I looked at both, and chose the Isaac. Climbing out through the cage and out the window with the Hans on looked more difficult to me than pulling the quick-release pins on the Isaac.

 

Gregg, how does the Isaac device deal with the compression load on the neck? From the pictures, it seems the device is almost vetical in its normal position, and in a collision, there would be a very significant vertical force vector compressing the spinal column. Was that measured in the tests? The HANS force vector is very close to horizontal, so it would cause almost no compression load on the spinal column. We had an incident where a car became airborne, dug in its nose on landing, and the driver had cracked vertabrae in his neck. Not trying to be critical here, just asking. I'm getting long in the tooth, looking for protection, and doing some research.

 

Larry,

Glad you like it.

I told you we would find you a good one! It's not new though; if you look carefully at the top end of the shock you can see where the lanyard cabling has worn the finish.

 

I can't answer for Gregg, but it's my understanding that as your body moves forward in the crash, the shocks roll along the belts with you. When your head is thrown forward with your body, the shocks are no longer in a vertical position (think back to what a body looks like in a slow-mo crash test at full extension). That's simply where they stay under normal circumstances.

 

Bryan, if it performs as you described, the shock absober would deal only with the tensile force acting parallel to the spine, and would not counteract the rotation of the head. Dealing with the rotation requires a counterforce along the circumference of rotation. You are describing a radial counterforce. With the HANS device, the operating principle is very clear: it pulls back more or less perpendicular to the vertical centerline of the helmet throughout the impact, i.e. along the circumference of the rotation, and thus reduces the force of rotation. To be quite gruesome, I guess the question is whether basillar skull fractures are the result of compression, extension or rotation. I don't know the answer, but intuitively it seems that rotation would be the culprit, as the shoulder straps stop the torso, and the head keeps moving forward. Where are the forces actually measured in the various tests?
Let me make it clear once again that I'm not trying to be argumentative or difficult, just trying to understand this stuff so I can make my own decision. No affiliation with anyone. It may be impossible to get an answer anyway for liabililty reasons.

 

You guys are keeping me busy here--and right before Daytona. Here are some replies to last night's posts, then I'll try to get current


Fatbillybob,

Re getting out:

This appears to be an issue only to drivers who have never used the product. No one has every returned an Isaac system because they were concerned about getting out quickly. See the second entry here:

http://www.isaacdirect.com/html/Othe...sComments.html

Also, see comments below from Jack Olsen.

Re seating position:



No. The ISAAC is not “worn” in the classic sense, so there are no sizes or seat angle criteria. It has been used in lay-back Formula Vees and very upright stock cars. We have used shorter shocks for children, but that just made everything proportional.

You will get different head loads depending on the seat angle, but that will occur regardless of product.


Jack Olsen,



You are not the only one who feels this way. I was looking up an old article about a driver who needed assistance to get out of his HANS in an upside-down car that was leaking raw fuel, when I ran across this quote from today:

“Drivers have for decades climbed in and out of their cars through the driver's-side window. But wearing NASCAR-mandated head restraints such as the HANS device has made it more difficult to escape rapidly through the window in case of fire.”

It’s about halfway down in Hinton’s article of this morning:

http://www.orlandosentinel.com/sport...orts-headlines

If you saw Labonte’s flaming wreck of a couple weeks ago, you may recall that he got out of the car without his HANS device—he had to stop and take it off while the car was on fire.


George:



We’ve given this some thought. We have sketched up some designs, but haven’t moved on the concept because 1) it would have to be sized to both the driver and seating angle, 2) it would become increasingly uncomfortable as the belts were tightened and 3) it would be very expensive.




I tend to agree. The ones that look thrown together, however, do remove about 50% of the head loads and are dirt cheap to make.

The HANS device has a longer history than the ISAAC, but has only been developed into its general current form since 1996, and the F1 version wasn’t tuned until after ISAAC came out last fall. HANS was originally designed as a neck support (you should see the first patent drawings—they look nothing like the current version), and the safety thing was something of an afterthought.

Smokey,



Here is the bottom line, believe it or not: Both Isaac and HANS produce nearly identical compression and tension loads on the crash sled. Even stranger, compression loads will occur naturally with a naked head.

 

Smokey,

To hell with the lawyers. BTW, have you seen our waiver?

It does perform as Bryan describes, in general. It is designed to limit the load on the head, not the position of the head. One can limit the load by limiting the position, but why? That why we have helmets.

