Study of the features of the characteristics of a hybrid airship turn

the dynamics of aircraft motion is determined, as is well known, by the acting forces. When an airplane is flying, these forces include the total aerodynamic force, the thrust force of the propulsion system, and the force of gravity. Hybrid Airship differs from an aircraft by the presence, in addition to the above, of aerostatic force, the value of which depends, among other things, on the height of flight of the Hybrid Airship. The presence of aerostatic force affects the maneuverability of a Hybrid Airship. The proposed article analyzes the changes in the characteristics of a Hybrid Airship turn caused by the presence of aerostatic force.

A survey of human pilot models for study of Pilot-Induced Oscillation (PIO) in longitudinal aircraft motion

Pilot-Induced Oscillation (PIO), although an old issue, still poses a significant threat to aviation safety. The introduction of new systems in modern aircraft modifies the human–machine interaction and makes it necessary for research to revisit the subject from time to time. Given the need of aircraft manufacturers to constantly perform PIO tests, this study analysed the feasibility of using three different computational pilot models (Tustin, Crossover and Precision) to simulate PIO conditions. Three aircraft models with different levels of propensity to PIO (original, low propensity and high propensity) were tested, as well as two pilot gain conditions (normal and high). Data were collected for a purely longitudinal synthetic task through simulations conducted in MATLAB®. PIO conditions were detect using a tuned PIO detection algorithm (ROVER). Data were analysed in terms of both whether the pilot models triggered a PIO condition and for how long the condition was sustained. The results indicated that the three pilot models only provoked PIO conditions when high gain inputs were applied. Additionally, Crossover was the only pilot model to trigger a PIO for the three aircraft models. There were also significant differences between the pilot models in the total PIO time, as the Tustin model typically sustained the oscillatory condition for longer.

Вибір складу, параметрів робочого процесу і режиму роботи силової установки літального апарата з надзвуковою крейсерською швидкістю польоту

The issues of choosing a composition, operating process parameters and operating modes of propulsion for supersonic cruising aircraft providing transoceanic flights are considered. A condition of maximum payload relative mass is used as a criterion for choosing the composition of the propulsion. This criterion can be transformed using the aircraft mass balance equation into a condition of the minimum relative mass of fuel and propulsion. A predictor-corrector method is used to solve the task. Choosing the composition, operating process parameters and operating modes of propulsion according to the cruising segment, taking into account the remaining flight segments takeoff, climb and descent by the empirical coefficients, is used as a predictor stage. Based on the solving results of this stage, the best competing variants of propulsions are selected for the purpose of subsequent more detailed analysis at a corrector stage by numerically solving the differential equations of the aircraft motion along an entire flight profile. At the same time, on each elementary section of the path, the control parameters of the propulsion are optimized according to the criterion of the minimum required fuel consumption to overcome this section. Propulsion with turbojet engine, turbofan and mixed flows turbofan engine, turbo-ramjet engine and turbofan engines that have ramjet modes are considered. Patterns of the change in the relative mass of the fuel and propulsion for the indicated compositions of the propulsions according to cruising segment of the flight for the cruising speeds corresponding to the M = 1.5...4 are established. These dependencies make it possible to select variants of propulsion competing in terms of payload for a cruising speed or select the most advantageous cruising speed for propulsion composition which is given. These dependencies were used to determine competing variants of the power plant, providing a minimum of the relative mass of fuel and propulsion for the airplane with a cruising speed corresponding to the M = 3. At the stage of the corrector, these variants of the propulsion were evaluated according to the criterion of the relative mass of fuel and propulsion by solving the equations of the aircraft motion along the entire flight profile with the optimization of the control parameters of the propulsion on each elementary segment of the profile according to the criterion of minimum fuel consumption to overcome it. In doing so, the operating process parameters of the propulsion were optimized near of those values that were obtained at the stage of the predictor. The analysis of the obtained results indicates that, in comparison with the predictor stage at the corrector stage, the parameters of the propulsion operating process that are optimal from the point of view of the relative mass of fuel and propulsion changed by about 12.5 %, and the relative mass of fuel and propulsion by about 3...4 %.

