Bridge B/C

[bernard]

[JonB]

Anyone have insight into the "Pass Through Block"? This will definitely make things a little bit more difficult, but maybe that was the point? Or, maybe, this was a way to force a redesign from any previous bridge events?

[mklinger]

Anyone have insight into the "Pass Through Block"? This will definitely make things a little bit more difficult, but maybe that was the point? Or, maybe, this was a way to force a redesign from any previous bridge events?

One of my biggest concerns with the pass-through block is the event day testing. Unless I missed it, the rules don't specify whether the students or the proctors are the ones that pass the block through the device. Either way, if you build a device that has tight clearances (which will be desirable for lowest mass), it could be very nerve wracking to have someone send that block through your device as there will be a risk of breaking it due to shaky hands or a minor slip.

I'm somewhat surprised they left the 15kg bonus in this year's rules. I would have expected that to be added next year.

Also, this might be the first time, at least in recent history, that the Div C design can't just be a simple scaled up version of Div B due to the width of Div C being wider than the loading block. This will be a challenge to implement a low-mass solution.

It should be a good challenge this year. My gut says it'll be harder than the bridges and boomis from recent years, but maybe not as hard as the second year tower design which forced a 2-part column design.

[dholdgreve]

Many years ago (over 20) the bridge competition required an actual road bed be run through the bridge, the one end of the bridge to be placed on the loading block so it sloped, then a hot wheels or matchbox car of the student's choosing be allowed to run from one end to the other. The student got 3 chances to traverse the bridge... The the bridge was placed back in a level position and tested. It was amazing to see how creative kids got with their road beds!

[JonB]

Many years ago (over 20) the bridge competition required an actual road bed be run through the bridge, the one end of the bridge to be placed on the loading block so it sloped, then a hot wheels or matchbox car of the student's choosing be allowed to run from one end to the other. The student got 3 chances to traverse the bridge... The the bridge was placed back in a level position and tested. It was amazing to see how creative kids got with their road beds!

And this was for Science Olympiad? That's really interesting- slightly before my time!

mklinger- I agree with you- passing that object through will be an issue with tight tolerances. I would imagine that an experienced ES would have the students do this, but I can also envision that some ESs will want to do this action themselves, which could be disastrous.

Also, on my initial readthrough, I missed the idea that the loading block (5x5) is smaller than the 7cm wide pass through block size.... oh man.. that is tricky and adds a great deal of complication.

This sounds fun! Without a doubt (in my mind), tougher than previous bridges and boomi, and easier than towers.

[dd881117]

I have two questions about the Rule 3-c-ii & 3-d-ii, hopefully someone can help out.

1. Does it mean the object block would sit on the supporting bar before starting passing through the bridge?

2. According to the rule, the object passes through the bridge horizontally from one end of the bridge’s test support point, does that mean there would be a clear space without any bracing along the passage for a minimum height of 7 cm ( Div B), 12 cm ( Div. C) from the very bottom of the bridge?

[dholdgreve]

I have two questions about the Rule 3-c-ii & 3-d-ii, hopefully someone can help out.

1. Does it mean the object block would sit on the supporting bar before starting passing through the bridge?

2. According to the rule, the object passes through the bridge horizontally from one end of the bridge’s test support point, does that mean there would be a clear space without any bracing along the passage for a minimum height of 7 cm ( Div B), 12 cm ( Div. C) from the very bottom of the bridge?

As with all answers here, this is unofficial. For formal official responses you will need to submit on the national site. That being said, I think you are confusing the 2 blocks... We will have a block mounted to a dowel rod that will need to pass from one end of the bridge to the other. This block is to be sized based on the division. (I highly recommend that all event coordinators adopt a "no touch" policy and have the kids do this as well as place the bridge on the scale. I'd also suggest the front edges of the this block be gently rounded to avoid damaging the bridges). The second block is the loading block that sits on top the bridge and is used for the testing.

Regarding your second question, yes, this is what that means... This effectively forces all DIAGONAL bracing into the upper part of the bridge.

[mklinger]

I have two questions about the Rule 3-c-ii & 3-d-ii, hopefully someone can help out.

1. Does it mean the object block would sit on the supporting bar before starting passing through the bridge?

2. According to the rule, the object passes through the bridge horizontally from one end of the bridge’s test support point, does that mean there would be a clear space without any bracing along the passage for a minimum height of 7 cm ( Div B), 12 cm ( Div. C) from the very bottom of the bridge?

I also have this question and I think it'll be important to get clarification from the National folks what the intent is as it isn't clear from the rules as I read them. Basically, can you have ANY horizontal bracing at the bottom of your bridge or not?

What is really missing from the rules is in anything in the testing procedure for the pass-through block. It should probably be specified that the students (not proctors) do this and if the intent is no cross-bracing at the bottom, say something like the block will be placed on the test support and needs to be able to slide through to the other side without contacting the bridge.

If the intent IS to allow cross bracing of some kind, then say something like the pass-through block needs to pass through a "hole" in your bridge the complete length of the span.

These two options are very different and could have drastic effects on the design.

I have a feeling the intent was no cross bracing like what Dan mentioned, but a strict reading of the rules as written would tend to allow cross bracing at the bottom. Rule 3-c-ii currently does not say it must pass through starting at height 0, only that it needs to go from one of the test support point to the other. If you look at their pictured design, you could easily have horizontal cross supports at the very bottom of that bridge (like a road bed) and you'd be able to get the pass-through block to go through the entire span.

[dd881117]

Thanks for both Dan’s and Marc’s replies.

In August, our head coach shared the link to us to view the information he got from Science Olympiad Summer Institute. From the pictures and videos of Bridge session, I could see some horizontal crossing bracing on the bottom of the bridge. The instructor held the bridge in one hand when passing the object block through the bridge by the other hand. There are more detailed descriptions included in the official rules that released recently, comparing with the draft rules we had at that time, but it looks like we still need some more clarification.

[knightmoves]

mklinger- I agree with you- passing that object through will be an issue with tight tolerances. I would imagine that an experienced ES would have the students do this, but I can also envision that some ESs will want to do this action themselves, which could be disastrous.

General guidance for ES always says "don't handle the student's builds", but I agree that this is a danger, and it would be good for the rule to be clarified so that the student passes the block through the build.

The block is required to pass though the build "horizontally" - but a modest amount of shimmying around to get through a tight spot is hard to observe. If you've got a tight spot on one end, choose to send the block though that end first.

The rules as written do not require the pass-thru block to start at rest on the test support, or to be moved through the build at that height. The requirement is to move the block through the build at a constant height ("horizontally") from one end to the other, at any height of the student's choice between the support and the loading block.
So, for example, a student device that was a thick-walled box section with 4x7 cm or 7x12 cm interior dimensions would be legal under the rules as written.