WRC Deaths

What factor - if any - does harness-strap length have in all this (inclusive OR regardless of angle). I have a friend, he is an advocate of "longer is better" shoulder-harness straps; and of shallow angles (off the horizontal). His reasoning is, that the longer strap can "give and stretch, then spring back" a bit (or something like that, I may be inadvertently mis-representing what he was trying to tell me). Shorter straps have little give, little cushion.

Thoughts?

---

Parfois, on fait pas semblant!

I am:
I know:
I am from:

Nobody.
Nothing.
Nowhere.

Quote
Creech
What factor - if any - does harness-strap length have in all this (inclusive OR regardless of angle). I have a friend, he is an advocate of "longer is better" shoulder-harness straps; and of shallow angles (off the horizontal). His reasoning is, that the longer strap can "give and stretch, then spring back" a bit (or something like that, I may be inadvertently mis-representing what he was trying to tell me). Shorter straps have little give, little cushion.

Thoughts?

Personally, the least I move in a crash, the better. I doubt belts "spring back". If they stretch, they stretch methinks. That's kind of the thinking with the HANS, if your neck head doesn't move (much), a lot less likely to get hurt.

The human body can withstand a lot of G's, just not so much when it is applied at an odd angle or in a specific location.

Quote
HiTempguy

Quote
Creech
What factor - if any - does harness-strap length have in all this (inclusive OR regardless of angle). I have a friend, he is an advocate of "longer is better" shoulder-harness straps; and of shallow angles (off the horizontal). His reasoning is, that the longer strap can "give and stretch, then spring back" a bit (or something like that, I may be inadvertently mis-representing what he was trying to tell me). Shorter straps have little give, little cushion.

Thoughts?

Personally, the least I move in a crash, the better. I doubt belts "spring back". If they stretch, they stretch methinks. That's kind of the thinking with the HANS, if your neck head doesn't move (much), a lot less likely to get hurt.

The human body can withstand a lot of G's, just not so much when it is applied at an odd angle or in a specific location.

I try not to engage you in conversation and do not now intend to do anything but ask "You ever heard the saying "it's not the fall, it's the stop" ?

If I were to punch you hard right on your nose and you head was against a wall, it would hurt in a different way than if you head was not against a wall.
Further if you were drunk as a skunk near liquid--ie no muscle tension but close to a Salvador Dali painting drunk, the punch would be even less of an impact.


Have you even thrown yourself down on the ground while traveling at 70-75ish mph?
It didn't hurt much did it. because you keep skipping along.

But slam into rock wall at even 10 mph, that hurts more..

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
Creech
What factor - if any - does harness-strap length have in all this (inclusive OR regardless of angle). I have a friend, he is an advocate of "longer is better" shoulder-harness straps; and of shallow angles (off the horizontal). His reasoning is, that the longer strap can "give and stretch, then spring back" a bit (or something like that, I may be inadvertently mis-representing what he was trying to tell me). Shorter straps have little give, little cushion.

Thoughts?

I think the idea with limiting belt stretch is so that you slow down with the car in a crash. That way the crumple zone can do its work to dissipate the energy of the crash over a longer period of time. If the belts are allowed to stretch more that creates more of a speed differential between you and the car. So the car is slowing down while you are not. Once the belts reach the end of their stretch you become the crumple zone. Thats how I see it, anyways.

I stand corrected... Shorter belts are better....

---

First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

Quote
john vanlandingham
Blame is for idiots. losers.

Edited 1 time(s). Last edit at 08/30/2013 01:31AM by Morison.

Quote
john vanlandingham
I try not to engage you in conversation and do not now intend to do anything but ask "You ever heard the saying "it's not the fall, it's the stop" ?

If I were to punch you hard right on your nose and you head was against a wall, it would hurt in a different way than if you head was not against a wall.
Further if you were drunk as a skunk near liquid--ie no muscle tension but close to a Salvador Dali painting drunk, the punch would be even less of an impact.


Have you even thrown yourself down on the ground while traveling at 70-75ish mph?
It didn't hurt much did it. because you keep skipping along.

But slam into rock wall at even 10 mph, that hurts more..

What exactly is your point? Are you trying to say that it is best to be loose in the car during a crash?

My understanding is that, again, it's a trade-off. A little stretch is good for a frontal, but stretch that would allow the person to shake from side-to-side in a roll-over could be deadly.

