John Veninger

I had finally decided to try an ISAAC device. Took advantage of the "rental" for the Sebring Club Race. I experienced most of the same feeling of wearing the device that other users have commented in the past. The device attaches easily (the tip on attaching the shocks first, putting on the helmet and clicking in the shoulder harness was great!)
The device feels a bit restrictive (like all restraint systems I guess) while sitting in the grid, but fine if you leave the shoulder harnesses loose until your ready to head out onto the track. Once I moved the car off the grid and pulled second gear I didn't notice the device at all until I pulled off the track.
I hope to order my own next month. Very impressed with the product.
Wish I could "rent" a HANS to compare, but that's not available and the engineering of the ISSAC just makes so much more sense to me.
FYI- I have no relationship with ISAAC or Greg, just a happy renter and future customer

buckdr1

John, I quite happy w/ it. Have had it a year now, and a few rear/side impacts No problems!
A buddy of mine totaled his C2 @ Sebring last week and came out fine. He's going to send his back for a check up. I'll advise what if anything, the outcome.
Hope you don't need to.
Regards
Bill

ColorChange

I'm happy with mine.

mitch236

At this point, I don't understand why anyone would buy an Issac. There may be a time when a HANS would be required for racing and Isaac hasn't gotten the approval yet.

ltc

Mitch,
I can think of several reasons.

1. The purchase is not for (sanctioned) racing; therefore the 'certification' is not an issue. For example, DE.
2. The ISAAC, by design, can not come off/out from under the shoulder harnesses. The HANS may/may not address this issue with 'wings' being added back to the design, new 4 belt shoulder harnesses (as was discussed in a previous thread by Greg Fishman et. al. and is currently being worn by Ryan Newman in NA$CAR) and dual horizontal harness bars.
3. The ISAAC works on a different principle of kinematics/mechanics; i.e. controlling velocity (thru the use of a dashpot or shock absorber) prior to fianl displacement/length being achieved. The HANS works strictly on displacement/length, which is why the test results can vary widely based on tether length (and there are some who prefer a longer tether, which does not play into the strength of a HANS device). Again, this has been discussed before.
4. Personal choice, based on other factors: comfort, etc.
5. The perception that a newly created specification may hot be based solely on technical merit. Unfortunately, marketing, finance and engineering do not always coexist; such is the nature of people and processes.

As long as the driver purchases/wears ANY H&N restraint, they have started down the path of thinking about their personal safety, which is a good thing.

buckdr1

Mitch, there may also be a time when it is approved as well. SAE specs out like the Hans w/o all the bondage straps. Simplicity was a factor for me. Plus no ones yet to prove Newton wrong ...yet
And as mentioned I've wacked a few walls w/ it on( not that I wanted to) and saw a fellow CVR'er Total his C2 last week @ Sebring w/o any head/neck problems.
Buyers choice.....Great Country, eh?
Bill

mitch236

I wasn't trying to detract from the ability of the Isaac, just that a HANS may become required equipment. I agree that Isaac may get approval as well. It's just that economically speaking, I would get the approved version in case it becomes required.

buckdr1

Mitch, No problem, you have a valid point.
Lewis, nice summation. Agreed. Anything(almost) is a step toward better health.
I would hope that if PCA mandated HNR's Isaac would be equally acceptable.
Bill

SundayDriver

I don't have a huge issue with the ISAAC, but want to address a couple of issues...

What is it that is important in a H&N system? What are we trying to prevent?
I believe the sole answer is head displacement. No study, nor expert, that I am aware of, has linked basal skull fracture to head velocity - only to displacement. In that case, as long as the ISAAC STOPS the head motion, it should work just fine, but I fail to see any indication of any evidence that velocity control offers an advantage over displacement control.

The HANS makers disagree with your assertion that length impacts test results. Quite the contrary.

I do have a few concerns/questions about the ISAAC:
1) What are the mechanics in a crash? I would really like to see sled video to understand where the restraints (shoulder belt parts) go during a crash.
2) Related to 1 - There seems to be an assertion that ISAAC is better in side impacts. I am really curious about this - especially what happens to the shoulder belt restraint part. Is there a chance of these binding on the belts? We know what happens in dumping - is this a risk to the belts with the ISAAC?
3) PERSONAL OPINION - I do not like the idea of having to release two extra points after a crash. Yeah, fine - it is easy to do is the claim. But how easy is it if you are stunned from impact or in the panic of a fire. Can the workers get you out quickly when they can't see through the smoke that you are wearing an ISAAC.

I think that items #1 & #2 are real and have not been addressed for this product. Everyone gets to choose their own compromises in safety (#3).