An approach to minimize aircraft motion bias in multi-hole probe wind measurements made by small unmanned aerial systems

A multi-hole probe mounted on an aircraft provides the air velocity vector relative to the aircraft, requiring knowledge of the aircraft spatial orientation (e.g., Euler angles), translational velocity and angular velocity to translate this information to an Earth-based reference frame and determine the wind vector. As the relative velocity of the aircraft is typically an order of magnitude higher than the wind velocity, the extracted wind velocity is very sensitive to multiple sources of error including misalignment of the probe and aircraft coordinate system axes, sensor error and misalignment in time of the probe and aircraft orientation measurements in addition to aerodynamic distortion of the velocity field by the aircraft. Here, we present an approach which can be applied after a flight to identify and correct biases which may be introduced into the final wind measurement. The approach was validated using a ground reference, different aircraft and the same aircraft at different times. The results indicate a significant reduction in wind velocity variance at frequencies which correspond to aircraft motion.

МЕТОД ВИБОРУ СКЛАДУ І РЕЖИМУ РОБОТИ СИЛОВОЇ УСТАНОВКИ, РЕЖИМУ РОБОТИ ДЛЯ ЛІТАЛЬНОГО АПАРАТА З НАДЗВУКОВОЮ КРЕЙСЕРСЬКОЮ ШВИДКІСТЮ

The power plant (PP) of a supersonic aircraft is a system that is part of a more complex system - the aircraft. Therefore, the efficiency of the aircraft significantly depends on the PP composition and its operating mode. Choice of composition and operation mode of PP is a part of the complex integrated variational optimization task, where parameters of flight profile, aircraft and PP are varied. Due to the complexity of the task in complete formulation, it is usually simplified. Typically, for the supersonic aircraft, the flight profile, flight mode for the cruising segment, payload, geometric shape and aerodynamic coefficients of the aircraft are specified. The dimensions and weight of the aircraft, as well as the parameters of the PP are varied. The required fuel and PP mass are determined. The minimum takeoff gross weight of the aircraft is a criterion of choosing the composition of the PP. A main disadvantage of this method is the insufficiently successful decomposition of the complex problem. In particular, the issues of aircraft aerodynamics, aircraft design and the theory of air-breathing engines are being comprehensively resolved, which complicates the task both in scientific and organizational terms - it is difficult to set design tasks for specialized organizations. Another decomposition method based on decomposing a complex problem into its components is proposed. The first component is the problem of choosing the composition and parameters of the PP, for the flight profile, mass, geometric and aerodynamic characteristics of the aircraft which are set; the second one is the problem of choosing the parameters of the aircraft, for the flight profile and the geometric shape of the aircraft that are set by varying the size and mass of the aircraft; the third one is the problem of choosing the parameters and geometric shape of the aircraft for the flight profile which is given by varying the geometric shape of the aircraft and the associated aerodynamic characteristics of the aircraft; the fourth one is the problem of choosing the parameters of the flight profile. Moreover, the first task is an integral part of the second one, the second one is an integral part of the third, and the third one is an integral part of the fourth. Thus, the composition of these tasks allows solving the complex problem of choosing the parameters of the flight profile, aircraft and its PP.Another disadvantage of the applied methods is the choice of a single solution based on one criterion. In practice, the choice of the solution depends on many factors; therefore, it is advisable to have a number of solutions that slightly differ in the chosen criterion, but have different vectors of flight, aircraft and PP parameters. A method of selecting the composition and parameters of the PP according to the one criterion, which ensures the receipt of a number of vectors of the PP parameters with the aim of the subsequent selection of the parameter vector that satisfies a number of criteria is proposed in the article. In addition, the use of a complete mathematical model which is used the differential equations of aircraft motion in the optimization task requires large computing resources. A more rational method is a rough search for a solution using a simplified model, followed by a correction of the solution result using a complete model ("predictor-corrector" type methods). The method of choosing parameters using the "predictor - corrector" scheme is proposed in the article. The predictor is a simplified model based on the use of the cruising flight segment for the selection of aircraft and PP parameters. The corrector is the complete model using the differential equations of aircraft motion and fuel consumption, applied to all segments of the aircraft flight profile.The developed method provides obtaining a number of PP parameter vectors that are best according to the given efficiency criterion, which makes it possible to make a subsequent choice of the PP parameters vector taking into account all efficiency criteria.