Wind Power B/C

User avatar
dragonfruit35
Exalted Member
Exalted Member
Posts: 202
Joined: February 28th, 2015, 7:49 am
Division: C
State: VA
Location: TJHSST
Contact:

Re: Wind Power B/C

Postby dragonfruit35 » May 1st, 2016, 5:09 pm

chalker wrote:As I mentioned above, there seemed to be some confusion due to the diagrams in the rules this year. Below are some modified diagrams I've made. Any suggestions / comments on whether these will help clear up the confusion?
Slide2.PNG

Slide1.PNG


Looks good, except it's a little hard to tell what the 3cm is pointing to. :)

Last Year: (VT/ FFX/ Reg/ State/Nats)
Mousetrap 1/1/5/-/- Mission 3/4/4/-/- Herp 7/2/4/-/-
WiFi -/-/-/4/13 Indoor Bottle Rocket -/-/-/1/- Codebusters -/-/-/-/1
This Year: (Duke/Reg/???)
Mousetrap ?/?/? Mission ?/?/? Sounds ?/?/? Codebusters ?/?/?
Gooooooo Colonials!

PHXcoach
Member
Member
Posts: 37
Joined: May 20th, 2013, 10:23 am
Division: B
State: AZ
Contact:

Re: Wind Power B/C

Postby PHXcoach » May 1st, 2016, 5:19 pm

chalker wrote:As I mentioned above, there seemed to be some confusion due to the diagrams in the rules this year. Below are some modified diagrams I've made. Any suggestions / comments on whether these will help clear up the confusion?

I am not sure about showing the generator on the front view. This might lead to more questions about the 3 cm keep out being both the front and the back.

Maybe show a front view (without the generator) and a rear view next to it that shows the generator and the 3 cm keep out.

User avatar
JustDroobles
Member
Member
Posts: 162
Joined: February 9th, 2009, 3:28 pm
Division: Grad
State: MI
Location: WI
Contact:

Re: Wind Power B/C

Postby JustDroobles » May 1st, 2016, 5:39 pm

chalker wrote:As I mentioned above, there seemed to be some confusion due to the diagrams in the rules this year. Below are some modified diagrams I've made. Any suggestions / comments on whether these will help clear up the confusion?


The biggest area of confusion when I have run Wind Power is the cleared area in a 3 cm radius on the back. So maybe instead of showing a front view, show a back view with the forbidden area outlined with a dashed line. I would also suggest showing the 3 cm radius the same as you show the blade radius, even if you have to make the diagram a bit bigger. Another issue is that competitors may not have put their blade in the 3 cm radius, but put tape or glue of something else that could still interfere with mounting their device. Rule 3f could be reworded to clarify this.

PHXcoach
Member
Member
Posts: 37
Joined: May 20th, 2013, 10:23 am
Division: B
State: AZ
Contact:

Re: Wind Power B/C

Postby PHXcoach » May 2nd, 2016, 10:51 am

Has anyone seen inconsistency in the test stand voltage results, specifically the Ward Science stand ?

I have been using a test stand based on a CD motor taken from a used portable CD player as my main test stand at all of the invitationals, regionals and state final and it has been consistent in that my reference blade assembly has always returned the same voltage range (305 to 315 mV) all season.

I have also been using a Ward Science test stand as a backup and a comparison. When the test stand first arrived it was reporting approximately 30% higher voltages (430 mV) than my CD motor based stand. Recently I have noticed that the voltages reported by the Ward stand are dropping:
a) The initial high voltage is getting a little lower
b) While a blade assembly is being tested it initially peaks and then the voltage slowly drifts down by 20 to 50% over 5 minutes of continuous running
c) After testing a number of other blade assemblies and then going back to the original reference the voltage reading is significantly (10% to 20%) lower than it measured at the beginning of the test session.
d) If the test stand is left until the next day it seemed to recover but not to the original 30% higher results I used to get with it.

