S1-4.3 Jan. 5 Creating a flap: Different ways to wing it HEDRICK, TL*; DANIEL, TL; Univ. of North Carolina, Chapel Hill email@example.com
Hovering insects appear to precisely maintain their position and orientation while flapping with nearly unchanging wing motions. However, simulations of hovering flight in the hawkmoth Manduca sexta suggest maintaining position and orientation over an extended series of wingbeats requires continual variation in wingbeat kinematics. But, the degree of inter-wingbeat variation employed by actual, rather than simulated, insects is poorly characterized, as are any tradeoffs between maintenance of position and the frequency of variation in wing kinematics. Here we analyze the variation in body position, orientation and the kinematics of wingbeats over extended sequences of hovering flight in Manduca sexta. We collected high-speed, three dimensional kinematics from six individuals feeding from a stationary flower in a laboratory flight chamber. Each flight sequence contained at least two seconds of continuous flight, allowing us to extract sequences of 60 or more wingbeats. The wingbeat kinematics were reduced to a series of 10 parameters specifying wing motions and abdominal flexions through a single wingbeat; these parameters are similar to the output from the simulated hawkmoth. The magnitude and rate of variation in the kinematic parameters was similar to that predicted by the simulation. However, the recorded kinematics also contained correlations between different parameters that were not present in the simulation results. For example, the amplitude of wing rotation about the spanwise axis was closely related to the mean forward sweep of the wing in the prior stroke. The mechanisms underlying such correlations are unknown, but may relate to sensory delays, dynamics of the mechanical system or some combination of these.