definitive statement regarding PCA rules and ISAAC?
#31
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Bolts versus welds is a stupid thing to argue about. Either can be as strong as the other. If the bolt is the right size and the joint is properly designed. Lots and lots of very important things use bolts. Airplane wings. Helicopter blades. Elevators. Car wheels.
#32
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As I said, $50 head? Buy a $50 helmet.
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the problem with the airplane and helicopter analogy is that helicopter and airplane bolts go through a lot more scrutney and testing then the bolts used for roll cages unfortunately. It is all about money. They can charge $80k for helicopter blades, I tend to think they are spending a little more time finding a the right bolt with the correct tensil strength.
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While I'm open to correction, I don't think that Isaac has ever presented "head-on" sled hit data, although the 38.1 test protocol seems to require it. All the sled hit data you will see published about the Isaac system are for offset sled runs. I've read the assertion that "Well...if the offset hit data fall inside the acceptable window, we can mathematically predict that the head-on hits will too". Well...maybe...and maybe not. That's why, in this world, we test things rather than just rely on suppositions/predictions of performance.
So...next time the subject of the Isaac system comes up, ask "Has the system been tested in head-on hits, and if it has, where is the data ? If it has not, why hasn't it ?". If you don't show me all the data, I'll think you're hiding something, even if you're actually not.
So...next time the subject of the Isaac system comes up, ask "Has the system been tested in head-on hits, and if it has, where is the data ? If it has not, why hasn't it ?". If you don't show me all the data, I'll think you're hiding something, even if you're actually not.
THIS IS PURE CONJECTURE ON MY PART.
I don't know what a sled test costs. I don't know how difficult it is to schedule one either. I can't imagine either is easy to manage. If I had only the money/time for one test, it would most definitely be an offset test. They are the deadliest, and probably the hardest to model, anylize, or predict.
I don't know all the ins and outs, but I do know that Isaac has tested their device numerous times, with excellent results. They also eventually paid to have their device tested to the SFI standard, assumedly to prove a point, and knowing it would ultimately not be "certifiable" under the current statutes. I believe a HANS was also tested concurrently, perhaps as a baseline for comparison to a unit that "met" the standard.
I'm also willing to surmize that you COULD indeed predict with at least fair certainty that a device that performed well for offsets would perform at least as well or even better for straight on hits. They are the "easiest" to control in my understanding.
While I have used a head & neck protection system since 2001, I'm really curious why club racing sanctioning bodies are suddenly mandating them. Is it something demanded by their insurance carriers ? I'm glad that SCCA backed off mandating them, actually.
#35
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If bolt strength was an issue they would increase the mounting plate size and spec larger bolts. I think an M10 bolt (class 10.9) has something like 24,000 lb minimum yield strength. Multiply that by the number of bolts in a mounting point and the load shared by the adjacent mounting points and I doubt that hardware failure is the concern.
#36
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sorry for the somewhat ![offtopic](https://rennlist.com/forums/graemlins/offtopic.gif)
The physics would tend for me to disagree with the first part of your statement, but I agree with the latter part of your statement (regarding design overkill....sorry, no pun intended)
Displacement must be controlled (keep your head on your shoulders, in the same relative position to the rest of you)....priority # 1...check.
Next would be deceleration as we get to the end of the displacement. Assuming both devices would "keep your head on your shoulder" and keep moments to an acceptable anatomical limit, then next up on the menu would be intracranial soft tissue damage..in other words, keeping your brain from splatting against the forward wall of your skull, resulting in contusion to hemmoraging.
I view it in this manner (when I was discussing H&N restraints with my son when I bolted the Leatt brace to his neck the first time he wore it in karting)
2 men jump off a bridge, each with 10' of "tether".
One tether is a chain (zero stretch)
One tether is a bungee cord (LOTS of stretch, but limited to 10' when fully stretched).
Attachment to the person is the same for both (you pick how, except not around the neck please)
They both jiump.
