11-08-2003, 01:51 PM
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Join Date: May 2003
Location: Sydney Australia
Posts: 3,577
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BigSwede,
Sounds like Sweden have it sorted, but I think the problem is that not all countries have it this well spec'ed.
In NZ and Australia (I think) there are just general guide lines ... and scrutineers are not necessarily engineers.
Pete
__________________
ps: Remember it's all just opinions 
'71 1750 Series 2 GTV: http://www.alfabb.com/bb/forums/showthread.php?p=208078
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11-09-2003, 10:04 PM
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Join Date: Mar 2003
Location: Chatsworth, CA
Posts: 167
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I RAN A 1:34.202 at Willow Springs in my Alfa GTV wearing a Hutchinson device. I swear, if I knew now how good it was I would have used it earlier. One of the unspoken benefits is the lateral head support. For instance your head doesn't get pulled on by lateral G's allowing for great head support.
Richard
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11-14-2003, 11:18 AM
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Join Date: Nov 2003
Location: Orlando, FL USA
Posts: 8
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My name is Gregg Baker. I'm an engineer with the Isaac company. We noticed a spike in Web traffic coming from your site--we don't know who anyone is, our software just tells us where referrals are coming from on the Web.
Normally we would just check it out and leave, but several things have come up on this excellent thread and I thought I might offer some observations. Hope I'm not intruding.
1) General injury:
There was some discussion as to whether Basilar Skull Fracture (BSF) injuries are real, and whether sanctioning bodies have jumped the gun in recommending/mandating the use of head and neck restraints. As safety improvements have been made over the decades, BSF has become the #1 cause of racing fatalities. In North America, a driver dies of this injury about once a month on average. Less than 2% of racers use any form of head and neck restraint.
2) Belt Stretch:
This subject has been thoroughly researched, although I can't offer any references off the top of my head. The results are that you should keep your belts as short and as tight as possible. These results may seem counterintuitive, i.e. they don't make sense at first glance. Loose, "stretchy" belts will allow the body and the head to continue accelerating away from the seat for a longer period time, so that when the body finally does stop, it must do so with more energy than would be the case with short, tight belts. In a 45G crash impact the body will move off the seat 8-10 inches and load the belts with several tons of tension.
3) Inexpensive Helmet Pins Upgrades:
Yes, it is possible to buy a Basic Isaac system with the simple pins and then purchase quick-release pins from an industrial supply catalog--at least in theory. PLEASE, PLEASE, PLEASE do not do this! The quick-release pins we use are certified aerospace-grade pins made for us and comply with military QC specifications. They have a double-shear strength of about 4 tons. Industrial supply catalogs say their pins are "really good,"--or something to that effect--and are not certified. You get the point. Given that an Isaac system will last years, the annual cost difference is that of a six pack.
Didn't mean to butt in here, but some very good questions have been asked, and points raised.
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-14-2003, 12:11 PM
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Super Moderator
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Join Date: Nov 2002
Location: Northridge, California
Posts: 6,116
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Gregg,
How much do they run? I was planning on buying two for christmas (one for me and one for my brother)
__________________
Anthony Rimicci | 64 Giulia Spider | 65 GTA | 68 GT Jr.
Last edited by italcarguy; 11-14-2003 at 02:15 PM.
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11-14-2003, 01:21 PM
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Join Date: Nov 2003
Location: Orlando, FL USA
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Anthony,
They start at $725. Product descriptions are here: http://www.isaacdirect.com/html/product.html
There are more details on the order form, which is a PDF file located here: http://www.isaacdirect.com/html/order.html
We occasionally have demo systems available at a 15% discount. We have taken these to tracks for drivers to try and after a while they get a little dinged up, so we pull them only because they are not cosmetically perfect. They are usually not available, maybe 10 to 20 units per year.
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-14-2003, 02:50 PM
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Join Date: May 2003
Location: Rancho Cucamonga
Posts: 34
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welcome Gregg
Gregg,
Thanks for joining in on the discussion.
Anthony,
I have the Intermediate ISAAC system, I had it out at the Enduro and also wore it at Vegas. I'll have it at the annual tech day with VARA and the following day at Willow with AROSC if you want to check it out. It would be a great present to yourself and your brother! Unfortunately, I won't be at Willow next weekend with VARA, I'll be at the Cal Club Enduro at Buttonwillow.
