01-26-2022, 01:27 PM | #15 | |
Drives: 2017 SS 1LE, 2016 1SS (previous) Join Date: Apr 2016
Location: Metro-Detroit
Posts: 1,863
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-The head going backwards is supported/restrained by the seat. The MX/ATV brace wouldn't really do anything here as it's design targets, most substantial, a reduction in that direct, where the seat will already do this. -The head going forward is the big issue in a track vehicle - high speed = high forces/high acceleration on the head. The MX/ATV brace, I don't see how will help much here as it doesn't prevent the head from going forward, only slightly limiting how forward can go. An automotive head restraint (HANs, Hybrid, etc.) significantly limits how much the head can go forward and tethers that movement to the body (couples the force absorption to the body). |
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01-26-2022, 02:57 PM | #16 | |
Drives: 2020 ZLE A10, 2018 F250 Diesel Join Date: Apr 2020
Location: Atlanta
Posts: 148
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Quote:
Not to derail the original post. I think a Hans is a great idea in a race car. I just wonder if that’s true with an airbag equipped vehicle with factory components. Maybe that’s why they don’t make more hybrids? |
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01-26-2022, 03:27 PM | #17 |
Drives: 2018 ZL1 1LE Join Date: Oct 2018
Location: New England
Posts: 13
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Related to the above post, understanding what head and neck restraints do may lead you to conclude that, while they are critical in a racecar, their use in a street car, even on track, might be cosplay.
First, what are they designed for: Protecting the wearer from a basilar skull fracture (BSF, a break of a bone in the base of the skull) during a rapid forward longitudinal deceleration (generally a collision) in a racecar having a racing harness. The latter is important because a racecar harness does not stretch. The former is important because there are other ways to suffer BSF in a car that restraints can't help; e.g., lateral penetration of the car by an object contacting the helmet. And second, some reasoning: 1) OEM marketing: Manufacturers market these for racing in racecars, not street cars, and detail why they are a benefit in that capacity. This really isn't scientific evidence, but it does foreshadow some of the following. 2) Dearth of literature on street-car BSF: What little one can find in street-car BSF is buried in general collision studies and is almost always the result of cabin penetration by an object or significant cabin deformation--basically accidents that were not survivable regardless of safety equipment. If restraints worked in street cars, we'd expect to see studies demonstrating this (why? Because the bread and butter of academics is finding something new, and showing that street-car BSFs are common enough to address would easily get funding or contribute to tenure, and would breeze past any Ph.D. dissertation committee, never mind leading to proposals for "head seatbelts" or other BSF-related safety items). 3) Wealth of literature on racecar BSF: Lots of papers in the literature on BSF in racecars--it's definitely an issue in racecars (but why? Read on!). 4) Street car seatbelts: Street car seatbelts and tuner belts (e.g., Schroth) are really ingenious designs. Unlike racing harnesses (and by the end of this sentence you should see why you should never install a racing harness without 5 or more points, a race seat, cage, and HANS), street-car and tuner harnesses stretch, first to bend you at the waist so you can't submarine underneath (smart, right?) then to prevent deceleration injuries by ensuring the driver/passenger decelerates more slowly than the car itself. It does this often in two ways: one is the natural stretch in the material due to its weave (that's why you need to replace your belts after any accident); the other (sometimes) is a section of belt that is folded on itself with stitching that will rip with enough force, then unfolding to make a longer belt. And these make it hard to experience BSF in a street car (and easy in a racecar). A ton of info on this is provided by Schroth at the HMS Motorsport site. And yes, seatbelts are pretty phenomenal. 5) Airbags: I'm tired of typing, hopefully this one is self explanatory (i.e., how far can your head travel when it's hitting an airbag?). 6) Unintended consequences: Better is not always better--could head restraints in street cars cause unforeseen problems (e.g., two concussive events vs. one due to the first when reaching the end of the tethers followed by a second contacting the bag?); probably not, but never assume that all race stuff is better (try commuting in your DD using race pads and see how much "better" that is; related, apparently one race school has gone to "less safe" open-face helmets because they have found that the maxillofacial bar can cause neck injuries upon contacting the airbag). Check with the manufacturer. This is all just based on my research and you should certainly conduct your own (though if you want factual information, try to avoid anecdotes, feel good "peace of mind" thoughts, best guesses, gut instinct, and advice from the fastest guy at the track) and find what works for you. Just some thoughts; the best experts on this are at the HANS OEMs--it would be great to hear from some of their biomechanical and/or human dynamics engineers. Enjoy the track! |
01-26-2022, 09:10 PM | #18 |
Drives: 2020 ZLE A10, 2018 F250 Diesel Join Date: Apr 2020
Location: Atlanta
Posts: 148
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Thank you for the write up and very detailed explanation. I think that is very beneficial to everyone. I really do appreciate it. I tried doing some searches on Hans devices in street cars and really couldn’t find much info related to street cars. All the literature was around race cars with safety harnesses, race seats, no air bags and cages.
