So... What did it take to win your State?

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Re: So... What did it take to win your State?

Post by MIScioly1 » April 30th, 2017, 12:37 pm

In Michigan, I know of a tower that was right around 1900 that did not place in the top 8. I believe the cutoff was around 2000, and the best was above 2500. The competition was really tough at States this year.
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Re: So... What did it take to win your State?

Post by MIScioly1 » April 30th, 2017, 12:38 pm

MIScioly1 wrote:In Michigan, I know of a tower that was right around 1900 that did not place in the top 8. I believe the cutoff was around 2000, and the best was above 2500. The competition was really tough at States this year.
That is for Division C ^^^^^
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Re: So... What did it take to win your State?

Post by Balsa Man » May 1st, 2017, 10:10 am

Girlpower05 wrote:Our states tournament (Michigan) just occurred yesterday, and we took 4th place in towers. The efficiency of our tower was 2860, and it was a nonbonus B tower. The tower weighed 4.69 grams, and held 13.25kg. Unfortunately, the top three scores in Michigan are unknown, but they were all likely above 3000. Until regionals, our tower had been of Balsa Man's design, and we reached scores of 2200 with it. After regionals, we spent a month pursuing the nonbonus only X's tower, and succeeded in breaking 3000 with that design. We could not have gone as far in towers as we did without the help of forums, and I would like to thank everyone who contributed to this book of information.
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Re: So... What did it take to win your State?

Post by Balsa Man » May 1st, 2017, 10:22 am

Balsa Man wrote:
Girlpower05 wrote:Our states tournament (Michigan) just occurred yesterday, and we took 4th place in towers. The efficiency of our tower was 2860, and it was a nonbonus B tower. The tower weighed 4.69 grams, and held 13.25kg. Unfortunately, the top three scores in Michigan are unknown, but they were all likely above 3000. Until regionals, our tower had been of Balsa Man's design, and we reached scores of 2200 with it. After regionals, we spent a month pursuing the nonbonus only X's tower, and succeeded in breaking 3000 with that design. We could not have gone as far in towers as we did without the help of forums, and I would like to thank everyone who contributed to this book of information.
Its great what collectively we've compiled, and its great to hear its helping folk. That IS the idea. 2860 is very respectable.
Working on the important, engineering principle, "if it works, it works, even if you don't fully understand how it work", we're (B team and C team I'm working with) taking the path you took after Regionals for Nationals, going to all Xs. Think we have enough specs info to have a run at all Xs meeting circle bonus, which will involve strengthening lower Xs, because of the greater length. One thing that it looks like will help that is going to 5/32" legs-lighter and higher buckling strength than the 1/8 we used at State. This way, don't have to create new, good jigs. I really appreciate the good info on what it takes to make an all Xs non-circle bonus high performing tower work.

As I've said before, don't...fully/deeply understand the numbers on all Xs like I do for ladders and Xs, but hopefully do understand how to convert/adapt working non-circle bonus specs to circle bonus configuration. We'll see in the next few days.
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Re: So... What did it take to win your State?

Post by Crtomir » May 1st, 2017, 12:15 pm

Balsa Man wrote:One thing that it looks like will help that is going to 5/32" legs-lighter and higher buckling strength than the 1/8 we used at State.
That's an interesting idea: going to a larger cross-sectional area for the main columns. Theoretically, for the same density of balsa wood, 5/33"x5/32" should have higher buckling strength than 1/8"x1/8", right? So maybe you can get away with less density wood for the main columns, or, alternatively, use less X-braces.

For most of the season, our girls were building Div-B towers with the bonus. The best scores (2200 to 2500) came with a bracing geometry that mimics what you see on power line transmission towers (a little bit of Wind Power event thrown in right here ;) ). That enabled the long X-braces to be braced themselves. The drawback was that the bracing ended up being a little more wood than for pure X-braces alone.

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Re: So... What did it take to win your State?

Post by Balsa Man » May 1st, 2017, 2:33 pm

Crtomir wrote:
Balsa Man wrote:One thing that it looks like will help that is going to 5/32" legs-lighter and higher buckling strength than the 1/8 we used at State.
That's an interesting idea: going to a larger cross-sectional area for the main columns. Theoretically, for the same density of balsa wood, 5/33"x5/32" should have higher buckling strength than 1/8"x1/8", right? So maybe you can get away with less density wood for the main columns, or, alternatively, use less X-braces.

For most of the season, our girls were building Div-B towers with the bonus. The best scores (2200 to 2500) came with a bracing geometry that mimics what you see on power line transmission towers (a little bit of Wind Power event thrown in right here ;) ). That enabled the long X-braces to be braced themselves. The drawback was that the bracing ended up being a little more wood than for pure X-braces alone.
Yeah (on the 5/32nd). For example, on our B tower, in 1/8. best stick > our design buckling strength was 1.22gr/36", w/ 110% of design BS. In 5/32, best is 0.97gr/36" w/ 120% design BS.

