Aerodynamics and Design for Ultra-Low Reynolds Number Flight

Chapter 6
116
Incidence (deg.)
20
16
0
12
8
4
FIGURE 6.20 Comparison of laser scanning incidence data and quadratic fit with error bounds
for one blade of the Sample-1 four-blade 2.5cm rotor.
The incidence distributions for the Sample-1, Sample-2, and Sample-3 rotors based on
quadratic fitting of the scan data are shown in Figures 6.21, 6.22 and 6.23. The cause of
these variations is not clear at this time. The SDM process results in the correct
geometry prior to the part being removed from the substrate, so the deformation must
occur either during the extraction of the finished part or after production due to material
aging or environmental factors. This is one area for further study, but is outside the focus
of this work.
0 2 4 6 8 10 12 14
r (mm)
Knowledge of the as-tested rotor geometries does permit further insight into some of the
variations seen in the thrust and power required data presented earlier for rotors that are
ostensibly the same design. The rotor performance with dissimilar blades is difficult to
estimate quantitatively, the rapid analysis method assumes identical blades, as does the
current OVERFLOW-D calculations using a periodic domain, but reasonable qualitative
arguments can be made using this information.
Scanning Data
Quadratic Fit
Fit +/- Atan(t/c)