It seems that NASCAR style oval short track cars especially ameteur cars seem to have fuel cells pretty exposed in the rear. I clearly see them usually held in with steel band straps and just a skeleton box of tubes around them. It does not appear that anyone is scared of a rearend collision on one. Is the rubber bladder with foam inside contained in an aluminium can really that strong? Is the primary fear getting the cell ripped off the car more of an issue than it getting crushed?

 

The bag is made of quite heavy kevlar - extremely tough and puncture resistant - but not indestructible either. Some of those sanctioning bodies require tech inspection of the bladder - like belts they must be replaced every couple of years.

For all of the crashes and rear-ending that goes on it is surprising there are not that many fireballs - with that exposed tank like that. It's probably easier to tear a fuel line off a pump or fitting than tear a bladder open.

 

There is a second piece to these tanks. The foam in the bladder has two jobs. one keeps the fuel from sloshing from side to side the second is to slow the fuel so it does not gush out of the tank if it does get torn.

 

They must be doing somthing right. How many times have you seen the cars rear ended, slammed into wall, etc. and not burst into flames? I think the fuel cell is held in by a cage that is welded to the frame. No straps.

As a thought, what we see might not be the actual cell, but a container for the cell?

Any NASCAR guys here?

 

Hey;

I am sure - depending on the sanctioning body - they mandate a pretty serious frame that is integrated right into the chassis. I've seen a few, and most were tube structures welded right in with the frame members. If a metal "can" is used, most guys use the bolt flange for the top cover and integrate it as a mount flange. Poly cells - if allowed - would be the only ones utilizing straps. Often times, what you are probalby seeing is actually a tube structure cradling the bottom of the steel "can," acting as abrasion/skid protection.

 

Yes. I see what guys do to 911's and they look so well protected. They have bars around and then some crumple zone before an impact can even touch the cell. With NASCAR, truck series, IMCA etc. it looks like tubes lined by sheetmetal then the metal/rubber bladder cell goes right in there where the entire system takes the impact directly with no crush zone. It must be O.K. however. Have you guys played with or seen that new Cymat aluminized foam? It sounds awesome for some crush protection and semi structural firewalls and such. NASCAR is using it around fuel cells now or in the near future.