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Purpose: The purpose of this paper is to present the result of simulations that were performed to assess the uncontrolled motion of the passenger aircraft following its wing tip was suddenly cut. Such a simulation can help to understand the tendencies of aircraft behaviour after wing tip cut, assess how fast this phenomenon is going on and estimate the values of angles of attack, sideslip and pitch angle basing on given aerodynamic characteristics. Also, answer the question if pilot can counteract high deviations from flight path initially planned during the final phase of approach to landing. Design/methodology/approach: Simulation is based on the full non-linear equations of motion derived from generalised equations of change of momentum and moment of momentum of rigid body. Dynamic equations of motion in the so-called normal mode are solved in the so-called stability frame of reference. Findings: It was found that asymmetric rolling moment must be compensated by essential increase of pitching moment. Moreover, it appeared that aircraft goes into high angles of attack and high pitch angle and, therefore, for reliable simulation, the available aerodynamic characteristics must include angles of attack till 90 degrees when total flow separation occurs. Practical implications: For accurate simulation, it is strongly recommended to perform to perform first the wind tunnel testing in the range of +20o ÷ 120o and use it in flight simulation. Originality/value: The presented methodology is an original for numerical simulation of flight trajectory during the final phase of approach to landing in a hazardous state of flight. For reliable simulation, the available aerodynamic characteristics must include angles of attack till 90 degrees when total flow separation occurs, whereas usually maximum angles of attack used in wind tunnel experiments for passenger aircraft are not higher than 25 degrees. The influence of limited range of experimental data on results of simulation is another value which can be adopted in the future investigations of hazardous states of flight. [ABSTRACT FROM AUTHOR]

Purpose: 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. Design/methodology/approach: 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. Findings: 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. Originality/value: 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. [ABSTRACT FROM AUTHOR]

Purpose This paper aims to present and discuss the requirements for flying targets which sometimes are contradictory to each other and to perform a trade-off analysis before the design activity is started. It also aims to demonstrate conceptual and preliminary design processes using a practical example of PW-61 configuration and to show how results of experimental flight tests using a scaled flying target will be described and analyzed before manufacturing the full scale flying target.Design/methodology/approach An important part of the paper consists of the selection of tailplane configuration of the flying target UAV to protect some expensive on-board systems against serious damages and to obtain a sufficient dynamic stability, independently of the amount of the petrol in fuel tank. Inverted V-tail, U-tail and H-tail configurations were considered and compared both, theoretically and in-flight experiments.Findings Flight dynamics models and associated computational procedures were useful both in a preliminary design phase and during the final assessment of the configuration after flight tests. Selection of the tailplane configuration for the flying target UAV is very important to protect some expensive on-board systems against serious damages and to obtain a sufficient dynamic stability, independent of the amount of the petrol in fuel tank.Practical implications Flying targets should be speedy, maneuverable, cheap, easy in deployment and multi-recoverable (if not destroyed by live ammunition), must have relatively low take-off weight and an endurance of at least 1 h. This paper can be useful for proper selection of requirements and preliminary design parameters to make the design process more economically effective.Originality/value This paper presents very efficient methods of assessing the design parameters of flying targets, especially in an early stage of the design process. Stability computations are performed based on equations of motion and are supplemented by flight tests using the scaled flying models. It can be considered as an original, not typical, but very practical approach because it delivers lots of data in the early design stages at relatively low cost. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study is to investigate the influence of gyroscopic effects on the dynamic stability and the response of light aircraft to manoeuvres following either a rapid deflection of the control surfaces or wind gust.Design/methodology/approach The analyses were conducted for several different mathematical models of aircraft motion, which allowed for the investigation of the relationship between introduced simplifying assumptions and the aircraft response, including non-linear terms in equations of motion expressing the influence of inertial coupling. The analytical and experimental methods (measurements in the wind tunnel for the scaled model and during flight tests of I-31T prototype aircraft) were used.Findings It was found that gyroscopic moments are induced mainly by the propeller, and their influence on dynamic stability of a light aircraft is negligible. However, these phenomena in manoeuvring flight investigation should not be excluded, although for general aviation (GA) aircraft, they are not strong. Hence, two types of gyroscopic effects depending on the level of steady flight disturbances were distinguished. The authors differentiated weak gyroscopic effects, corresponding to classical dynamic stability, and strong gyroscopic effects, corresponding to rapid manoeuvres.Practical implications Conclusions include some findings on the nature of gyroscopic effects (i.e. sensitivity of flight stability versus turboprop power unit parameters) and practical recommendations for aircraft designers dealing with new configurations of GA aircraft.Originality/value The analysis focuses on the assessment of the flight dynamics of light aircraft with a novel, compact, lightweight, fast-rotating turbopropeller engine and strong/weak gyroscopic effects. [ABSTRACT FROM AUTHOR]