Another HANS datapoint
#31
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Originally Posted by fatbillybob
What I have posted was from Dr. Hubbard directly unless otherwise stated. Since the post of Kary993 chart we are now getting into conjecture to explain the chart and I for one am not trained in biomechanics. John,DJF, Kary I don't think we can draw any conclusions. The only pro biomechanist is GBaker and perhaps if he can explain the variation between the link and the damper ISAAC in this chart we could "guess" about HANS only if the HANS function and ISAAC are similar enough. I would have loved to ask Dr. H about this chart.
Of all the numbers on that chart, the one in which we have the least confidence is the high HANS number. We heard that someone somewhere, several years ago, tested the HANS with loose tethers and the loads were about doubled--albeit from a low starting value. This is consistent with theory. Some drivers have loosened the tethers so much the thing looks like a kite on a string, so this was intended to remind drivers of the manufacturer's instructions. If anyone has any fresh data, we would be happy to edit the chart.
The Link model is adjustable, so the loads will increase with increased slack. The lower end of the range is from crash testing; the upper end of the range is our estimated load with slack, say an inch or so.
The Isaac (damper model) is not adjustable, although the amount of pre extension of the damper rod affects the mix between tension and compression loads. This is an entirely different issue and can't be expressed on that chart.
From a practical standpoint none of this matters to you guys. It's just salesman's bragging rights and gearhead minutae. Any device having loads under 400# on that sled is good for impacts up to 100Gs, or more. Those are rare, even in the pro ranks. Now, if I expected to put my IRL car into the wall at 220, I'd study that chart closely. If I'm worried about putting my 996 into the trees, I'd use the Link, Isaac or HANS and move on to things like side impact, egress, etc.
#32
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Thank you, Gregg;
Not bad for a dummy, eh? As yet un-crash-tested notwithstanding.
Your detailed addition (whose principles I am aware of) was the basis for my reasoning. I might go further in applying these principles.
The basis for saying that any H&N system is better than nothing is that all of them likely control ultimate head/neck extension within a surviveable range. The difference in the test data comes in how quickly that control is generated.
Since KE is a function of the time interval, it makes perfect sense that stopping head motion as soon as possible would be helpful in reducing the ultimate stress levels on the neck.
The previously vaunted Hutchens device and similar Simpson D-Cel (both made by Safety Solutions) has a fallen out of favor for that reason. It does control neck extention, but it does so rather liesurely. Long straps take up against clothing, that takes up against skin, that takes up against bone, until the head is fully restrained is indeed better than nothing, but not even close to its more recent and sophisticated competition. In case anyone wondered why NASCAR dropped the Hutchens, it was for this, not because a competitor (HANS) offered everyone a case of Bud.
I see that the G-force is substantially less effective than the HANS or Isaac. I might imagine the strap type would be the same, or worse. It would be my guess that the R3 might be slightly better, but not up to HANS/Isaac levels because it too is "waiting" for belts and body parts to run out of elasticity before taking up fully.
The Isaac appears to be King in this catagory, if only slightly more effective than the HANS. I would have guessed the HANS might stop the head quicker, given that it is "actively" held back by the belts where the Isaac is "passively" waiting for the belts to stop stretching to activate fully. Pure guesswork on my part, and subject to the counter-intuition that must be VERY prevalent in this field.
Neat stuff!
Not bad for a dummy, eh? As yet un-crash-tested notwithstanding.
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Your detailed addition (whose principles I am aware of) was the basis for my reasoning. I might go further in applying these principles.
The basis for saying that any H&N system is better than nothing is that all of them likely control ultimate head/neck extension within a surviveable range. The difference in the test data comes in how quickly that control is generated.
Since KE is a function of the time interval, it makes perfect sense that stopping head motion as soon as possible would be helpful in reducing the ultimate stress levels on the neck.
The previously vaunted Hutchens device and similar Simpson D-Cel (both made by Safety Solutions) has a fallen out of favor for that reason. It does control neck extention, but it does so rather liesurely. Long straps take up against clothing, that takes up against skin, that takes up against bone, until the head is fully restrained is indeed better than nothing, but not even close to its more recent and sophisticated competition. In case anyone wondered why NASCAR dropped the Hutchens, it was for this, not because a competitor (HANS) offered everyone a case of Bud.