--Daryl DeArman
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11-14-2003, 03:09 PM
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Join Date: Nov 2003
Location: Orlando, FL USA
Posts: 8
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Daryl,
Thanks for the welcome! I hope your Isaac is serving you well.
All,
At Button Willow will be Craig Sanford of Advanced Fire and Rescue. He witnessed the recent fatality there and ordered an Isaac system with helmet and mounts just for demonstration purposes. Actually, he paid for the helmet and we donated the Isaac. (Note: We have no business affiliation with his company.)
We understand he has the system and helmet in a mock-up seat and harness with a dummy. Please check it out, and keep in mind that everything is fully functional, so you can take it on the track if you like. He told us that several drivers tried it in Vegas.
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-19-2003, 05:18 AM
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Join Date: Aug 2003
Location: 58 Deg. North
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This is great, finally someone to ask dumb questions. 
Is your device tested and certified by FIA or any other organisation?
Is it race legal in Sweden?
Will I be able to look sideways? The real questions is: Is the damping at low piston speeds low and high at high piston speeds?
Have you done any crash testing in any direction other than straight ahead? What will happen if I go sideways into the gravel and roll in 150MpH (knock on wood)... Is there damping only in the forward motion or also in the rear (towards seat) motion?
What happens if the body rotates but not the head, for instance if the lap belts are loose and I roll. 
__________________
Mats Strandberg
GTV 2000 -77 [URL=http://www.alfapower.nu/gallery/gtv]Pics[/URL] <= These are picture links you know...
75 Turbo -87 *sold* [URL=http://www.alfapower.nu/gallery/75T-Modificata]Pics[/URL] <=
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11-19-2003, 04:12 PM
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Join Date: Nov 2003
Location: Orlando, FL USA
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[quote] Originally posted by BigSwede
 Quote:
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This is great, finally someone to ask dumb questions.
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Quote:
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Is your device tested and certified by FIA or any other organisation? Is it race legal in Sweden?
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The Isaac system was tested at the Wayne State University Bioengineering Center crash lab in Detroit, Michigan. We chose this lab because it has been around for many years and has tested every head and neck restraint product available to racers.
The product is certified/approved by many racing organizations, but not FIA. FIA (Dr. Hubert Gramling) refuses to test any product other than the HANS device. I believe that the HANS testing for FIA was subsidized by DaimlerChrysler, which now has a distribution agreement with HANS. Hence, FIA is not motivated to test any competing product.
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Will I be able to look sideways? The real questions is: Is the damping at low piston speeds low and high at high piston speeds?
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Yes, the force is low at low speeds, and high at high speeds.
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Have you done any crash testing in any direction other than straight ahead? What will happen if I go sideways into the gravel and roll in 150MpH (knock on wood)... Is there damping only in the forward motion or also in the rear (towards seat) motion?
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Our testing was conducted at 30 degrees offset from straight ahead, so there is a significant lateral component. Computer simulations suggest that the product will remove about 50% of the head loads in a side impact. The damping occurs in all directions, both linear and rotational.
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What happens if the body rotates but not the head, for instance if the lap belts are loose and I roll.
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It will provide some protection from rotational loads. The tighter the belts, the more protection you will have.
We have video of a customer crashing and rolling on an oval track. They could feel the Isaac working though the entire event.
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-19-2003, 09:54 PM
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Join Date: Jun 2003
Posts: 172
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GB Replied:"Will I be able to look sideways? The real questions is: Is the damping at low piston speeds low and high at high piston speeds?
Yes, the force is low at low speeds, and high at high speeds.""
A problem I see is if you turn left lets say then look ahead the piston does not necessarily return to the static position of say 6mm of piston out of shock body (the installation point) In fact the issac on that side can roll on the free end toward the back of the seat and sholder belt thus shortening the full travel of the device in a crash. Have you doe testing to see if this is an issue? Or in a crash is the increase in shock dampening force so great and so fasr with large hits that "any" remaining travel is protective? Are there positions that you could get into where you could use up your piston travel and negate the protection of the device or even at full piston travel the device is protective due to the likelyhood of perhaps 8-12 inches of belt stretch with head movement?
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11-20-2003, 03:21 AM
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Location: 58 Deg. North
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Tnx Gregg.