Finally, I disagree with the last statement about ANY H&N being better than nothing. Some of the early strap systems have proven to cause fairly serious injuries yet have not been proven to actually work as a H&N restraint (in large part due to critical nature of adjustments). That makes it far from clear that these systems reduce overall risk.

mitch236

The other point that I just realized is that the Isaac cannot be cut off. Isn't that the way most extractions occur. Forget the quick release, they will just cut you out. Can't do that with the Isaac, at least I don't think so (correct me if I am wrong)

John Veninger

Cut the shoulder belts and the whole ISAAC system comes off attached to your helmet.

mitch236

Humm..... Still HANS for me.

ColorChange

Wrong. The total travel or extension is roughly the same with both systems. When the HANS straps pull tight, that is a realively hard stop. When the dashpots on the ISAAC pull tight, that is a relatively hard stop. So, from you first perception, the systems are comparable. Here is where the ISAAC is better. When your hit something in a HANS, your head continues at 100 mph until you hit the tethers and then the velocity quickly drops to zero with a major g deceleration. With the ISAAC, your head is slowed but the shocks and is only going maybe 70 mph when it's "tethers" pull tight, with a dramatic reduciton in g force deceleration. Doctors here can talk about "brain slap", but it is much less with the ISAAC.


Mark, wrong again.

1. The rollers are pulled forward until they eventually transfer all of the force to the belts.

2. The same principal I described above in a head on crash works on a side crash. The ISAAC slows your head down so it never gets moving as quickly, lowering the deceleration energy (damage) involved. If they did bind, it would only slow your head quicker, a good thing.

Again, I disagree. In our litigious society, any safety product that doesn’t work will be quickly exposed.

Now, IMO, is the ISAAC better than the HANS, yes, and that’s why I bought one. But, if I were a racer, I would own the HANS for all the sanctioning reasons. I think they’re both good.

buckdr1

Mark, Note I said (almost) any
FWIW- I have good sized Isaac Equiped stickers on the rear quarter windows And on the Helmut!
Bill

ltc

Mark,
Do me a small favor if you would. While sitting in front of your computer or TV, please rotate your head downwards as far as you can, so that your chin presses against your chest.
Are you still alive?
IMHO, the primary difference between ISAAC and HANS is NOT limiting displacement (both devices limit head motion: in the case of the HANS it's primarily due to tether length; in the case of the ISAAC, it's primarily due to full stroke length of the dashpots; mechanical stops if you like).
The primary difference is the velocity (or momentum if you prefer) at which your skull is traveling when the aforementioned mechanical means terminates head motion. Based on the fundamental laws of motion as described by Sir Isaac Newton, your skull will be traveling at a lower velocity at mechanical terminus with an ISAAC compared to a HANS.
Your brain, floating around inside your skull, will notice the difference in these 2 velocities when once again Sir Isaac Newton steps in (think F=mA here). The faster your head is moving when forward motion is stopped (re: decelerated), the harder your brain impacts the front wall of your skull, followed by plastic deformation of said grey matter. This is the primary reason behind the levels of headaches in post crash recovery.

IIRC, the HANS owner's manual strongly recommends not extending tether lengths from the factory set points.
Again, shorter is better (for either device), as the shorter the tether/restraint, the shorter the distance the mass (skull) is allowed to travel thru and thus the lower the terminal velocity. If taken to an extreme level of safety, a zero length tether (i.e. rigid mechanical restraint of your skull/spinal alignement) would be the safest; although zero head movement would not be appropriate for driving. Of course, your brain would still be subject to F=mA, but your skull would not.

With regards to side impact protection, HANS would expected to have near zero; based on the fact that you can't push on a string; the tethers have zero rigidity until their max length is reached. The ISAAC may have some, due to mechanical rigidity in the dashpots, but it is a fairly moot point, since anything is greater than zero. I would expect side impact to be addressed with seat/driver nets; some mechanical means to limit head excursion apart from the H&N.

Agreed. Based on SAE test results, some early (tether based) H&N restraints showed minimum reduction in certain loads in sled tests, so you are correct.
My ascertion was that someone who purchases any H&N restraint has begun to think about personal safety, which is a good thing. Someone who drives without a foam collar, then buys one certainly hasn't purchased the most sophisticated H&N system, but it is a start. Hopefully, it will begin their personal education into safety.

PERSONAL DISCLAIMER:
I am not a biomechanical engineer (but I did sleep at a Holiday Inn Express last night).
The area of H&N/safety systems is of personal interest to me, as I find the physics behind it fascinating (noted, yes I do need to get a life).
As I have learned in design and law, there are seldom optimal solutions; only compromises.