Composite Fuel Tanks

[autogyro]

unless the car sits for a long time its not in the tank long enough to matter. I have read some articles about ethanol fuels breaking down fuel bladders though.

If it were me I would have a second bladder that was flexible like a garbage bag then vent to the back side of it. It would be hard to have baffles though.

I think the problem does not occur with petrol/ethanol mixes and you are correct when ethanol is used in some American racing on it's own, because it does not last long enough to dilute (large fuel consumption of 1950's V8's and big heavy race cars).
However, I do believe the problem will become more obvious as Europe embraces the fuel more readily. (Fuel cells may need a quality fuel concentration).
It is also interesting that from my own experience's with many fuels, ethanol still burns fine in an IC with fairly large amounts of added water but with lower power output. (Perhaps the Yanks do not know!!!) The water can also improve anti detonation and allow higher compression ratios (ask the Luftwaffe in WW2).

[Mystery Steve]

I would like to add something to this thread.
With ethanol being used in larger quantities in motor sport and the possibility of wide spread road vehicle use. Can some of the obviously gifted readers, please give some design ideas for keeping the surface of such liquid fuel out of contact with air to prevent water absorption?

Some fuel/oil storage tanks have tops that move relative to the level of the fluid inside. This is mainly to eliminate fuel vapors inside so that the tanks don't become huge bombs. Perhaps a similar idea would accomplish this task. Would be tricky to design and manufacture though.

I wasn't thinking about installing a bladder in to the tank i was more along the lines of a series of baffels to reduce fuel surge (what this project is all about) if i just bought a bladder (not readily available as far as i'm aware) it would defeat the object.

If this is an academic project, I can understand why you wouldn't want to make the project too simple just for the sake of learning. But if the simplest solution is the best, why ignore it? If you're worried about baffling/sloshing, you might consider multiple bladders within the carbon hull? Some of the newer large aircraft (I believe the B2 bomber does this...) use rubber bladders to hold their fuel, and they actually have pumps running among the different bladders so they can shift their fuel around and control their center of gravity as the fuel is burned. Perhaps we'll see a similar solution in F1 next year (assuming it's legal) to make packaging of the larger tanks easier?

[autogyro]

I would like to add something to this thread.
With ethanol being used in larger quantities in motor sport and the possibility of wide spread road vehicle use. Can some of the obviously gifted readers, please give some design ideas for keeping the surface of such liquid fuel out of contact with air to prevent water absorption?

Some fuel/oil storage tanks have tops that move relative to the level of the fluid inside. This is mainly to eliminate fuel vapors inside so that the tanks don't become huge bombs. Perhaps a similar idea would accomplish this task. Would be tricky to design and manufacture though.

I wasn't thinking about installing a bladder in to the tank i was more along the lines of a series of baffels to reduce fuel surge (what this project is all about) if i just bought a bladder (not readily available as far as i'm aware) it would defeat the object.

If this is an academic project, I can understand why you wouldn't want to make the project too simple just for the sake of learning. But if the simplest solution is the best, why ignore it? If you're worried about baffling/sloshing, you might consider multiple bladders within the carbon hull? Some of the newer large aircraft (I believe the B2 bomber does this...) use rubber bladders to hold their fuel, and they actually have pumps running among the different bladders so they can shift their fuel around and control their center of gravity as the fuel is burned. Perhaps we'll see a similar solution in F1 next year (assuming it's legal) to make packaging of the larger tanks easier?

I had thought of a surface plate that moved with the fluid but it is the design detail I am interested in.

[flynfrog]

you could do away with the baffles and add a few fuel pumps and a surge tank.

You might not even need the extra pumps you could use the return line back to the tank to keep the surge tank full

[marcush.]

maybe you should not take the ethanol thing all too easy after all.most seals most pumps most fuelhose do not like ethanol and this is in racing terms a possible dnf after all....
so assuming anything is highly adventureous to put it in nice terms.
same goes for biodiesel btw,had this in a racecar the other year and it was simply amazing how this stuff ate away on the fuel hose of the diesel storage tank...
coming back to the fuel tank ,fabricating something with baffles or movable plates inside in a harsh racing environment out of carbonfibre with no experience with fuel system nor in carbonfabrication to rely on ,is really a bit optimistic.
look ,current top notch racing does not use any such device ,they rely on bladders and this stuff has come a long way since introduction in the 70s .
I also think you are not even allowed to race something like a selfmade fuel tank anywhere ,are you? to use something like that on the road is also not legal of course.

[flynfrog]

maybe you should not take the ethanol thing all too easy after all.most seals most pumps most fuelhose do not like ethanol and this is in racing terms a possible dnf after all....
so assuming anything is highly adventureous to put it in nice terms.
same goes for biodiesel btw,had this in a racecar the other year and it was simply amazing how this stuff ate away on the fuel hose of the diesel storage tank...
coming back to the fuel tank ,fabricating something with baffles or movable plates inside in a harsh racing environment out of carbonfibre with no experience with fuel system nor in carbonfabrication to rely on ,is really a bit optimistic.
look ,current top notch racing does not use any such device ,they rely on bladders and this stuff has come a long way since introduction in the 70s .
I also think you are not even allowed to race something like a selfmade fuel tank anywhere ,are you? to use something like that on the road is also not legal of course.

E85 is not that hard to plan for. Tygon tubing silicone seals. Replace anything AL with Stainless

[swordfish]

wow, lots of replies for me to sift through thanks.

Mystery Steve: Basically our project has to be a new/original idea so an alloy tank just wouldnt get me the marks i require, i'd hate to do whole years worth of work just to get 45% because i copied an idea that has been around in saloon car racing for years.

i'm starting to think more about bladders now and i'll do a bit more research in to them, however i'm not ready to write off the baffels just yet as they can be hugely effective.

