H&N restraints - need opinions
12-08-2005, 10:27 AM
#91
Race Director
Originally Posted by David K.
OK, let's see a chart like this from Mr. Baker!
http://members.rennlist.com/davidk/lft2%20charts.jpg
http://members.rennlist.com/davidk/lft2%20charts.jpg
I have much apperciated Gregg's comment here on Rennlist and on the Improved Touring Forums. He has valuable input and from all the that I have seen and heard is great guy.
I got a H&N device and when with HANS due to SFI and sanctioing body reasons athough I have full faith in the ISAAC. However I also purchased a safety solutions (R3 Manufacturer) side net as shown in thier printed material on the R3. Why? Well I do not trust HANS, ISAAC, R3 or anyother device in hard side impact. I feel that adding in the side net the best method to ensure my head and torso maintain the best position they can in a side or offset impact.
12-08-2005, 10:48 AM
#92
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Originally Posted by M758
Interesting... It seem that in the side impact picture they are using side net along with the R3. I wonder if they will be used the HANS with side net? Seems shady to me if they did the offset R3 with side net and HANS without and them compared the numbers.
12-08-2005, 11:54 AM
#93
Originally Posted by David K.
12-08-2005, 12:04 PM
#94
Mr. Excitement
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The in seat version of the R3 is the standard one with a provision for it to be held in position with velcro. It does not stay with the seat in an impact but moves with you where ever you go just as the standard one does. The idea is one of ease of getting in and out of the car with all the gear.
Hans does not always move with the body and in fact the grip area on the front of the Hans where the straps lay cause the body to move foward but not the Hans device to some extent. As this happens the Hans to head relationship changes in the way you (F.B.B.) were thinking of but not to the extent you might be thinking of. The thought is this is for the better as it acts to reduce the foward movement of the head. The down side it it relies on the straps and the interaction of the device to the strap as does the Issac. It is another vairable to deal with.
Hans does not always move with the body and in fact the grip area on the front of the Hans where the straps lay cause the body to move foward but not the Hans device to some extent. As this happens the Hans to head relationship changes in the way you (F.B.B.) were thinking of but not to the extent you might be thinking of. The thought is this is for the better as it acts to reduce the foward movement of the head. The down side it it relies on the straps and the interaction of the device to the strap as does the Issac. It is another vairable to deal with.
12-08-2005, 12:13 PM
#95
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Originally Posted by racergreg
Thanks, Gregg. One more question, then: is the basal skull fracture caused by extension of the head from the body, or extreme forward angle of the neck from vertical (chin to chest)? I thought is was the latter....
It has nothing to do with the position of the head. A hangman's noose creates a BSF with the entire body vertical. If you strike your chin sufficiently hard your jawbone can be driven into your temporal mandibular joint and cause a BSF.
Can a BSF occur when the head is in an extreme forward position? Yes, but it's the force that causes the fracture, not the position.
Move your head as far forward as you can. Are you dead?
This is one of the two greath myths of H&N restraints left over from the last millennium.
12-08-2005, 12:39 PM
#96
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Originally Posted by Geo
The in-house testing I described would be 100% paid for by the manufacturer, so not cost to HR.org. I understand the liability issue and that is why the set-up of a separate but related corporation to establish minimum standards and issue the pass/fail.
The thing I am concerned about with having the manufacturer certified requirement is that who determines the validity of the tests, the uniformity of the tests, what the standard is/should be?
If every manufacturer submitted all their existing test results to HR.org, like we do, it can be verified by anyone.
This is already done now. Look at any set of belts meeting SFI 16.1. The tag reads, "The manufacturer certifies...".
And what is the penalty for cheating?...
12-08-2005, 12:49 PM
#97
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Originally Posted by RedlineMan
...What is even more shocking and fascinating to me is that he also reports up to a 15% reduction in NECK LOAD in the same situations!...
