For Your Viewing Pleasure

[M. Hurst]

Originally posted by Knestis@Dec 19 2005, 07:38 PM
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

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What's generally regarded as fatal neck loads, (4,000N) at the highest repeatable level we can test at (68G), frontal and 30deg offset.....I'm OK with that. There was talk from the SFI to update the seat belt standards to the level (68G?) of the H&N standard...good.

I would like to see them require 2 offset tests (demonstrate repeatability).

The single point of release...Yes for Rally, but Isaac release pins wouldn't bother me so much on a race track.

The seat and dummy position....The flat steel seat is not real-world representative, and no device gets any help from it, but there's so many variable with seats, that it's probably best to stick with it the way it is.


Is it applicable to rally? A definite yes considering the possibility of a frontal or low offset hit on a tree very near the road with almost no reduction in speed. No H&N device is going to help much when the tree trunk comes through the car and nails you in the side of your head. For that we need better cage standards (In progress) and a padded structure between the occupant's head and the outside of the car.

Another thing that bugs me about the tests I've seen: The tech and safety experts fidget for hours over mounting everything perfectly to the sled, getting the straps in the perfect position etc. I can see needing to do this to eliminate variables, but what about the real world where everything's not so perfect? How about Rally where you're bouncing out of a ditch before you nail that tree? The hardest hit I ever took was after doing a 360 on my roof! After the techs are done setting the dummies perfectly, I'd like to reach up and kick the dummy in shoulder, or mount the seat with a 40deg lean and duplicate a real world crash.

One more point, and I hope Mr. Baker will agree: There is a tendancy to oversimplify, and say "I'm safe because I have a H&N device"..which is like saying "My car is fast because it has a K&N filter". The mounting and angle of the belts, the relationship of the H&N device, belts, and seat, the seat and it's mountings, the strength of the cage, padding, and its location relative to the occupant..all of this has to be viewed as a complete system...but it still ain't safe, it's racing.

 

[Knestis]

Thanks, Mike - I appreciate the input.

K

 

[lateapex911]

This is a GREAT discussion.

I'd like to direct this to Mike, as he seems to have lots of experience, but I'd appreciate anyones thoughts as well.

I may as well put my foot in my mouth right away....in my crashing experience, I have never hit anything "square on". There has always been rotational (yaw?) aspects, and the hit has always been offset. Broke a couple ribs on the seat slapping the guardrail after being "turned" at Watkins Glen this summer.

Thats just my experience though.....what does the historical crash data tell us about the real world probablilities???

Or, if I were to look at purchasing a H&N restraint, and one of the factors influencing my decision was crash performance, would I be wise to weigh heavily the devises' offset performance ....more than the straight frontal performance????

 

[tderonne]

Side nets...

 

[ddewhurst]

Hi-jack

Posted by Mike.

***For that we need better cage standards (In progress) and a padded structure between the occupant's head and the outside of the car.***

Mike, if you have any data or test data on driver protection relative to door tubes please pm me @ [email protected] Example true NASCAR parallel tubes intruding into the door cavity & what I'll call the Rally "x".

Thanks

 

[Knestis]

Originally posted by lateapex911@Dec 20 2005, 02:05 AM
.....what does the historical crash data tell us about the real world probablilities???  ...

That's a hell of a good question.

One complaint that the headresraint.org proeject is trying to address is that issues like this get lost in the quest for repeatability. SFI 38.1 assures that a system will react in a particular way to ONE SPECIFIC crash. Is that the crash that we need to be protected from, that is most likely to inflict the injuries that H&N systems are supposed to prevent?

Particularly as more and more cars get data acquisition systems, we should be able to learn more about the complex dynamics involved. I was pretty sorry that I didn't have the DL1 on when I rolled at Rally TN. It doesn't handle Y-axis accelerations but it would still have been interesting.

K

 

[gsbaker]

Originally posted by M. Hurst@Dec 19 2005, 10:43 PM
...I would like to see them require 2 offset tests (demonstrate repeatability).

I disagree, and I'm disappointed that there is more than one frontal required. The reason is science and statistics. There will be little variation in the results given that the variables are so closely controlled--same input, same output.

