Sanjeevan

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Jeeva

ltc

Back in my early days (during the Cold War, Reagan, unlimited defense budgets....ah, the good days), there were a few planes assembled with binary adhesives on exterior panels. Some of them you know: F117A, B2, F22, YF-23 (personal favorite).....some of them you don't yet know about. Binary adhesives are very strong and reliable and would pose no issues in bonding to a helmet.

With respect to bolts and drilling helmets, helmet manufacturers are NOT thrilled about this; be it for HANS or ISAAC. Helmets are homologated AS DELIVERED from the manufacturer; not a single hole added.
Stand21 is now offering pre-drilled helmets (for HANS) that are homologated with these holes. I'm sure others will soon follow.
(yup, lawyers and liability)

ltc

BINGO!

Geo

Boy howdy!

I agree, I'd love to have Snell independently test H&N restraints. Gregg indeed takes great care of his drivers. I've seen that first-hand. And don't forget, I'm a HANS owner, so I'm not biased here. I don't always agree with Gregg, but there is nobody doing more to protect and educate the amateur racer than Gregg.

Geo

Lewis, you are so right.

I personally know the engineer who supplied Isaac with their adhesive. I can't say I know for a FACT, but I'd bet my next paycheck that the bond of the adhesive used by Isaac is stronger than the resin used in the helmets.

That said, I think the whole thing about modifying helmets is a total scare job. Every dagum pro has a painted helmet with a bunch of holes for drink tube, H&N restraint, radio gear, you name it. It's all about legal mumbo jumbo.

In fact, the SCCA even came out with an official statement that the scru crew couldn't fail people's helmets simply on these grounds.

924RACR

Quite true, they tested the adhesive bond to the helmet to failure. It didn't; the helmet did. The composite construction of the helmet will fail before the adhesive does. When I crashed with the ISAAC, it was bolted on; I'm now using the adhesive (new helmet) with no reservations.

You think SFI 38.1 is bad for being written for one product - you should read the FIA cert for H+N devices! It's a quality control process designed exclusively for the HANS! No other device would even fit into the test rig as I recall. And it is available for d/load on their website..

RJay

Aaaaaaaahhhhh and this is good how? It doesn't matter whether the joint fails or the helmet fails. Its the level the system fails at. A bonded joint will place a pure torsional stress on the helmet, a bolt through will act more through compression. The question is how much pressure can be applied (and over what period) before the helmet fails and is that level likely to be seen in an accident? I can't imagine that currently, it is a design concern for a helmet to deal with torsional stress on outer layers. Despite the concerns about bolt through, theres plenty of real world evidence that the system works. Given the varied construction types of helmets, I'd want to see data on my helmet before I went this way.

Geo

RJ I think you'd find the stress to be quite the same. In the case of a bolt (ala HANS) there is a large plate (similar in size to a fender washer) that the bolt goes through. Both devices should see pretty similar loads both in type and size because from what I can tell the area of Isaac mounting piece is pretty similar to the size of the mounting piece on my HANS.

IMHO if you're ripping the mounting from the helmet, you're probably dead already.

Sanjeevan

Gbaker, you've got a p.m.
Jeeva

fatbillybob

When I used the ISAAC I bolted and bonded! I use glues in my profession and do not trust them. Aerospace applications are under very strict control and some glues are autoclaved etc... ISAAC askes us to be quality control and get it right the first time. It is really easy but still there are things that can theoretically effect the glue bond. 1) the mount plate is not curved with the helmet for close approximation but flat. That means the plate meet the helmet at a tangent point and the glue now has varried thickness upon application. 2) the glue bond is usually better when the film thickness is controled as specified by the glue manufactureer. If glue is too thin you get no bond. If too thick you get cohesive failure. 3) screws put different loads on the helmet as posted above. But the forces are worse and helmet damage can occur if screwed improperly with a flat plate forced onto a curved surface. I screwed and glued for several reasons. I wanted a flat surface to screw to so that reasonable torques could be applied to the screws without loading the helmet. I wanted a firm mount so that there was no rattling. Torque any bolt at home it stays tight if all the surfaces mate. When there is slop screws back out. I spoke to GB about this and he used physics to explain why technically some of my ideas are sound that what I do is overkill with his design. Screws and or glue works fine with ISAAC. Death occures before the helmet fails.

fatbillybob

OH, on the simple to remove from car to car thing. Well It is a matter of degrees. I can walk the pits with a HANS and jump into any car. With the ISAAC you currently have to take these circle retainers off and then install them on the shoulder belt then get in the car. Faster for some more coordinated for others. ISAAC does have an new (may be for the general public now) set of quick release pins so that guys who swap out of cars during dirver changes can still use their ISAAC. If you have a situation with an ISAAC in the car if you are not an ISAAC wearer the thing cannot be easily repositioned out of the way. It hits you on the head and stabs you in the neck etc... So it has to be removed from the car for the non-user. It is just a time and convenience thing. You see I bet simple 3 point seatbelt use on the street would drop off dramatically if you had to bolt them in and install them everytime you got in and out of the car.

Sanjeevan

GBaker, thanks for the phone call...I went ahead and placed the on-line order for the intermedaite Isaac and had left the choice between the single vs dual release based on availability.
Thanks
Jeeva

JackOlsen

Yeah, there are compromises on both sides. The Hans is limited to cars with belts that fit a pretty narrow set of parameters (belt width, belt anchoring, lateral seat support, etc), where the Isaac is more flexible, but has to be attached to both belts in any car you get into. If I was moving around between club racing cars that are all set up similarly, the Hans would probably make more sense. But in my case, I instruct for DE's, where there's a lot of variety in harness and seat combinations. For that world, the Isaac will work in more cars than the Hans.

I don't mean to knock the Hans, of course. Both devices are great, and can potentially save a lot of lives on the track. But no one should let the SFI nonsense or Nascar endorsement get in the way of picking the device that works best in their application.

gbaker

Jeeva,

Thank you for your order.

This is a very good thread, and I owe posters some responses. I hope to get to that soon.

ltc

BINGO!
BTW, contact SFI and ask for a copy of the 38.1 specification....and wait for a reply.
At least the FIA documents can be downloaded.