I have tried with two different fans and swapped out the volt meter and power cables and am still seeing the same behavior. The resistor does not seem to be warming up so I don't think that is the problem (but I didn't measure it very scientifically), and I was not able to measure the motor windings temperature.

I am particularly concerned about observation (c) that the voltages are reducing throughout a test session because it could give teams competing later in the day a disadvantage. I am still investigating but in the mean time was wondering if anyone else has seen this test stand behavior.

Noel
Member
Member
Posts: 10
Joined: September 10th, 2015, 2:41 pm
Division: C
State: FL
Contact:

Re: Wind Power B/C

Postby Noel » May 2nd, 2016, 1:04 pm

PHXcoach wrote:Has anyone seen inconsistency in the test stand voltage results, specifically the Ward Science stand ?

I have been using a test stand based on a CD motor taken from a used portable CD player as my main test stand at all of the invitationals, regionals and state final and it has been consistent in that my reference blade assembly has always returned the same voltage range (305 to 315 mV) all season.

I have also been using a Ward Science test stand as a backup and a comparison. When the test stand first arrived it was reporting approximately 30% higher voltages (430 mV) than my CD motor based stand. Recently I have noticed that the voltages reported by the Ward stand are dropping:
a) The initial high voltage is getting a little lower
b) While a blade assembly is being tested it initially peaks and then the voltage slowly drifts down by 20 to 50% over 5 minutes of continuous running
c) After testing a number of other blade assemblies and then going back to the original reference the voltage reading is significantly (10% to 20%) lower than it measured at the beginning of the test session.
d) If the test stand is left until the next day it seemed to recover but not to the original 30% higher results I used to get with it.

I have tried with two different fans and swapped out the volt meter and power cables and am still seeing the same behavior. The resistor does not seem to be warming up so I don't think that is the problem (but I didn't measure it very scientifically), and I was not able to measure the motor windings temperature.

I am particularly concerned about observation (c) that the voltages are reducing throughout a test session because it could give teams competing later in the day a disadvantage. I am still investigating but in the mean time was wondering if anyone else has seen this test stand behavior.


It's probably the pitch of your turbine. I also see a consistent drop in the voltage output of my turbine after it peeks and when retested later in the day. This can be corrected by rebending before testing or spraying with a sealant to help maintain shape. Unfortunately, with flimsier materials, such as cardboard or card stock, the pitch will never be entirely consistent and a minuscule change in pitch can significantly affect the voltage output. Ultimately, you shouldn't be concerned with your set-up...just improving the stability and consistency or your turbine blades.
2015-2016 Events
It's About Time
Protein Modeling
Robot Arm
Wind Power
Write It Do It

ASingh
Member
Member
Posts: 2
Joined: May 2nd, 2016, 12:41 pm
Division: C
State: MI
Contact:

Re: Wind Power B/C

Postby ASingh » May 2nd, 2016, 1:26 pm

chalker wrote:There are some REALLY good insights and comments in this thread so far. Instead of replying to each of them, I'd like to share some general comments to hopefully steer the conversation. I'd also like to request suggestions on specific, concrete changes to the rules wording.

1. This is a Physics committee event. Hence our general philosophy is that the theoretical and practical portions of the event should contribute equally to the score. What that specifically means is that we don't do tiering in Physics events (as that would make the practical portion outweigh the theoretical portion).


I think the way the event played out, this balance between the theoretical and practical portions was not realized in practice. I am OK with using Power (square function of Voltage) as the metric, but I think normalizing the score with the top team getting a 50 causes a distortion. Most turbine designs are only capturing a very small amount of the energy in the wind, and small differences (compared to the amount of available energy) in their performance are getting exaggerated. So a team may be capturing 2% (score of 50) of the energy and another 1.5% (score of 37.5) of the energy. There is no such scaling on the written part, and even achieving a 5 pt difference would be hard.

