Aerodynamics and Design for Ultra-Low Reynolds Number Flight
Aerodynamics and Design for Ultra-Low Reynolds Number Flight
Aerodynamics and Design for Ultra-Low Reynolds Number Flight
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these variations <strong>and</strong> possible solutions, but even the current error magnitude only<br />
marginally diminishes the utility of the rapid analysis method. The one glaring<br />
Chapter 6<br />
exception is the small-hub rotor. In this case per<strong>for</strong>mance radically differs from both the<br />
predictions <strong>and</strong> the other experiments. Similar problems are seen in the last of the three<br />
designs.<br />
6.4.3 Five-Blade 2.2cm Diameter Rotor<br />
This rotor has the most non-traditional plan<strong>for</strong>m of all three designs. Key features are<br />
the small hub radius <strong>and</strong> root chords, large mid span chords, <strong>and</strong> high local solidity. This<br />
rotor is predicted to per<strong>for</strong>m similarly to the four-blade rotor, generating three to four<br />
grams of thrust between 35,000 <strong>and</strong> 45,000 RPM, but the experimental results have been<br />
surprising <strong>and</strong> quite disappointing. The predicted <strong>and</strong> measured thrust <strong>for</strong> the original<br />
version of this rotor is presented in Figure 6.18. The behavior is very similar to that of<br />
the small hub four-blade rotor <strong>and</strong> is explained in the next section.<br />
Thrust (g)<br />
4.5<br />
4.0<br />
3.5<br />
3.0<br />
2.5<br />
2.0<br />
1.5<br />
1.0<br />
0.5<br />
<strong>Low</strong>-order Method<br />
5-Blade Rotor, Experiment<br />
0.0<br />
10000 20000 30000<br />
RPM<br />
40000 50000<br />
FIGURE 6.18 Predicted <strong>and</strong> experimental thrust of the five-blade 2.2cm rotor.<br />
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