If you have two numbers you have no idea where they fall on the distribution curve. Only a t statistic will help and for that, with an acceptable level of confidence, you need ~30 tests. Won't happen.

It might boost the feel-good factor, but there is no practical conclusion one can draw from multiple tests. It is much more productive performing variations with computer simulations.

The single point of release...Yes for Rally, but Isaac release pins wouldn't bother me so much on a race track.

You really need to speak with pro EMTs on this one, Mike. They much prefer leaving everything back in the car. For a conscious driver, I suggest you poll some of the users on this forum.

The seat and dummy position....The flat steel seat is not real-world representative, and no device gets any help from it, but there's so many variable with seats, that it's probably best to stick with it the way it is.
Is it applicable to rally? A definite yes considering the possibility of a frontal or low offset hit  on a tree very near the road with almost no reduction in speed.  No H&N device is going to help much when the tree trunk comes through the car and nails you in the side of your head.  For that we need better cage standards (In progress) and a padded structure between the occupant's head and the outside of the car.

Agreed.

another thing that bugs me about the tests I've seen:  The tech and safety experts fidget for hours over mounting everything perfectly to the sled, getting the straps in the perfect position etc.  I can see needing to do this to eliminate variables, but what about the real world where everything's not so perfect?  How about Rally where you're bouncing out of a ditch before you nail that tree?  The hardest hit I ever took was after doing a 360 on my roof!  After the techs are done setting the dummies perfectly, I'd like to reach up and kick the dummy in shoulder, or mount the seat with a 40deg lean and duplicate a real world crash.

They love seeing us show up at the crash lab...

How to test an Isaac system.
Step 1: Put helmet on dummy.
Step 2: Connect Isaac to belts. Click, click.
Step 3: Connect Isaac to helmet. Click, click.
Step 4: Push big red button.

One more point, and I hope Mr. Baker will agree:  There is a tendancy to oversimplify, and say "I'm safe because I have a H&N device"..which is like saying "My car is fast because it has a K&N filter".  The mounting and angle of the belts, the relationship of the H&N device, belts, and seat, the seat and it's mountings, the strength of the cage, padding, and its location relative to the occupant..all of this has to be viewed as a complete system...but it still ain't safe, it's racing.

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Big agreement there.

 

[gsbaker]

Originally posted by Knestis@Dec 20 2005, 10:14 AM
That's a hell of a good question.

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...with a very scary answer, I think.

A lot of crash data is not published, but the rumor we're hearing regarding the pro series is that the largest hits are lateral. I'll type that again so everyone knows it's not a typo: ...the largest hits are lateral, and frequently involve more than one impact.

With the belts coming off the HANS device, that's not good. Any way you look at it, you can only be confident of a HANS device if you have excellent lateral support or you only crash head on.

Granted, much pro racing is roundy-round and it would be reasonable to assume different crash types in road racing, but this explains why the new tin top seats are CF over beads/foam. Cost? Don't ask.

 

[JIgou]

Originally posted by M. Hurst@Dec 19 2005, 05:18 PM

...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

Uhhmmm......yeah. Luckily #1 impact into the wall wasn't too bad, so I didn't get to do the full test...but I still got to replace my car.

I'd put "multiple impacts" high on the list of possibilities.

Jarrod

 

[M. Hurst]

A couple of the latest seats (mass produced) with proper lateral support for the head and shoulder area.

Lajoie and Kirkey

 

[gsbaker]

The seat will need over 3,000# of lateral strength above the waist to hold up to the offset SFI test.

Are these strong enough for that, Mike?

 

[Bill Miller]

Originally posted by M. Hurst@Dec 20 2005, 12:00 PM

A couple of the latest seats (mass produced) with proper lateral support for the head and shoulder area.

Lajoie and Kirkey

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Mike,

Those both look like stock car / short track seats. I have the Kirkey Road Race seat, and from it's design, it does not look to be adaptable to the lateral head support. I am curious as to what the design considerations are for a short track / oval track seat vs. those for a road race seat.