Who comes home for dinner.
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The physics would tend for me to disagree with the first part of your statement, but I agree with the latter part of your statement (regarding design overkill....sorry, no pun intended)
Displacement must be controlled (keep your head on your shoulders, in the same relative position to the rest of you)....priority # 1...check.
Next would be deceleration as we get to the end of the displacement. Assuming both devices would "keep your head on your shoulder" and keep moments to an acceptable anatomical limit, then next up on the menu would be intracranial soft tissue damage..in other words, keeping your brain from splatting against the forward wall of your skull, resulting in contusion to hemmoraging.
I view it in this manner (when I was discussing H&N restraints with my son when I bolted the Leatt brace to his neck the first time he wore it in karting)
2 men jump off a bridge, each with 10' of "tether".
One tether is a chain (zero stretch)
One tether is a bungee cord (LOTS of stretch, but limited to 10' when fully stretched).
Attachment to the person is the same for both (you pick how, except not around the neck please)
They both jiump.
Who comes home for dinner.
2 men jump off a bridge, each with 2" of "tether".
Attachment to the person is the same for both and it is a hard foam cocoon which will absorb shocks like the inside of a helmet.
One tether is a nylon or polyester strap - limited stretch.
One tether is a damper.
Attachment to the person is the same for both (you pick how, except not around the neck please)
They both jiump.
Who comes home for dinner. I think they both do with the same level of, or lack of, injury.
Again, I don't deny that the damper is better. What I question is whether it has any real world benefit.
#37
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I think a closer analogy is this...
2 men jump off a bridge, each with 2" of "tether".
Attachment to the person is the same for both and it is a hard foam cocoon which will absorb shocks like the inside of a helmet.
One tether is a nylon or polyester strap - limited stretch.
One tether is a damper.
Attachment to the person is the same for both (you pick how, except not around the neck please)
They both jiump.
Who comes home for dinner. I think they both do with the same level of, or lack of, injury.
Again, I don't deny that the damper is better. What I question is whether it has any real world benefit.
2 men jump off a bridge, each with 2" of "tether".
Attachment to the person is the same for both and it is a hard foam cocoon which will absorb shocks like the inside of a helmet.
One tether is a nylon or polyester strap - limited stretch.
One tether is a damper.
Attachment to the person is the same for both (you pick how, except not around the neck please)
They both jiump.
Who comes home for dinner. I think they both do with the same level of, or lack of, injury.
Again, I don't deny that the damper is better. What I question is whether it has any real world benefit.
The HANS has always bothered me, especially the "evolution of recommendations and designs" regarding the retentive (or lack thereof) nature of the belts staying on top of the collar.....it's been a long path.
But again, I don't see how the device works in certain scenarios, I only see how the device might NOT work in certain scenarios.
Yes, I realize nature abhors perfection and prefers entropy.
My apologies.
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Isaac has not been head on tested, but its 1300N score in the offset test indicates that it should pass the head on test with ease (spec is 3200N for both tests).
Isaac won't pay for the head on test because they feel it's pointless if they still don't meet the single point of release (and paying a large licensing fee) to be certified.
HANS complains about Isaac posting fake test results where the HANS cannot stay in the harnesses. Despite several requests from Gregg at Isaac, Howard at HANS cannot clarify how the tests were faked or show any decent resolution videos of a HANS staying in a 3" harness.
NASA's response to protests of the Isaac not being allowed is (paraphrased) 'If you don't like it, race elsewhere'.
Isaac won't pay for the head on test because they feel it's pointless if they still don't meet the single point of release (and paying a large licensing fee) to be certified.
HANS complains about Isaac posting fake test results where the HANS cannot stay in the harnesses. Despite several requests from Gregg at Isaac, Howard at HANS cannot clarify how the tests were faked or show any decent resolution videos of a HANS staying in a 3" harness.
NASA's response to protests of the Isaac not being allowed is (paraphrased) 'If you don't like it, race elsewhere'.