At the same density, going from 1/8 to 5/32 increases weight by a factor of 1.56, while "I" goes up by a factor of 2.44.
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Re: So... What did it take to win your State?

Post by Ripplestar » May 1st, 2017, 3:02 pm

MIScioly1 wrote:In Michigan, I know of a tower that was right around 1900 that did not place in the top 8. I believe the cutoff was around 2000, and the best was above 2500. The competition was really tough at States this year.
I built the tower for Power Middle. Our score was around 3,500. First place, division B.

9 layers of X-bracing, 1/8th inch compression members, 1/16 inch sq and 1/16*1/32 bracing members. Weighed 3.87 grams and held around 13.7 kilograms. No bonus.

Our team built lots of towers and recorded data (compression member weight, bracing pattern, bracing weight, etc.) in a data sheet to see what worked, what didn't, and ways we could improve our design. We discovered that we were using way too much glue prior to states.

We wouldn't have gotten this score without all of the sharing on the forums. Thank you!

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Re: So... What did it take to win your State?

Post by Crtomir » May 2nd, 2017, 4:40 am

Ripplestar wrote:
MIScioly1 wrote:In Michigan, I know of a tower that was right around 1900 that did not place in the top 8. I believe the cutoff was around 2000, and the best was above 2500. The competition was really tough at States this year.
I built the tower for Power Middle. Our score was around 3,500. First place, division B.

9 layers of X-bracing, 1/8th inch compression members, 1/16 inch sq and 1/16*1/32 bracing members. Weighed 3.87 grams and held around 13.7 kilograms. No bonus.

Our team built lots of towers and recorded data (compression member weight, bracing pattern, bracing weight, etc.) in a data sheet to see what worked, what didn't, and ways we could improve our design. We discovered that we were using way too much glue prior to states.

We wouldn't have gotten this score without all of the sharing on the forums. Thank you!
That's a really good job you and your team did! Key point: you built a LOT of towers and recorded the data. Your tower design sounds very similar (only better) than the tower our girls build for the Ohio state tournament (Div-B, 3rd place)
• 4 columns, 1/8” x 1/8” at 7.5 # density
• 9 X braces per side, 1/16” x 1/32” at 5.7 # density
• No horizontal braces at top or bottom, just X’s all the way up, equal spaced at about 5.7 cm
• Tower was a little over 51 cm tall
• We did not go for the bonus because that would require long X braces at the bottom since the bottom is wider for the bonus. At the really low density X pieces we needed to use, we were afraid they could not hold the tensile load at those lengths.
• Tower for State, as built, weighed 4.11 grams and held about 13357 grams for a score of about 3250.


It's interesting that all the tower designs seems to be converging on nearly the same solution.

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Re: So... What did it take to win your State?

Post by sciencepeeps » May 2nd, 2017, 4:44 am

Unome wrote:
JZhang1 wrote:Interested in hearing scores from Illinois, Michigan, and Pennsylvania States.
^ especially considering how Grayslake beat Daniel Wright, and Woodlawn was 6th.
Here were the rankings for Div B Towers along with an estimated score (I saw all of these except Daniel Wright and NSCDS):
1: Grayslake. Score of about 3090. It was a perfect break, right at the end, nd it weighed about 4.85 grams. No bonus.
2: Daniel Wright. Score of about 3000. I heard that it broke a little early, with maybe 13-14kg of sand already in the bucket, but was also very light and went for the bonus (i think).
3: Science and Arts: Score of 2970. It held the whole weighht, but was a little heavier than others, at 5.05g, No bonus.
4: Marie Murphy: It has a similar design to Grayslake and SAA, but did not have some pieces that the rest have. It held the whole weight, but was probably heavier, because they scored from 2700-2800.
5: North Shore Country Day: I didn't see this one, but I heard from the students and coaches on it that it broke a lot earlier than anticipated, at around 2700. It was light, around 4.7g, but it dd not gold as much sand.
6: Woodlawn. The tower was crazily light, at 3.8g or less (I didn't see the exact weight). It did not go for the bonus. However, it broke very early, after almost no time on the testing table. It probably held 7-9kg. However, because it was so light, it managed to place 6th.

Sorry I couldn't explain everyone's design in detail. As you can see, IL B is super competitive in towers (even though I saw a tower that was so heavy they had to weight it on the scale that weighs the SAND :P )
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Re: So... What did it take to win your State?

Post by Crtomir » May 2nd, 2017, 4:45 am

[quote="Balsa Man
Yeah (on the 5/32nd). For example, on our B tower, in 1/8. best stick > our design buckling strength was 1.22gr/36", w/ 110% of design BS. In 5/32, best is 0.97gr/36" w/ 120% design BS.

At the same density, going from 1/8 to 5/32 increases weight by a factor of 1.56, while "I" goes up by a factor of 2.44.[/quote]

It sounds like you are on to something here! We never tried larger than 1/8" x 1/8" legs. I'm pretty sure most people thought the opposite. We even tried 3/32" x 3/32" once. The idea that you make it bigger to make it lighter and stronger is somewhat counter-intuitive to most people.

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