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The paper focuses on the evaluation of a light aircraft spin. The main purpose of this paper is to achieve reliable mathematical models of aircraft motion beyond stall conditions to subsequently predict spin properties based on calculation only. Another vitally significant objective is to verify whether the aerodynamic characteristics determined numerically are coherent with the wind tunnel measurements performed on the dynamically scaled aircraft models.

The analysis was carried out for two certified conventional light aircraft. The first part of the investigation is devoted to the verification of the simplified methods used to identify the aircraft recoverability from spinning steady-state turns and estimate the primary post-stall flight parameters. Then, the spin simulations were executed. The computational results were thereafter compared with the in-flight data recordings.

The study confirms the coincidence between the calculated spinning behaviour and the observed aircraft response during the flight tests. The mathematical models of aircraft spatial motion have been found to be credible for predicting spin properties. The simplified methods are reliable to determine the basic spin performance of light aircraft at the preliminary design stage, whereas the spin simulations enable recognition and comprehensive examination of all spin modes.

The outcomes of conducted calculation and comparisons of computational spin properties with flight test recordings have indicated that the qualitative assessment of spinning motion is enabled at each stage of the designing process.

The paper involves the comparison of the computational results with the recordings of spin in-flight tests and the correlation between calculated and experimentally obtained aerodynamics of light aircraft.

The paper aims to present an innovative method for identification of flight modes in the spin maneuver, which is highly nonlinear and coupled dynamic.

To fix the mode mixing problem which is mostly happen in the EMD algorithm, the authors focused on the proposal of an optimized ensemble empirical mode decomposition (OEEMD) algorithm for processing of the flight complex signals that originate from FDR. There are two improvements with the OEEMD respect to the EEMD. First, this algorithm is able to make a precise reconstruction of the original signal. The second improvement is that the OEEMD performs the task of signal decomposition with fewer iterations and so with less complexity order rather than the competitor approaches.

By applying the OEEMD algorithm to the spin flight parameter signals, flight modes extracted, then with using systematic technique, flight modes characteristics are obtained. The results indicate that there are some non-standard modes in the nonlinear region due to couplings between the longitudinal and lateral motions.

Application of the proposed method to the spin flight test data may result accurate identification of nonlinear dynamics with high coupling in this regime.

First, to fix the mode mixing problem in EMD, an optimized ensemble empirical mode decomposition algorithm is introduced, which disturbed the original signal with a sort of white Gaussian noise, and by using white noise statistical characteristics the OEEMD fix the mode mixing problem with high precision and fewer calculations. Second, by applying the OEEMD to the flight output signals and with using the systematic method, flight mode characteristics which is very important in the simulation and controller designing are obtained.

The paper aims to present an idea of automatic control algorithms dedicated to both small manned and unmanned aircraft, capable to perform spin maneuver automatically. This is a case of maneuver far away from so-called standard flight. The character of this maneuver and the range of aircraft flight parameters changes restrict application of standard control algorithms. Possibility of acquisition full information about aircraft flight parameters is limited as well in such cases. This paper analyses an alternative solution that can be applied in some specific cases.

The paper uses theoretical discussion and breakdowns to create basics for development of structures of control algorithms. Simplified analytical approach was applied to tune regulators. Results of research were verified in series of software-in-the loop, computer simulations.

The structure of the control system enabling aerobatic flight (spin flight as example selected) was found and the method how to tune regulators was presented as well.

It could be a fundament for autopilots working in non-conventional flight states and aircraft automatic recovery systems.

The paper presents author’s original approach to aircraft automatic control when high control precision is not the priority, and not all flight parameters can be precisely measured.

The purpose of this paper is to describe an integrated approach to spin analysis based on 6-DOF (degrees of freedom) fully nonlinear equations of motion and a three-dimensional multigrid Euler method used to specify a flow model. Another purpose of this study is to investigate military trainer performance during a developed phase of a deliberately executed spin, and to predict an aircraft tendency while entering a spin and its response to control surface deflections needed for recovery.

To assess spin properties, the calculations of aerodynamic characteristics were performed through an angle-of-attack range of −30 degrees to +50 degrees and a sideslip-angle range of −30 degrees to +30 degrees. Then, dynamic equations of motion of a rigid aircraft together with aerodynamic loads being premised on stability derivatives concept were numerically integrated. Finally, the examination of light turboprop dynamic behaviour in post-stalling conditions was carried out.

