Elevated Bridge B/C

[smartkid222]

who was the winner?

[frontlineballer1]

The person that won PM'ed me and personally i dont want to release their name because i don't want any of the information to get out. I will let you guys all know later on in the year once more people hve competed.

[smartkid222]

oh ok, it wasnt' me then, i thougth i was pretty close

[Arthur]

we had regionals today and our bridge did horrible!!! i'm not even sure why.

[Thequestionmark]

Peter's 2006 bridge has been the highlight to-date; won State with a 2485, which best I could tell would have medaled at Nats (the Team missed making Nats). What he learned from it was a good head start this year. I'll try to get a picture up, oh, a little before State; there are some interesting things to share about it. More than glad to share;believe that....part of what Science-O and this board is all about. Doing it in a way and at a time that doesn't help the competition too much, is, of course understandable. I think State is going to be quite competitive- hope to hear some numbers from Southern Colorado Regionals- that would make it more fun for all of us in the run up to State...

Yea, Poudre is one giant powerhouse (hard to compete from a school of sub-500). Things always get quite a bit more heated at State, but the Northern Region is still the dominant force in Colorado.

When we started the bridge, we discarded the A-frame because we assumed that it would be too wide (and slightly too short). You're sons bridge proved otherwise, though I'm not sure if I'm a skilled enough craftsman to construct a bridge of that caliber(let alone design a bridge like that).

For State, our current goal is to break 800. Our current game plan probably involves constructing 2 more bridges per team, an A-frame/Arch/or standard. At regionals, 4 problems on our bridge quickly became apparent:

1. Truss Design (Too Many and too thick)
2. Glue (We were using the recommended "Weldbond" but it didn't seem to hold too well.)
3. Wood Quality - Our B team bought wood from a specialty shop, it was much stronger and consistent than the balsa from the hobby store. One of our longer pieces was slightly bent, causing a slight difference between both sides. When it hit 14kg, that flaw became apparent in a pretty loud crack.
4. Height, we tried to minimize the overall height in order to reduce weight, but that seems like a silly idea come to think of it.

Someone here mentioned baking the wood and stressing it in the opposite direction, two things we might try. Our coach also recommended using some sort of steamer to bend the archs, we should be doing better by the time we get there.

[frontlineballer1]

Yeah with the weight held smart kid you were close the only thing was you never guessed a mass for the bridge. But the closest person who posted in this forum was jazzy.

[Balsa Man]

3. Wood Quality - Our B team bought wood from a specialty shop, it was much stronger and consistent than the balsa from the hobby store. One of our longer pieces was slightly bent, causing a slight difference between both sides. When it hit 14kg, that flaw became apparent in a pretty loud crack.

Thanks, and good luck, Thequestionmark; hope you can get to that 800, and even a little more.

As to wood, for what its worth, getting THE right pieces is absolutely critical; they have to be straight, they have to have the right grain, and you have to know what each piece weighs (and what load pieces at various weights will carry. By specialty shop, I'm guessing you're talking Specialized Balsa. That is the place to get your wood. Its really cool that its right here in Loveland. Figure out the density you need in various places (as in 1/8th at 0.9 gr/36", or 1.0, or 1.1, or....whatever) Even then, as I've said in earlier, if you take a good looking stick, at the density you're looking for, and cut a number of pieces out of it, and weigh them accurately (to a thousandth), you are going to see....20% or so variation; the lower the density, generally the greater variability. So, you end up buying a lot more sticks than you think you need, cutting a lot of pieces, and building with a select few.

Cheers.
N. Colo rocks
Len Joeris
Fort Collins, CO

[gyourkoshaven]

My team's bridge had an efficency of 338 I think, and we got 8th at a pretty tough competition. Also, what have peoples top efficiencies been?

[croman74]

My top has been around 615.
I haven't had regionals yet though.

[Arthur]

My team's bridge had an efficency of 338 I think, and we got 8th at a pretty tough competition. Also, what have peoples top efficiencies been?

308 actually and we got 8th. most of the bridges got 2nd tiered so that's why we did so "well".