Efficiencies

[lllazar]

Wow, so our latest order of wood came in and i specified for them to select hard wood only - basically all the sheets i've stripped have resulted in sticks that are quite stiff and sooo light...anyway we're planning to build tomorrow and our estimated tower mass is 6 grams with a glue (assuming it accounts for 10% of the weight, which is pretty generous as i use very little glue). If that held all the weight, it's eff would be 37.5. Im expecting it to hold that much as it is the same design as my last few towers, which all held >14.9 kg....anyway, if anyone has been to invitationals or even regionals if any states have already had them, what have the top tower scores been?

[dragonfly]

To any and all tower builders that were at the Conestoga invitationals this past Saturday, I'd like to let everyone know that the event supervisors apparently did not read this year's rules and instead scored without squaring the mass held (if you hadn't noticed already). As I had a bad day, this proved unfairly helpful to my score, but I'm sure proved detrimental to others as well. Hopefully this will never occur again at this or any other invitational, and if you see something of the like and are confused, don't hesitate to ask early on.

Congratulations on your tower sj, but as a reminder: everyone should not get to comfortable with the idea of this score as the highest currently since, due to this error in scoring, results would have turned out differently.

To those of you competing at Athens on Saturday, I'll see you there!

[iYOA]

Congratulations on your tower sj, but as a reminder: everyone should not get to comfortable with the idea of this score as the highest currently since, due to this error in scoring, results would have turned out differently.

To those of you competing at Athens on Saturday, I'll see you there!

Although this may be true, sj's tower would still have the highest ratio since it held all the weight and i can prove it too.

according to the judges, sj's tower would have a ratio of 15/9.7 (notice i will keep mass in kg because it is easier)

now, let us examine another arbitrary tower at the invitationals.
The maximum possible ratio this tower can get with the new system while maintaining the same ratio in the old system is if it holds all the weight. Assume its mass is M grams.
Therefore, its ratio according to the judges is 15/M. however, we know that 15/9.7 is the highest ratio there. So, the arbitrary tower must have a mass greater than 9.7. This means that with the new system, its ratio would be 225/M .however that would still be less than 23.1 because M>9.7 and therefore, would still not have won.


So, it can still be said that a 23.1 is the highest efficiency for that invitationals.
In general, many of the relative rankings will still hold. The lighter tower which fail at light loads are the ones which should have had a considerably lower rank.

[dragonfly]

True, I wasn't trying to take away from his accomplishment, and that tower would have gotten first, but other rankings below (mine included) would have been changed.

[Arthur]

does anyone know the winning efficiency from the conestoga invite?

Yeah, I had a 9.7 gram tower that held all 15 kilos so a 23.1 efficiency.

wow, that's awesome! congrats!

[S4BB]

So, we just tested our first tower and it weighed 8.45 grams and ended up holding 22.3 kg, we need to start cutting down on the weight of the tower. Hard to tell for sure, but it looks like one of the cross braces broke loose. Very good start and we have a few weeks before our first invitational.

[eta150]

Same with us: my first tower ever, at Athens, 8.93 g, held solidly past 15kg (then they stopped us), never cracked. I scanned for places that were overly stressed, found nothing. I guess I over-engineered it.

[Lowell]

Ok we built a tower that weighed 4g that held 10.43kg. I figured out the formula, and based on that we score a 27.196 which I think is good, but I know we can improve. The trick is figuring out how to stay at or VERY close to 4g and pick up another 1kg or so. That would yield 32.66 and should be more than enough to medal at our county event this Saturday. Thing is, I did not see it break when we tested this build. However, I can say the legs did not break. I wonder if I put a SMALL drop of glue where the trusses meet if that would help.

[DanielleS]

I'm new to building towers, so whats a good weight for the tower to be?

[lllazar]

Well as light as possible

Lol but in all seriousness, you want the tower to hold at least near max load (14+ kg) and yet weigh as little as possible. Most COMPETITIVE regional tournaments the top scores i'd expect to see would be in the 20 mil range, which would require around a 10g tower that held all the weight. I think you should aim for 15g or less seeing as it's your first time building balsa structures, and also make sure you have a gram scale handy so that you can pick sticks that aren't too heavy (if your going to buy at a hobby store and such). You can also order online, and that would probably be best because you can get it cheaper if you buy in bulk.