Experimental Study on Forewing–Hindwing Phasing in Hovering and Forward Flapping Flight

Three-dimensional effects on the aerodynamic performance of flapping wings in tandem configuration

“…If the mean thrust of each wing is compared to its two-dimensional counterpart (table 2), a reduction of approximately 21% and 11% is obtained for the fore-wing of A = 2 and 4, respectively. Preliminary simulations of isolated wings (not shown here) have shown that the thrust generated by the fore-wing is independent of the vortical interaction between the fore-and hind-wings, in agreement with previous works (Maybury & Lehmann 2004;Nagai et al 2019). This suggests that the aforementioned thrust reduction is mainly due to wing-tip effects, namely, induced downwash velocity.…”

“…They found that, for the range of velocities studied, the required power was lower than the maximum available power. More recently, Nagai et al (2019) studied the effect of phasing of tandem flapping wings in forward flight. Their results suggest that actual dragonfly might not select the phase differences in term of aerodynamic efficiency but also in terms of other factors such as longitudinal manoeuvrability or flight stability.…”

Tandem-wing interactions on aerodynamic performance inspired by dragonfly hovering

“…The phase difference is an important kinematic parameter for the interaction which is defined as the phase angle by which the HW leads the FW. According to the observations of dragonfly flight [9][10][11][12][13][14][15][16][17] and the studies of phase difference [18][19][20], it was concluded that dragonflies could make various kinds of interactions by adjusting phase difference in different flight conditions, and the change of phase difference had an impact on aerodynamic performance of tandem-wing (TW) flapping. Adjusting phase difference in a TW flapping might be an outstanding method to control flight performance.…”

“…The simulation results showed that when γ = 0°and 90°, the hover efficiency was less than that of single-winged flapping, and when γ = 180°, the hover efficiency was greater than that of single-wing flapping. Nagai [20] investigated the effect of phase difference in TW hovering experimentally. The results showed that the vertical force efficiency for the total wings in tandem is smaller than that in isolation, except for γ = 0°and 45°; the maximum hovering efficiency for the total wings in tandem at γ = 0°is 4.3% larger than that in isolation.…”

Numerical simulation of flow over flapping wings in tandem: wingspan effects

“…Although some authors have analyzed realistic dragonfly-like wing and kinematic models [18,19,20,21], we are still not capable to design efficiently micro air vehicles with two pairs of flapping wings. To overcome this limitation, a better understanding of the fundamentals of unsteady aerodynamics of flapping wings in tandem is still needed.…”