Труды сотрудников ИЛ им. В.Н. Сукачева СО РАН

[Text] / D. L. GRODNITSKY, P. P. MOROZOV // J. Exp. Biol. - 1993. - Vol. 182. - P11-40. - Cited References: 59 . - 30. - ISSN 0022-0949РУБ Biology

Аннотация: Tethered flight of six insect species (two pentatomid bugs, a moth, a butterfly, a muscid fly and a crane fly) was studied using several modifications of a dust flow visualization procedure. The spatial structure of the near vortex wake of flying specimens was reconstructed on the basis of two-dimensional flow pictures. The dynamics of the wake was followed during a stroke cycle, revealing interspecific differences in vortex formation. It is suggested that insects create a single vortex ring during each stroke. Therefore, the hypothesis of double vortex chains advanced by Brodsky is not verified. The same is true of the jet hypothesis of Bocharova-Messner. While pronating at the top of their trajectory, the flapping wings throw air masses off their lower surfaces, but there is not a jet from between their upper sides. Flow separation from leading edges was found to be a rare phenomenon, taking place irregularly during the stroke cycle. That is why, contrary to widespread theoretical expectations, the Weis-Foch fling mechanism is not likely to contain a leading edge separation bubble, which must follow stalling at the front part of the wings. It is suggested that flying animals possess special mechanisms for extracting energy back from the near vortex wake. Some hypothetical adaptations for such an extraction in insects are put forward. Possible pathways for the evolution of insect flight are described.


Доп.точки доступа:
GRODNITSKY, D.L.; MOROZOV, P.P.

[Текст] / D. L. GRODNITSKY // Zool. Zhurnal. - 1993. - Vol. 72, Is. 7. - С. 84-94. - Cited References: 48 . - 11. - ISSN 0044-5134РУБ Zoology

Аннотация: Vertical and horizontal periodic movements of the body following each wing stroke were investigated in three butterfly species during their free flight in a transparent cage. Distribution of the movements along the stroke cycle shows that specimens climb during downstroke, supination, and upstroke. Pronation of the wings in the top of their trajectory (Weis-Fogh's clap-and-fling mechanisms) is followed by height reduction. The horizontal distance that insects cover during pronation and downstroke exceeded mean value and it was less than the mean value during supination and upstroke. The data acquired suggest that distributions in lift and thrust along a stroke cycle are characterized by sinusoid-like curves as a first approximation. Maximal lift is generated during the end of each downstroke, while the maximal thrust coincides in time with the end of the upstroke and the clap of the wings. A new non-steady mechanism of aerodynamic force generation is proposed. The mechanism is connected with air throwing off the flapping planes during their pronation and supination. Horizontal flight speed is negatively correlated with the angle between the body and the horizon, but does not depend on wing beat frequency. A hypothesis is suggested that insect flapping flight power regulation system includes a finite number of stable kinematic patterns each corresponding to a particular flight mode and characterized by specific values of intimately correlated stroke parameters.


Доп.точки доступа:
GRODNITSKY, D.L.