Scioly.org

kenniky wrote:Is there a cheap, fast way to make a reliable test stand setup? Currently we are using a music stand (http://static.musiciansfriend.com/stati ... -15-13.png) with a motor duct-taped onto it, but obviously that is far from optimal as it wobbles quite a bit (If you hold the bottom it's fine but it would be nice to get a stabler one)

Before you ask - yes, I do know of the instructions on the website; however, they are pretty involved. Is there a way I can make a relatively stable setup out of common household materials within about 2 days?

Thanks

We used a science lab ring stand, and a test tube clamp, set on a lab bench to hold our motor. Then use a wood-working clamp to help hold the stand steady on the bench.

Are there cheap ways to test different airfoil shapes without having to build a new wind turbine each time? And any ways to make the angles of the blade more consistent?

I'm seeing contradicting information about when the first windmill was invented. Wikipedia says it was Hero in ~50 AD, but some websites say that they were used in China in 200 BC and in Persia around 500 BC.

Does anyone have a reliable source for this?

JonB wrote:

mkfiddler11 wrote:

JonB wrote:

This.

Does that mean, the output voltage is same for both setups using 5 and 25 ohms?

No, I am not sure that would be possible. I was referring to the fact that our turbines that work best with low resistance are also working best with high resistance.

The only difference would be a lower output voltage at a higher resistance, and it is harder to get spinning at 25 ohms. However, if it is spinning relatively fast at 5 ohms, it will do the same at 25 ohms. The turbine wouldn't do well at one resistance and not another.

Alex-RCHS wrote:I'm seeing contradicting information about when the first windmill was invented. Wikipedia says it was Hero in ~50 AD, but some websites say that they were used in China in 200 BC and in Persia around 500 BC.

Does anyone have a reliable source for this?

Persia for grinding grain and pumping water.

What year was that?

Alex-RCHS wrote:What year was that?

I stand corrected...the Persians used their windmill around 500-900 AD, so it looks like the Heron of Alexandria's was earlier.

what is a good material for the fan blades?

Darkstalker wrote:what is a good material for the fan blades?

Depends on what your blades will look like...I like to work with thinner material like cereal box rather than thicker blades like some prefer. Tends to vary depending on blade design.

Riddle me this: a competitive team had a curious experience with this event recently. Their rotor caught no wind at our fan's low speed but recorded extremely high values (we're talking an order of magnitude higher mV than nearly everyone else) at our high speed. Clearly, their practice fan is more powerful than ours, but what I want to know is what the effectiveness of their design is, then. Is this something I want my teams to attempt to emulate? Anyway, if anyone was curious, they did not recover from losing so many points.