Aerodynamics and Design for Ultra-Low Reynolds Number Flight

Chapter 5
78
����
FIGURE 5.3 Photomicrograph of an SDM wing cross-section, based on the NACA 4402
camberline.
5.2.2 Dual Surface Machining
In addition to the epoxy SDM micro-rotors, samples of the same design have been
manufactured in aluminum in order to evaluate the benefits of a stiffer material. The
material selected was 7075-T6 aluminum alloy. This process involves precision
machining of both the rotor itself and a fully supporting fixture which allows machining
of the second side of the rotor. For a detailed description of the manufacturing process
the reader is once again directed to the thesis by Cheng [32].
5.2.3 Composite Press Molding
1 mm
The largest rotor being considered here, a five inch radius two-blade configuration, is
manufactured using a two-piece press molding technique. One of the two-piece molds is
pictured in Figure 5.4. Two sets were required for left and right handed rotors. The
fabrication of the molds was completed by the Stanford Rapid Prototyping Laboratory;
rotor fabrication has been completed by the author. The rotors consist of a five-ply wet
lay-up of fiberglass, carbon fiber, and Kevlar with epoxy laminating resin. The carbon
fiber provides the majority of the structural stiffness, the fiberglass provides a smooth