National Tower Scores?

[Balsa Man]

I'm still curious as to why none of the towers were able to get 3800 or better at Nationals? Were the teams just "playing it safe"? Did they not want to risk too much with the team score on the line? Or was there systematic testing errors? Was the humidity too high? Any opinions? I was hoping to see a team break 4000. Maybe all the teams used up their best wood during the season and at States. Some states are really competitive to get to Nationals.

The top score in C division was 3280. I know we were by no means playing it safe but I can't speak for others. The humidity did affect it somewhat: we massed our tower before we left and when we were in the dorms the night before and it was 4.49 grams, however when they massed it when we checked in, it had gained weight and was up to 4.57. I don't know if it affected other towers this much though

A lot of factors at play, so likely no single answer/factor. That weight increase from ambient humidity is 1.78%. That's not very much. I've not seen/found any real data on balsa, in terms of modulus of elasticity vs moisture content. Data from other wood at.....lumber dimensions does suggest that if....wet enough, there's some loss in stiffness/MOE. My guess is a 1-2% change isn't gonna be.....material- as in enough to make a measurable difference in outcome. You'd think the most likely 'systematic testing error' would be if test surfaces weren't perfectly level. Not being there to know, I'd bet a) they were very carefully leveled at the start, and b) there were periodic checks. With the test rigs on a hard surface, I wouldn't expect material variation. Having 'used up best wood', taken in conjunction with the interesting, and always in play, variation of properties between two pieces that as far as you can measure are 'the same', can and does have a material impact on outcome. And the closer to the limits you're playing, the more likely you are to run into an unsuspected/undetected variation the wrong way. And even with serious program/attempt to get to really special/high performance wood, there are limits- time sorting through, measuring, assessing, and the cost of a lot of good sticks to sort through to find the best. Bottom line? Over the years, I've seen both years like this, when expectations from prior results just..... aren't quite met, and years when expectations for Nationals are exceeded (and not coming from some neat, new/creative design/engineering approach). When you get into the upper end of competitive level, its very small differences, intentional and unintentional, that decide the outcome.

[a boy]

The humidity affected us too, increased mass from 6.17g to 6.24g

[dholdgreve]

This, being the first year for towers,I think maybe most took a "Play it Safe" approach, This, coupled with substantially higher humidity than found in many parts of the country, which raised the mass of the towers, thus lowering the scores even when carrying the same loads all contributed. I watched carefully from 9:00 AM until almost noon, and only saw one table adjustment during this time. The actual top was slid an inch or 2 toward the C testing by the E/C. I don't know the logic, and I doubt it had any affect on the later tests, but it was curious. As far as I could tell, the table top was not rechecked for level at that point or any other while I was there. I'm not positive, but I think the testing apparatus was sitting on a short level loop carpet. Again, not ideal, but probably not significant.

From what I could tell, all of the E/Cs and assistants did a truly remarkable job, taking the time to talk to the competitors... and not just small talk... after testing, they spent considerable time discussing potential design improvements with each team. While I certainly understand that allowing carrying cases near the testing opens up potential opportunities to weigh one tower and test another, I think this could be overcome with a box check when entering the immediate area, and allowing only 1 tower in 1 box. I can't imagine any other reason for not allowing boxes in the testing area. I know of at least 3 teams that were forced to test already broken towers. Did it happen because the towers were out of the box? I don't know... maybe they were broken in transit... I just think it wrong to make the kids take the towers out of the box, then walk down a flight of dimly lit stairs, through the crowd of other coaches and spectators as well as their competition without ant protection for their towers..

[Crtomir]

While I certainly understand that allowing carrying cases near the testing opens up potential opportunities to weigh one tower and test another, I think this could be overcome with a box check when entering the immediate area, and allowing only 1 tower in 1 box. I can't imagine any other reason for not allowing boxes in the testing area. I know of at least 3 teams that were forced to test already broken towers. Did it happen because the towers were out of the box? I don't know... maybe they were broken in transit... I just think it wrong to make the kids take the towers out of the box, then walk down a flight of dimly lit stairs, through the crowd of other coaches and spectators as well as their competition without ant protection for their towers..

I agree. They should have let the students keep their towers in boxes. Was the check-in/weighing done far away from the testing? It's usually best if they check-in and weigh the towers right next to the testing stations.

[dholdgreve]

It was a little strange... the venue was sloped seat lecture hall that probably could seat 100 to 150 people. It had 2 doors plainly marked (1 for C Div, 1 for B Div). It appeared that there was a check-in, check out table at the top of the stairs, just inside the door for each division. Kids would come in and check in at the top table, then sit down until called to the "stage" area. No boxes were allowed in the stage area,so the kids had to take the towers out of their protective boxes at their seats and carry them down to the stage area, where it was weighed, checked in, then tested. Of course there were parents and coaches standing on the steps, trying to take pics of the teams currently testing, because they cordoned off the bottom 4 or 5 rows of seating... They had the lights turned down pretty low, so the live video feeds of the towers being tested would be more visible...

like I said, the E/Cs did a great job! I totally understand why each of the issues were resolved in the manner that they were... nevertheless, I think the resolutions to one set of problems very well may have created a new set of issues that was not resolved.

