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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Practical implications
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.
Originality/value
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.
Details
Keywords
Zdobyslaw Jan Goraj and Ewa Cichocka
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…
Abstract
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.
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Ewa Marcinkiewicz, Zdobyslaw Jan Goraj and Marcin Figat
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…
Abstract
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.