I see that the G-force is substantially less effective than the HANS or Isaac. I might imagine the strap type would be the same, or worse. It would be my guess that the R3 might be slightly better, but not up to HANS/Isaac levels because it too is "waiting" for belts and body parts to run out of elasticity before taking up fully.
The Isaac appears to be King in this catagory, if only slightly more effective than the HANS. I would have guessed the HANS might stop the head quicker, given that it is "actively" held back by the belts where the Isaac is "passively" waiting for the belts to stop stretching to activate fully. Pure guesswork on my part, and subject to the counter-intuition that must be VERY prevalent in this field.
Neat stuff!
#35
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Originally Posted by RedlineMan
Since KE is a function of the time interval, it makes perfect sense that stopping head motion as soon as possible would be helpful in reducing the ultimate stress levels on the neck.
That said, I imagine there are forces on the head itself, especially within, that could be significantly affected. About 20 years ago there was a big problem in CART with driver's brains sloshing around in their skulls in certain incidents that cause closed head injuries (but not basal skull fracture). I would think this sort of potential injury would be mitigated by the dampers vs. straps.
This was not meant to be part of a HANS vs Isaac argument, rather just a discussion of what is/may be going on.
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Geo,
Was the closed head injury problem ever solved? Dr. H. illuded to a type of closed head injury (skull spins brain stays still) when he talked about how the HANS helps. He illustrated his point with the 30 degree offset crash and it's lateral componant. He showed how the HANS limited head movement.
Personally, I think the ISAAC/ HANS debate would disappear into a taste great/less filling argument if only we could get the major sanctioning bodies to allow the device as an alternative to HANS. The likes of F1/CART/IRL/NASCAR see HANS as mandatory. Do they know something we layment just don't or is the HANS marketing really that strong?
Was the closed head injury problem ever solved? Dr. H. illuded to a type of closed head injury (skull spins brain stays still) when he talked about how the HANS helps. He illustrated his point with the 30 degree offset crash and it's lateral componant. He showed how the HANS limited head movement.
Personally, I think the ISAAC/ HANS debate would disappear into a taste great/less filling argument if only we could get the major sanctioning bodies to allow the device as an alternative to HANS. The likes of F1/CART/IRL/NASCAR see HANS as mandatory. Do they know something we layment just don't or is the HANS marketing really that strong?
#37
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Greg... any word one SFI and ISAAC?
.... At this time it looks very much like I will be going for a HANS. They are similar in performanace to the ISAAC, but have the major advantage of "Approved" (SFI Cert and Racing Org Rules and such) thus my $1000 or so investment will be better protected.
I have said it before and I will say it again buying a $300 or $1000 H&N Device only to find it is not "Approved" for my racing org is not a something I want to do. (even if the reason it is not approved is stupid). I feel 100% certain that I can use a HANS for many years, but not so sure about the ISAAC.
.... At this time it looks very much like I will be going for a HANS. They are similar in performanace to the ISAAC, but have the major advantage of "Approved" (SFI Cert and Racing Org Rules and such) thus my $1000 or so investment will be better protected.
I have said it before and I will say it again buying a $300 or $1000 H&N Device only to find it is not "Approved" for my racing org is not a something I want to do. (even if the reason it is not approved is stupid). I feel 100% certain that I can use a HANS for many years, but not so sure about the ISAAC.
#38
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Originally Posted by fatbillybob
Geo,
Was the closed head injury problem ever solved? Dr. H. illuded to a type of closed head injury (skull spins brain stays still) when he talked about how the HANS helps. He illustrated his point with the 30 degree offset crash and it's lateral componant. He showed how the HANS limited head movement.
Was the closed head injury problem ever solved? Dr. H. illuded to a type of closed head injury (skull spins brain stays still) when he talked about how the HANS helps. He illustrated his point with the 30 degree offset crash and it's lateral componant. He showed how the HANS limited head movement.
Now that I think about it, Champ Cars have had the high sides around the head for a number of years now. Perhaps this is what effectively solved the problem? Gregg, do you have any knowledge of this sub-topic?
