Annotation: The process of creating modifications of aircraft in the transport category is a very relevant and widespread phenomenon in modern aircraft construction. A separate group of military transport aircraft has been distinguished in connection with the specific character of their mission: – the need to formulate the characteristics “cargo – range” for light, medium, operational tactical and strategic military transport aircraft, since it is precisely according to this characteristic that they are positioned by their purpose; –specific requirements are imposed on military transport aircraft cargo compartment not only with respect to its geometrical dimensions and usable volume, but also with respect to the possibility of simultaneous accommodation of military equipment and people, as well as the placement of a stretcher with t he wounded during their evacuation from the war zone; – the possibility of airborne landing of military equipment and paratroopers, which requires specific hatches and means of maintaining weight balance in flight; – the possibility of basing on poorly prepared sites with a runway length of less than 800 m in the short take-off and landing (STL) mode, especially for operational tactical military-technical vehicles, which significantly expands their use in combat zones; – the possibility of conversion into a civilian aircraft: for the delivery of goods to areas of the far north, when fighting fires, when evacuating victims from disaster zones, etc. The article shows that creation of modifications of expensive military transport aircraft is the main direction of their development. All leading aircraft manufacturing companies in the world use modification procedures as the way to most quickly meet constantly changing requirements for military transport aircraft. Along with the traditional methods of designing the modifications, the domestic school proposed a new methodology for determining the necessary parameters for “deep” modifications in wing geometry and propulsion system. The methodology is based on the use of three principles: – ensuring growth of carrying capacity and the required range of modifications of military transport aircraft of various purposes; – geometric re-arrangement of wing and system of carrying surfaces “wing + tail units” according to the criterion of minimum inductive resistance when lifting forces are equal to basic version; – coordination of modifications in wing with the required parameters of propulsion system as a condition for ensuring the required fuel efficiency.

Annotation: This paper suggests method for analysis of the dynamics of the aircraft with weight asymmetry (transverse displacement of the center of mass) maneuvering in the atmosphere under the impact of the short-time alternating moment of engine thrust, spread out over a period. The engines are installed on the bottom of the aircraft at the maximum distance from its longitudinal axis. Angular motion with nominal and perturbed performances of the aircraft and flight conditions has been consistently considered. Before maneuvering, the aircraft is set at the trimming angle of attack, determined by the magnitude of transverse displacement of the center of mass and aerodynamic characteristics. The direction of the aircraft maneuvering in the atmosphere depends on the acting moments of forces and time diversity of the engine firings to speed up and shutdown the angular motion. In the absence of disturbances, the angular motion of the aircraft shows in part signs of regular precession (almost constant precession velocity and nutation angle) and autorotation (close to zero self-rotation angle). Under the influence of disturbances, the spread of the aircraft angular motion parameters increases, mainly at the angle of precession, which characterizes changes in the direction of maneuvering. Composition of disturbances includes the spread of the aircraft technical characteristics (position of the center of mass, moments of inertia, aerodynamic coefficients, velocity head, etc.), errors associated with the operation of the engines (thrust spread, time of ignition and shutdown, angular alignment of their longitudinal axes). Terminal control was introduced to realize the given final state and to reduce the disturbances impact on the maneuvering parameters based on the registered deviations of the angular motion from the nominal one after the first shutdown of the attitude maneuver engine. Monte Carlo method (1000 variations of random realizations of the acting perturbations) confirmed the effectiveness of the proposed terminal control of the angular motion of the aircraft to provide the specified maneuvering parameters.