For Your Viewing Pleasure

[Bildon]

Gregg,
Thanks for those clarifications. hmmmmmm
Great, now I'm not going to sleep so well
I'm going to be dreaming about 30 deg. impacts

[planet6racing]

Originally posted by M. Hurst@Dec 17 2005, 11:46 PM
As Paul Harvey sez...The rest of the story.

1. HANS passes the offest test even with only one side of the collar under the belt.

2. They don't put those big shoulder and head restraints on nextel cup cars for looks.

While the HANS does pass with only one side under the belt, there is a rotational component of the head as a result that scares me as an engineer. Additionally, any additional contact beyond the first impact is compromised by the HANS no longer being properly supported.

Secondly, why should they have to put those restraints in if there is something that can be just as effective, yet give the visibility back to the drivers?

One last thing- just in the interest of full disclosure (OK, two things) - M. Hurst - could you reveal who you are? This is the second board you've commented on and you seem pretty knowledgeable regarding the Head and Neck restraint testing. And, as most on this board know, I am Bill of "All Hail Bill!" fame and do have ties to the Isaac product, not just as a user.

[M. Hurst]

Originally posted by planet6racing@Dec 19 2005, 10:28 AM
One last thing- just in the interest of full disclosure (OK, two things) - M. Hurst - could you reveal who you are? This is the second board you've commented on and you seem pretty knowledgeable regarding the Head and Neck restraint testing.

I've built and raced a couple of IT cars, but not since 2001. I've been involved with the SCCA since 1980, where I started as a worker at Nelson's Ledges.

I've been a Pro-Rally and Club Rally competitor since 1982, and won the 2001, 02, 03 Club Rally national championships in Group 5.

I was the SCCA Club Rally Series Manager in 2004, and am starting my second year as technical director of Rally-America.

My position(s) have allowed my to participate in and attend testing with Hubert Gramling (who has also attended our events) and the FIA, Dr. John Melvein (IRL, OWRS), and NASCAR's Steve Peterson.

I was also a mechanic / pit crewman for 3 time Winston Cup champion David Pearson, 1983-85, and crew chief for a local ARCA and LMSC team.

So I have ties to the SFI foundation (they certify my scruiteneers) and the FIA, but none to HANS or any other manufacture.

..You may claim I'm part of a vast conspiracy against the Isaac, but my opinions, (Isaac won't pass the 38.1 frontal test) are just opinions, and probably academic given the SFI stand on the single release. I would be happy to be proven wrong by a sled test, because I also believe the dashpot idea is a promising one, I just don't believe they work well enough to pass 38.1 when attatched at a steep angle to the helmet (at rest), because this is common trait of all the devices (reaction link not approximately horizontal) that have failed to meet 38.1.

The Hutchens failed, a collar was added to make the reaction link nearly horizontal, and it passed.

Like I said, ..please prove me wrong.

Mike Hurst
Technical Director
Rally-America
SAE6115318102

[gsbaker]

Originally posted by Bildon@Dec 18 2005, 11:54 PM
Gregg,
Thanks for those clarifications. hmmmmmm
Great, now I'm not going to sleep so well
I'm going to be dreaming about 30 deg. impacts

[snapback]68669[/snapback]

I wouldn't lose any sleep over this. The HANS device is a good product. When used properly--proper belts and good lateral support--it will work well. My concern is that amateur racers don't recognize the importance of lateral seat support--or, put another way, think that they are as safe as a NASCAR or F1 driver with their vacuum-fit cockpit.

You have to keep things in perspective, also. 68Gs is a massive blast. We put enough cushion into component design to be good for ~120-150Gs; titanium versions to ~150+. At some point it all gets a little silly for most racers.

[Knestis]

I appreciate you chiming in here, Mike. I think the rally perspective, while not necessarily DIRECTLY related to IT-type cars on road courses, can be very useful. (But I'm kind of a rally guy, myself.)

Knowing the RA is now an SFI sanctioning body member, I'd be interested in your thoughts about SFI 38.1 specifically - not what it takes to pass it, but whether or not it is a sufficient approximation of "real crashes" in context (particularly as relates to rallying), or if it provides sufficient evaluative power to be useful to racers.

A cynic (and to be fair, you need to know that I include myself in this group) might suggest that the purpose of SFI is to protect member sanctioning bodies and manufacturers, but is it doing so to the detriment of individual racers' ability to make informed decisions about H&N systems?