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Originally Posted by RedlineMan
I see that the G-force is substantially less effective than the HANS or Isaac. I might imagine the strap type would be the same, or worse. It would be my guess that the R3 might be slightly better, but not up to HANS/Isaac levels because it too is "waiting" for belts and body parts to run out of elasticity before taking up fully.
G-Force, 4010 Newtons (source is G-Force publications)
R3, 3000 Newtons
HANS, 1700 Newtons
The latter two are from a HANS press release. I have no problem with these numbers, BTW. They are consistent with what one would expect.
The Isaac appears to be King in this catagory, if only slightly more effective than the HANS. I would have guessed the HANS might stop the head quicker, given that it is "actively" held back by the belts where the Isaac is "passively" waiting for the belts to stop stretching to activate fully. Pure guesswork on my part, and subject to the counter-intuition that must be VERY prevalent in this field.
I don't believe the Isaac is that much better than the HANS
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This is interesting stuff but we've gone beyond the practical. Both products work so well the arguments/debates are whether the head load values are safe at 180+Gs. Who cares? Somewhere around 150Gs your heart will tear away from your aorta, so it doesn't matter. Actually, there is recent evidence that people may be able to survive higher loads, so the magic number for H&N designers may become 200Gs.
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Originally Posted by fatbillybob
Personally, I think the ISAAC/ HANS debate would disappear into a taste great/less filling argument if only we could get the major sanctioning bodies to allow the device as an alternative to HANS.
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Originally Posted by M758
Greg... any word one SFI and ISAAC?
.... At this time it looks very much like I will be going for a HANS. They are similar in performanace to the ISAAC, but have the major advantage of "Approved" (SFI Cert and Racing Org Rules and such) thus my $1000 or so investment will be better protected.
I have said it before and I will say it again buying a $300 or $1000 H&N Device only to find it is not "Approved" for my racing org is not a something I want to do. (even if the reason it is not approved is stupid). I feel 100% certain that I can use a HANS for many years, but not so sure about the ISAAC.
.... At this time it looks very much like I will be going for a HANS. They are similar in performanace to the ISAAC, but have the major advantage of "Approved" (SFI Cert and Racing Org Rules and such) thus my $1000 or so investment will be better protected.
I have said it before and I will say it again buying a $300 or $1000 H&N Device only to find it is not "Approved" for my racing org is not a something I want to do. (even if the reason it is not approved is stupid). I feel 100% certain that I can use a HANS for many years, but not so sure about the ISAAC.
We hear ya.
We'll have an SFI certified product in the near future, even though we don't like the SFI design. In fact, we've already tested it and it works well. We just need to go through the "process." Current designs can be retrofitted.
The SFI thing has little to do with head load reduction. SFI demands a design we consider dangerous. In time, I believe the lawyers will be over this like white on rice.
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Originally Posted by Geo
To my knowledge it was not really, but it stopped happening. There was a spate of them about 20 years ago. Some were really bad. IIRC, this is the injury that took Roberto Guerraro (sp?) from a regular front runner (I saw him win at Mid-O a week before his injury) to simply good enough. It was a hot topic of conversation in racing for about a year and then I never really heard of it again.
Now that I think about it, Champ Cars have had the high sides around the head for a number of years now. Perhaps this is what effectively solved the problem? Gregg, do you have any knowledge of this sub-topic?
Now that I think about it, Champ Cars have had the high sides around the head for a number of years now. Perhaps this is what effectively solved the problem? Gregg, do you have any knowledge of this sub-topic?
Now that H&N restraints have kept drivers alive by keeping their heads on, we are left the results of drivers' helmets hitting something in the cockpit. A lot of bells are getting rung, regardless of the product used. There is no agreement on a solution.
#44
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Originally Posted by rockitman
So are there any belt slippage reports of the belts coming off a Hans with Recaro GT3 seats and 3" schroth shoulder belts ?
#45
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Originally Posted by Geo
Only on fourth Thursdays under a waning gibbous moon.
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Just want to make sure I am not buying the wrong setup...schroth and hans for my GT3 seats...
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