One solution might be to use those first 4 or 5 rows as a staging area for the 2 or 3 teams in the process of checking in or testing. Someplace away from the general public, coaches, photographers, and all but a couple of other teams to place the boxes. Just a thought

[Balsa Man]

Another interesting issue came up in the towers competition at Nationals.

The issue relates to the rule “constructed of wood and bonded by adhesive. No other materials are allowed.” The B division team I’ve worked with this year were advised during check-in that the markings on their tower (done with felt-tip markers/highlighters) were….a problem; that they could be DQ’d- that by the rules, there could/should be no marks on the tower. The decision was made, very appropriately IMHO, not to DQ them, with a….warning not to do it next year… But a couple hours later, the C team I’ve been working with checked in with similar markings, and not a word was said about them….

I totally understand and support the intent to limit “materials” in the structure to wood and glue, and to prohibit anything that increases strength/performance beyond what can had using only wood and adhesive. And I understand the importance, particularly at the Nationals level, of requiring full compliance with the rules. The use of marks (done with pencil or felt tip markers), however, in no way increases strength/performance, and marks are not “materials” of construction.

What I hope can be done is getting language in the rules for next year (and subsequent years) that clearly allows for marking done in a way that ….gains no advantage in terms of structure performance. Just a simple statement that marks to guide/facilitate construction are not considered “materials”; just like the statement that bamboo is not considered wood.
I cannot imagine any scenario/way that pencil or marker marks could provide any structural/performance advantage. Can anyone else? I also find it hard to believe it was an intention of the rules writers to make the kids build without any marking- as an….added but not explicitly stated challenge. I’m hoping/guessing it was just an oversight; an unintended potential interpretation issue that didn’t get thought of. It’s just something you would probably not think of if you hadn’t spent hours and hours deep into the process of building a high-performance structure……

One of the important things we as coaches teach, of course, is the importance of precision. Part of precision is precisely aligned…parts. Precise marking is how you get precise alignment. It’s a normal, standard tool for anyone doing….fabrication; carpenters, engineers… There’s also a second important use of markings. We’ve gotten into some good discussion this year about the inherent variability in wood/balsa; how some pieces are better than others in structural efficiency; and discussed how to sort through, and measure, to the extent you can, to get the “best” wood to go into that competition tower. Little ‘color-coding’ marks are critical to that process.

So, I’d like to think …we’re all on the same page here; marking is not a way to any unfair advantage; it’s just that as the rule is written, a well totally well meaning judge could understandably interpret it in an unintended (and inappropriate) way. Having done my share of supervising events, I understand the challenges of getting everything right, fairly, for all competitors. It sounds like the crew running towers did a really good job meeting those challenges, and we all appreciate and respect that!

[cheese]

I know of at least 3 teams that were forced to test already broken towers. Did it happen because the towers were out of the box? I don't know... maybe they were broken in transit... I just think it wrong to make the kids take the towers out of the box, then walk down a flight of dimly lit stairs, through the crowd of other coaches and spectators as well as their competition without ant protection for their towers..

Yeah, My tower was around 6 grams, but after we checked in, one of the x braces came loose which cost us to break at 10.5 kg. It would of held max tho..

[cheese]

I know of at least 3 teams that were forced to test already broken towers. Did it happen because the towers were out of the box? I don't know... maybe they were broken in transit... I just think it wrong to make the kids take the towers out of the box, then walk down a flight of dimly lit stairs, through the crowd of other coaches and spectators as well as their competition without ant protection for their towers..

Yeah, My tower was around 6 grams, but after we checked in, one of the x braces came loose which cost us to break at 10.5 kg. It would of held max tho..

If we were to have boxes, it probably wouldn't have broken. It was very scary walking down the stairs in the crowded auditorium.

[Crtomir]

No markings sounds a bit extreme. No tape or sticky labels seems reasonable, but no markings? How do the kids build it without marking on it? We never had any problem with pen/pencil marks on our towers. The kids even wrote their team name/number on their towers. Sometimes they even wrote the name of their tower on their tower. (They gave each of their towers a unique funny name.)

Glad your kids didn't get DQ'd, but the fact that it was brought up seems strange.

[Random Human]

No markings sounds a bit extreme. No tape or sticky labels seems reasonable, but no markings? How do the kids build it without marking on it? We never had any problem with pen/pencil marks on our towers. The kids even wrote their team name/number on their towers. Sometimes they even wrote the name of their tower on their tower. (They gave each of their towers a unique funny name.)

Glad your kids didn't get DQ'd, but the fact that it was brought up seems strange.

Lead or ink from your pen/pencil does add a bit of weight onto yoru tower.... just a piece of advice