The control of flight force by a flapping wing: lift and drag production
Tóm tắt
We used a dynamically scaled mechanical model of the fruit fly Drosophila melanogaster to study how changes in wing kinematics influence the production of unsteady aerodynamic forces in insect flight. We examined 191 separate sets of kinematic patterns that differed with respect to stroke amplitude, angle of attack, flip timing, flip duration and the shape and magnitude of stroke deviation. Instantaneous aerodynamic forces were measured using a two-dimensional force sensor mounted at the base of the wing. The influence of unsteady rotational effects was assessed by comparing the time course of measured forces with that of corresponding translational quasi-steady estimates. For each pattern, we also calculated mean stroke-averaged values of the force coefficients and an estimate of profile power. The results of this analysis may be divided into four main points.
(i) For a short, symmetrical wing flip, mean lift was optimized by a stroke amplitude of 180° and an angle of attack of 50°. At all stroke amplitudes, mean drag increased monotonically with increasing angle of attack. Translational quasi-steady predictions better matched the measured values at high stroke amplitude than at low stroke amplitude. This discrepancy was due to the increasing importance of rotational mechanisms in kinematic patterns with low stroke amplitude.
(ii) For a 180° stroke amplitude and a 45° angle of attack, lift was maximized by short-duration flips occurring just slightly in advance of stroke reversal. Symmetrical rotations produced similarly high performance. Wing rotation that occurred after stroke reversal, however, produced very low mean lift.
(iii) The production of aerodynamic forces was sensitive to changes in the magnitude of the wing’s deviation from the mean stroke plane (stroke deviation) as well as to the actual shape of the wing tip trajectory. However, in all examples, stroke deviation lowered aerodynamic performance relative to the no deviation case. This attenuation was due, in part, to a trade-off between lift and a radially directed component of total aerodynamic force. Thus, while we found no evidence that stroke deviation can augment lift, it nevertheless may be used to modulate forces on the two wings. Thus, insects might use such changes in wing kinematics during steering maneuvers to generate appropriate force moments.
(iv) While quasi-steady estimates failed to capture the time course of measured lift for nearly all kinematic patterns, they did predict with reasonable accuracy stroke-averaged values for the mean lift coefficient. However, quasi-steady estimates grossly underestimated the magnitude of the mean drag coefficient under all conditions. This discrepancy was due to the contribution of rotational effects that steady-state estimates do not capture. This result suggests that many prior estimates of mechanical power based on wing kinematics may have been grossly underestimated.
Từ khóa
Tài liệu tham khảo
Arbas, E. (1986). Control of hindlimb posture by wind-sensitive hairs and antennae during locust flight. J. Comp. Physiol. A159, 849–857.
Bennett, L. (1977). Clap and fling aerodynamics – an experimental evaluation. J. Exp. Biol.69, 261–272.
Cloupeau, M., Devillers, J. F. and Devezeaux, D. (1979). Direct measurements of instantaneous lift in desert locust; comparison with Jensen’s experiments on detached wings. J. Exp. Biol.80, 1–15.
David, C. T. (1978). The relationship between body angle and flight speed in free flying Drosophila. Physiol. Ent. 3, 191–195.
Dickinson, M. H. (1994). The effects of wing rotation on unsteady aerodynamic performance at low Reynolds numbers. J. Exp. Biol.192, 179–206.
Dickinson, M. H. and Götz, K. G. (1993). Unsteady aerodynamic performance of model wings at low Reynolds numbers. J. Exp. Biol.174, 45–64.
Dickinson, M. H. and Götz, K. G. (1996). The wake dynamics and flight forces of the fruit fly Drosophila melanogaster. J. Exp. Biol.199, 2085–2104.
Dickinson, M. H., Lehmann, F.-O. and Götz, K. G. (1993). The active control of wing rotation by Drosophila. J. Exp. Biol.182, 173–189.
Dickinson, M. H., Lehmann, F.-O. and Sane, S. P. (1999). Wing rotation and the aerodynamic basis of insect flight. Science284, 1954–1960.
Dickinson, M. H. and Lighton, J. R. B. (1995). Muscle efficiency and elastic storage in the flight motor of Drosophila. Science128, 87–89.
Dickinson, M. and Tu, M. (1997). The function of dipteran flight muscle. Comp. Biochem. Physiol.116A, 223–238.
Ellington, C. P. (1984a). The aerodynamics of hovering insect flight. II. Morphological parameters. Phil. Trans. R. Soc. Lond. B305, 17–40.
Ellington, C. P. (1984b). The aerodynamics of hovering insect flight. III. Kinematics. Phil. Trans. R. Soc. Lond. B305, 41–78.
