Tower B/C

[bernard]

[bernard]

I've supervised this event for a couple of tournaments this year and wanted to share some recommendations based on common issues I've seen with teams. These observations are from the MIT and Yale Invitationals and I've posted the same in the topic for the MIT Invitational (viewtopic.php?p=461814#p461814) so I'll just quote the relevant portion below.

1. Variation in Loading Assembly. Every year, a handful of teams struggle with a competition-day Loading Assembly that differs from the one they practiced with and designed their structure around. Remember that the rules allow a range of lengths for the eyebolt, so your structure must accommodate eyebolts of any length within that range. A slightly greater challenge—especially for Tower compared to other structure events—is that the S-hook specified in the rules does not have a fixed dimension. Therefore, teams should not design their Tower to fit precisely around an S-hook of a particular size.
   
   This was the most common challenge I observed during setup, where teams struggled to fit the S-hook through their structure without damaging the surrounding framework. Fortunately, no teams were completely unable to accommodate the Loading Assembly, but those that encountered this difficulty tended to spend significant time on setup.
   
   
2. Building precision. As with every year, a few teams built right to the dimensional specifications in the rules, which is impressive but risky when practicing on a tournament-day setup. Two key specifications where this was relevant this year were the Loading Block height and the bonus circle.
   
   Firstly, measuring accuracy varies, and it is difficult to dispute a difference of a couple millimeters between rulers. If the Event Supervisor's ruler measures slightly longer than yours, your structure built to 51.0 cm may not fall under 50.0 cm, but if you built exactly to 50.0 cm, you now have a Construction Violation.
   
   Secondly, measuring the Loading Block height is challenging because it is a vertical measurement that cannot be taken by simply holding a ruler against the Loading Block, especially with common Tower designs that are angled. Furthermore, an unlevel Loading Block relative to the Test Base can introduce and complicate parallax error correction. To improve accuracy, we mounted two bubble levels with a combination square to a meterstick at 49.9 cm, allowing for a direct, up-close measurement of Loading Block height. Even with this method, a few teams were still too close to the minimum dimension.
   
   Thirdly, even if your Loading Block measures exactly 50.0 cm prior to loading, once your Tower is loaded, it will begin to settle and arguably no longer meets that specification.
   
   Finally, for the bonus circle, drawing a precise 29 cm diameter circle is difficult without a large compass or stencil. Even with a precisely manufactured circle slightly under 29 cm in diameter, off by nearly 1 mm, a few teams' Towers barely missed touching the bonus circle. To avoid potential Construction Violations, teams should prepare for circles that may not be perfectly circular and could be marked with thick lines.
   
   My recommendations are to build your Tower to support a Loading Block at least 50.5 cm, even 51.0 cm, above the Test Base. For the bonus circle, design for a 29.5 cm diameter or larger. The structural and mass differences in building slightly larger are minimal compared to the risk of a Construction Violation, which could significantly impact your ranking.
   
   
3. Eye protection. Eye protection is required for this event and must be properly fitted. If you wear prescription glasses, wearing safety glasses over them that project outward from your face without proper seating on your nose bridge does not meet the requirements. This setup does not provide adequate protection and does not satisfy the event’s safety standards. Additionally, per guidelines, teams must be able to display the Z87+ marking.

In summary: be prepared for eyebolts and S-hooks that are smaller or larger than your usual size, do not build too close to the specifications for Loading Block height and the circle bonus, and present proper eye protection that is compatible with prescription glasses if you wear them.

[bernard]

I'm posting my perspective from the Yale Invitational, which took place on February 8, 2025, here since there isn't a dedicated topic for the tournament.

Setup: Structures were tested using a single automatic loading setup. Medium-coarseness, low-dust sand was used as the free-flowing material. (Compared to MIT, the sand was coarser, allowing for a faster maximum flow rate, with the entire hopper emptying in under 1 minute.) The Test Base was a sheet of birch plywood with laser-etched markings for the bonus circle and four quadrants. Engraving settings were adjusted to ensure a fine, superficial engraving, with the bonus circle intentionally designed with a 28.9 cm diameter to account for kerf width. Dimensions were verified after manufacture. The Loading Assembly consisted of a Loading Block made of solid wood, an eyebolt with length of approximately 3 inches, two S-hooks measuring approximately 1/4 inch by 2 inches, and a double-looped chain apprxoimately 80 centimeters in length.