Is it possible to watch this video somewhere on your companys site? sounds very interesting.
__________________
Mats Strandberg
GTV 2000 -77 [URL=http://www.alfapower.nu/gallery/gtv]Pics[/URL] <= These are picture links you know...
75 Turbo -87 *sold* [URL=http://www.alfapower.nu/gallery/75T-Modificata]Pics[/URL] <=
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11-21-2003, 03:59 PM
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Join Date: Nov 2003
Location: Orlando, FL USA
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Sorry I didn't get back to you sooner, but we were out of town and the Email notification seems not to be working.
Quote:
Originally posted by fatbillybob
GB Replied:"Will I be able to look sideways? The real questions is: Is the damping at low piston speeds low and high at high piston speeds?
Yes, the force is low at low speeds, and high at high speeds.""
A problem I see is if you turn left lets say then look ahead the piston does not necessarily return to the static position of say 6mm of piston out of shock body (the installation point) In fact the issac on that side can roll on the free end toward the back of the seat and sholder belt thus shortening the full travel of the device in a crash. Have you doe testing to see if this is an issue? Or in a crash is the increase in shock dampening force so great and so fasr with large hits that "any" remaining travel is protective? Are there positions that you could get into where you could use up your piston travel and negate the protection of the device or even at full piston travel the device is protective due to the likelyhood of perhaps 8-12 inches of belt stretch with head movement?
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fatbillybob,
You raise an interesting subject, namely how sensitive is the performance to variables such as shock stroke. You also bring up the subject of velocity, which most people tend to ignore when considering the design of a H&N restraint, but which is absolutely critical when you deal with a damper. After all, the force in a damper depends solely on the velocity--no velocity, no force; high velocity, high force.
Let's deal with velocity first:
This is a phone call I had recently with a rental customer (paraphrasing)...
Him: I had the Isaac at the track this weekend.
Me: How did you like it?
Him: Great. I could move my head around more than I thought I'd be able to, it was easy to hook up and was very comfortable. But I didn't use it in the race.
Me: Why not?
Him: Because I could jerk my head all the way forward, and that didn't seem right. I could move the shocks myself.
What has this guy done? He has assumed that the load on the head is determined by the position of the head. This is understandable because every other H&N product works based on position, and you can limit the load by limiting the position. But why bother? The injury is not caused by the position of the head, it is caused by the load on the head. You can prove this right now. Tilt your head over as far as you can. Guess what? You're not dead.
The mistake he made was not considering the velocity. I'm sure he tried to yank his head forward as fast as he could, but he probably spent a full second doing so. That may sound fast, but in a 45G crash the peak head loads occur in about 30 milliseconds, or 0.03 seconds. (For reference, the blink of an eye is about 25ms.)
He told me he could feel the shocks working, i.e. trying to pull back, but he didn't appreciate how much harder they would pull back if he could move his head 30 times faster. How much harder would that be? Well, look at this graph: http://www.isaacdirect.com/html/chart.html
On the left you see the head load for an unprotected crash dummy, with helmet, is about 1,800# (the injury limit is 900#). Now look on the far right. Adding the Isaac system reduces the head load to about 200#. Where did the other 1,600# go? Into the Isaac.
Because of belt stretch and geometry changes the physics isn't all that simple, but it is safe to say that if our rental customer moved his head from straight up to straight forward in 30ms, he would need to apply at least a half-ton of force. In a crash, the impact supplies that force for you.
It's a battle between the impact force trying to pull your head off your neck, and the reactive shock force trying to keep it on. In the end the impact force wins (200# load), but not enough to cause injury.
Now, let's factor in the shock stroke:
First of all, the shock stroke is imposed on us by the anatomy. The distance from the head to the back of the shoulders is X. The mechanical connections take up a distance Y. The available shock stroke is X-Y, and there is nothing anyone can do about it.
I had to chuckle when you asked if we ever tested a condition where the shock was somewhat extended prior to impact. The answer is yes.
We are located in Florida, and the Wayne State University Bioengineering Center crash lab is in Detroit, Michigan. We never had a detailed drawing of the crash dummy layout, so we had to make a rough estimate where to locate the helmet mounts on the test helmet, which we provided. The mounts were too high by about 25mm, so the shocks were nearly half extended at impact. You can see a photograph of this here: http://www.isaacdirect.com/html/Othe...shTesting.html
Now go back and look at the load graph. The extension of the piston didn't seem to matter, did it? Based on crash testing and computer modeling, we have concluded that the stroke is a factor, but it is not a significant factor. Even if some variable changed such that the loads were doubled, you would still be at less than half the injury limit.
