Wind Power B/C

mkfiddler11
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Re: Wind Power B/C

Postby mkfiddler11 » Fri Jan 06, 2017 2:49 pm

Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!

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Re: Wind Power B/C

Postby HandsFreeCookieDunk » Fri Jan 06, 2017 4:48 pm

mkfiddler11 wrote:Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!


Unfortunately, that information is kind of useless without knowing the motor as well. The motor itself has a huge effect on the voltage and those results would not be repeatable on any other motor. One of the most frustrating things about this event is that you can't really get an idea of how well your design performs ahead of time.

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Re: Wind Power B/C

Postby ashmmohan » Sat Jan 07, 2017 5:59 am

HandsFreeCookieDunk wrote:
mkfiddler11 wrote:Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!


Unfortunately, that information is kind of useless without knowing the motor as well. The motor itself has a huge effect on the voltage and those results would not be repeatable on any other motor. One of the most frustrating things about this event is that you can't really get an idea of how well your design performs ahead of time.


I concur; with different motors, it's almost impossible to get the same readings unless they are the same motor. However, that being said, as long as you improve on your team's setup, that will obviously translate to the competition setup, just with different readings.
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Re: Wind Power B/C

Postby mkfiddler11 » Sun Jan 08, 2017 2:03 am

I agree that the voltage output depends on the setup. Our team ends up getting lower voltages at the tournament even though the resistors used are higher, may be the motor used is of lower power than what we use. It would be helpful if someone can post the results from 2016 nationals.

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Re: Wind Power B/C

Postby windu34 » Sun Jan 08, 2017 6:14 am

mkfiddler11 wrote:I agree that the voltage output depends on the setup. Our team ends up getting lower voltages at the tournament even though the resistors used are higher, may be the motor used is of lower power than what we use. It would be helpful if someone can post the results from 2016 nationals.

Um okay how well do you know circuits...higher resistance means lower voltage because its harder for the turbine to spin the motor shaft
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Re: Wind Power B/C

Postby soyuppy » Sun Jan 08, 2017 3:48 pm

windu34 wrote:
mkfiddler11 wrote:I agree that the voltage output depends on the setup. Our team ends up getting lower voltages at the tournament even though the resistors used are higher, may be the motor used is of lower power than what we use. It would be helpful if someone can post the results from 2016 nationals.

Um okay how well do you know circuits...higher resistance means lower voltage because its harder for the turbine to spin the motor shaft

no...V=I*R. If R increase, assuming I remain the same, then V increase. V is the voltage drop. Or you can test it yourself. Just use higher resistance in you setup on the same blade and motor. See what happen.

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Re: Wind Power B/C

Postby soyuppy » Sun Jan 08, 2017 4:03 pm

mkfiddler11 wrote:Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!

I just helped ran an invitational event.

CD motor: https://www.amazon.com/gp/product/B00OT ... UTF8&psc=1
Load R: 10 Ohm

Top blade = 700mV+ on high, 500mV+ on low
Low blade = 80mv on high, 70mv on low

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Re: Wind Power B/C

Postby Unome » Sun Jan 08, 2017 4:14 pm

soyuppy wrote:
mkfiddler11 wrote:Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!

I just helped ran an invitational event.

CD motor: https://www.amazon.com/gp/product/B00OT ... UTF8&psc=1
Load R: 10 Ohm

Top blade = 700mV+ on high, 500mV+ on low
Low blade = 80mv on high, 70mv on low

Was this B or C? (I'll go ahead and assume this was at Mira Loma yesterday)
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Re: Wind Power B/C

Postby soyuppy » Sun Jan 08, 2017 4:18 pm

Unome wrote:Was this B or C? (I'll go ahead and assume this was at Mira Loma yesterday)

B

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Re: Wind Power B/C

Postby soyuppy » Sun Jan 08, 2017 7:35 pm

Just post similar question to SO inc.
When you buy a bundle of CD/DVD, usually come in 25/50/100, you get the plastic filler. Can this plastic filler be used for blade? Has the same dimension as CD/DVD, but it's much lighter.

