Elevated Bridge B/C

Re: Elevated Bridge 2009

Postby Pleiades on Thu Jul 24, 2008 6:16 pm

Elmer's school glue. only because at the time that i built it i didn't have any superglue. now that i have superglue i know that it wouldn't have worked anyway because the glue doesn't want to stick to the chopsticks for some reason...
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Re: Elevated Bridge 2009

Postby carneyf1d on Thu Jul 24, 2008 7:22 pm

hmm balsa wood is probably a lot more porous than chopstick...
when you use superglue buy some small glue tips: http://www.hobbylinc.com/gr/adc/adc121.jpg
something like those will work, saves a ton of glue weight and allows you to put the glue exactly where you want and only where you want.
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Re: Elevated Bridge 2009

Postby Aia on Thu Jul 24, 2008 7:35 pm

Pleiades wrote:now that i have superglue i know that it wouldn't have worked anyway because the glue doesn't want to stick to the chopsticks for some reason...


There's a similar problem with bass. I've found that balsa + balsa + CA glue provides for a pretty strong connection point.

Was this bridge made to the specs of a B or C division bridge?

Btw: By your definition of an A frame bridge, I did not build one. I may have to try building one of those soon... just to see its capabilities.
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Re: Elevated Bridge 2009

Postby Pleiades on Thu Jul 24, 2008 8:04 pm

This was my div B bridge. i'll test my div C one later once it stops raining here. it's been raining all week :( My div C one is just like the B one only it doesnt have the triangle thing on top. basically its like the one they show in the draft rules.
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Re: Elevated Bridge 2009

Postby andrewwski on Thu Jul 24, 2008 10:13 pm

Elmer's glue should be just fine for that bridge. I too have found thin CA doesn't work great for bass like it does balsa (but it still will work).

Obviously that design wasn't anything serious...but that form of lateral bracing isn't very effective. Try X's next time.

That type of bridge is interesting...I don't think it'll work out too well for C...but still interesting. I'm also thinking one overlooked design might be just raising a traditional bridge with pillars...supposing you build them like a small tower, I'd think they could stay light enough while still supporting the bridge. From there, it would be traditional bridge design, which I am a lot more comfortable with over anything else.

Also...just a tip...chain works much better than rope for hanging the bucket...I used string/rope for most of last year for Boomilever, once I tried a chain it made the bucket a lot less likely to spin and wobble.
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Re: Elevated Bridge 2009

Postby Aia on Fri Jul 25, 2008 4:45 pm

andrewwski wrote:
Obviously that design wasn't anything serious...but that form of lateral bracing isn't very effective. Try X's next time.


I think the toothpicks' length and rigidity provided some limitations there. ;)
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Re: Elevated Bridge 2009

Postby dudeincolorado on Mon Jul 28, 2008 11:14 pm

no invataionals here cept for one in C ummm regionals early march states late april
SO stressed!
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Re: Elevated Bridge 2009

Postby Earthsci_dude on Tue Jul 29, 2008 1:17 am

Aia wrote:I've thought about arching balsa... but it seems very difficult. To get a perfect arch, the balsa would have to be the same density throughout the stick, then multiply that by two for each side. When a friend of mine was competing in gliders, she told me that she baked the balsa somehow to get the arches.

What advantage would an arch give anyways? Would you be gaining strength or losing mass by using them?

Besides the A frame, I've also built a bridge that looks similar to the example on the rulesheet. However, I changed up the crossbeams and main supports to what I thought would be more efficient.



i tried to and arch design for bridges my first year in sci-o (even tried to bend bass) and it worked.. but it was way too much work. we spent like the first 2 months of the season trying to create a way that worked, we ended up with this complex bending devise, but i wouldn't ever try doing that again. (even tho an arch design would make alot of sense for E-bridge this year)

also, if anyone is interested, i got the efficiencies for e-bridge in IL this year (it was a trial event at state)
only like 10 teams ended up entering a bridge.. and alot of them seemed to be put together at the last minute, but the winning score was only about 800-ish (also with diff. rules than these draft rules)
[MCC SO - '04, '05, '06] [NN SO - '07, '08, '09, '10]

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Re: Elevated Bridge 2009

Postby Pleiades on Tue Jul 29, 2008 12:38 pm

The top score was only 800?? thats good!! i was scared after seeing the top boomilever and tower scores and wondering how i'm going to be able to do that with an elevated bridge. I knew they would be lower than the boomilever and tower scores but i didnt know it would be THAT much lower. 800 seems very do-able.
What were some of the other top scores?
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Re: Elevated Bridge 2009

Postby Earthsci_dude on Tue Jul 29, 2008 6:43 pm

Pleiades wrote:The top score was only 800?? thats good!! i was scared after seeing the top boomilever and tower scores and wondering how i'm going to be able to do that with an elevated bridge. I knew they would be lower than the boomilever and tower scores but i didnt know it would be THAT much lower. 800 seems very do-able.
What were some of the other top scores?



im pretty sure it will get much higher than that tho... it was only a trial event... so it didn't count. i'd guess that top scores will beat out boomi scores, but maybe not top tower scores? we'll see i guess.
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Re: Elevated Bridge 2009

Postby Aia on Wed Jul 30, 2008 12:13 am

After testing 3 bridges yesterday, I would agree that bridge efficiencies may be higher than boomilever scores.
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Re: Elevated Bridge 2009

Postby Pleiades on Wed Jul 30, 2008 3:20 pm

How much did yours hold? How much did it weigh?
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Re: Elevated Bridge 2009

Postby Aia on Thu Jul 31, 2008 11:59 pm

Sorry, but I can't post my masses/weight held/efficiencies here. I wish I could, but this event is awfully competitive in my state.

I can say that we've all identified the problem: the distal ends sliding out and away from each other. I tested one bridge that must have deflected 8cm downwards before breaking, in addition to each end sliding 4cm out away from each other. It was really quite the spectacle.
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Re: Elevated Bridge 2009

Postby Pleiades on Fri Aug 01, 2008 12:22 pm

That's fine, i understand. I have a feeling this event is also going to be really competitive in my state since the team from my state got 4th place in towers at nats so obviously they know their balsa
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Re: Elevated Bridge 2009

Postby spalding458 on Wed Aug 06, 2008 11:00 pm

Example bridges from Science Olympiad Camp:

http://i168.photobucket.com/albums/u165 ... 2_1815.jpg

This was my bridge. I used a combination of end and notched joints and for glue I used a medium CA.
http://i168.photobucket.com/albums/u165 ... 0_4265.jpg

This bridge was another design from my team.
http://i168.photobucket.com/albums/u165 ... 0_4266.jpg

I believe this bridge was one of the top three at camp:
http://i168.photobucket.com/albums/u165 ... 0_4292.jpg

This design would've done well, but the bridge was too long and I think they used hot glue:
http://i168.photobucket.com/albums/u165 ... 4_2758.jpg
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