Towers B/C

[Crtomir]

I know that this is really late in the season but I was wondering whether the bonus was more efficient or the non bonus was more efficient.

Good question. I would like to know the answer myself. In Div-B, our students built towers with the bonus all year and finally got over 3000 points at a few competitions. One team that was consistently beating us all year always went without the bonus.

Personally, I think going for the bonus is safer. If you have a light tower (<5.5g) and your tower breaks early for some unfortuante reason, you still end up with a decent score that doesn't ruin your team score. If you don't have the bonus and your tower breaks early, your Tower score will so much lower and your team score will be ruined, especially at Nationals where there are a lot of other teams to fill in the gap.

If our team was going to Nats, we would be building with the bonus. However, if you are doing well up to this point without the bonus, perhaps you shouldn't change what is working for you.

[TheSquaad]

I know that this is really late in the season but I was wondering whether the bonus was more efficient or the non bonus was more efficient.

Definitely worth it to go for the bonus. Extending the base out is way more efficient then adding enough balsa to hold 5 additional kilos

[MadCow2357]

I am planning to build a tower at nationals. However, there is one big problem. No one on my team will be driving to Colorado, and CA glue is not allowed on Frontier Airlines. I have checked Specialized Balsa, and they do not have the purple bottle medium gap filling CA glue. How do you suppose I solve my glue problem?

[DarthBuilder]

I am planning to build a tower at nationals. However, there is one big problem. No one on my team will be driving to Colorado, and CA glue is not allowed on Frontier Airlines. I have checked Specialized Balsa, and they do not have the purple bottle medium gap filling CA glue. How do you suppose I solve my glue problem?

Ship it to your hotel and call your hotel a few days in advance to save it for you and give your team’s name and coach’s name.

[MadCow2357]

I am planning to build a tower at nationals. However, there is one big problem. No one on my team will be driving to Colorado, and CA glue is not allowed on Frontier Airlines. I have checked Specialized Balsa, and they do not have the purple bottle medium gap filling CA glue. How do you suppose I solve my glue problem?

Ship it to your hotel and call your hotel a few days in advance to save it for you and give your team’s name and coach’s name.

My team is staying in the dorms. Also I don't want to pay shipping for just one bottle of glue.

[Cow481]

You could buy the glue somewhere in denver before going to fort collins

[reed303]

According to https://www.hobbytown.com/search?s=glue ... l=77&lg=fl the Fort Collins store carries this and the other BSI aka Pitsco glues

I would suggest calling them to confirm

[DarthBuilder]

According to https://www.hobbytown.com/search?s=glue ... l=77&lg=fl the Fort Collins store carries this and the other BSI aka Pitsco glues

I would suggest calling them to confirm

That’s what I was looking at too.

[MadCow2357]

I know this is very very very late in the season, but I am going to design a final tower that will hopefully help me break the 2000 score mark. After rereading through Balsa Man's (may he rest in peace) lengthy Euler's critical load formula, I finally understood at least some of the stuff he was talking about. But I do still have some things I have questions about:

For our “design strength” for this analysis, we’ll use 4499gr, which is applying a 10% safety factor to the 4090gr force a base segment leg in B tower meeting the 29cm circle bonus will see at a 15kg tower load.

Does this 4499g only apply to square base towers? I can only build rectangular base towers, since I do not have access to a good jig.

E = the modulus of elasticity (aka Young’s modulus) of column material. This is the inherent stiffness of a piece of wood; it doesn’t depend on, it doesn’t have a relationship to size/cross section. It does have a linear relationship to the density. As discussed in previous posts, as wood density increases, E increases. On average, if you double the density (increase it by a factor 2), E goes up by a factor of about 2.25, but there is significant “variation around the mean”- two sticks, same size and same weight can have significantly different E values, which means significantly different BSs. This is what I was talking about when I noted wood is not a homogeneous material.

Does this mean that if I have a 0.4g 12" 1/8"*1/8" stick, I should get a elasticity of about 0.45g? I am a little confused on whether I need to use certain units (eg pounds per cubic foot, but I don't know how to calculate that) for the equation to work properly.

I = minimum area moment of inertia (sometimes referred to as the 2nd moment of inertia) of the cross section of the column. For a square cross section leg, where the length of the sides are x, I = (x^4)/12. (that’s x to the fourth power, divided by 12

What is the minimum moment of inertia? I am still in middle school, so I apologize for not getting basic physics concepts.
And what are inverse square calculations?

Again, sorry for asking pretty basic questions. I will admit that the tower design I have been using for the last month or two was not formulated from any math.

[TheSquaad]

So my partner and I were planning to build our final tower for nats on Tuesday next week and then take it with us on a plane. However, today we got a note saying the Div B team is driving their builds to nationals and can take some of our stuff, but they are leaving tomorrow.

My question is, if we built our competition tower tonight, would it weaken between now and nationals (a week from today)? We would prefer to not have to take a tower on the plane, so building it farther in advance would be more convenient.