Front Bulk Head Support Question

[Taylor Hoff]

Trying to clarify some of the rules here. According to the rule B3.19.2:

The Front Bulkhead must be supported back to the Front Roll Hoop by a minimum of three (3) Frame Members on each side of the vehicle with one at the top (within 50.8 mm (2 inches) of its top-most surface), one (1) at the bottom, and one (1) as a diagonal brace to provide triangulation.

And rule B3.19.4:

All the Frame Members of the Front Bulkhead Support system listed above must be constructed of
closed section tubing per Section B3.3.1.

B3.3.1 Specifies all 1" tube for the primary structure and the front bulk head and front bulk head supports are defined as primary structures according to rule B3.2

Our current design currently has three 1" tubes connecting the front bulk head to the front roll hoop, but the piece triangulating the lower portion of the supports is only 0.5". I was curious if anyone knew if this piece was required to be 1" instead of 0.5". I was going over the rules and it seems as if this is the case, but I wanted to verify before anything is modified.

The image below illustrates our situation. I was specifically curious if the tubes outlined in red, or both the tubes outlined in red and yellow needed to be 1" instead of 0.5":

http://www.csulbsae.org/cpgsae/_albums/saepics/10001/normal_front_bulkhead.png

[Taylor Hoff]

Trying to clarify some of the rules here. According to the rule B3.19.2:

The Front Bulkhead must be supported back to the Front Roll Hoop by a minimum of three (3) Frame Members on each side of the vehicle with one at the top (within 50.8 mm (2 inches) of its top-most surface), one (1) at the bottom, and one (1) as a diagonal brace to provide triangulation.

And rule B3.19.4:

All the Frame Members of the Front Bulkhead Support system listed above must be constructed of
closed section tubing per Section B3.3.1.

B3.3.1 Specifies all 1" tube for the primary structure and the front bulk head and front bulk head supports are defined as primary structures according to rule B3.2

Our current design currently has three 1" tubes connecting the front bulk head to the front roll hoop, but the piece triangulating the lower portion of the supports is only 0.5". I was curious if anyone knew if this piece was required to be 1" instead of 0.5". I was going over the rules and it seems as if this is the case, but I wanted to verify before anything is modified.

The image below illustrates our situation. I was specifically curious if the tubes outlined in red, or both the tubes outlined in red and yellow needed to be 1" instead of 0.5":

http://www.csulbsae.org/cpgsae/_albums/saepics/10001/normal_front_bulkhead.png

[shark.ashwa]

Hello,

The red outlined tube from the lower corner of the front bulkhead to the upper A-Arm node needs to be a minimum of 1" OD and .049" wall thickness IIRC. None of the other tubes outlined need to be 1" but it depends on your load path calculations! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Sharath

[RobbyObby]

Actually, as far as I interpret the rule, both the tubes highlighted in red need to be 1" x 0.049". This is because there needs to be three members between the front bulkhead and front roll hoop. The bottom tube is 1. The middle horizontal tube is 2. And the red tubes comprise the 3rd, providing triangulation all the way back to the Roll Hoop. All those tubes need to be at least 1" x 0.049". The yellow tube, however, is unregulated and can be whatever tube you see fit.

The most important thing you should do, however, is get a cut and dry response from the rules committee about your situation before you start cutting and rewelding any more tubes, because as much as we know and say, we are not the final word, they are.

[Taylor Hoff]

Does anyone know a better way to get in contact with the rules committe? I've tried e-mailing the e-mail address listed on the sae.org sites for all rule inquiries, but I have yet to get a response. Thanks for the responses so far guys.

[Drew Price]

Taylor, have you seen this document about the alternative layouts for front bulkhead support that have already been approved?

http://www.fsaeonline.com/page...e1-89e1-489a8a4f08d9 (http://www.fsaeonline.com/page.aspx?pageid=5ade9b01-8903-4ae1-89e1-489a8a4f08d9)

Yours meets #16, and doesn't even need the 0.5" tube bridging the upper member to the front hoop braces.