Ellington, C. P. (1984c). The aerodynamics of hovering insect flight. IV. Aerodynamic mechanisms. Phil. Trans. R. Soc. Lond. B305, 79–113.
Ellington, C. P. (1984d). The aerodynamics of hovering insect flight. VI. Lift and power requirements. Phil. Trans. R. Soc. Lond. B305, 145–181.
Ellington, C., Vandenberg, C., Willmott, A. and Thomas, A. (1996). Leading-edge vortices in insect flight. Nature384, 626–630.
Ennos, A. R. (1989). The kinematics and aerodynamics of the free flight of some Diptera. J. Exp. Biol.142, 49–85.
Götz, K. G., Hengstenberg, B. and Biesinger, R. (1979). Optomotor control of wing beat and body posture in Drosophila. Biol. Cybernetics35, 101–112.
Jensen, M. (1956). Biology and physics of locust flight. III. The aerodynamics of locust flight. Phil. Trans. R. Soc. Lond. B239, 511–552.
Lehmann, F.-O. and Dickinson, M. H. (1997). The changes in power requirements and muscle efficiency during elevated force production in the fruit fly Drosophila melanogaster. J. Exp. Biol.200, 1133–1143.
Lehmann, F. and Dickinson, M. (1998). The control of wing kinematics and flight forces in fruit flies (Drosophila spp.). J. Exp. Biol.201, 385–401.
Lehmann, F. and Götz, K. (1996). Activation phase ensures kinematic efficacy in flight-steering muscles of Drosophila melanogaster.J. Comp. Physiol. A179, 311–322.
Liu, H., Ellington, C. P., Kawachi, K., VandenBerg, C. and Willmott, A. P. (1998). A computational fluid dynamic study of hawkmoth hovering. J. Exp. Biol.201, 461–477.
Lorez, M. (1995). Neural control of hindleg steering in flight in the locust. J. Exp. Biol.198, 869–875.
Marden, J. H. (1987). Maximum lift production during takeoff in flying animals. J. Exp. Biol.130, 235–258.
Maxworthy, T. (1979). Experiments on the Weis-Fogh mechanism of lift generation by insects in hovering flight. Part 1. Dynamics of the ‘fling’. J. Fluid Mech.93, 47–63.
May, M. L. and Hoy, R. R. (1990). Leg-induced steering in flying crickets. J. Exp. Biol.151, 485–488.
Robertson, R. and Johnson, A. (1993). Collision avoidance of flying locusts: steering torques and behaviour. J. Exp. Biol.183, 35–60.
Ruppell, G. (1989). Kinematic analysis of symmetrical flight manoeuvres of Odonata. J. Exp. Biol.144, 13–43.
Sedov, L. I. (1965). Two-Dimensional Problems in Hydrodynamics and Aerodynamics, pp. 20–30. New York: Interscience Publishers.
Spedding, G. R. (1993). On the significance of unsteady effects in the aerodynamic performance of flying animals. Contemp. Math.141, 401–419.
Spedding, G. R. and Maxworthy, T. (1986). The generation of circulation and lift in a rigid two-dimensional fling. J. Fluid Mech. 165, 247–272.
Tu, M. S. and Dickinson, M. H. (1994). Modulation of negative work output from a steering muscle of the blowfly Calliphora vicina. J. Exp. Biol.192, 207–224.
Vogel, S. (1967). Flight in Drosophila. III. Aerodynamic characteristics of fly wings and wing models. J. Exp. Biol.46, 431–443.
Wakeling, J. E. and Ellington, C. P. (1997). Dragonfly flight. III. Lift and power requirements. J. Exp. Biol.200, 583–600.
Wang, J. (2000). Vortex shedding and frequency selection in flapping flight. J. Fluid Mech.410, 323–341.
Wilkin, P. J. (1990). The instantaneous force on a desert locust, Schistocerca gregaria (Orthoptera: Acrididae), flying in a wing tunnel. J. Kansas Ent. Soc.63, 316–328.
Wortmann, M. and Zarnack, W. (1993). Wing movements and lift regulation in the flight of desert locusts. J. Exp. Biol.182, 57–69.
Zanker, J. M. (1988). How does lateral abdomen deflection contribute to flight control of Drosophila melanogaster. J. Comp. Physiol. A162, 581–588.
Zanker, J. M. (1990a). The wing beat of Drosophila melanogaster. I. Kinematics. Phil. Trans. R. Soc. Lond. B327, 1–18.
Zanker, J. M. (1990b). The wing beat of Drosophila melanogaster. III. Control. Phil. Trans. R. Soc. Lond. B327, 45–64.
Zanker, J. M. and Götz, K. G. (1990). The wing beat of Drosophila melanogaster. II. Dynamics. Phil. Trans. R. Soc. Lond. B327, 19–44.