A couple of options:
1) An easy thing to do would be to normalize the written score also. So if the top team had a 35/50 and the next team had a 30/50, the scored would be 50 and 42.85. This would make it a little more balanced.
2) Instead of normalizing wrt to max power score in the event, normalize to some target power level (Betz limit, or best turbine power generated at this year's national, etc.). So then as in the written part, no one may get a 50 and your score would be dependent on how good your performance is compared to best possible performance.

Another thing that might help is if the equipment was standardized...box fan type, motor/generator...so that designs can be optimized to known conditions.

soyuppy
Member
Member
Posts: 84
Joined: September 18th, 2015, 12:08 am
State: -
Contact:

Re: Wind Power B/C

Postby soyuppy » May 3rd, 2016, 7:49 am

PHXcoach wrote:Has anyone seen inconsistency in the test stand voltage results, specifically the Ward Science stand ?

I have been using a test stand based on a CD motor taken from a used portable CD player as my main test stand at all of the invitationals, regionals and state final and it has been consistent in that my reference blade assembly has always returned the same voltage range (305 to 315 mV) all season.

I have also been using a Ward Science test stand as a backup and a comparison. When the test stand first arrived it was reporting approximately 30% higher voltages (430 mV) than my CD motor based stand. Recently I have noticed that the voltages reported by the Ward stand are dropping:
a) The initial high voltage is getting a little lower
b) While a blade assembly is being tested it initially peaks and then the voltage slowly drifts down by 20 to 50% over 5 minutes of continuous running
c) After testing a number of other blade assemblies and then going back to the original reference the voltage reading is significantly (10% to 20%) lower than it measured at the beginning of the test session.
d) If the test stand is left until the next day it seemed to recover but not to the original 30% higher results I used to get with it.

I have tried with two different fans and swapped out the volt meter and power cables and am still seeing the same behavior. The resistor does not seem to be warming up so I don't think that is the problem (but I didn't measure it very scientifically), and I was not able to measure the motor windings temperature.

I am particularly concerned about observation (c) that the voltages are reducing throughout a test session because it could give teams competing later in the day a disadvantage. I am still investigating but in the mean time was wondering if anyone else has seen this test stand behavior.

We had same issue with the CD motor that we extracted from a CD player. When motor was test initially, reading was consistent. Then over time, the reading start to fluctuate by large amount. Then we got these set of motor from Amazon.
http://www.amazon.com/Water-RC300-FT-08800-6000RPM-1-5-9V-Player/dp/B00OTCPDKW?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00. They work much better and has been consistent. Just use the mounting hub from the old motor.

soyuppy
Member
Member
Posts: 84
Joined: September 18th, 2015, 12:08 am
State: -
Contact:

Re: Wind Power B/C

Postby soyuppy » May 3rd, 2016, 8:07 am

ASingh wrote:
chalker wrote:There are some REALLY good insights and comments in this thread so far. Instead of replying to each of them, I'd like to share some general comments to hopefully steer the conversation. I'd also like to request suggestions on specific, concrete changes to the rules wording.

1. This is a Physics committee event. Hence our general philosophy is that the theoretical and practical portions of the event should contribute equally to the score. What that specifically means is that we don't do tiering in Physics events (as that would make the practical portion outweigh the theoretical portion).


I think the way the event played out, this balance between the theoretical and practical portions was not realized in practice. I am OK with using Power (square function of Voltage) as the metric, but I think normalizing the score with the top team getting a 50 causes a distortion. Most turbine designs are only capturing a very small amount of the energy in the wind, and small differences (compared to the amount of available energy) in their performance are getting exaggerated. So a team may be capturing 2% (score of 50) of the energy and another 1.5% (score of 37.5) of the energy. There is no such scaling on the written part, and even achieving a 5 pt difference would be hard.

A couple of options:
1) An easy thing to do would be to normalize the written score also. So if the top team had a 35/50 and the next team had a 30/50, the scored would be 50 and 42.85. This would make it a little more balanced.
2) Instead of normalizing wrt to max power score in the event, normalize to some target power level (Betz limit, or best turbine power generated at this year's national, etc.). So then as in the written part, no one may get a 50 and your score would be dependent on how good your performance is compared to best possible performance.

