Scioly.org

I posted instructions for building a test stand and fan stand for Wind Power.
Test stand instructions: http://scioly.org/wiki/images/9/9d/Wind ... _Stand.pdf
Fan stand instructions: http://scioly.org/wiki/images/8/86/Wind ... _Stand.pdf

Feel free to use them in full, or just to extract subsets of information (e.g. recommended CD/DVD motor can be purchased from Jameco https://www.jameco.com/z/RF-310TA-11400 ... 38465.html)

What would be considered to be a "great score" for blades in millivolts for Division C, given that a good score would get you placing in the top 10 in nats? I know things have changed since last year, but I kind of want to get a better estimate of how I (belatedly) did last year and what to improve upon this year. Thanks in advance!

Edit: How does the width of a blade affect performance in general in your experiences?

daydreamer0023 wrote:What would be considered to be a "great score" for blades in millivolts for Division C, given that a good score would get you placing in the top 10 in nats? I know things have changed since last year, but I kind of want to get a better estimate of how I (belatedly) did last year and what to improve upon this year. Thanks in advance!

Edit: How does the width of a blade affect performance in general in your experiences?

I couldn't tell you about a great score for div C, since I'm in B. But, I can give you a bit of insight on the width of blades. There is a kind of sweet spot on the width. Personally, I've found that a blade that starts at about 3 cm width and widening to be around 7 cm wide. The amount of blades that you are using also matters. I use 4, so the width of my blades wouldn't be as wide as if I was using, say, 2-3 blades. Likewise, if you had 5+ blades, you would want a smaller width (generally speaking). A good experiment you could do is making blades of different widths, say, 2 cm, 3 cm, and 4 cm, attaching them to a blade, and testing them. Whichever had the highest voltage production is likely the best width.

For a very general answer on how the blade width affected performance, the narrower I made my blades, the worse their performance was. Likewise, the wider I got, the performance lowered. To find the sweet spot, I just repeatedly tested blades, changing the width each time. The width of your blades should really depend upon your design. The best advice I could give you on finding the best width would be to test, test, and test some more. I couldn't tell you how many sets of blades I went through testing to find the best width...

daydreamer0023 wrote:What would be considered to be a "great score" for blades in millivolts for Division C, given that a good score would get you placing in the top 10 in nats? I know things have changed since last year, but I kind of want to get a better estimate of how I (belatedly) did last year and what to improve upon this year. Thanks in advance!

Edit: How does the width of a blade affect performance in general in your experiences?

Every competition will have different scores in terms of voltage due to differences in motors/fans/resistance. As long as you do relatively well compared to others, you should be fine. Specific to last years nats, I think 1st place got 650 mV on high power and 450 mV on low power (check old forums).

PHXcoach wrote:I posted instructions for building a test stand and fan stand for Wind Power.
Test stand instructions: http://scioly.org/wiki/images/9/9d/Wind ... _Stand.pdf
Fan stand instructions: http://scioly.org/wiki/images/8/86/Wind ... _Stand.pdf

Feel free to use them in full, or just to extract subsets of information (e.g. recommended CD/DVD motor can be purchased from Jameco https://www.jameco.com/z/RF-310TA-11400 ... 38465.html)

wow...this is good stuff. At least I can say that the blade will not be affected by the testing apparatus.
Not many may realize it, but test apparatus play an important role in blade performance.
- flimsy mounting pole will cause vibration/wobbling.
- the 20" fan is not stable if not supported properly causing more problem if the fan fell during the test.
The blade need to spin really fast to produce the most voltage. Wobbling pole/stand or fan unstable will contribute loss of energy causing blade to not fully optimize.

I have similar setup...I used 1/2 metal pipe with PVC fitting. I just hope/wish all events supervisors will put this kind of effort to create this kind of setup. May be we can ask Chalker to post this on SOINC so other can see, especially those will be proctoring the event

RestingDoll wrote:

daydreamer0023 wrote:What would be considered to be a "great score" for blades in millivolts for Division C, given that a good score would get you placing in the top 10 in nats? I know things have changed since last year, but I kind of want to get a better estimate of how I (belatedly) did last year and what to improve upon this year. Thanks in advance!

Edit: How does the width of a blade affect performance in general in your experiences?

Every competition will have different scores in terms of voltage due to differences in motors/fans/resistance. As long as you do relatively well compared to others, you should be fine. Specific to last years nats, I think 1st place got 650 mV on high power and 450 mV on low power (check old forums).

Each testing setup will be different. Your blade performance will depend on the the following factors in the testing environment.
1. Motor Efficiency
2. Load Resistance
3. Distance to the fan. Not all setup will allow you to position the blade as closes to the fan as you would like
But all of these factor will have the same bearing on all blades.
Remember that V = I(current) * R. I(current) will remain constant, so if R increase, V increase. The same motor with 5 Ohm resistance will yield less voltage than 10/15/20 Ohm resistance.
So 650mV reading is not meaning full unless you know at least the load resistance of the setup.

soyuppy wrote: May be we can ask Chalker to post this on SOINC so other can see, especially those will be proctoring the event

2 steps ahead of you on that;) It was posted (with permission from PHXcoach) yesterday!

To use a more specific way of telling what my blades are getting:
1) 7.5 ohms
2) 7 centimeters away from the fan
3) About 80% efficiency on my motor (Not exactly sure)

High Speed- 900 mV*
Low Speed- 650 mV*


*Division B

Hi, I'm completely new to this event. How do you measure your own turbine's voltage with a voltmeter? I'm not sure how to attach it.

BrS wrote:Hi, I'm completely new to this event. How do you measure your own turbine's voltage with a voltmeter? I'm not sure how to attach it.

Attach the leads of the voltmeter/multimeter to the silver ends of the motor (generator)'s wires. The best way to do this is probably alligator clips- if you don't have any, you can buy them at Home Depot, RadioShack, etc. Welcome to Wind Power, btw!