  Tail bending associated with maneuvering flight of insects is a known
phenomenon although there are only a few studies which analyze and quantify the
effects and benefits of body configuration changes. We hypothesized that these
configuration changes help reduce the energy expenditure in flight. This is
quantified by the magnitude of the aerodynamic torque generated by the insect
during the maneuver. To test our hypothesis, a dragonfly body model was
constructed with the ability to bend at the joint between the thorax and the
tail. An optimization problem was defined to find the dynamic body
configuration which minimizes the total pitch and yaw torque. The magnitude of
the tail deflection was found to be directly correlated with the yaw velocity
of the body. Most importantly, our results indicate that for executing the same
aerial maneuver, an insect with a flexible body was found to require
substantially smaller flight torque when compared to an insect with identical
morphology but possessing a rigid body. In addition, changes in the
instantaneous mass distribution of the body had the most substantial effect on
reducing the flight torque, while the inertial term due to the tail movement
had a smaller effect.
