Right side restraint vs Seat Bolster
12-20-2006, 11:58 AM
#17
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Gregg,
I guess you work with lots of different sanctioning bodies. Is the right side netting a pure head and neck issue? It would seem difficult to hit the netting correctly. So many variables on impact.
The rules I am trying to comply with just say something like Head and Neck device is recommended but seat bolsters or right side netting is required. I am paraphrasing and I am not an expert. This is a little confusing on what is trying to be accomplished.
I guess you work with lots of different sanctioning bodies. Is the right side netting a pure head and neck issue? It would seem difficult to hit the netting correctly. So many variables on impact.
The rules I am trying to comply with just say something like Head and Neck device is recommended but seat bolsters or right side netting is required. I am paraphrasing and I am not an expert. This is a little confusing on what is trying to be accomplished.
12-20-2006, 12:52 PM
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We're not sure what NASA is trying to accomplish either, but it sounds like their priorities could be revisited.
The side net thing began as a head and neck issue, and still is to my knowledge. The only time the subject has been studied is with respect to head loads. The SAE paper from 2004 is very thorough. I'd have to review it again to see if any comments are made re controlling body movement laterally, but that was not the purpose of the paper.
Watching the video of the typical Wayne State 30 degree offset test (50Gs) you can see the dummy's right shoulder slightly sneak past the shoulder support, but the belt tension pulls it back into position on rebound without any netting. I don't see a body problem. (The video is the slow motion version, third from the bottom here.)
This side load issue is heating up very quickly--as in hot-off-the-press quickly. I was chatting with Dr. Paul Begeman, who runs the WSU lab, at SAE two weeks ago about lateral load limits, then last week he e-mailed me just-published test data from Accident Analysis and Prevention. There's not a snowball's chance on a Florida beach in August that sanctioning bodies have incorporated this information into their rule books.
Drivers adding safety gear is great as long as they understand the trade offs. But requiring them to add something they may not need while complaining about release points is loony.
Gregg Baker, P.E.
Isaac, LLC
The side net thing began as a head and neck issue, and still is to my knowledge. The only time the subject has been studied is with respect to head loads. The SAE paper from 2004 is very thorough. I'd have to review it again to see if any comments are made re controlling body movement laterally, but that was not the purpose of the paper.
Watching the video of the typical Wayne State 30 degree offset test (50Gs) you can see the dummy's right shoulder slightly sneak past the shoulder support, but the belt tension pulls it back into position on rebound without any netting. I don't see a body problem. (The video is the slow motion version, third from the bottom here.)
This side load issue is heating up very quickly--as in hot-off-the-press quickly. I was chatting with Dr. Paul Begeman, who runs the WSU lab, at SAE two weeks ago about lateral load limits, then last week he e-mailed me just-published test data from Accident Analysis and Prevention. There's not a snowball's chance on a Florida beach in August that sanctioning bodies have incorporated this information into their rule books.
Drivers adding safety gear is great as long as they understand the trade offs. But requiring them to add something they may not need while complaining about release points is loony.
Gregg Baker, P.E.
Isaac, LLC
12-20-2006, 02:09 PM
#19
Great discussion!
I am interested in learning about the LEFT side nets as well (the top net pictured below). Would these have any viability in a DE environment, where window nets are not allowed? It seems as though they basically serve the same purpose as the right side nets, and therefore would suffer the same criticisms. Any thoughts?
I am interested in learning about the LEFT side nets as well (the top net pictured below). Would these have any viability in a DE environment, where window nets are not allowed? It seems as though they basically serve the same purpose as the right side nets, and therefore would suffer the same criticisms. Any thoughts?
12-20-2006, 02:15 PM
#20
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Originally Posted by shiners780
Would these have any viability in a DE environment, where window nets are not allowed?
Personally I consider my window net to be my 'left side net' to compliment my HANS and right side net.
Requiring window nets in DE is crazy, but at the same time so is NOT allowing them.
Just my thoughts....
Lets see what the fall out of this is...
12-20-2006, 02:20 PM
#21
Originally Posted by M758
Why are window nets not allowed?
Personally I consider my window net to be my 'left side net' to compliment my HANS and right side net.
Requiring window nets in DE is crazy, but at the same time so is NOT allowing them.
