Agreed.

The probability of a compressive spine injury due to the angle change is small compared with that of a H&N injury resulting from no protection.

 

Sort of...

I'd make the sleeved holes horizontal, bolt the eye bolt through, then use the 3-bar sliders and spring clips.

You should be OK as it is, at least for one event. Adding the extra tube will make it quite near "perfect."

 

George,
It depends. From a technical or legal perspective?
As John H pointed out later, this topic tends to be more about marketing, legal and liability than personal safety. Sad, but not totally unexpected that there is an 800# gorilla in the room when it comes to H&N restraints, but no one seems to acknolwedge its presence at times.

Drilling a hole in a helmet has been deemed unacceptable from a legal/liability perspective with regards to voiding the warranty/certification. I think most can agree on this.
This is likely the reason why Stand21 (and others) are now offering helmets homologated/certified pre drilled for HANS....which of course leads to the question:
'Is a hole for a HANS different from a hole for an R3?", noting that both are SFI38.1 (worthless IMHO, but that is a topic for another time) certified devices.

Now, from a technical perspective, it can be argued whether or not the hole, the creation of said hole, stresses placed on the helmet during the production of said hole (laser cut, mechanically cut, high pressure water cut, etc) and the stresses on the helmet surrounding the hole in a crash due to tether stresses applied, would actually matter or not. This is fairly simple, as it is based on the laws of physics, not common law; this can be modeled or simply verified by experiment, again, simple engineering laws.

Now, if attaching an object to the outside of a helmet, WHILE PRODUCING NO MODIFICATIONS TO THE STRUCTURE OF THE HELMET, voids the warranty/certificaiton, please explain why.

If the object is a sticker, custom paintwork or a H&N restraint (ISAAC mount) applied with a binary adhesive (chemical reactions set aside for this argument), does it matter? Do these objects weaken the helmet structurally? Have you altered the state of the helmet from its initial certified/warrantied state?
Technically yes, but to a lesser degree than mechanical changes.

This discussion quickly devolves into a "if a tree falls in a forest and there is no on there to hear it, does it make a sound?".....more philosophy and semantics than physics. Same with the issue of attaching a restraint termination on a helmet with regards to liability.

HANS, R3, ISAAC.... as long as somebody wears something, then as John has pointed out many times, it's a priceless discussion.

 

Well sometimes things are not what they appear. I think you are on the right track but without testing and thought even something as simple as a binary adhesive can be a problem. The adhesive is not just glued to the helmet. The helmet is prepped with taping off a rectangle, cutting the gelcoat with a razor blade (not too deep!), scraping sanding teasing off the gelcoat, cleaning the underlayment, gluing the non-helmet shapped anchors. Lots of things can go wrong like are you putting stress risers in the rectacngle and now a weak point in the helmet? How about glue failure from operator error. ISAAC is great in that you can glue or screw. The process is pretty idot proof but then there are always better idiots.

 

That photo of the harness bar is mine. Be carfeul of a few points. If you make the holes front to back the snap clips and the eyebolts add to the dimension and you may haev to put a kink in your harness bar so that your seat back will not hit the set-up. Do not do my method of sleeved holes and use an eyeblt because eyebolts are not ment to be in shear but in tension. Moot point since they are large but thats the physics of it. I like bolt in anchors as thay are stronger than clip ins and I wanted the space because my seat is just about touching my bar at the headrest and only 2.5 inches from the seatholes to harness bar and I did not want to make a kinked harness bar. If you do just weld a straight bar on top of the old one be sure to buy the lock rings from macmaster carr that also prevent the belts from sliding first so that you can make sure the lower bar clears the lock rings. The only problem I don't like about my method is that the bolts are in single shear. But they are big 1/2" bolts and there are 4 shoulder straps in my set-up so I think I'll live. It is also an unnecessary pain to drill and sleeve the harness bar but what the heck it was kinda trick.

