Efficiencies

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Arthur
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Re: Efficiencies

Postby Arthur » February 27th, 2011, 3:18 pm

I'd say upper -teens and low twenties (with a few scores beyond that, from schools who are really good with building events).

A score of 22.5 would mean that you had a 10g tower that held all the weight, and I'm thinking most "good" towers at the Regional level (even for overly competitive SE PA) are going to be a little more than 10g.
thanks!
Has anyone in Division C gotten a score above 30 yet?
I've only come close, but I think I've seen it done.
close to 30? wow that's amazing. :o

_HenryHscioly_
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Re: Efficiencies

Postby _HenryHscioly_ » March 4th, 2011, 8:14 pm

I am so disappointed.
I had a tower weighing 8.24g, held 17.1kg
Then, I build two more identical towers, using slightly less dense wood.
Ended up at 7.39g and 7.18g.
I turned up my heater to about 80-85degrees for 2 hrs or so.
They lsot about .03g.
Then I put them into a sealed plastic box with dessicants.
At competition, I used the heaver tower, which i built a bit more carefully,
It weight 7.09g....but broke at 8kg.
I don't know why, I may have used too little glue, or the reduced moisture weakend it substantially.
My other tower is 6.78g right now. I will test it at my school this week to see if my regional competition tower failed "accidentally" or because my glueing or the moisture reduction was the factor leading to failure.

Practically, I had a tower with efficiency of 27, then, I expected a 32 or so at regionals, but got a score of 8.
Still placed and got medal(dont know how that happened) but really, I am realllllly disappointed.

Also...my team didn't make it into state even though..

If anyone has any other advice for me, that would be nice.
Thanks!


------------
regionals 2011:
1st helicopter
6th dynamic planet
6th towers
9th anatomy

there is alwyas next year since i'm just a freshman..but.so sad.

dragonfly
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Re: Efficiencies

Postby dragonfly » March 5th, 2011, 6:35 am

I am so disappointed.
I had a tower weighing 8.24g, held 17.1kg
Then, I build two more identical towers, using slightly less dense wood.
Ended up at 7.39g and 7.18g.
I turned up my heater to about 80-85degrees for 2 hrs or so.
They lsot about .03g.
Then I put them into a sealed plastic box with dessicants.
At competition, I used the heaver tower, which i built a bit more carefully,
It weight 7.09g....but broke at 8kg.
I don't know why, I may have used too little glue, or the reduced moisture weakend it substantially.
My other tower is 6.78g right now. I will test it at my school this week to see if my regional competition tower failed "accidentally" or because my glueing or the moisture reduction was the factor leading to failure.

Practically, I had a tower with efficiency of 27, then, I expected a 32 or so at regionals, but got a score of 8.
Still placed and got medal(dont know how that happened) but really, I am realllllly disappointed.

Also...my team didn't make it into state even though..

If anyone has any other advice for me, that would be nice.
Thanks!

there is alwyas next year since i'm just a freshman..but.so sad.
Well, before anything else: I'm very sorry to hear this, but congratulations; know that you must be doing something right to be expecting these successful scores. On the other hand, I know all too what your situation feels like; sadly enough, a nearly identical thing happened to me at our Regionals...But luckily there is a way to (mostly) prevent this from happening again for both you, myself, and anyone else who's suffered the same affliction:
1. Look at the surprise that was your early breaking tower - Where did it fail, and why? Sometimes it's poorly constructed joints, in others (like my own) it's a case of bad wood (usually determined by the break being in an isolated area). Either way, the only way you can know what to look out for is to realize what went wrong in the first place.
2. Prepare carefully - Personally, the preparation for building a tower can take at least as much time, if not longer, than the actual construction of the tower itself. Organizing and assigning appropriate densities to appropriate places in your tower and weeding out the wood that is not up to par is crucial, as I feel I reiterate all the time... but only because it's true. If you're putting excess strength where it isn't needed and too little where it is, another chance for disaster can arise. I know I was definitely not nearly careful enough, and that was my ruin I think.
3. Construct at your own pace - Whether you're quick or need a little time to make things perfect, do whatever you've got and leave spare pieces in case something doesn't fit just right.
4. Check for breaks in transit & NEVER let anyone else handle your structure - This is pretty self-explanatory in reason. I also don't think that your moisture reduction (if only .03) would've made that big of a difference strength-wise, especially because that could have been gained back by simple exposure post-drying.