Just my thoughts....
Lets see what the fall out of this is...
Personally I consider my window net to be my 'left side net' to compliment my HANS and right side net.
Requiring window nets in DE is crazy, but at the same time so is NOT allowing them.
Just my thoughts....
Lets see what the fall out of this is...
12-20-2006, 02:21 PM
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Originally Posted by gbaker
I agree with John that the containment "wings" at the shoulders are valuable, especially for keeping the belts on, but there is nothing good about all that extra crap above the shoulders.
I use "wings" to refer to the angled shoulder supports on most generic seats. Are you refering to those, or to the perpendicular "fences" of a containment seat?
Also, just to clarify, are you saying that seat based head containment is of questionable value?
12-20-2006, 02:53 PM
#24
Race Car
Originally Posted by 924RACR
Still, no reason IMO to not do both a H+N restraint with good lateral capability AND a right side net.
12-20-2006, 03:38 PM
#25
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Originally Posted by shiners780
I have never been to a DE that allowed them here in the NE. I always assumed they were disallowed because they would interfere with passing signals.
I have never been to a DE were there were NOT allowed. My net has never prevented me from givng passing signals. Being in a 944 I am familier with passing signals even during races.
12-20-2006, 03:57 PM
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Originally Posted by JackOlsen
I don't think the window net is going to provide any lateral support for your helmet. It's too far away from the head, for starters, and most window nets aren't held in place with any meaningul amount of tension (imagine hurling a bowling ball at the net -- what would happen?). The nets are only designed to keep your arm from flying out of the car. If I didn't run with an Isaac, I'd want actual restraint nets on both sides.
However, I was talking about the right side net.
12-20-2006, 04:19 PM
#28
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Originally Posted by RedlineMan
There we hit the semantics;
I use "wings" to refer to the angled shoulder supports on most generic seats. Are you refering to those, or to the perpendicular "fences" of a containment seat?
I use "wings" to refer to the angled shoulder supports on most generic seats. Are you refering to those, or to the perpendicular "fences" of a containment seat?
Also, just to clarify, are you saying that seat based head containment is of questionable value?
In the perfect world your H&N restraint would handle all these loads, and there would be no need for any seat structure above the shoulders, like the WSU set up. However, in the real world some people are burdened with a H&N restraint that does not reduce lateral loads--or even increases lateral loads--so the driver is forced to go with lateral head fences and nets, which only jeopardize visibility and egress and add release points. Forced, mind you; the driver has no choice.
These things are like the aspirin you take after hitting your thumb with a hammer. Well, if you didn't hit your thumb with the hammer, you wouldn't need the aspirin.
12-21-2006, 09:16 AM
#30
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Regarding head containment aparatus mounted on the seat...
OK...
Product loyalty and bias aside, let me pose this differently. If you had a less than brilliant H&N device, are you saying that head containment is not advantageous, and even deleterious? Or... does it indeed make up for "shortcomings" in the scope and performance of the H&N device, and provide value?
By the way, that was quite artfully stated. Causal viewers might not even know from whence your paychecks eminate, or grasp the subtlety of your sarcasm!
Originally Posted by gbaker
It is of negative value.
In the perfect world your H&N restraint would handle all these loads, and there would be no need for any seat structure above the shoulders, like the WSU set up. However, in the real world some people are burdened with a H&N restraint that does not reduce lateral loads--or even increases lateral loads--so the driver is forced to go with lateral head fences and nets, which only jeopardize visibility and egress and add release points. Forced, mind you; the driver has no choice.
In the perfect world your H&N restraint would handle all these loads, and there would be no need for any seat structure above the shoulders, like the WSU set up. However, in the real world some people are burdened with a H&N restraint that does not reduce lateral loads--or even increases lateral loads--so the driver is forced to go with lateral head fences and nets, which only jeopardize visibility and egress and add release points. Forced, mind you; the driver has no choice.
Product loyalty and bias aside, let me pose this differently. If you had a less than brilliant H&N device, are you saying that head containment is not advantageous, and even deleterious? Or... does it indeed make up for "shortcomings" in the scope and performance of the H&N device, and provide value?
By the way, that was quite artfully stated. Causal viewers might not even know from whence your paychecks eminate, or grasp the subtlety of your sarcasm!