Fig 1.
(a) Renderings of the 3D bat models (orthographic projection). (b) Picture of Phyllostomus discolor in flight (c) Picture of Micronycteris hirsuta in flight. Both images copyright by Bruce D. Taubert and used with permission.
Fig 2.
a-b; The drag coefficients for the 7 species of bats as a function of tilt angle at 5 and 10 ms. Negative tilt angles indicate that the complete bat model was tilted nose-down, c-d; The lift coefficients as a function of tilt at 5 and 10 ms for each model. e-f; The lift-to-drag ratio as a function of tilt at 5 and 10 ms. The shaded area denotes 1 standard deviation. The lift (drag) coefficient is calculated by multiplying the lift (drag) force by . With q the dynamic pressure and A the approximate surface area of the standardized body model. m is a constant for all conversions at the same airspeed.
Table 1.
Lift forces compared to body weight.
The lift forces listed are the differences in lift between each bat model and the body model averaged across tilt angles between −10 and 10 degrees. The lift forces have been adjusted for the differences in scaling of the tested bat models. Data on the weight of each species were taken from the literature.
Fig 3.
Flight cost as a function of normalized pinna length.
Increase in lift to drag ratio due to the pinnae measured in the 7 models as a function of normalized pinna length, averaged across the full range of angles of attack. The normalized pinna length is calculated by dividing the pinna length by the cube root of the mass of the bat. Panel a: data for the 5 ms condition. Panel b: data for the 10 ms condition. The lines are least squares linear regression lines. The significance test results are indicated in both panels. Colours are the same as in Fig. 2
Fig 4.
Left: Drag coefficients for two version of the Macrophyllum macrophyllum model and the standardized body model.
Bat: the original model, No pinnae: pinnae removed from the original model, Body: the standardized body model. Right: idem for the lift coefficient. Vertical bars denote 1 standard deviation.