12-08-2005, 12:57 PM
#98
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Originally Posted by RedlineMan
...IF Isaac had the opportunity to participate in an SFI test - to the extent that this test is valid (which is a bone of serious contention, apparently) - then I too would like to see the numbers.
Because someone has not... or cannot post such info does not render them smoke. Only if they have it and DO not, or WILL not submit to equal testing. It is my experience that Isaac is not prone to rope-a-dope (like some in this game), but more likely to say "bring it on."
Whatever the case, further proof that independant multi-disciplinary testing is sorely needed. The truth will never be known otherwise.
12-08-2005, 01:02 PM
#99
I can't wait to see the numbers. I bought my ISAAC without seeing numbers because, intuitively, it is the most elegant solution from an engineering design perspective (and yes, I have an engineering degree, but not in crash dynamics and, thankfully, I have no practical experience in this area . . . yet).
12-08-2005, 01:02 PM
#100
Originally Posted by gbaker
When we go to Wayne State we tell Dr. Begeman we want the 30 degree offset NASCAR test. When we go to Delphi we tell Mike Donegan and company that we want the 30 degree offset SFI 38.1 test.
12-08-2005, 01:07 PM
#102
Originally Posted by RedlineMan
All;
It has been shown in testing, by both Schroth & Dr. Melvin, that shape change is universal, and responsible for most of the body motion you see in crash tests. Dr. Melvin has discovered that at least one key to limiting Shape Change is hip control. The best way known at this point to control that is a 6-point harness arranged in some form of cradle layout. By stopping hip motion as early as possible, shape change has been shown to be minimized greatly.
As I have mentioned many times, and everyone involved with this professionally would surely concur, the key factor in load reduction is time. Unlike the old paradigm of controlling motion slowly and gradually, it has been discovered that this is absolutely backwards. Reducing the length of time objects are in motion reduces kinetic energy and load. Dr. Melvin reports that he has measured as much as a 50% reduction is chest loading using a cradle type sub arrangement -vs- a single sub. What is even more shocking and fascinating to me is that he also reports up to a 15% reduction in NECK LOAD in the same situations!
Same hit. Same setup. Change the Sub. Bam... >50/15% reductions in loads. This proves the validity of the full containment model, and the worth of cradle subs, to me. It has been clearly demonstrated that the body can take abuse to quite a savage degree. Stop body movement quickly, and reduce the load substantially. Then, all you need to do is manage that most critical, tiny junction of neck-to-head, and you stand a good chance.
It has been shown in testing, by both Schroth & Dr. Melvin, that shape change is universal, and responsible for most of the body motion you see in crash tests. Dr. Melvin has discovered that at least one key to limiting Shape Change is hip control. The best way known at this point to control that is a 6-point harness arranged in some form of cradle layout. By stopping hip motion as early as possible, shape change has been shown to be minimized greatly.
As I have mentioned many times, and everyone involved with this professionally would surely concur, the key factor in load reduction is time. Unlike the old paradigm of controlling motion slowly and gradually, it has been discovered that this is absolutely backwards. Reducing the length of time objects are in motion reduces kinetic energy and load. Dr. Melvin reports that he has measured as much as a 50% reduction is chest loading using a cradle type sub arrangement -vs- a single sub. What is even more shocking and fascinating to me is that he also reports up to a 15% reduction in NECK LOAD in the same situations!
Same hit. Same setup. Change the Sub. Bam... >50/15% reductions in loads. This proves the validity of the full containment model, and the worth of cradle subs, to me. It has been clearly demonstrated that the body can take abuse to quite a savage degree. Stop body movement quickly, and reduce the load substantially. Then, all you need to do is manage that most critical, tiny junction of neck-to-head, and you stand a good chance.
The thought of my boys being "cradled" as I race, would certainly provide comfort and confidence. If it's via an umbrella girl or similar, I think it should be mandated by all sanctioning bodies poste haste.
