theory and the possession of accurate numerical data gathered by means of careful experiments. Appeal to nature is even necessary to obtain, through the observations of bird flight, some starting point in a line of research by trial and error that cannot be struck at random. For this reason the pursuit of success in actual flight is the most comprehensive branch of the science of aviation, and it will be enough to say that the work before us deals with the history of Dr. Langley's efforts to realise artificial flight to convey the impression that the account put before us is pregnant with details of the utmost interest to men of science and to non-technical readers alike.

The longitudinal stability of aerial gliders.

The main difficulty connected with the attempt to fly by means of a machine heavier than air is that of longitudinal stability. It is not difficult to construct an aeroplane system which shall be transversely stable. But for this difficulty the problem of artificial flight would probably have been solved already. Experiments in gliding under gravity have been always made with machines not too large to be kept balanced by the skill of the experimenter, and the glides, though undoubtedly successful, have been of short duration. Experiments have invariably stopped short of the performance of continuous flight by a mechanically propelled machine.

The Longitudinal Stability of Aëroplane Gliders

During recent years, a considerable amour of work has been done in attempting to solv the problem of artificial flight, and in the mai this work has been very successful. One by on the difficulties which beset the problem have been overcome, and now apparently there : only one difficulty which stands between us an the solution of the problem—namely, the diffculty of balancing the machine. In the follow ing paper an attempt is made to further tb solution of this difficulty, by showing that it : capable of mathematical treatment.We have not attempted to deal exhaustivel with the question ; we have confined ourselve to the consideration of simple forms of glider and the chief object of the paper is to draw the attention of all interested in the problem artificial flight to the capabilities of this method.

The Aeronautical Annual, 1896 Zur Mechanik des Vogelfluges

TILL quite recently, artificial flight was regarded in much the same light as perpetual motion, the philosopher's stone, and other insoluble problems. But, now that Maxim, Langley, and others have demonstrated the possibility of overcoming the purely mechanical difficulties of flight, a wide field has been thrown open for scientific research in investigating the laws underlying the flight of birds and their practical application to the flight of man. The present record of investigations performed and theories propounded during the past year, will prove of great value to all who are interested in the subject by indicating what work has been done and what still remains undone. The Aeronautical Annual, 1896. Edited by James Means. Medium 8vo, pp. 158. (Boston: W. B. Clarke and Co. London: Wm. Wesley and Sons, 1896.) Zur Mechanik des Vogelfluges. Von Dr. Fr. Ahlborn. Demy 4to, pp. 134. (Hamburg: L. Friedrichsen and Co., 1896.)

Experiments in Mechanical Flight

I HAVE been for some years engaged in investigations connected with aerodromic problems, and particularly with the theoretical conditions of mechanical flight. A portion of these have been published by me under the titles “Experiments in Aerodynamics” and “The Internal Work of the Wind,” but I have not hitherto at any time described any actual trials in artificial flight.

Experiments in Aërodynamics 2

THE subject of this memoir is of especial interest at the present time, when the skill of a distinguished inventor is understood to be engaged in attacking the many practical difficulties which lie in the way of artificial flight upon a large scale. For a long time the resistance of fluids formed an unsatisfactory chapter in our treatises on hydrodynamics. According to the early suggestions of Newton, the resistances are (1) proportional to the surfaces of the solid bodies acted upon, to the densities of the fluids, and to the squares of the velocities; while (2) “the direct impulse of a fluid on a plane surface is to its absolute oblique impulse on the same surface as the square of the radius to the square of the sine of the angle of incidence.” The author of the work3 from which these words are quoted, in comparing the above statements with the experimental results available in his time (1822), remarks:—“(i) It is very consonant to experiment that the resistances are proportional to the squares of the velocities. …(2) It appears from a comparison of all the experiments, that the impulses and resistances are very nearly in the proportion of the surfaces. … (3) The resistances do by no means vary in the duplicate ratio of the sines of the angle of incidence.” And he subsequently states that for small angles the resistances are more nearly proportional to the sines of incidence than to their squares.

“Artificial Flight Attainable”

It is now generally admitted that the balloon as a means of transit from place to place is essentially uncontrollable, and this remark applies in an almost equal degree to buoyant gas bags of whatever form. The main reason of this is obvious, viz., that, as regards horizontal, or even oblique progression, it is due to the great bulk offered to the wind (so much sail surface really), with which the vehicle must drift helplessly. This inevitable drifting no motor nor mechanism that the balloon will lift can counteract or cope with.

The Bearing of these facts on the Problem of Artificial Flight

The Bearing of these facts on the Problem of Artificial Flight

Artificial Flight

In the Paper which I read before the Äeronautical Society, at the General Meeting in 1878, I stated that; with respect to those of my models which are actuated by wing–movement, I had found a difficulty of sustaining the weight which appertains to the living example. But, from experiments which I have lately made, I find that the weight to be sustained depends upon power and strength of material employed, and also upon the right application of that power. For instance, in the wing–action of the bird, that portion of the pectoral muscle which depresses the wing is considerably more powerful than that which elevates it, because its functionis to sustain the whole weight of the bird by impact upon the air. In my models I attain that action by affixing india–rubber cord, more or less in tension (according to the powerused), underneath the wings, so that when the wings are elevated there shall be a strong downward impetus.

Recent Researches on Flight*

OF late the perplexing problem of flight has received a greater amount of attention from physiologists and savants than has been bestowed upon it for years, ana the result of their researches and experiences is in a fair way ot becoming remurk able for its fruit-bearing character. Whilst abroad, such men as Borelli, Straus- Durckheim, Chabrier, Girard, and Marey, have severally given to the world the gist of their labours in this branch of science; at home, the Duke of Argyll and Dr. J. Bell Pettigrew have awakened our deep interest by their views on natural and artificial flight. To the latter is due the honour of giving birth to the celebrated “figure-of-8 wave theory,”that is now attracting so much notice in our aeronautical schools.