 

[M. Hurst]

Originally posted by gsbaker@Dec 20 2005, 11:15 AM
The seat will need over 3,000# of lateral strength above the waist to hold up to the offset SFI test.

Are these strong enough for that, Mike?

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Both seats have mounting / reinforcement points in the shoulder / neck area for mounting to the cage...strong enough?..I think we're about to find out.

 

[gsbaker]

Originally posted by M. Hurst@Dec 20 2005, 12:32 PM
Both seats have mounting / reinforcement points in the shoulder / neck area for mounting to the cage...strong enough?..I think we're about to find out.

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The cage? That oughta do it.

 

[M. Hurst]

Originally posted by Bill Miller@Dec 20 2005, 11:29 AM
Mike,

Those both look like stock car / short track seats.  I have the Kirkey Road Race seat, and from it's design, it does not look to be adaptable to the lateral head support.  I am curious as to what the design considerations are for a short track / oval track seat vs. those for a road race seat.

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The head and shoulder supports are not "add ons" on these seats, the bases are designed for the supports (which in some cases are seperate pieces).

The seats appear to be symmetrical, and by the manufacturers claims, suitable for road racing. If I remember right from the PRI show, the Kirkey model shown did have a longer head support on the right side.

Remember, you don't want the head support without the shoulder support!

The old, alumimum "flap" type head and shoulder supports were useless in crashes.

Lajoie offers an "add on" system to bolt to an old-stlye common aluminum seat (any mfg), "safer system" on their website.

http://www.joieofseating.net/seats.html

http://www.kirkeyracing.com/seats.html

 

[planet6racing]

Not knowing exactly how these will mount to the cage in those areas....

I have to question the ability for that seat to absorb energy if it is that rigidly mounted in those areas. One of the biggest arguments held here (and we are NOT going to re-hash it!) is that the rear seat support for a non-FIA rated seat is actually a back breaker. I'd be concerned regarding a similar aspect here.

I still, as a road race, do not want one of those seats. I like to be able to see, to look ahead, and to turn my head to check the corner station at the last second...

 

[gsbaker]

You don't want a head surround providing lateral support. It just obscures your vision and hinders egress.

You want your Isaac system providing lateral support.

 

[M. Hurst]

Originally posted by planet6racing@Dec 20 2005, 12:22 PM
Not knowing exactly how these will mount to the cage in those areas....

I have to question the ability for that seat to absorb energy if it is that rigidly mounted in those areas. 

The seats not supposed to "absorb" energy, it's supposed to spead the load out evenly on the body. Your back needs to be held in place in relation to the chassis while the car is crushing and absorbing energy. This is not just my opinion, ask any recognized motorsports safety expert in the world.

The human body can withstand 100+G impacts without injury if it's supported well enough, (and no intrusion)...the IRL proves this almost every weekend!..They're basically sitting on a padded section of the tub!

A seat theat flexes very much is going to snap back (or break). The flexing that feels good for a 10 G impact can be fatal at 50G. H Gramling (FIA) had some interesting videos of rear impact testing of FIA seats, with the seatbacks breaking and subsequent (obviously) fatal loads.

 

[gsbaker]

Those IRL Gs are resultant values, typically with very short durations.

 

[Bill Miller]

Originally posted by M. Hurst@Dec 20 2005, 12:44 PM
The head and shoulder supports are not "add ons" on these seats, the bases are designed for the supports (which in some cases are seperate pieces).

The seats appear to be symmetrical, and by the manufacturers claims, suitable for road racing.  If I remember right from the PRI show, the Kirkey model shown did have a longer head support on the right side.

Remember, you don't want the head support without the shoulder support!

The old, alumimum "flap" type head and shoulder supports were useless in crashes.

Lajoie offers an "add on" system to bolt to an old-stlye common aluminum seat (any mfg), "safer system" on their website.

http://www.joieofseating.net/seats.html


[url='http://www.kirkeyracing.com/seats.html']http://www.kirkeyracing.com/seats.html[/url]

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Mike,

This is the seat I'm talking about

I've tried the circle-track seats, and don't find them well suited for road racing, especially in an IT or closed Prod car. I honestly don't see how the head supports from the other seats will work w/ the above pictured seat.