Easy car safety improvement, why hasn't it been done?

Production cars typically don't have racing-style fuel tanks, because the bladders get crusty and need changing which is too much of a PITA apparently.

BUT why not have a bladder that stretches around the outside of the tank? It's almost as good as having one on the inside and way better than none at all. No leaks if it gets too crusty and crumbles. About as easy to change as a fuel pump. Only needs to be chemical-resistant enough to hold up between an accident and scene cleanup. If a sufficiently stretchy material could be used, one-size-fits-many kits could make replacements easy. Only downside not related to the maintenance of a new item is that tank mounting would have to change slightly to make it easy for the bladder to stretch around most of the tank - no big deal. Why has nobody done this?

what does it make better?

Being outside the tank means that it's in the path for a puncture. which I thought is why it was there in the first place.

Kramerica attempted something similar back in the '90s http://www.youtube.com/watch?v=dZwI0S8bBWA

• Lee

alfadriver wrote: what does it make better? Being outside the tank means that it's in the path for a puncture. which I thought is why it was there in the first place.

It won't help if the tank gets stabbed by a sufficiently sharp object...but it's a lot easier to crack or puncture metal than a soft sheet of rubber.

Some tanks are now made of plastic. That seems like a more reasonable alternative.

My Porsche and many other cars have plastic gas tanks. Flexible and puncture resistant, they also don't rust and are lighter and can be larger since they are more easily molded into whatever shape was needed.

However they do age and crack and its unknown what effects ethanol might have on the older tanks.

GameboyRMH wrote:

alfadriver wrote: what does it make better? Being outside the tank means that it's in the path for a puncture. which I thought is why it was there in the first place.

It won't help if the tank gets stabbed by a sufficiently sharp object...but it's a lot easier to crack or puncture metal than a soft sheet of rubber.

I still don't see how that's better. As it stands, cars are reqired to not leak up to a .040" hole for 10 years and 150k miles, for the entire fuel system. And it's not as if they are going to start going bad immediately after that.

The placement of tanks very much reduces their leak due to a crash. Been through crash leaks a few times (Pinto, Chevy truck saddle tanks, etc).

Its not enough of a problem versus the costs involved.....and bladdered tanks can still rupture/leak/catch on fire. So, while good intentioned perhaps, it isn't practical nor necessary.

I've wondered similar various thoughts about fuel cells. I have to believe some effort could be made to find a material that could be used internally as a bladder. Our lives are much enriched by the many materials developed for specific purposes.