All kidding aside, I've never heard of any cradle arrangement, so any details would be very interesting to read. Not to mention, my wife wouldn't approve of my above suggestion.
12-08-2005, 01:16 PM
#103
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Originally Posted by David K.
Where's the SFI 38.1 test results for the Isaac?
And that's not the best part. Wait till you see some of the lateral load measurements.
We just finished our test series on Tuesday. Everyone is going to want to see all the data and all the videos of all the products on all the sleds--apparently there are some doubting Thomases out there. (Gasp!) We don't have enough bandwidth to be dishing out 100MB video files, so we are having them thinned down.
12-08-2005, 01:43 PM
#104
Originally Posted by gbaker
Right here: 2,211 Newtons (497 pounds force) upper neck tension for the 30 degree offset test per SFI Spec 38.1.
And that's not the best part. Wait till you see some of the lateral load measurements.
We just finished our test series on Tuesday. Everyone is going to want to see all the data and all the videos of all the products on all the sleds--apparently there are some doubting Thomases out there. (Gasp!) We don't have enough bandwidth to be dishing out 100MB video files, so we are having them thinned down.
And that's not the best part. Wait till you see some of the lateral load measurements.
We just finished our test series on Tuesday. Everyone is going to want to see all the data and all the videos of all the products on all the sleds--apparently there are some doubting Thomases out there. (Gasp!) We don't have enough bandwidth to be dishing out 100MB video files, so we are having them thinned down.
All we need is the SFI 38.1 sticker on your unit!
12-08-2005, 02:08 PM
#105
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Originally Posted by Super D
I use a 6pt, but I'd be interested to hear more about this "cradle" layout. Do you have a visual or more info on this?
The thought of my boys being "cradled" as I race, would certainly provide comfort and confidence. If it's via an umbrella girl or similar, I think it should be mandated by all sanctioning bodies poste haste.
All kidding aside, I've never heard of any cradle arrangement, so any details would be very interesting to read. Not to mention, my wife wouldn't approve of my above suggestion.
The thought of my boys being "cradled" as I race, would certainly provide comfort and confidence. If it's via an umbrella girl or similar, I think it should be mandated by all sanctioning bodies poste haste.
All kidding aside, I've never heard of any cradle arrangement, so any details would be very interesting to read. Not to mention, my wife wouldn't approve of my above suggestion.
Not your fault of course. We've gone over these pretty in depth. A cradle is any arrangement where the belts terminate behind the driver. To whatever degree you utilize them through angle of approach, these control the natural phenomenon of hip rotation out and from under the lap belt. When speaking of a 6-point, the only difference is in equipment used and the comfort levels each provides.
The two keys are 1) Direct loading of the lap belt, and 2) Angle of mounting. These are key to getting the quickest full loading or "take-up" of the harness system.
The less direct the sub termination is to the lap belt, the tighter worn and more aft the mounting must be. These include the open wheel "formula" or "D-ring" style subs. They must be worn tight and mounted behind the driver. The "T-bar" type sub is a direct lap mount type. It can be mounted closer to the driver's "spine line," but because the T hardware requires raising the lap belt slightly for clearance, you must still mount them somewhat aft (40 degrees+/-). The unique Schroth Hybrid allows the lowest lap belt position with direct lap belt termination in a double sub, and can be effectively mounted 10-20 degrees aft the spine line. all of these a "split" subs that give your boys a lot of room to breath.
The more direct the lap belt termination, and the lower that lap belt can be positioned, the less the system relies on the sub to directly and physically stop hip rotation, and the farther forward they can be mounted below.
While a "V" does terminate directly at the lap belt, no one I know is man enough to wear it tight enough in a static state to have it forwarded mounted like the other directly mount subs. Therefore, it needs to be rear mounted, where it will crush the family if you bonk.
Blue Range = single sub
Green Range = "T" or "Hybrd" sub
Red = "V" or "Formula"