Another thing that might help is if the equipment was standardized...box fan type, motor/generator...so that designs can be optimized to known conditions.

Not sure I agree with with either 1 or 2. The score are always compare among those team that compete in the event for that day. All events in SO follow this scheme. Regardless of what baseline, the placement of your score doesn't change. If you actually score 20/50 or 30/50 and this happen to be the best score for that event for that day, it doesn't matter what normalization takes place, your are still in 1st place.

soyuppy
Member
Member
Posts: 84
Joined: September 18th, 2015, 12:08 am
State: -
Contact:

Re: Wind Power B/C

Postby soyuppy » May 3rd, 2016, 8:16 am

Resistance in the setup
In my setup, I have a 5 Ohm Resistor(verified by Multi-Meter), but when connected to CD motor, resistance drop to 3.5 Ohm.
How do you measure resistance in the setup? Is the 5-7.5 ohm measure on the entire circuit, including the CD motor connect or CD motor disconnect?

User avatar
daydreamer0023
Member
Member
Posts: 187
Joined: January 29th, 2015, 5:44 pm
Division: C
State: -
Location: I have no idea where I am, but I can tell you exactly how fast I'm going ;)
Contact:

Re: Wind Power B/C

Postby daydreamer0023 » May 3rd, 2016, 9:22 am

This is very urgent: I just got put on Wind Power for Nationals and I have no idea where to start. :oops: My partner has done it before and I can probably study my way through it somewhat (since it's similar to the format of Simple Machines last year), but what I really need help with is building the turbine blades, since we're thinking of remodeling them from what we previously used for states.

Can someone please share some design ideas that have worked well for them (I understand if you all don't want to give away team secrets), or at least some starting points for thoughts on building the device? Thanks in advance! :)
"I am among those who think that science has great beauty. A scientist in his laboratory is not only a technician: he is also a child placed before natural phenomena which impress him like a fairy tale." - Marie Curie

PHXcoach
Member
Member
Posts: 37
Joined: May 20th, 2013, 10:23 am
Division: B
State: AZ
Contact:

Re: Wind Power B/C

Postby PHXcoach » May 3rd, 2016, 10:24 am

soyuppy wrote:Resistance in the setup
In my setup, I have a 5 Ohm Resistor(verified by Multi-Meter), but when connected to CD motor, resistance drop to 3.5 Ohm.
How do you measure resistance in the setup? Is the 5-7.5 ohm measure on the entire circuit, including the CD motor connect or CD motor disconnect?

The resistance of 5 to 7.5 ohms only applies to the load resistor (rule 2.d.iv). The resistance of the rest of the circuit (motor and wire) is not specified.
Just measure the resistance across the resistor without the motor in parallel or series with it.

HandsFreeCookieDunk
Member
Member
Posts: 81
Joined: January 14th, 2016, 4:53 pm
Division: C
State: PA
Contact:

Re: Wind Power B/C

Postby HandsFreeCookieDunk » May 3rd, 2016, 12:18 pm

daydreamer0023 wrote:This is very urgent: I just got put on Wind Power for Nationals and I have no idea where to start. :oops: My partner has done it before and I can probably study my way through it somewhat (since it's similar to the format of Simple Machines last year), but what I really need help with is building the turbine blades, since we're thinking of remodeling them from what we previously used for states.

Can someone please share some design ideas that have worked well for them (I understand if you all don't want to give away team secrets), or at least some starting points for thoughts on building the device? Thanks in advance! :)


This late in the season, you might be better off just keeping the States blades, especially if they got you this far. If you do decide to change them, I've found that cereal box cardboard works well, although the blades have to be pretty big to drive the weight of the entire CD.

