H&N Support Devices

[craigS]

You can contact Gregg Baker of ISAAC on Rennlist.com . There's a ton of good (and bad) safety info in the threads there as well. Note that much of it may not be applicable to Subies (or most rally cars).

The best source of research is, well, reading the (peer-reviewed) research. Most of the manufacturers have published papers in SAE journals, or made presentations at conferences.

As for SFI, I have little faith in them. They do absolutely zero compliance testing, so as far as I'm concerned, an SFI sticker stands for squat just for that reason. It also seems like if they don't want to pass a manufacturer's H & N restraint - particularly if the manufacturer isn't a member of SFI - then the SFI standard is seemingly revised just enough to exclude that product. Coincidence? ...

As for HANS pricing, everybody has to advertise the same price. Actually paying that price is an entirely different matter ... :-D

[wedge]

They do absolutely zero compliance testing

I'm not sure what you mean by that...

It also seems like if they don't want to pass a manufacturer's H & N restraint - particularly if the manufacturer isn't a member of SFI - then the SFI standard is seemingly revised just enough to exclude that product. Coincidence? ...

SFI standard 38.1 for head and neck restraints has never been revised since its creation. I've seen that there's a lot of people who feel there is a conspiracy behind that standard. For example, the fact that the G-Force SRS failed by just 10N. But that truely is a coincidence. When Neck Tension is >4000N, that is the point where injury can occur. That number is an international safety standard, it was not determined by the SFI. G-Force scored 4010N, therefore it simply doesn't provide effective protection. No conspiracy there, just facts.
Some people feel the Isaac is unfairly excluded also. It meets all the safety standards, but fails because it does not have a single point of release. That particular rule might be questionable, but personally I agree with it.
This standard certainly isn't perfect, mainly because the technology is new and everyone is still learning. In any case, between the current FIA and SFI standards for head and neck restraints. I still think SFI does a better job.
Since no sanctioning body has the ability to allow or disallow products on a case-by-case basis. They must rely on one of the existing standards.

[craigS]

wedge wrote:

They do absolutely zero compliance testing

I'm not sure what you mean by that...

",,, to randomly select test samples from the marketplace and test them to the minimum performance requirements of the applicable standard..."
http://www.nhtsa.dot.gov/cars/testing/comply/Mission/1_ovsc_1.html

FIA does it.
Snell does it.

No compliance testing means that the design passed the standard. Compliance testing makes it possible to calculate the odds that what I actually buy will meet the standard.

Although Snell doesn't publicize failures (AFAIK, last time I looked), the FIA does - and models from respected manufacturers have had their certification lifted. No compliance testing means that would never happen.

Please note that I am not saying the manufacturers in question deliberately did this. However, I do find it very comforting that someone is watching. I don't get that feeling with SFI.

As for gForce and ISAAC - you are right, the facts that you state are indisputable. The differences are in the timeline of events and in analysis.

Good luck with your search, I am very interested in what restraint you end up with!

[wedge]

Copied and pasted from SFI 38.1:

9.0 PERIODIC REVALIDATION
Test reports with successful test results must be submitted to SFI at least once every 12 month period following the date of the initial design validation test for each model of Head and Neck Restraint System manufactured by the participant. If multiple test reports are required to obtain all test results, then the earliest test date shall be used to determine when the periodic revalidation reports are due. Also, SFI shall retain the option to conduct random audit reviews. SFI shall purchase the product on a commercial basis and test for compliance to the specification. The submitting manufacturer shall reimburse SFI for all audit costs.

10.0 CERTIFICATION OF COMPLIANCE
Upon demonstration of successful compliance with all the requirements of the specification and the self-certification program and upon entering the licensing agreement with SFI, the manufacturer may advertise, present and offer the Head and Neck Restraint System for sale with the representation that their product meets the SFI Specification 38.1. Continuing certification is contingent upon the following additional considerations: (1) the product shall be resubmitted for testing following any change in design, materials and/or methods of manufacturing not specifically excluded, and (2) periodic revalidation test reports are submitted when due to SFI.

SFI claims they will purchase the product and re-test it periodically. Whether they actually do that or not... I have no idea. But I would think the threat of it would be enough to keep most manufacturers in check.
Devices must also be recertified after any changes in design. How well that is enforced, I have no idea.

I am very interested in what restraint you end up with!

Me too! :-? It turns out, we might have no say in the matter afterall...

[wedge]

Here's a quote which I completely agree with. Particularly the part in bold.

