This paper analyzes the open-loop spin dynamics of a fighter configuration that exhibits yawing moment asymmetry at high angles of attack. High-fidelity aerodynamic model, in a look-up-tables form, is developed using the experimental data from static, coning, and oscillatory coning rotary balance wind tunnel tests. As a first step, all attainable equilibrium spin modes along with their sensitivity to control settings are predicted. Investigation of the dynamic characteristics of the predicted spin modes is performed using six degrees-of-freedom time history simulations, which showed that both, right and left flat spins are oscillatory and divergent. Influence of high-alpha yawing moment asymmetry on the spin recovery piloting strategies with control inputs is also studied with six degrees-of-freedom time history simulations. Our studies reveal that the proposed spin recovery strategies effectively reduce the recovery time for the left flat spins. However, aircraft's inherent tendency to yaw rightwards due to high-alpha yawing moment asymmetry renders proposed spin recovery strategies ineffective in accelerating the recovery of the right flat spins.

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In this paper, we analyze the spin dynamics of an aerodynamically asymmetric aircraft in open-loop configuration and also evaluate the performance of gain scheduled flight control law in improving dynamic characteristics of aircraft spin. A look-up tables based aerodynamic model is developed from static, coning and oscillatory coning rotary balance wind tunnel test data. As a starting point, all possible steady spin modes are identified by solving the aircraft dynamic model comprising moment equations. The influence of high-alpha yawing moment asymmetry on predicted right and left spin modes is discussed. Six degree of freedom simulations of left and right flat spins are performed in open-loop and closed-loop configurations with the flight control law. Our studies reveal that large amplitude oscillations in the angle of attack and sideslip observed in the open-loop configuration are significantly damped by the control law. The control law reduces the recovery time of the left flat spin. However, the aircraft natural tendency to rotate rightwards due to yawing moment asymmetry at high angles of attack renders flight control law ineffective in aiding the recovery of the right flat spin. Keywords

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Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.