Good efficiency?

9Fire
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Re: Good efficiency?

Postby 9Fire » March 27th, 2015, 5:04 am

This is my schools first year in the SO and my bridges keep maxin out at about 1000 efficiency in the division B 2015 rules. Could somebody please give me some tips to raise the efficiency. Your help is greatly appreciated thanks

nxtscholar
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Re: Good efficiency?

Postby nxtscholar » March 27th, 2015, 5:50 am

1. Is there any way you can reduce the weight of your structure without compromising the structural integrity? There are several ways to explore this:
a. Last year and this year, teams used 1/4 in by 1/4 in balsa sticks excessively for their structures. Can you use pieces with smaller (and lighter) dimensions?
b. As a followup, can you use pieces with smaller densities? Even if pieces have the same dimensions, they will have different weight possibly.
c. Consider also sanding a structure carefully or air drying the structure to knock off weight due to moisture.
d. Bracing. Will a Z-bracing work over an X-bracing? (you can possibly remove some pieces from the design and thus weight)
e. Glue. This is one of the biggest source of unnecessary weight. You don't need to apply a lot.

2. The way you load.
a. Some teams have the sand hit their hands first to reduce the force of the sand upon impact with the bucket. They usually increase their score by a couple ten's of a point.
b. It doesn't matter if the sand is level within the bucket. But do not load in such a way as to make the bucket sway. This introduces different directional forces to the bridge.
c. Consider placing the loading block in different locations.

3. Design Changes
a. Have you tried using gussets? Don't underestimate the value of them in certain locations.


If I think of something more, I'll tell you. This all said, the biggest help you can do for yourself is research. That's how the best teams did it. That's how we did it.

sr243
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Re: Good efficiency?

Postby sr243 » March 27th, 2015, 7:55 am

9Fire wrote:This is my schools first year in the SO and my bridges keep maxin out at about 1000 efficiency in the division B 2015 rules. Could somebody please give me some tips to raise the efficiency. Your help is greatly appreciated thanks


If you could give some specific information about your bridges, we could help out more. What basic design and wood dimensions are you using? What mass is the bridge and what weight does it hold? I think selecting good light wood could help. Measure the masses of each stick before you use them and make sure they are approximately the same.

9Fire
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Re: Good efficiency?

Postby 9Fire » March 27th, 2015, 2:25 pm

The wood is usually 1/8" or 1/16", usually the bridges are arch bridges with a warren truss and x bracing on top, which we migh change to z bracing to help save weight. We also load on the top usually.

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Re: Good efficiency?

Postby 9Fire » March 27th, 2015, 2:26 pm

I never thought of weighing each piece, good idea thanks

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aditi
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Re: Good efficiency?

Postby aditi » March 28th, 2015, 2:29 pm

Wow, those are some REALLY good efficiencies! Our bridge snagged first at Regionals, but that's not impressive feat.
It's been scientifically proven that people who have more birthdays live longer... ;)
Scientists say that the world is made of protons, neutrons and electrons. They forgot to mention morons. :lol:

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