Here's how the injury occurs: The body stops but the head keeps going, until it reaches the "end of the rope" (read neck). Like the end of a whip, the upper neck goes into tension as it attempts to stop the head. There are some rotational loads, but they are about 5-10% of the total, at most.

All these load are measured in great detail, and synchronize with high-speed video.

 

Thanks, Gregg. That makes sense, and you've obviously done the appropriate testing. Good to know.

 

I completely agree on both points but here's a bunch of SCCA Formula Continental racers who feel the same way about SFI's latest cash extraction device: http://www.apexspeed.com/cgi-bin/ult...24;t=000033;p=

I have all but given up on the SFI. From now on I'm only using FIA-certified equipment in my car.

 

Smokey,

Anytime.

The important load, of course, is the tension/compression load on the neck as this is the cause of BSF. The Wayne State dummy measures 33 different responses--everything from sled deceleration to linear and rotational upper neck loads about all three axes. They are sampled at up to 10,000 times per second, so a lot of data is gathered for each test.

Before someone gets the impression that I'm saying our product is better than any other in every set of circumstances, I should note that the Isaac and HANS work differently, and each can cause secondary injuries. Paul noted above some of the HANS issues. There have been no reported injuries with the Isaac from customers who have crashed, and no evidence on the crash dummy, but it is conceivable that the driver could receive a shoulder injury as the body is slammed back into the seat on the rebound. That's about the worst thing we can think of. (Can you tell I'm not in the marketing department?)

With all products there is a chance you will wake up in the hospital, but at least the odds are that, after the average "big hit," you will wake up.

 

Just another update/testimonial on Isaac: I just finished my third race of the season using the Isaac; I've also done six DE days this year, so figure 30-40 hours in the car with Isaac now. Happy to report I havn't given it the ultimate test but can update my earlier comments on wearability etc. Having gotten used to the device, I now can clip it on pretty quickly although rushing makes it harder. With my enduro pit timer ticking away, I got rushed and wound up losing 15 seconds or so fussing with the right hand pin. Certainly part my fault not being back in the car quicker. I also drove off w/o my gloves; more rookie nerves.

Anyway, in general the device is almost unnoticeable while you have it on. I have more head mobility than I did with a neck horseshoe. I pay close attention to keep ing the shoulder harness very tight: it should be anyway but now it is also integral to the head restraint. (well gee I guess w/hans it is too...) My biggest concern continues to be getting out in a hurry. I have an exit routine where I always hit the pin releases before my lap belt, thinking if I have to do it in a daze someday, I'll remember if it is routine. But the reality is you now have three releases between you and a quick exit. Eventually I think I'll buy Isaac's newer quick release pins (just pull vs. push button and pull). Secondly, I'm really hoping there is sufficient market adoption for the system that I won't be the only one on the track with the system, and rescue workers will know what they are seeing...

Final thought: It was sort of a pain drilling through my helmet to mount the cleats, but I think I'd do it again vs the super glue. I like seeing those four carriage bolts.

Brandon H
G #77

 

Had a chance to check out Adam Richman's Isaac this week at lunch. Was my first time seeing one in person, and I'm quite impressed. I'll certainly be placing my order in the offseason...I'd place it today if my racing budget hadn't already been spent "ahead" of time. Here's to hoping I don't end up needing it sooner than later.

I tend to drive a lot of different cars, from Formula/Sports Racer to Sedans, so having a device that I can transfer from car to car without modification is great for me. Even better is the ability to "share" the Isaac with my father by purchasing a couple more helmet cleats for him and using it during Enduro's!

Gregg - What is the stronger mounting method? Bolting or gluing? I'd prefer the glue for a more attractive mounting, and according to my limited knowledge of composites, I would think that it could actually be stonger than drilling and bolting?

 

The "sharing" aspect is great. I bought an extra set of cleats for my wife's helmet (she uses the car for DEs occasionally)
Brandon

 

I have not followed this aspect of wearing the HANS or any restraint type devise but consider this. I think there are quite a few drivers out there who wear these devises but have not taken the time to learn the proper exiting routine before finding themselves in an accident situation. I know that before any VIP experience in the military, you go through an orientation on how to exit. Try this...strap yourself in the car while it's sitting in the paddock. Close your eyes and have someone time you exiting the car with zero visibility. Try and get your time down to the length of time you can hold your breath.

 

It would be the glue, because it spreads the load more evenly over the surface of the helmet. In lab tests, the glue stayed together while the fiberglass broke.