Engineering 102 - Section 002 (Dr. D. Birnie)
Wind Turbine Results - April 1999
 
Parameters For Each Team's Wind Turbine Design:
 
Team Number Number of Blades Pitch Angle at Hub (degrees) Blade Radius (cm) Load Used (Ohms) Volts Generated Milliamps Generated Output Power (mWatts)
1
3
16
15
82
4.7
58
272.6
2
2
9
14.5
82
6.6
83
547.8
3
3
10
13
82
6.3
77
485.1
4
3
21
12.5
100
6.0
61
366.0
5
3
9
15
100
4.5
46
207.0
6
2
14
15
68
6.2
93
576.6
7
3
9
15
100
1.6
20
32.0
8
3
10
13.5
79.6
5.1
65
331.5
 
In my estimation -- based on the mA, Rload, and Req values for these motors, and the data in Figure 10 on p216 of the book -- each team reached the following RPM values:
 
Team RPM
1 2770
2 3960
3 3675
4 3235
5 2440
6 4055
7 1060
8 3055
Warning: The accuracy of these numbers depends primarily on the validity of Figure 10 in the book.

All rotors were trimmed or otherwise allowed for a pitch dependent on radius -- a twist component. This was very important for achieving good scores.

Craftsmanship or general care in building the rotors was paramount. Slight imbalances, unintended flex or other disturbances can add significant wind resistance or energy dissipation.
 

General Information:

Team 1
Full View. Illustrates use of support ring to impose twist to the blades.

Team 2
Front View. Nice paint job.
Side View. Shows blade tilt -- these blades were double layers superglued together to make a much stiffer airfoil.

Team 3
Front View.
Side View. Blades tilt back slightly.

Team 4
Front View. Plastic easter egg as nose cone!
Side View. Showing manual adjustment to blade twist near hub.

Team 5
Front View. Easter egg nose and wide blades.
Side View.

Team 6
Front View. Very nicely trimmed.
Side View. These pictures don't show much because of the black paint
Motor Close-Up. Cooled down in dry ice to reduce resistance in winding. Assist magnets glued to side to improve output.

Team 7
Front View. Not much trimming.
Hub+Motor Close-Up. This motor not used during competition.
Custom Resistor. This variable resistor was used to optimize output power. This wasn't used during competition because the range chosen was too large.

Team 8
Oblique View.
Top View. Nice trimming at tip to reduce drag.

(c) 1999, by Dunbar P. Birnie, III