It's one and the same. A brilliant product would not need any assistance in side impacts--that's why it's brilliant (). If the H&N device has shortcomings, however, the driver must look elsewhere.

Ironically, all safety products are unsafe when not needed. Suits contribute to heat stroke, window nets hinder egress, helmets limit visibility, etc., so we are back to the issue of trade offs. But why make a trade off if you don't have to?

 

Maybe I missed something but non-full containment seats in general have poor shoulder and rib supports and plastic seats flex while unsupported metal seats deform. These seat properties allow a driver to spill from the seat upon impact regardless of what his head does. So isn't a sidenet supposed to be big enough to not only capture the head but lower onto the shoulder area to capture a driver? If so the sidenet has a dual purpose in a single item which would make John very happy. Therefore, the head capture of a sidenet is a bonus of a device and has proven itself in ontrack warfare. It is also then imperative that driver's realized the side nets need to be big enough to do both jobs and the HNR is really a non-issue since the sidenet provides protection with or without a HNR.

 

Ummm...

Of course you make a hugely salient point that all the stuff we use to keep us safe has drawbacks and requires compromises be made.

However, this still does not quite answer my question, nor clarify your statement regarding whether you feel that seat mounted head control devices are actually benificial. We have well established that all of the safety devices accepted as helpful have strengths and weaknesses. It is also apparent that the Isaac device seems to have some level of advantage in all axis related to noggin control.

Divorcing yourself from the efficacy of your product for a moment - if you kindly would (can? ) - put yourself in the shoes of the test engineer looking at optimizing the performance of devices "less optimal" in the lateral arena. Further, in the vast majority of cases where no H&N device is employed.

Question; Do you now see any advantage of seat based head retention devices?

 

Hey;

The general purpose of the side net is to augment the seat. If the seat were to break, or the occupant spill out of the seat, it is there to catch whatever comes its way. It is rather rare (from what I've seen) for the hips to escape the seat. The side net is there to catch the two items that do escape on a fairly regular basis; the head and shoulders. Thus, the straps of the net are placed at a height conducive to this capture; one at head level, one at shoulder level. The NASCAR side net pictured previously is a perfect example, assuming it is mounted at the height of the driver's pertinent assemblies.

Some NASCAR teams have taken to mounting the same 3-4-point side nets on the driver's side as well, to further improve the torso/head retention on the side where the head halo is far less restrictive.

 

Advantage? No. They improve the safety portfolio if they address other shortcomings in the system of course, but in and of themselves they are a negative. Who is safer with reduced visibility and egress?

The differences are not trivial:



and



You want a full containment seat (with fences, not wings), absolutely nothing above the shoulders and an ISAAC system. Every other combination is Plan B.

 

Greg while I like the ISAAC...

I have HANS and right side net and I am quite comfortable with that.

If I had an ISAAC I would comfortable on track, but quite nervious that one day it would be made illeagal.

Safety gear like this serves 2 purposes.
1) protect you incase somthing bad happens... This actually rare, but consquences are severe
2) Give you a nice comfortable feeling and allows you to sleep at night. (This effect is 24/7 365!)


So for me the choice is clear... HANS with side net and don't ever need to worry about SFI 38.1 or what my scantioning body may require...
Works for me.

 

That's fine 'til you get stuck going out the window.

 

I'm going to buy a H&N system in probably 5 months or so. I realize that the ISAAC is a superior product, but I won't be purchasing one. I thought there was something in the works for a single release for the ISAAC system?

 

Yes this is what I am getting at. I see too many right sidenets being too small either used as a head net or a shoulder net or in the middle and missing both. I think it was BSR products who made a nice big sidenet that fits the bill, but I see that little sprintcar Gforce elcheapo thing most often and it is too small.

 

Gbaker,

Chart 10 is with no sidenet and is a moment on the head relative to shoulders right and not comparing apples to apples. I'm no engineer but perhaps the relative moment of head to shoulders is zero with a sidenet if the whole body is ejected from the seat and captured in the net at basically the same instant. So while there is lateral force it is all without sheer on the head to neck joint. I think it was Dr. Melvin or Melville one of the biggest voices in safety that pretty much confirmed that sidenets are a huge benefit irregardless of and HNR use. The only way sidenets are a "no advantage" (egress aside) is if the seat contains the body 100% of the time and the ISAAC does its job 100% of the time. I'm not sure you can guarantee that especially with seats. We have all seen seats too old that crack or unsuporrted metal seats that fold. Either is a receipe for the body spilling out of the seat.

 

Melvin did not test an Isaac system.

The lateral component of the load was 35Gs. Offhand, I don't know the load limit for seat tests.

You make a good point. These systems are not well balanced. Why are we testing HNR at 70Gs when belts are tested at a lower level--well, pull tested to an equivalent lower level?

 

Sorry, Gregg, but I have to put in a voice to try to temper your enthusiasm for your product.

Background for those who aren't already aware: I use an ISAAC, am VERY VERY happy to have one, and have USED it in a couple of instances - most notably a lateral impact in my first season running it. Without a right side net (got one after that).

The basic underlying thread of occupant restraint is as follows: You can't stop the brain moving until you've stopped the head. You can't stop the head until you've stopped the shoulders. You can't stop the shoulders until you've stopped the pelvis. Anklebone's connected to the leg-bone, ya know.

You see this in the belts - the reason the 6-point belts are so much better than the 6-points is that they stop the pelvis sooner, allowing the rest of the restraint sequence to proceed sooner.

So as great as the ISAAC is in reducing the head/neck loads (and I can personally vouch for this from experience) - you've still gotta stop the shoulders. Furthermore, as pointed out already, seat-based containment is limited in its effectiveness - it's just not flexible to different angles, multiple impacts, etc. So adding a net gives you more flexibility with or without a full containment seat; in the event you do have an odd oblique impact, the net (properly installed) will actually help keep you in the seat, in that protected cocoon where you're safest.

PS - everyone here does have a fire system, RIGHT???

 

I agree on the right-side nets, Vaughn. They can compliment a seat that has "wings", don't alter visibility much and are out of the picture if you bail through the window. But I'm not certain they are necessary for a seat that has substantial "fenders". Couldn't hurt though, I guess.

I'm definitely not sold on the head surrounds/bolsters found on some seats--unless, of course, the driver is using an SFI H&N restraint.

 

Yes...this is what I understand Dr. Melvin to be saying. There is no question it helps HANS which has questionable lateral support but the point is that the sidenet helps under all conditions except egress.