Page 21 of 21

Re: Scores B/C

Posted: May 21st, 2015, 2:18 pm
by someusername
7th place bridge at nationals (Lincoln Southwest High School, NE)

It weighed 5.15 and held 12.65kg for a score of 2456, though our scores were usually around 2600-2700 with the design

IMG_1133 (800x600).jpg

Re: Scores B/C

Posted: May 23rd, 2015, 1:49 pm
by sjwon3789
4th Place National Bridge (post Nationals)- Boca Raton Community HS. The design had a test efficiency of almost 3000, but we scored 2633 at Nationals.
What's your tension? Is that balsa or bass? It looks interesting...

Re: Scores B/C

Posted: May 25th, 2015, 5:24 pm
by PatrickMcPherson
7th place bridge at nationals (Lincoln Southwest High School, NE)

It weighed 5.15 and held 12.65kg for a score of 2456, though our scores were usually around 2600-2700 with the design

IMG_1133 (800x600).jpg
Major kudos, I won my state tournament with a score of 2455.4 (albeit that was the heighest efficiency I've achieved, and it wouldn't have scored that exact number at nationals) It's great to see such beautiful bridges from all of you!

Re: Scores B/C

Posted: May 25th, 2015, 5:28 pm
by PatrickMcPherson
4th Place National Bridge (post Nationals)- Boca Raton Community HS. The design had a test efficiency of almost 3000, but we scored 2633 at Nationals.
Your design is the most similar I've seen to mine. I Would guess it's all balsa, and the range of density in your compression and tension members is really cool to see. However, I have never used those long members to connect the tension and compression members together, and I was wondering how significant of a difference they made. Most importantly congratulations on a fourth place finish, you definitely earned it!

Re: Scores B/C

Posted: May 25th, 2015, 5:39 pm
by PatrickMcPherson
Here are the pictures of my two bridges for the NC state tournament the one pictured on the left would have placed 8th at Nationals with a score of 2455 (6.06g 14.88kg held). The one on the right was constructed before and in what was essentially the exact same manner as the one tested. I used all balsa, the tensile members are 1/64 by a 1/4 inch. The compression members' outside pieces are 3/32 by 3/8 the inner members are 1/8 by 1/8. All of the cross-members are 1/16 by 1/16. They're roughly 15 cm tall, and have an outer edge length of 49 cm, with an inner length of 46 cm. (The horizontal cross members are literally the excess tensile members) If you want to know more just ask, I'll speak on anything I know.

Re: Scores B/C

Posted: May 26th, 2015, 7:38 am
by JonB
4th Place National Bridge (post Nationals)- Boca Raton Community HS. The design had a test efficiency of almost 3000, but we scored 2633 at Nationals.
What's your tension? Is that balsa or bass? It looks interesting...
It is bass and we laser cut it to a specific width (it is dark because of the laser cutting process).

And thanks! The team worked very hard on the design. I am still curious what design places 1-3 were. That is a pretty drastic increase in efficiency up to ~3600.

Re: Scores B/C

Posted: May 26th, 2015, 11:32 am
by someusername
4th Place National Bridge (post Nationals)- Boca Raton Community HS. The design had a test efficiency of almost 3000, but we scored 2633 at Nationals.
What's your tension? Is that balsa or bass? It looks interesting...
It is bass and we laser cut it to a specific width (it is dark because of the laser cutting process).

And thanks! The team worked very hard on the design. I am still curious what design places 1-3 were. That is a pretty drastic increase in efficiency up to ~3600.
I'm going to assume they were something like yours, only maybe they were half the width and had a useless beam running the length of the bridge to satisfy the 5cm width requirement. That way, you would still retain almost all the strength of the bridge at a lighter weight, assuming it is perfectly balanced.

Re: Scores B/C

Posted: May 26th, 2015, 6:45 pm
by retired1
That is what out teams did. 3/32 main members, 5 cm truncated top, 1/32 x 1/8 tension member. 3/32 feet to 2 1/64 outriggers to get the 5 cm, Used 1/2" spacing. Prone to tip over. Gusset plates on top joints of 1/32. Ran out of time to build and test. Under 4 grams. Got above 2500 and with a couple of changes might have gotten to 3,000. At state, a poor glue joint did in the best ones.
I too would like to see the 1-3 bridges. I am still in awe of those scores.