## EV Scores at Nationals

windu34
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### EV Scores at Nationals

What scores are you guys predicting for the top 1-6?
I'm predicting a 1.5 second run with 1cm off from the target for first (score of about 16)
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Bazinga+
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### Re: EV Scores at Nationals

I dont think the winning score will be quite that low because the uncertainty at that speed is huge (not to mention 2 dimensional), so first will probably be a very fast car (1.6 sec) which is usually accurate to like 10-15 cm which gets like 3-5 cm off, so around 20 pts. It honestly comes down to luck. I'm thinking that cars with scores under 25-30 will medal, or at least get top 10.
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gh
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### Re: EV Scores at Nationals

Under ideal conditions:
• 9 meters distance
• wheels with µ = 1.0 tires
• motor(s) supplying maximum necessary torque from zero to top vehicle speed
Your device would accelerate from distance = 0 to 4.5 m at µ * g = 9.8 m/s² then at -9.8 m/s² from distance = 4.5 m to 0 m.

For the first leg:
$x = \frac{1}{2} \mu g t^2 = \frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right) t^2 = 4.5 \text{m}$
$t = \sqrt{\frac{4.5 \text{m}}{\frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right)}} \approx 0.96 \text{s}$

Both legs combined would be 1.92 seconds. The more astute (or experienced) of you would know that one of my given conditions isn't strictly "ideal."
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windu34
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### Re: EV Scores at Nationals

gh wrote:Under ideal conditions:
• 9 meters distance
• wheels with µ = 1.0 tires
• motor(s) supplying maximum necessary torque from zero to top vehicle speed
Your device would accelerate from distance = 0 to 4.5 m at µ * g = 9.8 m/s² then at -9.8 m/s² from distance = 4.5 m to 0 m.

For the first leg:
$x = \frac{1}{2} \mu g t^2 = \frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right) t^2 = 4.5 \text{m}$
$t = \sqrt{\frac{4.5 \text{m}}{\frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right)}} \approx 0.96 \text{s}$

Both legs combined would be 1.92 seconds. The more astute (or experienced) of you would know that one of my given conditions isn't strictly "ideal."

who said anything about decelerating before the 8.5m mark?
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iwonder
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### Re: EV Scores at Nationals

windu34 wrote:
gh wrote:Under ideal conditions:
• 9 meters distance
• wheels with µ = 1.0 tires
• motor(s) supplying maximum necessary torque from zero to top vehicle speed
Your device would accelerate from distance = 0 to 4.5 m at µ * g = 9.8 m/s² then at -9.8 m/s² from distance = 4.5 m to 0 m.

For the first leg:
$x = \frac{1}{2} \mu g t^2 = \frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right) t^2 = 4.5 \text{m}$
$t = \sqrt{\frac{4.5 \text{m}}{\frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right)}} \approx 0.96 \text{s}$

Both legs combined would be 1.92 seconds. The more astute (or experienced) of you would know that one of my given conditions isn't strictly "ideal."

who said anything about decelerating before the 8.5m mark?

For a given symmetric acceleration/deceleration you'd need to go from 'full throttle' to 'full brakes' at the halfway mark. Since the limiting factor in this calculation is the tire grip it's symmetric.
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windu34
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### Re: EV Scores at Nationals

iwonder wrote:
windu34 wrote:
gh wrote:Under ideal conditions:
• 9 meters distance
• wheels with µ = 1.0 tires
• motor(s) supplying maximum necessary torque from zero to top vehicle speed
Your device would accelerate from distance = 0 to 4.5 m at µ * g = 9.8 m/s² then at -9.8 m/s² from distance = 4.5 m to 0 m.

For the first leg:
$x = \frac{1}{2} \mu g t^2 = \frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right) t^2 = 4.5 \text{m}$
$t = \sqrt{\frac{4.5 \text{m}}{\frac{1}{2} \left(9.8 \frac{\text{m}}{\text{s}^2}\right)}} \approx 0.96 \text{s}$

Both legs combined would be 1.92 seconds. The more astute (or experienced) of you would know that one of my given conditions isn't strictly "ideal."

who said anything about decelerating before the 8.5m mark?

For a given symmetric acceleration/deceleration you'd need to go from 'full throttle' to 'full brakes' at the halfway mark. Since the limiting factor in this calculation is the tire grip it's symmetric.