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Isaac has not been head on tested, but its 1300N score in the offset test indicates that it should pass the head on test with ease (spec is 3200N for both tests).
Isaac won't pay for the head on test because they feel it's pointless if they still don't meet the single point of release (and paying a large licensing fee) to be certified.
Isaac won't pay for the head on test because they feel it's pointless if they still don't meet the single point of release (and paying a large licensing fee) to be certified.
HANS complains about Isaac posting fake test results where the HANS cannot stay in the harnesses. Despite several requests from Gregg at Isaac, Howard at HANS cannot clarify how the tests were faked or show any decent resolution videos of a HANS staying in a 3" harness.
#40
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So, to summarize... the feeling is that because it doesn't have a "sticker", it won't pass? Don't you think they'd use language that is more specific if that is what is required? I can only hope. Colin, I think you're a PCA scrutineer - your thoughts?
#41
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Couple of things to stir the pot even more.
Bolt in cages are allowed by the largest group of motorsports. (Circle track/Dirt track)
The issue with Bolt in cages, from my limited knowledge is the mounting points. I've seen a number of weld in, custom cages, that have extremely poor mounting points. I've also seen bolt-in cages with extremely strong and well thought out mounting points.
I could be talked into the opinion that bolt in cage with a dash bar would be safer than a weld in cage without one.
How many times out of 10 would the average weld found in a PCA or BMWCCA cage fail before 4 top grade bolts.
All that being said the cage that will be going into my next tin top will be a custom built weld in.
Bolt in cages are allowed by the largest group of motorsports. (Circle track/Dirt track)
The issue with Bolt in cages, from my limited knowledge is the mounting points. I've seen a number of weld in, custom cages, that have extremely poor mounting points. I've also seen bolt-in cages with extremely strong and well thought out mounting points.
I could be talked into the opinion that bolt in cage with a dash bar would be safer than a weld in cage without one.
How many times out of 10 would the average weld found in a PCA or BMWCCA cage fail before 4 top grade bolts.
All that being said the cage that will be going into my next tin top will be a custom built weld in.
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Nothing against the Isaac device but I wouldn't let it pass.
It simply does not meet the SFI 38.1 standard or the FIA standards.
#43
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Sorta like a Porsche not meeting the Yugo standard.
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I got an email yesterday from the race licensing group for PCA, with the following statement:
"Also, after June 1, 2008, a head and neck restraint meeting either the standards of SFI 38.1 or FIA 8858 will be required."
Since the scrutineers at each event seem to hold the final opinion on the rules, is the ISAAC not allowed after 6/2008? It meets the crash standards of 38.1.
"Also, after June 1, 2008, a head and neck restraint meeting either the standards of SFI 38.1 or FIA 8858 will be required."
Since the scrutineers at each event seem to hold the final opinion on the rules, is the ISAAC not allowed after 6/2008? It meets the crash standards of 38.1.
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It's all about the SFI sticker....actually the $ the sticker generates (I do not know the exact percentages, but on a $125 rib/chest protector, it's about $15 more for the same unit with the SFI tag)
This past season in karting, a spec was approved, SFI 20.1, for chest protectors for younger drivers (in the event of a crash where their sternum hit the steering wheel/column).
Now, there are lots of chest protectors that work (Kevlar body armor would also work), but it's simple. Don't see an SFI 20.1 label and/or they don't recognize the device as being on the list, you are failed at scrutineering.
A lot of parents had to go out and buy new safety gear with that little label.
This past season in karting, a spec was approved, SFI 20.1, for chest protectors for younger drivers (in the event of a crash where their sternum hit the steering wheel/column).
Now, there are lots of chest protectors that work (Kevlar body armor would also work), but it's simple. Don't see an SFI 20.1 label and/or they don't recognize the device as being on the list, you are failed at scrutineering.
A lot of parents had to go out and buy new safety gear with that little label.