Schroth makes a funky belt for street cars that tries to walk a fine line down the middle. The inside shoulder's belt is designed to stretch more than the outside. Thus, you have some give (and a way to escape the roof if you roll a cageless car), but you don't end up banging against the window or flying out of your seat.

Quote
Ferdinand
Unless you keep your belts cinched so tight that you're already in danger of compressing your spine...

Quote
Josh Wimpey
It was always my impression that the lap belt was designed to hold you DOWN into the seat by your pelvis while the shoulder belts should hold you BACK into the seat. So, any time the top of your shoulder/HANS assembly sits above the bottom of the harness slot-opening, it has the potential to induce vertical spine load (even if the attachment point is horizontal or even with the height of the shoulder/HANS). In my case, this is made even worse because in most seats, the harness slots through the hole and then up and over the shoulder/HANS effectively magnifying the leverage of the harness to induce a vertical load.

Excellent point, Josh. Being 6'-3" tall myself, I have the same issues as you.

But the root cause here is improper belt routing. That's dangerous in any case. The additional height of the HANS can contribute to that problem, but it is not the HANS that's causing the problem. It's still improper belt routing.

Quote
Josh Wimpey
The Hans yoke & padding adds about 1" in total height to my shoulders which already exceed the height of most race seat harness slot openings. So, now the harnesses induce additional vertical load on the spine in both frontal and vertical impacts.

In a frontal impact, certainly. In a vertical impact, not necessarily.

If you're talking about dropping inverted onto the roof, then maybe. But even in that case, the shoulder belts are already pre-loaded with whatever tension you've applied while cinching them tight. Your body will ultimately apply the same vertical (upwards) load into the harness either way. With the belts already pre-loaded (as opposed to slack) that same ultimate belt load will be reached earlier, possibly keeping your head from smacking the roof.

In a downward vertical impact, (i.e. hard landing off a jump, suspension bottomed, floor hitting the ground), your body mass is pressed down into the seat, relieving tension in the shoulder belts. The HANS plays no role whatsoever in such in impact.

Quote
Josh Wimpey
Wearing a HANS requires that you wear your belts tighter than you might have previously--this may be because you used to wear them looser than you should have and never noticed until your HANS was slipping around underneath it.

Belts should always be tightened snugly. But there is no need to tighten them more than you normally would have without a HANS. Obviously they need to be at least tight enough to prevent the belts from slipping completely off the HANS while you're jiggling around in the car. But not so tight that you can't breath.

In a severe enough frontal impact, where the benefits of the HANS are actually required, your body will be pressed forward into the shoulder belts hard enough to induce several thousand pounds of belt tension. That will certainly be sufficient to keep the HANS in place against your shoulders, even if the belts were slack to begin with.

Quote
Ferdinand
Excellent point, Josh. Being 6'-3" tall myself, I have the same issues as you.

But the root cause here is improper belt routing. That's dangerous in any case. The additional height of the HANS can contribute to that problem, but it is not the HANS that's causing the problem. It's still improper belt routing.

Agreed completely. Point is, if your belts attach to the cage close behind your seat and you go from no HANS to HANS, you likely need to move the harness bar and I doubt that many people other than top teams and new builds do this....

---

____________________________________________________________-

One. Class -- 2WD

www.quantumrallysport.com

http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf

Quote
HiTempguy
That's kind of the thinking with the HANS, if your neck head doesn't move (much), a lot less likely to get hurt.

The primary function of the HANS is to stop your skull from tearing away from the spine in a severe frontal impact.

The belts restrain your body, keeping it from moving forward. Your head, without a HANS, is restrained only by your neck. Your head keeps moving forward after your body has already stopped. The heavy mass of your head will whip around on the end of its tether, i.e. your neck.

If the deceleration is severe enough, and the forces on your neck are high enough, separation will occur at the weakest point. Typically that would be a basal skull fracture. Effectively the top of your spine tries to tear a chunk out of the bottom of your skull.

Quote
wikipedia
"Basilar skull fractures are a common cause of death in many motor racing accidents. Drivers who have died as a result of basilar skull fracture include Formula One drivers Roland Ratzenberger and Ayrton Senna, Indianapolis 500 drivers Bill Vukovich, Tony Bettenhausen, Floyd Roberts, and Scott Brayton, NASCAR drivers Dale Earnhardt Sr., Adam Petty, Tony Roper, Kenny Irwin, Jr., Neil Bonnett, John Nemechek, J. D. McDuffie, and Richie Evans, CART drivers Jovy Marcelo, Greg Moore and Gonzalo Rodriguez, and ARCA drivers Blaise Alexander and Slick Johnson.

