Wind Power B/C

[chalker]

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).

2. We don't want to allow competitors to 'break the rules' with the chance of scoring so high it offsets any potential penalty.

3. The Power scoring formula wasn't included out of any general philosophical reason. Rather, we previously measured raw voltage (without a resistor) and realized that wasn't giving very consistent measurements. The electrical circuit was essentially an open circuit without a resistor due to the extremely high resistance of a typical multimeter. The inclusion of a resistor naturally lead to us being able to calculate power, which we did 'just because'.

[dragonfruit35]

2. We don't want to allow competitors to 'break the rules' with the chance of scoring so high it offsets any potential penalty.

At VA states, I witnessed a team get "device failure" (they broke their blades during setup and were unable to start within 2.5 min), and they still got 4th...

[PHXcoach]

I have tried to capture my concerns into specific rule wording changes:

4c. Event supervisors must verify that the blade assembly meets event rules before a team’s blade testing period is permitted to begin. This verification may take place during impound. Teams must be notified as soon as possible if a blade assembly does not meet specifications.

Section 5 – I would like to ensure that bringing a failing blade is not penalized more than not bringing any blade assembly. I also wanted to clarify that violating blades don’t get to run unless they are fixed, and that construction violations identified by the event supervisor after impound still incur a construction violation even if they get fixed. I had 3 options depending on your objectives for the scoring. My preference would be option 1, but I don't know your scoring philosophy.

Option 1
5f. A penalty equal to 30% of the Part I score must be applied to the final score for any construction violations not corrected before impound or if the team misses impound.

5g. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

Option 2
5f. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

5g. A 15-point penalty must be applied to the final score for any construction violations not corrected before impound, if the team misses impound, or if the Part I score was 0 due to rule 5f.

Option 3
5f. A 15-point penalty must be applied to the Part I score for any construction violation not corrected before impound or if the team misses impound. Negative Part I scores will be made 0.

5g. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

[calvin102111]

I have tried to capture my concerns into specific rule wording changes:

4c. Event supervisors must verify that the blade assembly meets event rules before a team’s blade testing period is permitted to begin. This verification may take place during impound. Teams must be notified as soon as possible if a blade assembly does not meet specifications.

Section 5 – I would like to ensure that bringing a failing blade is not penalized more than not bringing any blade assembly. I also wanted to clarify that violating blades don’t get to run unless they are fixed, and that construction violations identified by the event supervisor after impound still incur a construction violation even if they get fixed. I had 3 options depending on your objectives for the scoring. My preference would be option 1, but I don't know your scoring philosophy.

Option 1
5f. A penalty equal to 30% of the Part I score must be applied to the final score for any construction violations not corrected before impound or if the team misses impound.

5g. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

Option 2
5f. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

5g. A 15-point penalty must be applied to the final score for any construction violations not corrected before impound, if the team misses impound, or if the Part I score was 0 due to rule 5f.

Option 3
5f. A 15-point penalty must be applied to the Part I score for any construction violation not corrected before impound or if the team misses impound. Negative Part I scores will be made 0.

5g. The Part I score must be zero if a team is disqualified for unsafe operation, uncorrected construction violations, modifying a CD, or fails to bring a blade assembly. Teams must still be allowed to compete in Part II.

As someone who did Wind Power for every competition, I do like what you said in option 2. Too many teams at our regional got away with competing (and actually beat us... ) after missing the impound. Also, the 15 point deduction seems a bit high, but I like the idea of a reduction, as teams that got a 0 on their Part I score due to violations were still able to be at a competitive level.

[chalker]

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?

[dragonfruit35]

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.

[PHXcoach]

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.

[JustDroobles]

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]

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]

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.