Having the testing area completed, we proceeded to build a stand for the force sensors. We took 4 blocks of wood and screwed them together in a way to build an frame which would hold the force sensor in place. Then we added a threaded rod and screwed the structure on the testing area floor.
We constructed a mount for the fan to rest on. Support extensions were added to the drive section in order to build a frame. The fan was then mounted at the center of the cross section and joined to the electric motor through the belt. Walls were added to enclose the fan and improve air drag.
The force of the wind suggested that a single sensor that would hold the
entire wing would not suffice, so we constructed a similar stand for a
second sensor. Now two sensors side to side would be attached to the test wings measuring the lift of the wing.
In order to measure the drag force on the wing, we built another force sensor stand and placed it in front of the other two aligned force sensors. A string was tied to the force sensor, and the other end of the string would be tied under the center of mass of the test wing. The string would be under low tension so that the drag force readings would be more accurate.
At first we were having trouble aligning the rods so that the wing would be leveled properly. Likewise, it was tricky to center the drag sensor. This was solved to the best of our abilities. The small apertures between the joints of the boards inside the diffusers were sealed with liquid nail to prevent air escape.
Two wings (one of them showed above) were provided by the DBF team as test subjects.
Although at the beginning we considered puting a variac to vary the voltage output from the electric motor, we dismissed this approach since we considered that the rpm delivered onto the fan was acceptable.
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