The computational method used to evaluate spin was positively verified by comparing it with the experimental outcome. Moreover, the Euler code-based approach to lay down aerodynamics could be considered as reliable to provide high angles-of-attack characteristics. Conclusions incorporate the results of a comparative analysis focusing especially on comprehensive assessment of output data quality in relation to flight tests.

The conducted calculations take into account aerodynamic and flight dynamic interaction of an aerobatic-category turboprop in spin conditions. A number of manoeuvres considering different aircraft configurations were simulated. The computational outcomes were subsequently compared to the results of in-flight tests and the collected data were thoroughly analysed to draw final conclusions.

This paper aims to provide a detailed review of the experimental research on the prediction of aircraft spin and recovery characteristics using dynamically scaled aircraft models.

The paper organizes experimental techniques to predict aircraft spin and recovery characteristics into three broad categories: dynamic free-flight tests, dynamic force tests and a relatively novel technique called wind tunnel based virtual flight testing.

After a thorough review, usefulness, limitations and open problems in the presented techniques are highlighted to provide a useful reference to researchers. The area of application of each technique within the research scope of aircraft spin is also presented.

Previous reviews on the prediction of aircraft spin and recovery characteristics were published many years ago and also have confined scope as they address particular spin technologies. This paper attempts to provide a comprehensive review on the subject and fill the information void regarding the state of the art aircraft spin technologies.

This paper focuses mainly on the experimental and in‐flight spin investigations for an executive light airplane, named I‐23 and built in the Institute of Aviation (Warsaw, Poland). It is a single‐engine, all composite, straight wing, retractable undercarriage, conventional configuration and flight control system airplane. In‐flight spin tests confirmed good rudder and elevator effectiveness for spin recovery in a wide range of positions of the center of gravity. A typical time history of a spin entry and the developed spin and recovery is shown as well.

This paper aims to present a literature review on analytical research on the prediction of aircraft spin and recovery characteristics, as it progressed from the early years of aviation to current state of the art spin technologies.

Aerodynamic model development approaches that have been generally used in past spin studies are presented. Past contributions in application of these analytical techniques to predict spin and recovery characteristics on various fighters, general aviation and airliners are discussed, thus providing useful reference for researchers embarking aircraft spin research. An overview of the development of spin prevention and spin recovery technologies to mitigate stall/spin susceptibility is presented.

The challenges associated with the presented techniques that prompt possible future research directions are discussed.

Despite considerable progress in the recent years, no comprehensive review on the analytical and computational research techniques to predict aircraft post-stall/ spin characteristics has been undertaken in the recent years.

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.

THE complete study of the tail spin divides itself into four distinct parts: the entry into the spin, the steady spin maintained by the action of the controls, the uncontrolled spin, and the recovery from the spin. In this paper we will limit ourselves to the study of the uncontrolled tail spin, i.e., the spin which has reached the state of steady motion, and persists in it with controls neutralized, or even against controls. When we speak about steady motion, we imply that all forces and moments are in a state of complete equilibrium, and that there are no accelerations. The study of the uncontrolled spin is therefore the study of equilibrium in spin. If the proportions of an aeroplane are such as to make possible equilibrium in spin with controls set for recovery, there evidently will be no recovery, because recovery means lack of balance and resulting acceleration. In order to be safe the aeroplane must be proportioned so as to make equilibrium in tail spin impossible, unless the controls are set lor spinning.

THE serious nature of difficulties which might be encountered in tail spins, was brought forcibly to the attention of the Material Division of the U.S. Army Air Corps, in the Spring of 1926, when Lieutenant E. H. Barksdale lost his life in attempting to determine the cause of difficult recovery from spins in a military aeroplane being flight tested at Dayton, Ohio. Trouble in recovery from spins had been encountered in several instances in foreign countries, and one or two cases had occurred in the United States: however, the problem was not considered as one generally applicable to all aeroplanes, because, in most cases of previous trouble, the aeroplanes concerned possessed unusual design features which were thought to be mainly responsible for their abnormal behaviour. Prior to this time, general conjectures had been made, regarding probable reasons for difficult recovery from spins, but very little in the nature of systematic investigation had been attempted, consequently no generally applicable principles had been determined. Numerous studies had been made in wind tunnels, and it was recognised that the normal aerofoil would rotate automatically under certain conditions, but the magnitude of the forces involved, and therefore the ability of an aeroplane to recover a normal attitude by use of the controls, could not be readily determined by wind tunnel tests. A few flight tests had indicated that the centre of gravity location, with respect to the resultant air force vector on the lifting surfaces, influenced the type of spin and the case of return to a normal attitude.