AdamR
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| posted on 18/12/07 at 01:46 PM |
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Protecting the fuel tank
Call me a worrying ninny but isn't the fuel tank a bit exposed on your average seven? I'm concerned that a rear impact would burst the
tank and cover me and my passenger with it's contents.
Has anyone thought about this and come up with any good ideas? (Other than moving the tank, which isn't possible in my case). I was browing the
MNR website the other day and read something about a deformable structure - presumably some extra tubes - used on the Vortx for this purpose.
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bigbird
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| posted on 18/12/07 at 01:54 PM |
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I've heard they use some fancy foam filled tanks in racing, but hey are expensive ( try demon tweeks ) or a much cheaper solution is to fit
cortina brakes. This works on the theory that the guy behind you will have stopped long before you do
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iank
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| posted on 18/12/07 at 01:57 PM |
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If you were feeling paranoid you could use a bagged fuel cell inside the aluminium shell.
But it isn't a real problem (for some value of real problem) as the car that burst the tank would be embedded in your spine before it caught
fire.
7's aren't the safest design in a shunt.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Mr Whippy
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| posted on 18/12/07 at 02:17 PM |
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My chassis is outside this moment for storage, I turned it upsides down to so it rests on the roll bar and noticed that at that angle any fuel leaking
from the tank would pour on to the drivers head  how lovely 
Yeah it's a crazy old place to put a tank and I thought the landys were bad with their ejector seat
did you know that when cars were first being made to run on petrol, you had to obtain a licence to handle the stuff due to the extreme danger...how
times have changed 
[Edited on 18/12/07 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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02GF74
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| posted on 18/12/07 at 02:23 PM |
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I think you are being overly cautious. Petrol tanks only explode on impact in amercian tv and films, if petrol was that easy to ignite, there would
be no need for the AA, RAC or Green flag.
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Mr Whippy
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| posted on 18/12/07 at 02:26 PM |
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quote:
Originally posted by 02GF74
I think you are being overly cautious. Petrol tanks only explode on impact in amercian tv and films, if petrol was that easy to ignite, there would
be no need for the AA, RAC or Green flag.
ah you must be to young to remember the old formula one races where the whole track would be ingulfed in flames BOOM!! I've set fire to cars in
the past and they do explode, trust me I know 
Fame is when your old car is plastered all over the internet
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ash_hammond
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| posted on 18/12/07 at 02:29 PM |
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If someone has just rear ended you the last thing i would be worrying about would be gettting covered in fuel, as the next thing they are going to hit
it u!
.: www.mac1motorsports.co.uk | www.m1moc.com :.
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RichieW
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| posted on 18/12/07 at 02:54 PM |
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Have you thought about side impact protection yet? 
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ash_hammond
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| posted on 18/12/07 at 03:04 PM |
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quote:
Originally posted by RichieW
Have you thought about side impact protection yet?
Dont forget air bags
.: www.mac1motorsports.co.uk | www.m1moc.com :.
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iank
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| posted on 18/12/07 at 03:10 PM |
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quote:
Originally posted by ash_hammond
quote:
Originally posted by RichieW
Have you thought about side impact protection yet?
Dont forget air bags
Air bags are designed to catch people who aren't wearing proper harnesses.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Mr Whippy
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| posted on 18/12/07 at 03:11 PM |
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quote:
Originally posted by RichieW
Have you thought about side impact protection yet?
I once fitted sidepods to my 7 to gain side protection, no really (I have this obsession with side pods ) but it didn't work out as I could
find no way of dealing with the exhaust system. I'll post a pic tonight to show you what it looked like.
lets face it your safer on a scooter, skateboard or a 2CV than in a 7, just don't crash say's Mr twelve crashes and counting
[Edited on 18/12/07 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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iank
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| posted on 18/12/07 at 03:17 PM |
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This is where we get into the old chestnut of passive vs active safety.
Passive safety - crumple zones, air bags, side beams, roll cages etc.
Active safety - better breaking, abs, acceleration and steering agility.
Passive is good once you're in the accident, Active means you don't have the accident in the first place...
7's (and classic mini's) have better active safety so aren't in so many accidents, but once you've hit/been hit things are
worse than if you are in a modern tin-top.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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AdamR
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| posted on 18/12/07 at 03:31 PM |
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The car that's hitting me has to travel through a couple of feet of steel tube, suspension gubbins, diff and the mighty strength of my ali
bulkhead and seats before it'll touch me or my passenger. The fuel tank, on the other hand, is the first solid thing it'll meet. So whilst
I'll be demolished in any kind of high-speed impact, I think there are a whole range of situations where I could be the receiver of a nice
refreshing petrol shower yet be otherwise uninjured.
I guess it comes down to how much force it would take to burst a tank and whether there's any practical way of mitigating the risk.
Foam fuell cells sound good, but presumably eats a huge amount of tank capacity and is not cheap?
