Asymmetric ground effects of a tailless unmanned aerial vehicle model

Abstract

Ground effect is asymmetric when an unmanned aerial vehicle takes off by using the catapult nearest to the edge of the deck from a carrier, because a large part of the wing is out of the deck. Asymmetric ground effect would induce rolling and yawing moments, which are critical factors affecting the safety of takeoff operations. In this research, focus was on asymmetric ground effect, especially on the lateral and directional aerodynamic characteristics. Effects of height, velocity, and wind over deck were studied. Computational fluid dynamics method was used and validated by comparing it with the experimental data presented in early reports. Height is the most important factor that influences lift, rolling moment, and yawing moment. Lateral and directional stabilities are weakened by reducing height. Lateral stability decreased 2.8% and 5.6% as the height was reduced from 1.5 m to 1.2 m and to 1.0 m, respectively. By increasing velocity, lift is increased significantly, while yawing moment is little influenced. Magnitudes of both lift and rolling moment are amplified slightly with the increase of wind over deck. When wind over deck varied from 0 m/s to 15 m/s, lift and rolling moment varied only within 1% and 3.4%, respectively, and thus the effect of wind over deck is secondary.

Sea-unammned aerial vehicle takeoff characteristics analysis method based on approximate equilibrium hypothesis

“…Because when aircraft is closer to ground or water surface, the induced drag decreases and effective angle of attack increases while the down-wash on upper wing decreases. 16…”

“…There are a lot of applications in aviation, space, ships, and marine engineering. 14,16,17 But on the other hand, the CFD software has different demands in aerodynamic and hydrodynamic simulations. Different fluid characteristics make the simulations to have different mesh quantities, first layer heights in boundary layers, and solution methods.…”

“…During the takeoff, the existence of ground effect will influence the aerodynamic; it should be taken into consideration in the calculation. Yang and Ma 16 analyzed the ground effect of the carrier-born UAV by dynamic mesh. They simulate the UAV takeoff and landing on a carrier and discuss the relationship between aerodynamic asymmetric ground effects.…”

“…For example mesh quantities, first layer heights in boundary layers and solution methods requirements are totally different for different fluid characteristics. 8,16,17 Thus, it will be more difficult and work in the sea-UAV takeoff process simulation.…”