Fig 1.
Ground and body coordinate systems.
Rotations relative to the body frame are defined as roll, pitch, and yaw as depicted. A stroke plane is defined for the right and left wings separately by connecting the shoulder point with a regression line passing through the locus of wingtip points.
Table 1.
Morphological parameters of the subject.
Fig 2.
Top: Body trajectory of the bat during the U-turn flight from the top and side view. Bottom: Velocity, angle of ascent, and curvature of the turn. The curvature is defined using the standard definition: (radius of curvature)-1. The grey shaded regions denote upstrokes, and one complete wingbeat cycle consists of the upstroke+downstroke.
Fig 3.
The vertical (a) and horizontal (b) stroke plane angle are shown for the right and left wing separately at each half-cycle as defined in the schematic above.
Fig 4.
The motion of the wings relative to the stroke plane are characterized by the flap angle, stroke plane deviation angle, and the half-span for the 180 degree U-turn flight (a) and a straight flight (b) for comparison.
Fig 5.
Wingbeat frequency by half-stroke.
The mean frequency over the flight is 8.7 Hz.
Fig 6.
Trajectory of the wingtip and wrist for each wingbeat cycle of the U-turn shown in the body fixed coordinate system (a). A comparison from a representative straight flight is also provided (b).
Fig 7.
Force coefficients in the body frame for the U-turn flight (a). For comparison, results from a straight flight by the same bat is also provided (b).
Fig 8.
Comparison of observed and predicted position and velocity of the bat body.
Fig 9.
Rotational orientation of the bat using both body-based angles (roll, elevation, and yaw) and velocity-based angles (bearing angle and climb angle).
Fig 10.
Tangential, radial, and vertical components of aerodynamic force relative to the flight trajectory.
Fig 11.
Half-cycle mean aerodynamic moments relative to the approximate center of mass calculated from the aerodynamic forces (a). Half-cycle mean angular acceleration of the bat body defined as rate of change of rotational velocity about the body-fixed coordinate axes (b).
Fig 12.
Thrust force (a) and lift force (b) calculated in the body-fixed frame partitioned by where the force is acting. Solid lines represent right and left wing totals. The dashed and dashed-dotted lines represent the force acting on the outer and inner right and left wings.
Fig 13.
Total power expenditure defined as the sum of aerodynamic power, kinetic energy expenditure, and potential energy expenditure.
Table 2.
Mean total power expenditure for a straight flight, sweeping turn [13], and U-turn.