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01-27-2022, 05:27 AM | #19 |
Drives: 997 GTS, ZL1 A10, ZLEM6, ZLEA10 Join Date: Dec 2017
Location: NYC/NJ
Posts: 630
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I suffered a front collision in my ZLE into a concrete pillar (immovable) at a speed of 80-100 mph (I don’t know the exact speed as you can imagine). The full front of the car was crushed. However the windshield was intact if that gives you a sense of the impact. I do not wear any device - all stock. The only thing I do is to “lock” my seat belt so that I am not sliding around.
The front airbags deployed and the helmet did what it’s supposed to do. I am thankful to say that I did not need as much as an ibuprofen the next day and walked out of the car and cleared concussion protocol and did not pass out etc. I did have what is referred to as a post concussion syndrome for 3 months - which is like a lingering haziness that comes and goes. I have to say with the stock set up - I feel very confident that a front collision - the car is designed well and I do not see the need for a additional device. I further believe (right or wrong) that safety is a system - not one device by itself. And mix and match of systems is not going to make you more safe - but in most cases make you less safe. I am sticking to the OEM setup for now. |
01-27-2022, 06:34 AM | #20 | |
Drives: 2004 BMW 330CI, 2022 1SS 1LE Join Date: Dec 2021
Location: NC
Posts: 759
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01-27-2022, 07:50 AM | #21 | |
Drives: 2023 ZLE Join Date: Jun 2009
Location: Detroit
Posts: 1,717
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01-27-2022, 07:52 AM | #22 | |
Drives: 2023 ZLE Join Date: Jun 2009
Location: Detroit
Posts: 1,717
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01-27-2022, 12:58 PM | #23 |
Drives: 2020 ZLE A10, 2018 F250 Diesel Join Date: Apr 2020
Location: Atlanta
Posts: 148
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Yes and a race Kart is more akin to a race car with a race seat and race harness. Definitely makes sense there.
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01-27-2022, 03:33 PM | #24 | |
Drives: 2017 Blue Camaro 1SS 1LE with PDR Join Date: Sep 2018
Location: Houston, TX
Posts: 966
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Quote:
After driving on 100 treadwear tires for the first time, I decided that it is worth buying a Hybrid S for the peace of mind. The added weight of the helmet works against you if you ever have a big frontal impact on track without a Hybrid S. |
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01-27-2022, 05:05 PM | #25 |
Drives: 2018 ZL1 1LE Join Date: Oct 2018
Location: New England
Posts: 13
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Thanks for this--I see that I could have been more clear. In terms of research papers, I was referring to all the literature I looked at for automobile BSF. This included street cars on the street (the point being BSF doesn't seem to present in street cars operated on the street outside of catastrophic, otherwise unsurvivable accidents which makes one--or at least me--wonder, why doesn't it?). I didn't expect to find any literature on street cars used on track (and I didn't) and I certainly didn't expect to see any literature on racecars used on the street (and didn't; I was actually surprised how much was published about BSF and racecars on track, i.e., there's not a lot of examples/case studies and how many ways can you study the same cases?!). To summarize maybe a little more clearly, the literature would seem to indicate there are relatively little to no preventable (i.e., with a head restraint) BSF in street accidents, which is not the case in a racecar and the reason would seem to be the function of the street belt and bag vs. the race harness. And again, these are just some ideas--it would be great to get contributions from some HANS experts. And absolutely no judgement here on any peace-of-mind or other views, I'm simply deeply interested in this area--and safety in general--and am always very open to hearing other data- or science-based evidence and ideas. Sorry I was confusing about that and thanks again for pointing it out!
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01-27-2022, 07:14 PM | #26 |
Drives: 2021 2SS 1LE Join Date: Aug 2020
Location: Cary, NC
Posts: 807
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I just bought a Hybrid S at the end of last season.
Was planning on getting one anyway, but happen to have my first significant off-track excursion at VIR (90 mph at turn 10) last Sept. I lost the rear on corner entry (my fault) and had enough awareness and control to send the car to outside after the first catch-attempt failed. So no harm done to the car or me (just ran into the grass). But if I had hooked it to the inside, I surely would have crashed into the tire wall. You don't necessarily need to be pushing really hard in order to have off-track excursion; Too much trail braking, too late into the brake zone, fluid on the track, etc. And when you do have an unexpected off, you can't be guaranteed to have plenty of run-off area in front of you (some tracks just don't have tons of run-off at all corners). I'm relieved to hear that ZL1+911 got away from his crash without any bodily harm. But not all of us might be so lucky. I've read somewhere that crash systems in road cars are designed for 35mph impacts, not 2-3 times that like we routinely see at HPDE. It just makes sense to me to try to protect your head from BSF. I'll draw the line at installing a cage/harness/etc because my car is for DD. The Hybrid S is a good option for those that want some extra protection beyond stock. |
01-28-2022, 03:34 PM | #27 |
Drives: 2020 Camaro ZL-1 1LE Join Date: Jul 2018
Location: Nashville
Posts: 215
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Simpson Hybrid
Simpson Hybrid is the only approved Hans device for OEM 3 point belts.
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Home Track: NCM Motorsports Park
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