Sprint Car Nets for side restraint?

[Speed Raycer]

Anyone using sprint nets or know of some online pics of them mounted?

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Scott Rhea
It's not what you build...
it's how you build it
http://www.izzyscustomcages.com/images/IzysLgoSm.jpg (http://www.izzyscustomcages.com)
Izzy's Custom Cages (http://www.izzyscustomcages.com)

[gsbaker]

Originally posted by Speed Raycer:
Anyone using sprint nets or know of some online pics of them mounted?

Scott,

Be careful of some online pics of these things. Many of them show incorrect mountings, i.e. the forward mounting point is too high. The problem here is that as your head moves forward (and to the side) it can slide under the net. Not only do you loose the side protection, but things get very nasty on the rebound back into the seat if your head is outside the net. Ugly image, isn't it?

Images you find of NASCAR mountings are good.

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Gregg Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com

[Knestis]

What are your general thoughts, Mr. B., regarding combining an Isaac system, a "wingback" seat (a la Recaro SPG Racer), and nets?

http://it2.evaluand.com/gti/images/itcockpit2.jpg

K

[This message has been edited by Knestis (edited November 23, 2004).]

[gsbaker]

Kirk,

The best advice I can offer right now is to wait until next week. The SAE/Motorsports Engineering Conference runs Tuesday through Thursday in Detroit. It will include several presentations on this and related subjects, including, but not limited to, the following papers:

#2004-01-3513, "Race Car Nets for the Control of Neck Forces in Side Impacts." (Gideon)

#2004-01-3515, "Biomechanical Principles of Racecar Seat Design for Side Impact Protection." (Melvin)

#2004-01-3516, "Sled Test Evaluation of Racecar Head/Neck Restraints Revisited." (Melvin)

#2004-01-3538, "Validation of Earplug Accelerometers as a Means of Measuring Head Motion." (Knox)

#2004-01-3539, "Brain Injury Prediction for Indy Race Car Drivers Using Finite Element Model of the Human Head" (Zhang, Begemen, Melvin)

I am familiar with the results of the first three papers, although they are not yet available.

Long story short on the net thing:

1) Since your head will tend to move downward and forward on impact regardless of what H&N restraint you use, make sure the forward net mounting position is not too high. Just sit in the seat and move your head forward and toward the center of the car; you'll get the idea.

2) If at all possible, place the rear mounting location of the net inside the seat wing. Why? Because if the net is outside the wing, the wing can snag the bottom of the rear of the helmet on rebound. I haven't seen the video, but I'm told it's not pretty.

I suspect more details will be presented next week, but this is good place to start if you absolutely must install your net this weekend.

Personally, I believe there is a better way to solve the lateral load problem--but we aren't there yet. In the meantime, nets are a great safety purchase when used properly.

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Gregg Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com

here is what the stock car guys are using

http://www.simpsonraceproducts.com/product...227&prod_id=929 (http://www.simpsonraceproducts.com/products/product_detail.aspx?cat_id=227&prod_id=929)

[gsbaker]

Thanks 7.

If you click on the zoom option for this page you can see a good installation of the net used with a LeJoie seat. Notice that the seat has build-in loops to capture the net:

http://www.simpsonraceproducts.com/product...29&prod_id=4122 (http://www.simpsonraceproducts.com/products/product_detail.aspx?cat_id=229&prod_id=4122)

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Gregg Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com

[gsbaker]

Hot off the press...

(I don't have the paper yet and this is from memory, so please forgive any errors. The below is much more right than wrong.)

This morning Tom Gideon, Director of Racing Safety at GM, presented SAE paper #2004-01-3513 titled "Race Car Nets for the Control of Neck Forces in Side Impacts." He covered the issues noted above, plus the following:

1) The vertical position of the rear of the net is also important. The upper-most strap should be no lower than the center of mass of the head (otherwise the head can slide over the top) and the lower strap should be low enough to catch the shoulder. This lower strap position also prevents the head from sliding under the net. These mechanics were evident from 90 degree crash tests conducted at Wayne State University, along with other crash protocols.

2) These nets seem to work well. In a full 90 degree impact the head load reduction (HLR) was about 90%. This series was conducted with a HANS device in place. Without the net, the HANS device HLR was zero.

3) The nets don't need large seat wings to work well.

GM racing has a 'Vette and a Caddy in the hotel. Both are equipped with side nets as described in this thread. And, no, I forgot the camera. (sigh)

[Edit: Oops, the Racetech seat is in the Viper.]

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Gregg Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com


[This message has been edited by gsbaker (edited December 02, 2004).]

[Al Seim]

Gregg:

Many thanks, once again, for the effort you put into safety education in these forums. (OK purists, fora)

The pictures referred to from this thread are the first I've seen doing a decent job of showing side net installs.

I'm a little confused, though. I had been expecting the right side net to look about like the "left side net" also on the simpson page, ie with webbing to make it a net. But the "right side net" shown has no webbing, just upper and lower straps, which I would think would make positioning much more tricky. Are the ones you're seeing "V-straps" (like the Simpson Right Side) or "V-nets" like the Simpson Left Side?

Is there typically a vertical cage bar (in main hoop plane) to get the right height of mounting, or is it coming off existing bars?

Also, it sounds like I ought to get a copy of the SAE paper - every once in a while my SAE membership comes in handy!

By the way, will you be at PRI next week? I'd like to chat.

Thanks again,

Al Seim
Action Digital Race Data Systems
www.actdigital.com (http://www.actdigital.com)

[gsbaker]

Originally posted by Al Seim:
...I'm a little confused, though. I had been expecting the right side net to look about like the "left side net" also on the simpson page, ie with webbing to make it a net. But the "right side net" shown has no webbing, just upper and lower straps, which I would think would make positioning much more tricky. Are the ones you're seeing "V-straps" (like the Simpson Right Side) or "V-nets" like the Simpson Left Side?

Both, and everything in between, including a fine mesh screen between straps. This is a relatively new subject so folks are still working out the details and the racing community is a long way from consensus. Also, I see developing a temptation to use the left side net in lieu of a window net which, of course, will open up another can of worms.


<font face=\"Verdana, Arial\" size=\"2\">Is there typically a vertical cage bar (in main hoop plane) to get the right height of mounting, or is it coming off existing bars?</font>

The mounting locations seem to be whatever is handy. We haven't seen a dedicated mounting bar for the net, but I suspect they are out there.


<font face=\"Verdana, Arial\" size=\"2\">Also, it sounds like I ought to get a copy of the SAE paper - every once in a while my SAE membership comes in handy!</font>

The SAE botched getting the PDF version to me, so I have yet to see it, but the presentation was good.


<font face=\"Verdana, Arial\" size=\"2\">By the way, will you be at PRI next week? I'd like to chat.</font>

Unfortunately, no. It will be the first I have missed in several years. Give me a call/e-mail.

BTW, we are still shopping for a small, ultra dirt-cheap, two axis accelerometer to give away with Isaac systems. We can go mechanical but prefer electronic. The guys at Pi were polite, but it was obvious they thought we were nuts. http://Forum.ImprovedTouring.com/it/biggrin.gif


<font face=\"Verdana, Arial\" size=\"2\">Thanks again</font>

Anytime.

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Gregg Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com