Efficiencies

[icyfire]

to a point your logic is true, but one has to remember that as the chimney gets smaller, it weighs less and it becomes stronger with the shorter cross section pieces. My idea is to have it slant from a 3" X 3" opening at the top of the chimney to a 5 x 5 one at the 15inch mark. I t makes my tower more balanced and it cuts weight while only making a 1.6˚ slant which is nothing compared to the 28˚ slant for the lower leg.

remember that the rules say that the chain can be as wide as 3cm in diameter but only the competition director will know the width of the chains, so shoot her/him an email.

Oh I can see your logic. I think I will also try something like this, as I haven't actually tried using a non-rectangular prism top tower. Thanks for the feedback.

[smartkid222]

to a point your logic is true, but one has to remember that as the chimney gets smaller, it weighs less and it becomes stronger with the shorter cross section pieces. My idea is to have it slant from a 3" X 3" opening at the top of the chimney to a 5 x 5 one at the 15inch mark. I t makes my tower more balanced and it cuts weight while only making a 1.6˚ slant which is nothing compared to the 28˚ slant for the lower leg.

remember that the rules say that the chain can be as wide as 3cm in diameter but only the competition director will know the width of the chains, so shoot her/him an email.

just remember everything is in cm not in inches.

[dholdgreve]

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

Baking a tower (or any balsa structure) will drive off the weight of the moisture, but the results will be temporary at best. It will reacclimate to ambient humidity within an hour or 2. In addition, if you are using cyanacrylate glues, it will make them much more brittle... Not worth the risk if you ask me

10 or so years ago, My oldest son competed in the Ohio state tournament in bridges... Both his bridge and one from a neighboring town carried the full load and weighed EXACTLY the same to the 1/100 of a gram. In an attempt to break all ties per the rules, both bridges were reweighed after the competition. His competitor's bridge had gained .03 grams from the initial weigh-in. In talking to them after the competition they admitted taking a blow dryer to it that morning, then wrapping it in a LDPE sleeve from the newspaper to keep the humidity out, nut they had no way to protect it after initial impound.

[TYG]

Not sure if this is the right place to post this, but can't find anywhere else better..
Does anyone know how reloading a tower will effect its efficiency/score?

[SLM]

Not sure if this is the right place to post this, but can't find anywhere else better..
Does anyone know how reloading a tower will effect its efficiency/score?

Generally, cyclic loading (repeated loading and unloading) of wood,
or any other structural material, alters its internal structure and
reduces its strength. However, depending on the magnitude of the
load and the size of the members, the strength reduction may not be that significant.

Last year, we tested some of our competition bridges by loading them around 100 cycles
(we have a testing machine that makes this very easy. Each loading cycle took about 10 seconds).
For those bridges, obviously, strength reduction due to the repeated loading was not significant.
But, the testing also confirmed that more had to be done to reduce the weight of the bridge.

If the design and construction of a tower is close to optimal, then repeated loading could
lead to unexpected failure. On the other hand, if a tower can withstand cyclic loading, then
you know, with a high degree of confidence, how your not-so-optimum structure is going
to perform in the next tournament.

[Arthur]

can anyone give a wild guess at what efficiencies will medal at PA's southeastern regional competition this monday? i'm trying to figure out where i'll place.

[AlphaTauri]

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.

[phillies413]

Has anyone in Division C gotten a score above 30 yet?

[TYG]

Not sure if this is the right place to post this, but can't find anywhere else better..
Does anyone know how reloading a tower will effect its efficiency/score?

Generally, cyclic loading (repeated loading and unloading) of wood,
or any other structural material, alters its internal structure and
reduces its strength. However, depending on the magnitude of the
load and the size of the members, the strength reduction may not be that significant.

Last year, we tested some of our competition bridges by loading them around 100 cycles
(we have a testing machine that makes this very easy. Each loading cycle took about 10 seconds).
For those bridges, obviously, strength reduction due to the repeated loading was not significant.
But, the testing also confirmed that more had to be done to reduce the weight of the bridge.

If the design and construction of a tower is close to optimal, then repeated loading could
lead to unexpected failure. On the other hand, if a tower can withstand cyclic loading, then
you know, with a high degree of confidence, how your not-so-optimum structure is going
to perform in the next tournament.

Okay, so worst comes to worst, I'll use my old tower as backup. Thanks again for your help

[eta150]

Has anyone in Division C gotten a score above 30 yet?

I've only come close, but I think I've seen it done.