It's the first link, called "FSAE Front Bulkhead Support Configuration Examples" (http://www.fsaeonline.com/content/FSAE_Front_Bulkhead_Support.xls)



<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by shark.ashwa:
The red outlined tube from the lower corner of the front bulkhead to the upper A-Arm node needs to be a minimum of 1" OD and .049" wall thickness IIRC. None of the other tubes outlined need to be 1" but it depends on your load path calculations! </div></BLOCKQUOTE>



Just in case anyone takes this as correct, it isn't. The load path requires 1"x0.049" minimum from the front bulkhead all the way back to the front hoop for all 3 required members (upper, lower, and triangulating.)

[Taylor Hoff]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Drew Price:
Taylor, have you seen this document about the alternative layouts for front bulkhead support that have already been approved?

http://www.fsaeonline.com/page...e1-89e1-489a8a4f08d9 (http://www.fsaeonline.com/page.aspx?pageid=5ade9b01-8903-4ae1-89e1-489a8a4f08d9)

Yours meets #16, and doesn't even need the 0.5" tube bridging the upper member to the front hoop braces.

It's the first link, called "FSAE Front Bulkhead Support Configuration Examples" (http://www.fsaeonline.com/content/FSAE_Front_Bulkhead_Support.xls)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by shark.ashwa:
The red outlined tube from the lower corner of the front bulkhead to the upper A-Arm node needs to be a minimum of 1" OD and .049" wall thickness IIRC. None of the other tubes outlined need to be 1" but it depends on your load path calculations! </div></BLOCKQUOTE>

Just in case anyone takes this as correct, it isn't. The load path requires 1"x0.049" minimum from the front bulkhead all the way back to the front hoop for all 3 required members (upper, lower, and triangulating.) </div></BLOCKQUOTE>

Drew,

I have looked at the document and seen that ours meets #16. My main concern was if all the members in that diagram were required to be at least 1" x 0.49". I've added the diagram below, and highlighted the same portions I highlighted in the photo above. I'm fairly certain the portions in red need to be at least the 1" x 0.49", but does the portion in yellow need to be as well (since it is included in the diagram as part of the bulk head support, as it completes the triangle)?

I have e-mailed the e-mail address listed on the SAE site, but haven't gotten a response yet.

http://www.csulbsae.org/cpgsae/_albums/saepics/10001/bulk_head_fig_16_modified.png

[coastertrav]

Yes, it also needs to be 1 x .049.

We ran into something similar with our main roll hoop bracing back to the lower and upper side impact members on our frame.

[RobbyObby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Taylor Hoff:
Does anyone know a better way to get in contact with the rules committe? I've tried e-mailing the e-mail address listed on the sae.org sites for all rule inquiries, but I have yet to get a response. Thanks for the responses so far guys. </div></BLOCKQUOTE>

When did you send it in? If it was 2 weeks ago, I'd send it again. But if it was a few days ago, give it a few more days. Especially this time of year, the Rules Committee gets swamped with questions. Also remember there is a file size limit for submissions (I found this out just recently) so if you sent in photos or diagrams, make sure they dont go over the size limit.

[Sormaz]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by coastertrav:
Yes, it also needs to be 1 x .049.

We ran into something similar with our main roll hoop bracing back to the lower and upper side impact members on our frame. </div></BLOCKQUOTE>

Refer to B3.3.1, that is the Main Hoop Bracing Supports which is clearly outlined in the rules as a requirement.

The question being asked here is not clearly required in the rules, hence his confusion

[Drew Price]

Good point. How long will it take you to change it out, vs. how long it may take to hear back from rules? I'd wager that's 2-3 hours to just change it and be totally safe, and if that's holding you up from building other things I'd go for it.

If it's not a hangup I'd probably wait, make sure you post back what the official verdict is.

[Taylor Hoff]

Hey guys,

I finally received a response to my inquiry, it turns out that the tube outlined in yellow does not need to be the 1.0" x 0.049". Here is the exact response I received:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Taylor,
The tubes highlighted in red must be 1” x 0.049”. The yellow highlighted tube is not regulated.
FSAE Rules Committee </div></BLOCKQUOTE>

So there it is, thanks everyone for their responses and help!