You also asked two specific questions:
1)"Or in a crash is the increase in shock dampening force so great and so fast with large hits that 'any' remaining travel is protective?"
Yes, any stroke of the shock, regardless of how small, will act to reduce the velocity of the head relative to the body.
2) "Are there positions that you could get into where you could use up your piston travel and negate the protection of the device or even at full piston travel the device is protective due to the likelyhood of perhaps 8-12 inches of belt stretch with head movement?"
Unless you are a giraffe, if you are at full piston travel upon impact it means that your head is already extended forward, and the Isaac then becomes, in effect, the world's most rigid head restraint. As the body moves forward with belt stretch, the head moves with it, and head loads will be very low. It would actually be a very safe way to drive your car, if not for the fact that you would be looking at the floor board.
Two things happen in a crash when using the Isaac system, both of them to your advantage. First, the shocks act almost instantly to slow the head. Then, as the shocks eventually reach maximum stroke, it becomes a very rigid head restraint.
The physics questions are interesting, but the bottom line is that nothing has ever outperformed an Isaac system in a crash test. Nothing.
How's that for a short answer?
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-21-2003, 04:35 PM
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Location: Orlando, FL USA
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Video
Quote:
Originally posted by BigSwede
Tnx Gregg.
Is it possible to watch this video somewhere on your companys site? sounds very interesting.
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No, unfortunately, it is not on the site.
The video is on analog tape (NTSC format). We may eventually convert it to digital and post with other videos.
As a crash video it's not very impressive. The impact is relatively low, but we found it fascinating for two reasons. First, it involved nearly every load vector one could imagine. It's a case of an oval track driver going for the lead exiting a corner. He gets pinched by the lead car, wheel-to-wheel contact, his car flips over, hits the wall, spins inverted and eventually comes to rest. He assures us that he could "feel" the product holding his head stable during the entire event. We suspected something like this may happen, but had no way to test for it.
Second, some drivers who have never used the Isaac system express a concern about having to get out quickly in an emergency. Every customer we have will tell you that this is nonsense--you can pop the helmet pins in less than a second. In the video, you can see the driver release the Isaac while he is in the car, upside down.
The amusing part? The driver is twelve years old.
We will eventually post this. If you can't wait to see it, let me know and we can send you the tape.
__________________
Gregg S. Baker, P.E.
Isaac, LLC
http://www.isaacdirect.com
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11-22-2003, 04:53 AM
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Can I fit the system to my helmet myself? To me it feels like it is most critical where the mounts go on the helmet so there is no rotation of the head/neck in a crash, for instance it they are mounted too far up the head would be tilted up/backwards. Ouch...
Is the system a use-throwaway or is it reusable? I'm thinking that there would be quite a lot of heat buildup when the system absorbs that amount of energy.
What kind of fluids are used? Flammable/high pressure/toxic?
"The video is on analog tape (NTSC format). We may eventually convert it to digital and post with other videos."
Hmm, Never The Same Color? (NTSC) It will play in my VCR if it hadn't broken down a couple of years ago. Please notify us if it's posted in digital format.
I'm mostly interested to see how the head moves (rotates) during a crash and that I think can be seen even in a very small impact.
"Second, some drivers who have never used the Isaac system express a concern about having to get out quickly in an emergency. Every customer we have will tell you that this is nonsense--you can pop the helmet pins in less than a second. In the video, you can see the driver release the Isaac while he is in the car, upside down."
The problem as I see it is that you place more responsibility in the hands of the marshals if the driver pass out, maybe thats something that they do not like and therefore won't let me use it... 
"Tilt your head over as far as you can. Guess what? You're not dead." 
Seem to me that you got a good design using shock absorbers instead of springs, excellent concept.
__________________
Mats Strandberg
GTV 2000 -77 [URL=http://www.alfapower.nu/gallery/gtv]Pics[/URL] <= These are picture links you know...
75 Turbo -87 *sold* [URL=http://www.alfapower.nu/gallery/75T-Modificata]Pics[/URL] <=
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