Quoted from: http://www.catchfence.com/html/2005/mt111005.html

... It struck me that a SFI certification is valuable to a degree, but, that it's not truly a performance measure. It is, in fact, an endorsement, but, it's an endorsment that a particular piece of safety equipment will do a particular thing under a particular set of test conditions."

"So, it struck me that the defined test protocol was wonderful in terms of repeatability, but, SFI tests are so narrowly defined to be repeatable, that the point becomes passing the tests at, potentially, the expense of performance out in the real world under real conditions. The simple fact of the matter is, an auto racing incident is a massively complex situation. The kind of crash, for example, that I might be involved in in my racing car on a road course is going to be very different than the kind of incident I might be involved in in that same exact car at a performance rally out in the woods."

In order to understand how this applies to head and neck restraints. It is nessesary for you to understand what forces are applied to the neck in a crash.

First, there is Neck Tension, and Compression. These are vertical forces. Tension is the force pulling the head upward (this is the primary cause of basal skull fractures). Compression is the opposite, it is a vertical downward force. These two forces are measured in Newtons.
Second, there is Neck Flexion, and Extension. These are known as Bending Moments, and they are measured in Newton-meters (Torque). Flexion is the amount of force trying to bend the neck straight forward. Extension is the force trying to bend the neck straight backward.
There are many other forces involved, but these are the most likely causes of neck injury.

Now, if you're thinking, you might ask the question: "But in a frontal car crash, there is no upward force on the neck. So how can Tension be the primary cause of injury?". Good question. It's because Tension, and Flexion work together to cause injury. Picture a zero degree frontal impact. The neck bends forward due to Flexion, now the head is pointing forward, and the force from the impact actually IS pulling the head "upward" and causing Tension on the neck.

So, the idea behind reducing Neck Tension in an impact is pretty simple actually. Just keep the head as upright as possible. Theoretically, it's probably possible to build a device which reduces neck tension almost down to zero. It would be unusable because it would basically involve completely immobilizing the head.

That is basically how the HANS and Hutchens devices work. When the neck bends forward, the tethers limit how far forward the neck can bend. Thus keeping the head relatively upright and reducing tension. The difficult part is to do it without unduely sacrificing mobility under normal circumstances.
These two companies seem to be in fierce competition with each other. It appears to me, that they are trying to reduce Neck Tension at all costs, simply for marketing purposes. The amount of Neck Tension that causes injury is 4000N. Both HANS and Hutchens now have that down to ~1000N. They continue to try to improve that number, simply to outdo each other. But at what cost?

Both HANS, and Hutchens have never released any testing results which show any data except for Neck Tension.
Go back to the bolded quote above. That's exactly what I feel is happening here. These guys seem to be trying to improve test results, while possibly sacrificing real world performance.
I do have evidence of this, but I won't post it publicly.


So, if I had to make a choice right now. I would definately choose the Leatt Brace. So far, they are the only company who has enough confidence in their product to publicly post a complete set of test results. Their neck tension results are not as low as their competition. But it is still well within the margin of safety. They have stated that if they wanted to reduce that number further, they could have, but it would sacrifice performance in other areas.
I believe the Leatt Brace has the best real world performance, in any/all types of impact. Not to mention the various other smaller advantages over its competitors.

Quoted from: Leatt Brace website
The Leatt-Brace™ not only limits neck tension, but reduces other neck forces too.

Quoted from Karl Ebel:
May it be known that our intention was never to have the lowest Fz (tension) otherwise our test results would have shown this. Quite the contrary, our company's philosophy has always been to provide the "Gold Standard" for neck protection, which means the best protection for the head and neck in all impact cases, catering for all forms of motorsport with the least restriction to the user.

Complete quote here.

[wedge]

Here's something VERY interesting that I just found out! I wish I'd known this a year ago, it could really have influenced my picks in the WRC pool.

Seb Loeb did not drive for a factory team in 2006. Which meant he was not required to wear a HANS device. It turns out he chose not to wear one during several events.
A good example is Cyprus, a rally known for its very tight and twisty roads. Loeb went without a HANS device for that event and beat Gronholm (who was required to wear a HANS) by 20 seconds.
However, in Finland, where the roads are much straighter, the disadvantage is less. Marcus beat Seb by over a minute.

I just find that very interesting...

[STeveD]

Is that why Subaru is so slow? ;-) Their drivers must be wearing an extra-ginormous big and clumsy HANS.