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Re: Wind Power B/C

Postby chalker » Sun Jan 08, 2017 11:23 pm

soyuppy wrote:
windu34 wrote:
mkfiddler11 wrote:I agree that the voltage output depends on the setup. Our team ends up getting lower voltages at the tournament even though the resistors used are higher, may be the motor used is of lower power than what we use. It would be helpful if someone can post the results from 2016 nationals.

Um okay how well do you know circuits...higher resistance means lower voltage because its harder for the turbine to spin the motor shaft

no...V=I*R. If R increase, assuming I remain the same, then V increase. V is the voltage drop. Or you can test it yourself. Just use higher resistance in you setup on the same blade and motor. See what happen.


There's a BIG assumption you made - I remaining the same. In reality, I won't usually remain the same in this circuit. Windu34 is correct in that by putting a higher resistor in the circuit, it makes it harder for the turbine to spin the motor. The reasoning behind this is due to something called EMF (https://en.wikipedia.org/wiki/Electromotive_force) and Faraday's Law of Induction (https://en.wikipedia.org/wiki/Faraday%2 ... _induction). The best way to think about this is that the blades generate a force on the shaft. That force has to overcome the 'physical resistance' of the motor to turn the shaft. That 'physical resistance' is due to a combination of the magnetic 'flux' of the motor windings and the electrical resistance of the circuit. Increase the electrical resistance, and the same amount of force will have more 'physical resistance' to overcome, resulting in less output (e.g. Power) from the generator (i.e. less current and voltage).

In many electrical engineering classes, the hydraulic analogy (https://en.wikipedia.org/wiki/Hydraulic_analogy) is used to help explain things, by comparing electrical circuits to water plumbing. In this situation, think of the generator as a water pump. By increasing the circuit resistance, you are effective making the hose connected to the pump a smaller diameter. If you hook up a smaller diameter hose to a pump, the amount of water you get out of the pump will go down (e.g. the current decreases), but that won't be necessarily offset by the water coming out of the hose being more forceful (e.g. the voltage), hence the net power is reduced.

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Re: Wind Power B/C

Postby chalker » Sun Jan 08, 2017 11:30 pm

soyuppy wrote:Just post similar question to SO inc.
When you buy a bundle of CD/DVD, usually come in 25/50/100, you get the plastic filler. Can this plastic filler be used for blade? Has the same dimension as CD/DVD, but it's much lighter.


As usual, this isn't the place for official statements / clarifications. That said, if you asked 100 random people off the street whether that plastic filler was a CD, what do you think the majority of them would say? I'd propose they'd say No, it isn't a CD.

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Re: Wind Power B/C

Postby LIPX3 » Mon Jan 09, 2017 1:11 pm

I've looked over the rules, and I haven't found anything that says you can't use a vertical axis turbine. Has anyone seen someone do this? I think it would be a way to increase surface area of the blades, as you can go as far in front of the CD as you want.

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Re: Wind Power B/C

Postby ashmmohan » Mon Jan 09, 2017 1:14 pm

Unome wrote:
soyuppy wrote:
mkfiddler11 wrote:Has any of you been to an invitational and know of top high and low voltage scores at the event? Please post the resistance used in the setup. Thanks!

I just helped ran an invitational event.

CD motor: https://www.amazon.com/gp/product/B00OT ... UTF8&psc=1
Load R: 10 Ohm

Top blade = 700mV+ on high, 500mV+ on low
Low blade = 80mv on high, 70mv on low

Was this B or C? (I'll go ahead and assume this was at Mira Loma yesterday)


Keep in mind that division B can have their blades extend as far as 20 cm from the center of the CD. 700mV is pretty high for any setup, but the 20 cm blades can increase results tremendously.
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Wind Power: 1/6/3/1/1/
Towers: 5/-/-/-/5/
EV: -/3
Hovercraft: 1/-/-

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Re: Wind Power B/C

Postby chalker » Mon Jan 09, 2017 2:20 pm

LIPX3 wrote:I've looked over the rules, and I haven't found anything that says you can't use a vertical axis turbine. Has anyone seen someone do this? I think it would be a way to increase surface area of the blades, as you can go as far in front of the CD as you want.


Read rule 2.d.iii closely, particularly the bolded part (which indicates it's new this year). We explicitly put that in place to prevent VAWT designs. In general, VAWT designs are much harder to make and put much more torque / stress on the motor / CD hub mount.

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