 

Agreed
I was merely following a rational line of thought to a somewhat irrational conclusion in an attempt to make a point.
I don't believe gelcoat is a structural element in a helmet. As far as chemical reactions, then one would have to consider helmet prep prior to custom artwork as potentially dangerous and hazardous.
Removing gelcoat by simple abrasive means (scuff) should not put stress in the corners, as no cutting/localized stress is applied.
As I said, mainly academic points in an attempt to establish a line of thinking.

 

I agree with you and understand. If you try to make the rectangle clean then you really need to tape it of and score the gelcoat with a razor blade. Then you can get the rectangle of gelcoat out perfectly and cleanly down to surface you can bond on. If you just sandpaper it off it looks bad IMO. Problem is that anytime you score something you put a potential stress riser in a material. That's how you cut and score glass before you snap it in half. I don't think this is a problem because you just want to be through the gelcoat... no deeper. But some guys really should stay away from sharp things and have otheres cut their meat or stick to hamburgers. Some people have the dexterity of cows. Contrast that with HANS and you drll one clean hole per side and most people can do that with a drill and not make a mess. ISAAC needs 4 holes per plate (or glue). With 4 holes people can be off center and put more stress into the helmet. Furthurmore the ISAAC plate is not contoured to the helmet so even more stress is placed into the helment when you just bolt it. When I did not ISSAC I glued and bolted. I wanted the glue to fillet in the areas that the ISAAC plate did not contour. It is a minor point but the connection is undoubtedly solid and puts minimal stress in my new holes that I drill in my now SFI voided helment. Yes...I am excessive you can see the pics of my rollcage and seat in a previous thread. Sorry for the thread hijack I went a little OT.

 

How many helmets have been tested by Snell with Isaac attachments in place?

This has nothing to do with warranties. Shoot, the helmet companies don't even want you to paint them. What it has to do with is how the helmet is tested by Snell.

Now, the reality is, people (including pros) paint their helmets, attach things do them like HANS, Isaac, radio wiring, drink tubes, you name it. IMHO arguing about this stuff is moot.

 

Agreed.
I was merely trying to point out some of the flawed logic behind the current 'rules' regarding certification and H&N restraints, many of which led M578 to purchase a 'certified' (and I still think SFI is a joke) personal safety device (HANS) vs. a non certified safety device (ISAAC) and then invalidate/modify a different safety device (helmet) because of it.
Sorry, as an engineer I tend to look at things different I suppose. No intentions of arguing at all, didn't mean it to sound like that.

 

We don't know, and we don't care. We already know what the results will be if tested. Besides, if you want to really test it you should test the entire assembly on a crash sled, as we have done repeatedly.

John's point is that rules/laws/regulations are always retrospective, so when something new comes along it's probably in violation of one rule or another and will remain so until the rules are changed. Our objective is maximum safety. If maximum safety breaks a safety rule, the rule should be changed.

This is what you are seeing with SFI 38.1. It's not a bad start, but as written it is dangerous. More drivers have died of head injuries while using SFI certified H&N restraints than non-SFI certified restraints. This trend will continue until the body count becomes so high it cannot be ignored by sanctioning bodies which, finally, are starting to get it.

 

This is a faulted statement. Since there are more drivers using SFI certified H&N restraints than non-SFI certified restraints, one would expect more fatalities with certified.

What we need to do as drivers, is to form a union and force the certifying community to set up a scientific, unbiased committie to assess these devices.

 

Fine, a higher percentage then.

That's what headrestraint.org is all about.

 

Since this topic has shifted somewhat, I have a question for Greg. Have you ever seen any helmet damage due to the H&N attachment when sled testing? It seems that would be a good time to look for it.

 

I don't mean to argue but do you have the data to support that?

 

Not for a final product. During our first test we attached one side with common rivets, just to see if it would work. It didn't and the results were rather ugly. (Headrestraint.org may publish the video as a "what not to do" advisory.)

The most common damage is to the shell, after the helmet smacks around the roll cage. If the mounts are attached with adhesive we can reuse the test helmet as is; if bolted we replace the bolts.

And to check for damage to the dummy that may have been caused by the belt connectors. So far, none, which is surprising.