Flynforg: I'm trying to keep the fuel system (not the tank) simple so i'd like to just have one pump and a small swirlpot to remove any excess air. I also want to keep the baffels to reduce weight transfer during cornering.

MarcusH: If people wern't sometimes optimistic then things would never evolve, do you honestly belive that for my final year degree project i should make nothing at all just have someone else do it...how do you believ that would work out for me?

You are allowed to make fuel tanks according to the MSA regulation G97, there is also no MOT regulations on fuel tanks as long as they are free from damage and in good condtion.

[flynfrog]

YOu still need to consider the fuel system as part of tank design there should be some articles on here about F1 tanks. Also DPcars.net has some custom tanks with a header tank built for his DP1.

Baffles are a good idea but they do not replace a bladder. The bladder is to hold the fuel after the tank cracks. Have a look at the early days of racing when drivers were being burnt in even minor crashes that's why we have bladders.

[autogyro]

maybe you should not take the ethanol thing all too easy after all.most seals most pumps most fuelhose do not like ethanol and this is in racing terms a possible dnf after all....
so assuming anything is highly adventureous to put it in nice terms.
same goes for biodiesel btw,had this in a racecar the other year and it was simply amazing how this stuff ate away on the fuel hose of the diesel storage tank...
coming back to the fuel tank ,fabricating something with baffles or movable plates inside in a harsh racing environment out of carbonfibre with no experience with fuel system nor in carbonfabrication to rely on ,is really a bit optimistic.
look ,current top notch racing does not use any such device ,they rely on bladders and this stuff has come a long way since introduction in the 70s .
I also think you are not even allowed to race something like a selfmade fuel tank anywhere ,are you? to use something like that on the road is also not legal of course.

I have played around with many fuels. Biodiesel does eat into hoses etc mainly because it tends to produce bio matter that is toxic if not completely anaerobic and clean. Ethanol also eats into seals but this is because the chemical composition of some neoprene based and rubber based seals reacts with it. You cannot blame either fuel for this. The seals and relevant tubings have to be changed to suit the fuel. I have come across many temperature and chemical oil reaction problems in transmission applications of ring seals and lip seals particularly automatics. I do not see this as any argument against particular fuel use anymore than for transmissions with such problems. The choice of seals in a vehicle is usualy dictated by the use of toxic fossil fuels and oils and their particular needs.

[autogyro]

maybe you should not take the ethanol thing all too easy after all.most seals most pumps most fuelhose do not like ethanol and this is in racing terms a possible dnf after all....
so assuming anything is highly adventureous to put it in nice terms.
same goes for biodiesel btw,had this in a racecar the other year and it was simply amazing how this stuff ate away on the fuel hose of the diesel storage tank...
coming back to the fuel tank ,fabricating something with baffles or movable plates inside in a harsh racing environment out of carbonfibre with no experience with fuel system nor in carbonfabrication to rely on ,is really a bit optimistic.
look ,current top notch racing does not use any such device ,they rely on bladders and this stuff has come a long way since introduction in the 70s .
I also think you are not even allowed to race something like a selfmade fuel tank anywhere ,are you? to use something like that on the road is also not legal of course.

I have played around with many fuels. Biodiesel does eat into hoses etc mainly because it tends to produce bio matter that is toxic if not completely anaerobic and clean. Ethanol also eats into seals but this is because the chemical composition of some neoprene based and rubber based seals reacts with it. You cannot blame either fuel for this. The seals and relevant tubings have to be changed to suit the fuel. I have come across many temperature and chemical oil reaction problems in transmission applications of ring seals and lip seals particularly automatics. I do not see this as any argument against particular fuel use anymore than for transmissions with such problems. The choice of seals in a vehicle is usualy dictated by the use of toxic fossil fuels and oils and their particular needs.

[marcush.]

of course I do not blame those fuels,I wanted to point into the direction that fuels are not fuels and todays incredients are quite aggressive so you just can´t take anything for granted.
Of course your comments are valid.

[nakul]

Hey all, i'm new here but i have used some information from this site to help me in the past (and it has allways been excellent)

I'm just starting my 3rd year doing a degree in MotorSport engineering and i have decided to take on a project of making a composite fuel tank for my Peugeot 205 because the standard one is total rubbish .

Now i'm not very clued up on composites, the only thing i have made before was a Carbon Fibre air box so i decided to do this project to further my knowlige on the subject. So to cut a long story short i'm after any information on cars that have used composite fuel tanks in the past and any literature that may have been published on the subject (it is a literary project after all)

Any help would be greatly appriciated. Thanks. Mark.

p.s. be gentle, i'm new

hey swordfish , i am trying out to make a composite fueltank and planning to use Beta foam as the molding material. have you worked with foams as molding material and doing wet layup processes on it? i am skeptical about the resin etaing away into the foam.

[flynfrog]

not sure what beta foam is but you have to pick a resin that is compatible with your mold. Resin is a pretty broad term.

[Ciro Pabón]

Betafoam is a brand name for polyurethane foam.

I would use a tiny bit of foam, a tiny bit of resin and do a test, but you know how I am: strange.

Of course, if testing is not an option, nakul should ask Dow, instead of asking us.

Here: http://www.dowautomotive.com/contact/

They will answer, I think.

I won't, I am afraid of zombie threads. They might eat my brain.

[alelanza]

When i saw this one being brought back to life i thought it was in relation to the V8 supercar tank explosion yesterday. Does anyone know what those are made of?