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Mr Whippy
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| posted on 18/12/07 at 03:43 PM |
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quote:
Foam fuell cells sound good, but presumably eats a huge amount of tank capacity and is not cheap? quote:
Not so, I have this stuff in my Falcon's tank, it looks very like bath sponge and weighs very little. The biggest down side is it take
absolutely ages to fill the tank, I mean like 5 minutes to put 30 litres in
[Edited on 18/12/07 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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iank
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| posted on 18/12/07 at 04:02 PM |
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Don't think I agree about there being much of anything to absorb a crash between the fuel tank and your back, in fact some of those 1"
steel tubes could even turn into spears. But there you go, if you're happy that's a good thing
Rubber bladder fuel cells are best. Can't find an easy UK link, but this US one has the theory and they have a catalogue full of pictures
etc.
http://www.racerpartswholesale.com/fsafe12.htm
Foam to fill fuel tanks is easily available - even in little cubes to stuff down the filler pipe, but it can degrade over time and doesn't do
much more than preventing it sloshing around. It takes up a surprisingly small volume of the tank.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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bonzoronnie
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 posted on 18/12/07 at 04:16 PM |
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Fuel tank protection
If you are fabricating your own tank.
How about making the tank base from thinner material !!?
Design the inner baffle plates so as they will puncture the bottom of the tank in the event of a rear impact.
Just a thought
Ronnie
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Bluemoon
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| posted on 18/12/07 at 04:25 PM |
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My indy has a mod at the back to take it's roll bar back braces, and spare wheel carrier. It also has the old hoop around the top of the boot
(as I'm using a ali back panel). There is a H arrangement of RHS with a spare wheel before you get to the tank...
In addition I have a removable tow bar across the back from 50mm x 50mm RHS (4mm thick), in a U that sits in a socket of RHS, weld to a strengthening
plate at the back on each side of the chassis. The U is held in with 2 12mm pins on each side.
So I think this could stop someone crushing the fuel tank. Trouble is there is so much metal I will probably get bad whip lash in the event of rear
end crash!
Dan
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britishtrident
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| posted on 18/12/07 at 04:32 PM |
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Nothing you can do will protect the tank in a Locost the up side is it so low it will probably not get craushed, however you can cover the outside of
the tank with grp (best to use woven fibre glass) to prevent the tank splitting. This tip used to be in the MSA Blue Book.
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Syd Bridge
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| posted on 18/12/07 at 05:20 PM |
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The only problem with laminating grp over a tank, is that it will delaminate with time. And if any moisture gets in between, you've got a bigger
problem than when you started.
One way I've seen used in my youth was to put foam sheet around the outside of the tank. If the tank is hit, the impact will be absorbed to a
certain extent, and the foam stops the contents spewing everywhere, giving you time to get clear.
Cheers,
Syd.
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Confused but excited.
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| posted on 18/12/07 at 05:36 PM |
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quote:
Originally posted by Mr Whippy
(I have this obsession with side pods )
Who would have guessed?
Tell them about the bent treacle edges!
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JB
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| posted on 18/12/07 at 05:44 PM |
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Safety
Basically if you are worried about vehicle safety drive the biggest newest car around or a Saab.......
For good fuel system integrity you need a deformable structure to absorb energy and the petrol tank enclosed in a survival area to minimise fuel tank
crush. The pipes must also be protected. There should be no sharp protrutions towards the tank or pipes. This will be difficult on a Seven.
Your best bet would be a bladder cell (such as ATL) with foam filling but this will cost in excess of £1,000.
If you could get the tank down the tunnel and behind the seats then that would be a positive step.
Side pontoons are a good idea for side impact.
Forget about airbags. An airbag system is a finely tuned interaction between vehicle pulse, steering column colapse and occupant kinamatics. There is
no way you could get a safe system on a DIY basis.
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kb58
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| posted on 18/12/07 at 07:10 PM |
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I used a real fuel cell in my mid-engine Mini. Steel box, rubber bladder, and foam filled. It is placed approximately where the transmission goes in a
Locost. It cost US$800 for a 10 gallon unit.
BTW, the foam in the cell is not to prevent fuel slosh, but to prevent fuel spray from being ejected violently in a crash. In fact I can hear the
fuel sloshing around when it's partly full. I can fill the cell as fast as I want and the foam has never impeded fuel flow.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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kb58
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| posted on 18/12/07 at 07:12 PM |
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quote:
Originally posted by JB
Side pontoons are a good idea for side impact.
And if they're integrated into the design correctly they can add greatly to chassis stiffness.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Hammerhead
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| posted on 18/12/07 at 07:23 PM |
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I have thought about this to.
My only conclusion was to make a Kevlar box for the tank to live in, hopefully this would be strong enough. Could even cocoon the tank in a kevlar and
expandable foam crush structure.
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Syd Bridge
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| posted on 18/12/07 at 07:41 PM |
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If you're gonna make a kevlar box, then you may as well go the one step on, and get a bladder to put in the box. Do away with the separate tank
you're trying to protect, and ending up with a much better setup.
Cheers,
Syd.
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