Part of the SFI standards charter says that specifications will be revisited when warranted. Particularly with an eye on rallying, is there any movement to do this? Are you satisfied that the current standard is sufficient, to the degree that we can expect RA to issue a 38.1 requirement?

Thanks for contributing to an important conversation.

K

[gsbaker]

Originally posted by lateapex911@Dec 18 2005, 03:30 PM
...It is unfortunate that the HANS in this test wasn't the current model, and that "realspeed" video wasn't availble so we can see how it happens in real time.

[snapback]68636[/snapback]

http://www.isaacdirect.com/images/Video/DelphiSled.avi

Don't blink.

~7.5MB

Please right click, save as.

[gsbaker]

Originally posted by M. Hurst@Dec 19 2005, 12:32 PM
...You may claim I'm part of a vast conspiracy against the Isaac,

There is no conspiracy Mike, but there are some assumptions about what causes head loads that have been proven incorrect. That nonsense should have died with the last millennium.

...but my opinions, (Isaac won't pass the 38.1 frontal test) are just opinions....I would be happy to be proven wrong by a sled test

We can arrange that. Tell you what, we'll all meet at Delphi and hit an Isaac system of your choice (even the Link) head on. You say it will flunk, I say it will pass. I'll buy the beer and the loser pays the lab fee.

And we could have a contest. Whoever gets closest in guessing the final number wins. If the Isaac passes they get a free Isaac; if the Isaac fails they get a free HANS.

Anyone up for this?

...I just don't believe they work well enough to pass 38.1 when attatched at a steep angle to the helmet (at rest), because this is common trait of all the devices (reaction link not approximately horizontal) that have failed to meet 38.1.

They have a common trait, but that's not it.

[M. Hurst]

Originally posted by gsbaker@Dec 19 2005, 02:10 PM
We can arrange that. Tell you what, we'll all meet at Delphi and hit an Isaac system of your choice (even the Link) head on. You say it will flunk, I say it will pass. I'll buy the beer and the loser pays the lab fee.

If you claim that your device can meet all of the impact test result criteria of 38.1, then the financial (and moral) obligation is on you to perform all of the impact tests of 38.1 and prove these claims.

I'm not selling anything. ..'cept maybe Isaac devices if you're right.(figuritively)

I can be at delphi in less than 2 hours.

[planet6racing]

Do you have to hit the same device the required number of times for the SFI test, or do you change it after each test? It'd sure be interesting to run 3 tests on one Isaac and one helmet and one belt set, then do the same for the HANS...

[M. Hurst]

Originally posted by planet6racing@Dec 19 2005, 04:33 PM
Do you have to hit the same device the required number of times for the SFI test, or do you change it after each test? It'd sure be interesting to run 3 tests on one Isaac and one helmet and one belt set, then do the same for the HANS...

[snapback]68706[/snapback]

I brought up this point at a roundtable discussion last year, but was interupted by someone from the IRL who said "statistically there is no second major impact". This may be the case for Indy cars on ovals with spotters, where chain reaction wreck are less common now, but I thought it would be a design consideration (NASCAR Talledega?).

A second major impact would be rare because you've lost all of the car's energy on the first impact, but not impossible...and the most important point is the survivability of the occupant, not the device.

...but I can imagine getting turned into the wall at Road America's kink, and then sitting on the track and getting blasted by another car who's not heeding the caution, =2 big impacts

If you ever have a big impact, throw out all the safety equipment, and the seat too.

In answer to your question, in general, a new device and belts for each test.

Edit: BTW, It would be interesting to see one straight frontal test on the Isaac, much less three.

[gsbaker]

Originally posted by M. Hurst@Dec 19 2005, 04:43 PM
If you claim that your device can meet all of the impact test result criteria of 38.1, then the financial (and moral) obligation is on you to perform all of the impact tests of 38.1 and prove these claims.

I'm not selling anything. ..'cept maybe Isaac devices if you're right.(figuritively)

I can be at delphi in less than 2 hours.

[snapback]68702[/snapback]

C'mon Mike, I thought you were convinced we'd fail the test. Don't you want free beer?

[gsbaker]

Originally posted by planet6racing@Dec 19 2005, 05:33 PM
Do you have to hit the same device the required number of times for the SFI test, or do you change it after each test? It'd sure be interesting to run 3 tests on one Isaac and one helmet and one belt set, then do the same for the HANS...

[snapback]68706[/snapback]

I think the Spec calls for fresh belts each shot. We've hit the same helmet there more than once, but, of course, it had the magic adhesive.

