[Potomac-Greg]

Originally Posted by Vicegrip

Ding! 3 point systems don't put the same forces on the body that 4 or more point systems do.

So I guess that means a head/neck device just isn't necessary or beneficial unless you're in a harness-equipped car.

[Jazzbass]

Originally Posted by Potomac-Greg

So I guess that means a head/neck device just isn't necessary or beneficial unless you're in a harness-equipped car.

That has always been my understanding.

[John]

Originally Posted by Irfan

I'm planning to get a HANS and would appreciate some advice on which model(s) to get.

Do yourself a favor and go to OG and try them on. Bring your helmet. Bring your car if you have seats/harnesses. If not, sit in the seats they have on display. I thought I knew what I wanted, but when I got there and spoke with the OG staff, I ended up with a different model than what I expected (the 30 degree model fit me better than the 20 degree).

[CanAm]

So are you guys saying the R3 isn't helpful?

[CanAm]

Originally Posted by John

Do yourself a favor and go to OG and try them on. Bring your helmet. Bring your car if you have seats/harnesses. If not, sit in the seats they have on display. I thought I knew what I wanted, but when I got there and spoke with the OG staff, I ended up with a different model than what I expected (the 30 degree model fit me better than the 20 degree).

Definitely will do, and thanks for the suggestion.

[Trak Ratt]

Originally Posted by Irfan

So are you guys saying the R3 isn't helpful?

Didn't hear that. Sounded more like no real data one way or the other.
But from looking at it, analyst not an engineer, it looks like keeping your upper torso ridged would cause your lower body to twist at the hips using a 3 point.

[BobNovas]

It's safest if you just go slow.

[Dr K]

Originally Posted by BobNovas

It's safest if you just go slow.

You would know!

[Potomac-Greg]

Originally Posted by Irfan

So are you guys saying the R3 isn't helpful?

I think the point / theory is that if you are not wearing a harness, your body will flex forward on impact, changing the stress on your neck into a more linear one, where a harness holds your torso and the head goes laterally forward (if that's possible ). And none of this considers the effect of airbags that a street car is likely to have.

[Vicegrip]

This is what I have noted. YMMV.
Next time you are around someone wearing an R3 grab it by the bottom of the brace and pull out with some force. You will notice that it comes away from the body a good amount. Now lift up. You will see that it lifts up a whole lot. (You might want to ask the wearer first for best results) The body will compress change shape and the chest strap will give up a lot of slack. Even when the chest strap is chinched up tight enough to cause a bit of discomfort it will dig in to the blubber, the ribs and guts, will compress and let in plenty of slack. Keep in mind that the R3 is only of use during a high G event and a high G event will have far more energy than you can get away with with the test subject in the paddock. OK so when needed the back board thing is not held as tight to the body as people often think. With a 3 point system you are not held upright and your back is not held tight to the seat back during an impact. (not too tight in a 6 point ether) Without the shoulder straps to catch the winglets on the R3 system the device simply follows along with the moving compressing body and this produces more slack than you have in your neck.
Important part to think about. H&N systems don not keep your head from moving foward. Your head will, not might, will move foward and the crown of your head will point at what your car just hit. H&N systems all work by keeping you mellon from extending too far away from your shoulders. The R3 can be lifted up many inches and can move more than your neck can extend. This is why the R3 has the wings that rest on your shoulders. The wings are what keep the relationship between your head and shoulders inside the range for survival.
I get the feeling that people think it will work like some kind of lever between the chest strap you shoulders and head. The problem with this is that the shoulders are moving and compressing and changing shape and lacking the shoulder straps it has nothing to lever against. For the most part the chest strap only keep the thing in place when you are walking around. If your chest and back were not flexable it would work better.

Google sled tests of standard seat systems and 5+ point systems and look at the body movement and shape change. Rag doll comes to mind.

Safety is a system. As an Instructor my safety system is control of the car via my student.