To prevent this injury, all major motor sports sanctioning bodies now mandate the use of head and neck restraints, such as the HANS device."

The HANS allows the head to swing forward only so far, until it stops at the limit of the HANS tethers. At that point your head is cushioned into the top of your helmet, while the tension loads on your neck are relieved and transferred instead via the HANS tethers to the shoulder belts. Under these same massive deceleration loads, the HANS device itself is firmly clamped between your body and the shoulder belts.

Quote
Carl S
What factor - if any - does harness-strap length have in all this (inclusive OR regardless of angle). I have a friend, he is an advocate of "longer is better" shoulder-harness straps; and of shallow angles (off the horizontal). His reasoning is, that the longer strap can "give and stretch, then spring back" a bit (or something like that, I may be inadvertently mis-representing what he was trying to tell me). Shorter straps have little give, little cushion.

Thoughts?

Quote
Creech
I think the idea with limiting belt stretch is so that you slow down with the car in a crash. That way the crumple zone can do its work to dissipate the energy of the crash over a longer period of time. If the belts are allowed to stretch more that creates more of a speed differential between you and the car. So the car is slowing down while you are not. Once the belts reach the end of their stretch you become the crumple zone. That's how I see it, anyways.

Carl is correct.

Quote
the longer strap can "give and stretch, then spring back" a bit

While there may be some benefit from give and stretch in certain limited circumstances, you never want anything to spring back.

For example, take a stuntman diving off a building and smacking into the sidewalk below. Obviously the sudden stop when hitting bare pavement is going to leave him in a splattered mess. But landing on a trampoline is not necessarily any better as it's going to launch him straight back up into the sky.

The best solution in every case is to decelerate as gradually as possible over as great a distance as possible until safely stopped. Hence the air bag. The stuntman uses a giant air bag to land on. When he hits the air bag, energy is absorbed (not reflected as by a trampoline) as air is forced out of the bag through vents. The volume of air originally in the bag, and the size of the vents, determines how much energy can be absorbed before the bag bottoms out.

In a rally car, it is the deform-able crush space outside of the rollcage that acts as your airbag. You want those zones to crush and absorb the impact, without springing back, in order to decelerate your safety cell as gradually as possible over as great a distance as possible. In a severe impact, like into a tree, all of that happens within milliseconds.

You want to be tied as tightly as possible to your safety cell in order to ride down the impact and take advantage of all the available crush space. If your belts are loose, or they give and stretch, you're still going to be moving long after the car has already stopped. Rather than slowing over the distance of the available crush space, you're now going to stop in whatever distance is made available by the belt webbing (or other interior features of the car) crushing you.

In that case, yes, it is an advantage if the belts stretch and give to the maximum extent without allowing you to contact any hard interior items in the car. But good luck with that...

Perversely, modern restraint systems in road cars have an astounding amount of give and stretch.

Seat belts come with pre-tensioners which, when triggered, fire an explosive charge to cinch the belts tight to remove any slack. That's a great idea. However, as belt loads mount during the crash pulse, once a certain level of belt tension is reached, the webbing is allowed to spool out. The idea is, especially with an aging population, ribcages can only withstand a limited amount of compression when applied by a single 2-inch wide belt. Rather than crushing the chest, it is better to allow the webbing to spool out and then catch the occupant on a nice soft air bag.

All of these systems are designed, optimized, and tuned to work perfectly in the government specified laboratory tests using a variety of standard sized test dummies. The USA even has a five-star NCAP rating system using various frontal, side, and rollover tests, beyond the normal regulatory requirements.

There's no doubt that cars are safer as result, because the statistics prove it.

But, these systems allowing belts to spool out and relying on air bags which are finely tuned to five-star perfection in each of these defined tests, are all a one-shot deal. After those systems are spent, you've pressed all the air out through the vents of the air bag, you're left with a yard of spooled out belt webbing loosely pooled in your lap, it's no good at all if your car subsequently does multiple barrel rolls, or is hit again by another car. Hence the need for more curtain air bags that drop down to cover the side windows. Even once they've deflated they still act as a window net to prevent the (now effectively unrestrained and uncushioned) occupants being ejected out the windows.

Rally cars have no airbags.