Rules clarification allows vehicles to go backwards. Just saying.
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cantthinkofausername
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### Re: EV Scores at Nationals

Bazinga+ wrote:I dont think the winning score will be quite that low because the uncertainty at that speed is huge (not to mention 2 dimensional), so first will probably be a very fast car (1.6 sec) which is usually accurate to like 10-15 cm which gets like 3-5 cm off, so around 20 pts. It honestly comes down to luck. I'm thinking that cars with scores under 25-30 will medal, or at least get top 10.

I would like to argue this. It is completely possible for multiple teams to score sub 20 total scores. I believe Mentor High School is one of the few that have already done this consistently without luck. At Wright State invitational they got a score of .5 cm off and 1.7ish seconds, giving score of 17.5. I have another friend who says he can get 1.5s runs with accuracy of a cm off but I haven't personally seen it. Assuming that mentor hasn't destroyed both of their vehicles and that my friend isn't a liar, that's at least 2 teams that are able to get sub 20 scores and I'm sure at least 4-6 more can and will.

windu34
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### Re: EV Scores at Nationals

cantthinkofausername wrote:
Bazinga+ wrote:I dont think the winning score will be quite that low because the uncertainty at that speed is huge (not to mention 2 dimensional), so first will probably be a very fast car (1.6 sec) which is usually accurate to like 10-15 cm which gets like 3-5 cm off, so around 20 pts. It honestly comes down to luck. I'm thinking that cars with scores under 25-30 will medal, or at least get top 10.

I would like to argue this. It is completely possible for multiple teams to score sub 20 total scores. I believe Mentor High School is one of the few that have already done this consistently without luck. At Wright State invitational they got a score of .5 cm off and 1.7ish seconds, giving score of 17.5. I have another friend who says he can get 1.5s runs with accuracy of a cm off but I haven't personally seen it. Assuming that mentor hasn't destroyed both of their vehicles and that my friend isn't a liar, that's at least 2 teams that are able to get sub 20 scores and I'm sure at least 4-6 more can and will.

Agreed
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GoldDigger
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### Re: EV Scores at Nationals

How tf are these teams getting speeds of 1.5 seconds with the 9V power restriction!?

Bazinga+
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### Re: EV Scores at Nationals

GoldDigger wrote:How tf are these teams getting speeds of 1.5 seconds with the 9V power restriction!?

The real limit is not 9V, but the traction with the floor hah. Most teams are using 7.2 volt battery PACKS, which can provide much more current than 9V batteries, along with AC motors (Brushless/stepper).
Innovation =/= success

GoldDigger
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### Re: EV Scores at Nationals

I'm currently using balloons as my traction, what would be the better bet for traction?

windu34
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### Re: EV Scores at Nationals

GoldDigger wrote:I'm currently using balloons as my traction, what would be the better bet for traction?

Look into different types of tires
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Bazinga+
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### Re: EV Scores at Nationals

windu34 wrote:
GoldDigger wrote:I'm currently using balloons as my traction, what would be the better bet for traction?

Look into different types of tires

Yes. There are wheels with much higher traction than balloons.
Innovation =/= success

iwonder
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### Re: EV Scores at Nationals

windu34 wrote:Rules clarification allows vehicles to go backwards. Just saying.

Personally, if I were an ES for this I would put a wall 1m after the line. It's an interesting solution but there's no guarantee of space to do it in. Planning on it or making arguments that try to supplant math/physics calculations is just useless.
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retired1
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### Re: EV Scores at Nationals

I saw Windu run at FL state event. Absolutely amazing! I timed him at under 2 sec. I have no idea what the electronic scoring was. My timing was not as accurate as it could have been because of a couple of people blocking the view. With unlimited open space beyond the target, he can run a good bit faster, but at some risk. Watching him back up in stages to an exact point blew my mind. I am jealous and would like to see the rule thrown out. I had asked for the FAQ change about batteries. Now I am on the other side. I would like to see one battery only. LIPO's should probably still be off limits because of problems with carrying them on a flight. They could still be shipped ahead of time and sent to the hotel or??
For this year, windu has worked long and hard to achieve these results within the rules. I am sure that there will be a few teams that will also be very competitive.

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