Aerodynamics and Design for Ultra-Low Reynolds Number Flight

3.13 Lift curves for 2% and 4% cambered NACA 4-digit airfoils at Re=12000........... 38
3.14 Drag polars for NACA 4-digit airfoils with varying amounts of camber.
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The maximum camber location is fixed at 70% chord........................................... 40
3.15 Drag polars for NACA 4-digit airfoils with variations in the maximum camber
location and a fixed 4% camber. ............................................................................ 40
3.16 Leading and trailing edge shapes used in the generation of constant
thickness airfoils..................................................................................................... 41
3.17 Drag polars comparing the radiused and blunt constant thickness airfoils
with the NACA 0002.............................................................................................. 43
3.18 Optimized airfoils for Re=6000 and Re=2000....................................................... 45
3.19 Camber distributions for the Re=6000 and Re=2000 optimized airfoils. .............. 46
3.20 L/D for the optimized Re=6000 airfoil and two NACA 4-digit airfoils. ............... 46
3.21 C p distributions for the Re=6000 optimized airfoil................................................ 47
4.1 Typical section diagram for the rotor equations. All variables are positive as
depicted. ................................................................................................................. 51
4.2 Effect of downstream distance on wake velocity profiles. INS2d
calculation of a 2% thick NACA 4402 camberline, Re=1000, α=4.0 degrees. ..... 59
4.3 Effect of Reynolds Number on wake velocity profiles one chordlength
aft of trailing edge. INS2d calculation of a 2% thick NACA 4402 camberline,
α=4.0 degrees......................................................................................................... 60
4.4 Average wake deficit model and INS2d data points at three Reynolds numbers. . 61
4.5 Initial streamlines for the contracted wake model of a candidate rotor. ................ 68
4.6 Converged wake streamlines for a candidate rotor after 6 iterations..................... 69
4.7 Flowchart of the rotor analysis and design process................................................ 73
5.1 Summary of rotor SDM process (from Ref. 32) .................................................... 77
5.2 Specified airfoil and blade section photomicrograph............................................. 77
5.3 Photomicrograph of an SDM wing cross-section, based on the NACA 4402
camberline. ............................................................................................................. 78
5.4 Two-piece aluminum press molds for the five-inch radius, two-blade rotor. ........ 79
5.5 Small test fixture in thrust testing configuration.................................................... 81