User avatar
dragonfruit35
Exalted Member
Exalted Member
Posts: 202
Joined: February 28th, 2015, 7:49 am
Division: C
State: VA
Location: TJHSST
Contact:

Re: Wind Power B/C

Postby dragonfruit35 » May 3rd, 2016, 1:35 pm

HandsFreeCookieDunk wrote:
daydreamer0023 wrote:This is very urgent: I just got put on Wind Power for Nationals and I have no idea where to start. :oops: My partner has done it before and I can probably study my way through it somewhat (since it's similar to the format of Simple Machines last year), but what I really need help with is building the turbine blades, since we're thinking of remodeling them from what we previously used for states.

Can someone please share some design ideas that have worked well for them (I understand if you all don't want to give away team secrets), or at least some starting points for thoughts on building the device? Thanks in advance! :)


This late in the season, you might be better off just keeping the States blades, especially if they got you this far. If you do decide to change them, I've found that cereal box cardboard works well, although the blades have to be pretty big to drive the weight of the entire CD.


Balsa wood also works well, or at least it did for my blades. Drag type blades are definitely better in my experience.

Last Year: (VT/ FFX/ Reg/ State/Nats)
Mousetrap 1/1/5/-/- Mission 3/4/4/-/- Herp 7/2/4/-/-
WiFi -/-/-/4/13 Indoor Bottle Rocket -/-/-/1/- Codebusters -/-/-/-/1
This Year: (Duke/Reg/???)
Mousetrap ?/?/? Mission ?/?/? Sounds ?/?/? Codebusters ?/?/?
Gooooooo Colonials!

User avatar
calvin102111
Member
Member
Posts: 38
Joined: April 29th, 2016, 1:55 pm
Division: C
State: IN
Contact:

Re: Wind Power B/C

Postby calvin102111 » May 3rd, 2016, 2:18 pm

dragon_fruit35 wrote:
HandsFreeCookieDunk wrote:
daydreamer0023 wrote:This is very urgent: I just got put on Wind Power for Nationals and I have no idea where to start. :oops: My partner has done it before and I can probably study my way through it somewhat (since it's similar to the format of Simple Machines last year), but what I really need help with is building the turbine blades, since we're thinking of remodeling them from what we previously used for states.

Can someone please share some design ideas that have worked well for them (I understand if you all don't want to give away team secrets), or at least some starting points for thoughts on building the device? Thanks in advance! :)


This late in the season, you might be better off just keeping the States blades, especially if they got you this far. If you do decide to change them, I've found that cereal box cardboard works well, although the blades have to be pretty big to drive the weight of the entire CD.


Balsa wood also works well, or at least it did for my blades. Drag type blades are definitely better in my experience.

Work with balsa wood if possible. With my setup, using 4 blades, we were able to generate about 700 mV on low speed and 900 mV on high speed (however this is all relative). Personally, we used a design with a very precise airfoil, but this late in the season I wouldn't worry about that unless you have worked with them before. As previously stated, drag designs seem to be the best performance wise and in consistency.

In my opinion, one of the factors you have to worry about the most is balance. A poorly balanced assembly can really harm your power output. I use clay to balance my assembly, and I do so by placing it on the mount and rotating it so each blade is facing up and balancing it so it no longer falls towards one side. Repeat that for all of the blades. If it comes down to it and you cannot create a better design, just stick with the state design. Don't stress out over this event specifically, worry about doing your best in the events that you were in at state.

Best of luck to you!
-Calvin
Captain for 2016/17 Season

Projected Events: Wind Power; Dynamic Planet; Ecology; Optics; R & M; WIDI

User avatar
fl0w
Member
Member
Posts: 18
Joined: January 29th, 2016, 9:52 pm
Division: C
State: MN
Contact:

Re: Wind Power B/C

Postby fl0w » May 4th, 2016, 6:11 pm

How is it that you guys have been finding drag type designs to be the best? Aren't those typically for vertical axis wind turbines?
Mounds View High School

2015-16 Events: Wind Power, It's About Time, Game On
2016-17 Events: Wind Power, Ecology, Game On

Wind Power National Champion, 2016 National Tournament


Return to “Wind Power B/C”

Who is online

Users browsing this forum: No registered users and 1 guest