Wind Power B/C

[geedee]

We have 2 different generator setups, one motor spins really easily and one seems to have a bit of "stiction". The thing that makes me nervous is that our best blades spin really well with the first setup, but won't start themselves spinning with the second one -- not sure what to expect from the Event organizers at the competition. Any suggestions?

[finagle29]

"stiction". Any suggestions?

We get stiction sometimes in our setup; it's caused by the CD motor being pushed back into the PVC holder so that the back mounting thing rubs against the PVC holder.

[pumpkinite]

For testing, is a cd motor necessary? Or will something like a servo work, assuming we can attach the cd?

[dragonfruit35]

For testing, is a cd motor necessary? Or will something like a servo work, assuming we can attach the cd?

Yes, you will need a CD motor to test. It has special clips that allow the CD to snap in.

[pumpkinite]

For testing, is a cd motor necessary? Or will something like a servo work, assuming we can attach the cd?

Yes, you will need a CD motor to test. It has special clips that allow the CD to snap in.

Oh, I have a way to secure the cd to the motor. I was just wondering if there would be a significant difference in voltage output depending on what type of motor I used for testing.

[chalker]

For testing, is a cd motor necessary? Or will something like a servo work, assuming we can attach the cd?

Yes, you will need a CD motor to test. It has special clips that allow the CD to snap in.

Oh, I have a way to secure the cd to the motor. I was just wondering if there would be a significant difference in voltage output depending on what type of motor I used for testing.

Yes, there will be significant changes in voltage output amongst different type of motors. I would highly recommend AGAINST using a stepper motor though. Stepper motors have a special kind of internal winding and as a result don't have only 2 wires connected to them. As a result, you are going to be only connecting to some of the winding. Some of the other unconnected winding will actually work against the fan and slow it down.

[noobforce]

How are you guys attaching the blades to the CD? Right now I'm using super glue and there is no chemical reaction so they're not sticking well... My blades are balsa.

[ceg7654]

How are you guys attaching the blades to the CD? Right now I'm using super glue and there is no chemical reaction so they're not sticking well... My blades are balsa.

Same here. Our team decided to slightly scrape off the coating at the top of the CD(not the shiny bottom part) so that they would stick better, but now I'm kind of worried that'll count as modifying the CD. It's kinda late for us to make any changes now though.

[GoofyFoofer]

How are you guys attaching the blades to the CD? Right now I'm using super glue and there is no chemical reaction so they're not sticking well... My blades are balsa.

I use balsa blades and super glue. It seems to work well for me, although I use a more of a gel-type super glue. You may want to try using that, and it dries remarkably fast. You can get it at a dollar store.

[PHXcoach]

Hi Chalker - thank you for the new testing setups document on the Wind Power page.

I think that using the 5cm tape on the table to align against the stand base may be incorrect. The rules require 5 cm from the blade assembly to the front of the fan grill. If the blade assembly sticks out in front of the CD a lot (e.g. a pin wheel design) then shouldn't the measurement be from the front of the blade to the fan grill rather than from the CD mounting point to the fan grill? (maybe I am guessing incorrectly as to how the 5cm tape was being used)

So far I have seen a 2 to 1 variation in voltages between different CD motors, keeping other conditions the same, so absolute voltages comparisons between different test set ups is not likely to be useful (as has already been stated multiple times on this thread)

Changing the resistor load also changes the output voltage due to the resistance of the motor wire and the connection leads, so even on the same test setup the resistor must remain constant to bae able to compare blade assemblies. You can't just calculate the expected voltage with a different resistor by equating the power and dividing by the new resistor value because the CD motor/test setup is not an ideal current source, but instead has internal resistance.