During testing for the 18th team of the day, the cover of the chute that dispenses sand snapped while the team attempted to stop the sand flow after their Tower broke. I believe this was no fault of the team, as they were operating the lever as instructed. This incident led to several challenges:

• For the team that had just tested, the sand flow did not stop, introducing error in evaluating their Load Supported. Since the setup had shifted in our attempts to stop the sand flow, a secondary mound formed in the bucket, marking where the excess sand had accumulated. The team was agreeable to correcting their Load Supported by my removal of that sand. (The team happened to have a second Tower, so they were allowed to return later for a retest that replaced their original attempt.)
• For the remaining teams that had not yet tested, this meant they unfortunately were not afforded the opportunity to test under the same setup conditions as the first half of the day. Wanting to allow students to test their structures and be recognized for their scores—but not wanting to impact overall team rankings given the unexpected irregularities—we made the difficult decision to score the event as a trial.
• The remaining teams (of which there were 22) loaded "manually" by scooping sand into the hopper of the automatic loader, with the option to pour at a controlled rate for the final 10 pounds of sand. (This limit was chosen since many common household items that are considered safe for an average person to carry weigh around 10 pounds.)

This failure was unexpected, as the YUSO Test Apparatus is relatively new compared to those at many other tournaments. Notably, the chute cover, which appears to have been 3D printed, failed along layer lines, and upon inspection, I was disappointed to find that the part had been printed as a hollow shell, which may have contributed to its failure. This raises concerns for other tournaments using similar setups, as I have previously observed delamination along layers in other setups. Fortunately, those setups have not yet failed catastrophically, even after several years of use.

Up until the failure of the Test Apparatus, we were running fairly on schedule. However, the failure and subsequent decision on how to proceed led to a pause in testing and a backlog of teams, as manual loading was slower. I appreciate the flexibility and patience shown by the teams affected by this change and the delays it caused. I’m also grateful we were able to continue testing teams for the rest of the day and award medals to top finishers in both automatic (morning) and manual (afternoon) loading categories, despite the event not counting toward team scores.

Tiers: Of the 57 registered teams, 39 presented devices, with 33 (85%) in Tier 1, 5 (13%) in Tier 2, and 1 (3%) in Tier 3.

Scores: The high score across all teams was 3,257.33, with a structure mass of 6.14 grams that successfully held all 15,000 grams. Tower masses ranged from 5.47 grams to over 90 grams. Fifteen teams supported the full 15,000 grams, of which 8 qualified for the bonus. Many teams attempted the bonus but did not earn it, as their structures broke before reaching 15,000 grams. One structure (attempting the bonus) unfortunately failed just shy of supporting the full load at 14,980 grams.

Comments/Observations:

I won’t repeat my comments and observations from above (viewtopic.php?p=461815#p461815), as they were written with the Yale Invitational in mind. However, all of the points apply just as much here.

In particular, the note about being prepared for eyebolts and S-hooks that are smaller or larger than your usual setup comes from this tournament. I observed a team accidentally break part of their structure while trying to assemble the Loading Block around it. If I were being strict, this could have been considered an alteration per rule 4.Part I.e. and thus a Competition Violation, but I chose not to push it, as this was a tournament at the invitational level, it was clearly an unfortunate and unintentional outcome, and the team was visibly stressed about it.

tower_2025_c_yale_scores.png

tower_2025_c_yale_setup-1.png

tower_2025_c_yale_setup-2.png

[bernard]

Hi All, Wicklund coach here. Thought I'd share our build scores in case it's helpful for anyone going to nats or just curious

Air Traj: state 6175 (1 inside bucket, 1 bucket rim, 425 mm near, 100 mm far)
MP: our best is 1800 with 90 s target time. At states, couple actions didn't go through so we got ~1450 with 77s target time
Scrambler: states 9.4 m target, 10.4 cm from barrier, 3.56 sec
Heli: we were getting 3:00 in our 19 ft mpr, states was 2:04 (heli hit wall midflight both times)
Tower: our best is 3400 (Jordanso), states was ~3008 i think

If you have any specific questions about them, I'll ask my students to share any knowledge they have!

[bernard]

If you’ve participated in Tower this season, I’d love to gather some data on your experience with the event and your testing setup. I’ll publish a summary of responses toward the end of the season.

https://docs.google.com/forms/d/e/1FAIp ... usp=header

If you want to review a specific tournament, feel free to do so, otherwise, select “Other” and skip to the general event questions.

[ccasediaz]

What were some of the top scores you received in tower this year? Please specify if you are B or C- just curious- thank you!

[HenryD]

Anyone knows the national finals scores?