I know plenty of other use strength testers and other machinery to ensure wood is sufficiently strong but if you've got a good eye for what's good vs. what's bad after a while you shouldn't make as many/if any mistakes. I'm interested to see how your other tower fairs, and know that stuff like this happens. Everyone had better watch out for you next year, though! Until then practice your technique. You'll get there.
``````( ) ( ) /
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PA 2009, 1st Bridges : 2010, 1st Bridges, 1st WM : 2011, 1st ED, 3rd Towers, 4th Heli
Nats Augusta 2009, 4th Bridges : Illinois 2010, 3rd Bridges, 9th ED : Wisconsin 2011, 3rd Heli, 5th Towers : Orlando 2012, 2nd ED, 5th Towers
Event Supervisor Balsa, ED

old
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Re: Efficiencies

Postby old » March 8th, 2011, 12:40 pm

Has anyone tried baking their towers at low temp., around 150degrees, and have their efficiencies go up?
maybe building two identical towers, and baking one and not the other to see if strength is significantly reduced?
The coaches at my school told me to bake my next tower, but I can see why some of my old friends say taht it will make it more brittle, actually making it less efficent
does anyone have data/results from an actual test/experiment?
thankss
Yes, and the answer is you better be sure you use adhesives that don't melt at those temperatures. Many people are unaware that most commonly used glues, including cyanoacrilate, epoxy, Sigment/Android, and many others, significantly soften at only 40 - 50 Celcius. If you know that your glue can take the heat, and you know that the less flexible dry wood won't be a problem, then you will lose some weight. As others have said though, the weight loss is very short lived. We have actually watched the weight come back while sitting the structure on a 0.01 gram scale. You can see the 0.01 grams ticking off like seconds on a clock as the moisture from the air goes back into the structure.

_HenryHscioly_
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Re: Efficiencies

Postby _HenryHscioly_ » March 8th, 2011, 5:59 pm

Well, I tested my back-up tower, which is the same as my reg. comp. tower, but a bit lighter
It was 7.18g when i finished building, after heater, it was 7.15g, after leaving it in box with dessicants for 4-5 days, it became 6.70g.
I tested it, and it only held 7.55kg....
I'm guessing the moisture loss weakend my glue or wood? but it didn't fail in the wood...
I didn't put it in much heat, so, just the dessicants, so melting glue shouldn't have been the problem
I am not sure..and I don't really feel like building a lot more towers to test this out..
maybe next year..got to focus on my grades now..they're suffering a lot..Dx
If anyone actually tests the difference in strenght for lose moisture or not, or soemthing simialr, sharing some data would be really nice!
Thanks!!

hogger
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Re: Efficiencies

Postby hogger » March 8th, 2011, 8:09 pm

Well, I tested my back-up tower, which is the same as my reg. comp. tower, but a bit lighter
It was 7.18g when i finished building, after heater, it was 7.15g, after leaving it in box with dessicants for 4-5 days, it became 6.70g.
I tested it, and it only held 7.55kg....
I'm guessing the moisture loss weakend my glue or wood? but it didn't fail in the wood...
I didn't put it in much heat, so, just the dessicants, so melting glue shouldn't have been the problem
I am not sure..and I don't really feel like building a lot more towers to test this out..
maybe next year..got to focus on my grades now..they're suffering a lot..Dx
If anyone actually tests the difference in strenght for lose moisture or not, or soemthing simialr, sharing some data would be really nice!
Thanks!!
You might be barking up the wrong tree worrying about moisture loss. It is true that moisture loss makes the tower lighter through special process like baking, but the structure quickly gains the weight and moisture back when the structure is put back in a normal room setting. The point of reducing weight is to quickly weigh the tower during impound and then let it sit for a short while, let it gain back the moisture and then test or compete. Unless you test right away after you take it out of the box, I doubt that the moisture loss is your problem.

What you really need to focus more on is WHERE the first failure occurs in your structure. When you went lighter from 8+ grams to 7 or less grams, which piece in the structure broke first and how much that piece went lighter from the 8+ grams structure. Beef up that piece or section of that piece to get rid of the weak point in the structure while the rest of the structure should stay as light as before. Some people use a video camera to record and play back in slow motion to pinpoint where the problem is. If there is not enough time, go with same wood density as the 8+ grams structure and be done with it. That is a score of almost 30 and very good for division C.

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lucwilder42
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Re: Efficiencies

Postby lucwilder42 » March 12th, 2011, 7:03 pm

so whats the highest score anyone's gotten so far?
I'm just here to build bridges

S4BB
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Re: Efficiencies

Postby S4BB » March 13th, 2011, 10:11 am

I coach a Division B and C team, and yesterday at our Regional, the B team won with a score of 30.9 and the C team won with a score of 29.6. B team moves onto states and the C team di not make it.

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hpfananu
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Re: Efficiencies

Postby hpfananu » March 14th, 2011, 1:51 pm

Hey, does anyone know if old efficiencies from Nationals are in the test packet? Our coach has then but before we try to dig them up, does anyone know if they even have old efficiencies? Thanks a bunch!
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Re: Efficiencies

Postby Flavorflav » March 14th, 2011, 5:10 pm

Yes, last year's efficiencies are in the test packet. Pictures, too.


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