This paper presents the second stage of a tandem fixed-wing unmanned aerial vehicle (UAV) aerodynamic development. In the initial stage, the UAV was optimized by analyzing its characteristics only in symmetrical flight conditions. Posted requirements were that both wings should produce relevant positive lift, the initial stall must occur on the front wing first, the center of pressure should be close to the center of gravity, and longitudinal static stability should be in the optimum range. Computational fluid dynamic (CFD) analyses were performed, where the applied calculation model was derived from the authors’ previous successful projects. The eighth version TW V8 has satisfied all longitudinal requirements. Lateral-directional CFD analyses of V8 showed that the ratio of the lateral and directional stability at the nominal cruising regime was optimal, but both lateral and directional static stabilities were too high. On further development versions, the lower vertical tail was eliminated, a negative dihedral was implemented on the front wing, and four inverted blended winglets were added. Version TW V14 has largely improved lateral and directional stability characteristics, while their optimum ratio at the cruising regime was preserved. Longitudinal characteristics were also well preserved. Maximum lift coefficient and lift-to-drag ratio were increased, compared to the V8.

The problems solved by the chemography method based on fixing oxidative reactions of ultra-low concentrations on the surface of solids are discussed. This method makes it possible to fix physical defects (microcracks, destruction, violations of structural homogeneity) and the energy (residual stresses) state of the surface layer of materials under operating conditions under the action of thermobaric loading. The change in these parameters is associated with the degradation of the cutting surfaces and, as a result, with a change in the rate of the reactions taking place. Applied chemography phenomena as a method of visualization of a destructive layer, a network of surface micro cracks in studying the processes of destruction materials, including nonmetallic ones, is shown. The main advantages of this method are the possibility of assessing the level of residual stresses and periodic visualization of surface defects due to the state of the studied materials, including nonmetallic ones. A relationship has been established between the presence of defects, the level of residual stresses, and the intensity of emerging photo molecular fluxes. In the applied aspect, the method makes it possible to evaluate the performance of cutting plates, and to study the formation and development of a network of microcracks by the intensity of the chemographic effect.

Optimization of wind turbine aerodynamic performances implies solving the problem in the domains such as airfoil selection, blade rotation angle, number of blades, etc. The current article studies the effect of blade rotation angle [ ] at the flow velocity in the wind tunnel [ ] and a specific number of revolutions on the horizontal axis wind turbine – HAWT output power. The experiment involved two models of blades. Based on planning the experiment, mathematical models were created to be applied in practice. The highest number of revolutions [ ] and generator output [ ] were achieved at the velocity of [ ]

Optimization of wind turbine aerodynamic performances implies solving the problem in the domains such as airfoil selection, blade rotation angle, chord optimization, number of blades, appropriate tip speed ratio, etc. The current paper studies the effect of blade rotation angle ( β = 5 , 7 , 10 ° ) on power coefficient ( C P ) , torque ( T ) and mechanical power ( P M ) in a small horizontal axis wind turbine ( HAWT ). The analysis involves two models of blades ( V and) of the airfoil class SD 7003 . The first part of the paper employs numerical analysis, that is, Ansys CFX and Ansys Fluent software packages, to define wind turbine characteristics. The obtained results indicate that as the rotation angle ( β ) increases the C P increases within an appropriate range of tip speed ratio ( λ ) change. The second part describes experimental investigation conducted on considered HAWT to define the values of T and P M for studied blade rotation angles and comparison with the values obtained from Ansys. Existing differences in values are a consequence of the design of the HAWT , that is, the influence of the mass moment of inertia of the rotor and generator as well as the placement of the generator. Experimental setup and methodology allow for investigating the effect of different blade models, rotor and generator structure on wind turbine torque and mechanical power output characteristic.