We could probably hit this Isaac again, because it looks fine, is dimensionally correct and the dampers are smooth. I don't trust some of the metal components, though.

The HANS cracked in two places. Probably just a fluke; the lab techs were very surprised, and Dr. Trammel recommend replacement at the 100G limit.

[Chris Wire]

Originally posted by gsbaker@Dec 19 2005, 02:10 PM
And we could have a contest. Whoever gets closest in guessing the final number wins. If the Isaac passes they get a free Isaac; if the Isaac fails they get a free HANS.

Anyone up for this?

Free is my favorite four letter word!

Count me in.

[gsbaker]

Mike,

I understand your position on the straight vs. offset test, but we are not going to waste time running a test when we already know the outcome--especially a simple pass/fail test.

We are not aware of any comparative testing which resulted in the frontal load being higher than the offset load. When we crash tested the Wright Device earlier this year, John Melvin told me, "You may as well do the offset. If you can pass that you can pass the frontal."

This relationship is also illustrated by SFI's own numbers: the passing offset level is 4,000N, the passing frontal level is 3,200N. Same with the HANS device. They are advertising the frontal loads at ~16XX, and the offset loads are higher.

I see what you are getting at concerning the damper possibly functioning differently in the two tests--that's an interesting element you have brought up--but it doesn't pencil out when we run the numbers. All said and done, there is no reason why the loads would actually increase to 3,200N rather than decrease.

[gsbaker]

Originally posted by Chris Wire@Dec 19 2005, 06:41 PM
Free is my favorite four letter word!

Count me in.

[snapback]68712[/snapback]

Sounds like time for a road trip!

[M. Hurst]

Originally posted by gsbaker@Dec 19 2005, 06:09 PM
This relationship is also illustrated by SFI's own numbers: the passing offset level is 4,000N, the passing frontal level is 3,200N. Same with the HANS device. They are advertising the frontal loads at ~16XX, and the offset loads are higher.

No, the passing level for the frontal impact is 4,000N.

If the results of the first two frontal impacts are less than 3,200N, you're excused from a 3rd impact. A device can pull 3,999N frontal three times and still pass.

Do you have a copy of 38.1?

By your logic, since at least 2 frontal impacts are required, but only 1 offset, then the frontal is tougher than the offset?

I say the offset is tougher for the HANS, because of design.

[Chris Wire]

Originally posted by gsbaker@Dec 19 2005, 06:12 PM
Sounds like time for a road trip!

[snapback]68716[/snapback]

Can't do the road trip but would love another contest. I missed the last one by that l---------------------------------------------------l much!

[gsbaker]

Originally posted by Chris Wire@Dec 19 2005, 07:30 PM
Can't do the road trip but would love another contest. I missed the last one by that l---------------------------------------------------l much!

[snapback]68718[/snapback]

That's right Chris, I remember. You were very close.

A contest may be a good idea. It's always entertaining and boosts interest. Hmmm, any ideas? We're flexible.

Or we could have a sale. Perhaps a discount on all those old Isaac systems, "old" meaning we now certify them to meet SFI 38.1 performance specs, but we haven't lazer engraved the new label. We'll provide a certificate on parchment, suitable for framing.

Ooo, I like that one.

Thoughts anyone?

[gsbaker]

Originally posted by M. Hurst@Dec 19 2005, 07:30 PM
No, the passing level for the frontal impact is 4,000N.

If the results of the first two frontal impacts are less than 3,200N, you're excused from a 3rd impact. A device can pull 3,999N frontal three times and still pass.

Correct, provided the Nij is no greater than 1.00. Good point.

Do you have a copy of 38.1?

I do.

By your logic, since at least 2 frontal impacts are required, but only 1 offset, then the frontal is tougher than the offset?

No, I'm saying that throughout the history of crash testing, offsets have always produced higher head loads than frontals.

I say the offset is tougher for the HANS, because of design.

I suppose that's possible because some of the load reporting is inconclusive, but it is our understanding that other designs produce similar results. I don't have a fundamental disagreement with your theory, Mike, I just don't see our numbers jumping to 3,200 from 2,211. Perhaps HANS should test the Isaac.

[Knestis]

I'm kind of hoping that Mike will respond to my questions about the substance of 38.1, rather than focusing conversation just on meeting it. I wasn't asking rhetorically - I'd really like to get firsthand perspective on what it all means.

K