The paper presents the results of a study of the flight dynamics of a hypothetical maneuverable airplane, the shortcomings of the stability and controllability characteristics of which are compensated by algorithms of the system of improving stability and controllability by introducing a complex border of the permissible angle of attack depending on the flight mode. The research was based on a mathematical model of the airplane as a material point, taking into account the restrictions on altitude and flight speed, g-load, angle of attack, as well as the rate of change of g-load and roll. The purpose of the research is to establish the effect of the operation of the specified control system algorithms on the nature and area of safe execution of the "coup-type" maneuver. As a result of the research, it was found that the functioning of special algorithms of the electric remote-control system, leads to the emergence of areas of the operational range of altitudes and flight speeds, in which there is a significant and sharp deterioration of the maneuverability of the aircraft. Consequently, any "improvement" of the aircraft's flight performance using an automatic control system requires an assessment of the effect of these changes on the aircraft's maneuverability in all possible flight modes. KeywordsAircraft automatic control system • The electric remote-control system of the aircraft • Flight dynamics • Flight safety • Simulation of aircraft flight dynamics List of symbols c xa Drag coefficient c ya Lifting force coefficient M Mach velocity α perm Permissible angle of attack z g Coordinates of the aircraft in the normal earth coordinate system along the z-axis x g Coordinates of the aircraft in the normal earth coordinate system along the x-axis V instr Instrumental velocity [m/s] V Aircraft velocity B Maxim Shkurin
Helicopters are widely used for air transportation and aerial work with cargo on external cables, one of the most challenging and dangerous uses. The main reason for the flight complication is the change in the controllability characteristics of the helicopter because of the presence of cargo. As of today, flight tests are mainly conducted to determine the feasibility of aerial transportation and aerial work involving external cargo. In addition, they are conducted to determine safe flight regimes when performing such operations. From a flight safety perspective, it is always desirable to know the changes in the control parameters before flight tests are performed. A proposal was made to use theoretical methods, including numerical simulations, to solve these problems. At present, work is progressing to isolate the effects of different cargoes on the external cable suspension and its direct effects on the static and dynamic characteristics of the helicopter’s control and stability. The effect of cargo mass and sail weight on the control efficiency is expressed by the helicopter’s angular acceleration, which is gained by deviating the cyclic pitch handle—a static control and stability indicator. When considering dynamic control and stability, the influence of the length of the external suspension cable on the transition time was investigated. The results obtained were refined for inclusion in all flight manuals for Mi-8 helicopters concerning flights with cargoes attached to the external suspension cables, the size and weight of the suspension cables as well as the methods of instruction and for preparing the crew for flights with upgraded cargo, including instruction via flight simulators.
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.
The engine failure, according to the flight safety inspection of the Federal Air Transport Agency, caused 4 of 6 aviation accidents in 2017, including 2 air disasters. In general, from 2001 to 2017, events related to the engine failure became the second most frequent cause of aviation accidents (13% of aviation accidents and 12% of air disasters). The worst consequences are associated with the engine failure at the most difficult and crucial stage of the flight landing. For example, it was the engine failure on the final approach that caused the crash of the L-410UVP-E20 RA-67047 aircraft near the Nelkan airfield on November 15, 2017. The article discusses a limiting situation in some sense – the landing of an aircraft with all failed engines under the wind conditions. The authors have proposed for this situation a methodology of calculating the landing approach of an aircraft under the wind conditions in case of failure of all engines of its power plant to an aerodrome equipped with an outer marker. The key features of such methodology are, firstly, the absence of necessity to link the path to the landmarks in the landing aerodrome area, and, secondly, the simplicity of the synthesis and the implementation of the aircraft control based on the proposed methodology during landing in both manual and director or automatic modes. To calculate the approach using the proposed methodology, the crew only needs to know the following values: the minimum drag airspeed on final approach, the height of the flight over an outer marker before landing and spiral approach leg. The content of the methodology in the article is illustrated by the results of the approach calculation when all of the main engines of the Russian short-medium-range MS-21 aircraft fail under the wind conditions.
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