You're relying solely on your harness and seat to hold you firmly within your protective rollcage. Everything outside of the cage can be crushed to slow you down. Everything inside the cage has to stay firmly in place.

You do NOT want your belts stretching and giving!

Quote
johnhuebbe

Quote
john vanlandingham
I try not to engage you in conversation and do not now intend to do anything but ask "You ever heard the saying "it's not the fall, it's the stop" ?

If I were to punch you hard right on your nose and you head was against a wall, it would hurt in a different way than if you head was not against a wall.
Further if you were drunk as a skunk near liquid--ie no muscle tension but close to a Salvador Dali painting drunk, the punch would be even less of an impact.


Have you even thrown yourself down on the ground while traveling at 70-75ish mph?
It didn't hurt much did it. because you keep skipping along.

But slam into rock wall at even 10 mph, that hurts more..

What exactly is your point? Are you trying to say that it is best to be loose in the car during a crash?

Oh for fuckssake---that INSTANT stop is the what creats hurt, that some squirm or wiggle is fine--that the common "I get the SM domina and her slave to pull the belts so tight I can't budge---then I exhale and have him pull the thing tighter till I'm about to pass out"

Is typical bullshit "if this much is good, way in excess is obviously better" bullshit, that some movement at limits allows deflection, lessening of POINT loading.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

In a side discussion on this, the issue of belt stretch has been shown to me in a different light. The key bits of information are:
- Everything happens over time.
- The rate of deceleration of the car shell in an accident isn't uniform - it actually increases through the first bit of the accident.
- The belt stretch is neither linear nor infinate, at some point you will reach the limit of the stretch.
- you will reach the limit of the stretch before the car reaches peak deceleration.

The result is that you end up putting higher loads on the body as you run out of stretch and your body ends up facing higher forces. This is supported by crash testing, or so I've been told by someone I trust. It also makes a lot of sense when you look at it without prejudice.

Now the interesting extrapolation from this.

Could lumbar injuries be aggravated by more cushioning in the seats being used?
Makes more sense than the HANS device being the cause.

---

First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

Quote
john vanlandingham
Blame is for idiots. losers.

Quote
Morison
- The rate of deceleration of the car shell in an accident isn't uniform - it actually increases through the first bit of the accident.

The shape of the crash pulse is highly dependent on what you hit, and with which part of the car you hit it.

The reason laboratory tests are done against a flat wall is that the results are consistently reproducible. The wall never changes. It can always be expected to connect with the bumper first, transferring loads as expected through a well defined load path via bumper supports directly into the collapsible frame members behind that.

How those frame members fold and collapse then determines the shape of the deceleration pulse. It certainly isn't a uniform smooth pulse. Those collapsible members are designed and tuned to "smoothly" absorb a certain amount of crush, depending on the mass of the vehicle and the required test configuration. Things eventually get much stiffer as the beams are crushed beyond their intended range and then other hard solid things start stacking up together, uncrushable stuff like engine blocks etc.

Offset wall impacts are also fairly predictable with the load path centred on only one of the bumper supports and from there into just one of the collapsible frame members.

It starts to get a lot more complicated if you run into something relatively soft, like broadside into another car, or into the more modern aluminum honeycomb barrier faces. In that case, the old-style bumpers mounted to two hard points on a collapsible vehicle frame might not collapse at all. Instead those two hard points will just punch straight through the soft barrier face, or through the soft broadside of the other vehicle, or under the other vehicle's bumper, while all the soft stuff like headlights, grill, rad, hood etc get shaved and peeled back from the stiffer frame members.

It gets worse. Things start getting totally unpredictable if you hit something other than a flat wall, like a tree. If you're lucky enough to hit the tree directly with one or the other of the bumper supports, then you'll have the benefit of directing the crash loads into one of the crushable frame members. Or maybe you can hit it centred on the engine. But if the tree misses either of the bumper supports and you have the tree come between the frame rails, missing the engine too, then you're going to see a whole lot more intrusion through the hood.

Or, if you do a Kubica, and have the sharp end of a guardrail entirely miss all the hard points and instead come straight back to punch through the firewall, well that deceleration pulse is certainly going to look a whole lot different than hitting squarely into a flat wall.

Quote
Ferdinand
The shape of the crash pulse is highly dependent on what you hit, and with which part of the car you hit it.

Understood. The only point I was trying to make with that is a crash, even into a brick wall, is anything but instantaneous.

---

First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

Quote
john vanlandingham
Blame is for idiots. losers.