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Feasibility of Adaptive Micro Air Vehicles
Published in Norman M. Wereley, Inderjit Chopra, Darryll J. Pines, Twelfth International Conference on Adaptive Structures and Technologies, 2017
Felipe Bohorquez, Chris Cadou, Darryll Pines
Figures 6 thru 9 illustrate these geometric scaling relationships for small birds and how they compare to three current MAV designs. Although approximate, these scaling relationships illustrate that most MAV designs have shorter wingspans and lower aspect ratios than their biological counterparts, suggesting a higher maneuverability than the equivalent size bird. However, higher maneuverability for the same mass also implies higher bandwidth control for these systems. Another important property of winspan and aspect ratio is its connection to the aerodynamic properties of an aircraft. As the wingspan and aspect ratio increases, the lift to drag ratio also increases affecting the glide ratio of the aircraft. Thus, birds with long wingspans and high aspect ratios are more akin to dynamic soaring. Since most MAVs have short wingspans and low aspect ratios, one would not expect for these vehicles to have great glide or soaring properties. Finally, Figure 8 displays the average wing loading (N/m2) values for birds as a function of body mass. Specific birds are displayed by the ‘x’ symbol. The wing loading for three MAVs is also displayed in this figure with the ‘o’ symbol. Notice that the wing loading for MAVs is significantly higher than the equivalent size bird. This suggests that MAVs must fly faster in comparison to birds of comparable geometric size, aerodynamic properties and weight to stay aloft. To accomplish this goal MAVs must expend more power to overcome the induced aerodynamic drag. Another interesting aspect of nature is that the wing and aspect ratio for hummingbirds tends to be independent of body mass while their wingspan increases monotonically with mass. Figure 9 summarizes these geometric scaling laws for birds on a single chart and indicates that nature has figured out more efficient ways of achieving flight at low Reynolds number than humans.
Surrogate-based bilevel shape optimization for blended-wing–body underwater gliders
Published in Engineering Optimization, 2023
Weixi Chen, Peng Wang, Huachao Dong
Based on the above facts, in this article, a novel bilevel shape optimization algorithm based on surrogate models is proposed. To explore the coupling effect, the layout is initially set up with three barrel-shaped buoyancy adjustment devices and six spherical flexible battery compartments. The four-section BWBUG, as shown in Figure 1, can be taken as an example. Figure 1 describes the parameters of a glider with six degrees of freedom. To overcome high pressure in the deep sea, titanium alloy is used as the shell material. The size of the layout and the position inside the glider are given in the upper right corner, and the remaining part depicts the relative distance of the shape control points. The wingspan and chord length (L, D1) are usually set as fixed value constraints. In this article, L is set at 3 m and D1 is 1 m.
Spectrum parameters for runway roughness based on statistical and vibration analysis
Published in International Journal of Pavement Engineering, 2022
Jinsong Qian, Yebo Cen, Xiangwei Pan, Yu Tian, Shifu Liu
The fuselage subsystem is required to define the aerodynamic forces of an aircraft. The lift force, resistance, and pitching moment of the aircraft are considered to be the aerodynamic forces of an aircraft taxiing at a constant speed. The formulae for these three factors are shown respectively as Equations (4), (5), and (6). where ρ is air density; V is the taxiing speed of the aircraft; W is its wing area; and l is the mean aerodynamic chord, which is related to wing area and wingspan (Span). Table 2 presents the properties of the B737–800's wing. Cl, Cd, and Cml represent the corresponding aerodynamic coefficients whose relationships with the angle of attack were calculated using Digital DATCOM software according to the aircraft's configuration.
Experimental and numerical study of turbulent flow around a Fanwings profile
Published in Engineering Applications of Computational Fluid Mechanics, 2019
Slimane Benferhat, Tayeb Yahiaoui, Bachir Imine, Omar Ladjedel, Ondřej Šikula
For several years, the improved performance of rotorcrafts and rotary wing aircrafts capable of vertical take-off and landing (VTOL) or a short takeoff and landing (STOL), has led research to innovation and the Fanwing is one. He requires a short runway. The novelty of this type of propulsion is to move an aircraft using a cylindrical fan. Fanwing is a rare concept, working at low Reynolds numbers, developed and patented by Peebles (2001); it was inspired by the paddle steamers that sailed the Mississippi River. This type of aircraft with motorized lift uses a turbine engine mounted on the entire wingspan of a wing similar to a rigid wing. This is a different mode of operation from the conventional aircraft. This type of turbomachine is called cross-flow fan. It was patented by Mortier (1893). The rotation of the fan is used to accelerate the air flow on the profile.