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Self sealing fueltanks: when did motorsport start to use them - and why not earlier?


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#1 Nemo1965

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Posted 27 February 2019 - 11:01

After seeing a see-through diagram of the Cooper T62 F3 car and,specifically, the position of the fueltank... after reading the book Black Noon by Art Ganer, I wondered: when was this technology of self-sealing tanks actually available? 

 

A short survey taught me that techniques were already invented at the end of the first worldwar, so about 1917. Certainly after the second world war most people who were acquainted with the airplane-industrty must have been aware of them.

 

https://en.wikipedia...aling_fuel_tank

 

I googled it but could not find when the first motorsport-entrepeneurs started to implement them. My guess is way after the sixties perhaps even AFTER the early seventies (if I think about the deahts of Piers Courage and Roger Williamson at Zandvoort, the accident of Icx at Jarama, Peterson in Monza).

 

Am I correct? Or is it perhaps the case that constructors started using the self-sealing tanks immediately but that the accidents in motorsport were just so different  that the techniques of protection against bullets and flak could not protect the drivers from fire?

 

I am curious if any of the technological experts roaming these shores have an idea about that.


Edited by Nemo1965, 27 February 2019 - 11:02.


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#2 Charlieman

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Posted 27 February 2019 - 14:07

BRM used tanks from FPT Ltd (Fireproof Tanks), later called FPT Industries, in the 1950s. I'd guess that they were used in the front engined 2.5 litre BRMs if not earlier -- see Doug Nye's BRM books. I am not aware of much use elsewhere during the multi tubular and space frame chassis era, but "bag tanks" were standard for everyone who copied the Lotus 25 onwards.

 

FPT were a major supplier to UK aircraft manufacturers during WWII and their tanks were designed to "heal" multiple punctures from small calibre shells. Their products would have been known to motor sport designers who had been exposed to the aircraft industry. However those tanks were not designed for accidents which tear apart tubular or monocoque chassis.

 

The accident involving Piers Courage occurred before deformable structures were required on the sides of F1 cars; the chassis contained magnesium sheet which exacerbated the fire. Roger Williamson's accident demonstrated that the deformable structures rules were inadequate (and a lot more, of course). The Jacky Ickx fire happened after a high speed T-bone collision in which fire proof tanks or deformable structures of the time would have had little influence.

 

The Peterson accident is interesting because he was in a Lotus 78 with a main tank behind the seat and two side tanks; the Lotus 79 and the vast majority of cars since have a single tank between the driver and engine. Following the Peterson accident, marshals controlled the fire quickly (cf Roger Williamson) and Ronnie sadly died of blood poisoning. Colin Chapman sought an exemption from F1 regulations to create the Lotus 79 design for competitive reasons but the single fuel cell has incidentally become a significant safety improvement.

 

The Cosworth DFV engine and others used as a structural element created a new fire risk when the structural engine element broke away in an accident. Self closing valves were built into the fuel delivery system to minimise loss.



#3 Nemo1965

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Posted 27 February 2019 - 18:05

BRM used tanks from FPT Ltd (Fireproof Tanks), later called FPT Industries, in the 1950s. I'd guess that they were used in the front engined 2.5 litre BRMs if not earlier -- see Doug Nye's BRM books. I am not aware of much use elsewhere during the multi tubular and space frame chassis era, but "bag tanks" were standard for everyone who copied the Lotus 25 onwards.

 

FPT were a major supplier to UK aircraft manufacturers during WWII and their tanks were designed to "heal" multiple punctures from small calibre shells. Their products would have been known to motor sport designers who had been exposed to the aircraft industry. However those tanks were not designed for accidents which tear apart tubular or monocoque chassis.

 

The accident involving Piers Courage occurred before deformable structures were required on the sides of F1 cars; the chassis contained magnesium sheet which exacerbated the fire. Roger Williamson's accident demonstrated that the deformable structures rules were inadequate (and a lot more, of course). The Jacky Ickx fire happened after a high speed T-bone collision in which fire proof tanks or deformable structures of the time would have had little influence.

 

The Peterson accident is interesting because he was in a Lotus 78 with a main tank behind the seat and two side tanks; the Lotus 79 and the vast majority of cars since have a single tank between the driver and engine. Following the Peterson accident, marshals controlled the fire quickly (cf Roger Williamson) and Ronnie sadly died of blood poisoning. Colin Chapman sought an exemption from F1 regulations to create the Lotus 79 design for competitive reasons but the single fuel cell has incidentally become a significant safety improvement.

 

The Cosworth DFV engine and others used as a structural element created a new fire risk when the structural engine element broke away in an accident. Self closing valves were built into the fuel delivery system to minimise loss.

 

Excellent, thank you! 



#4 GreenMachine

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Posted 27 February 2019 - 21:02

To clarify, to the best of my knowledge, bag tanks were not self-sealing.  The self sealing arose from a layer of (I think) rubber on the outside (or between an inner and outer skin?), which when exposed to petrol swelled up and sealed the hole.  As Charlieman says, it was designed to seal holes from small calibre gunfire.  One of the consequences of this was the extra weight, which together with the different failure mode would probably make that form of self-sealing unattractive in a racecar.  I have not seen any references to bag tanks being self-sealing - they were used because of their other advantages over rigid tanks.  It is no surprise that a manufacturer of self sealing tanks for (say) aircraft would be able to make a bag tank for racing cars (without the complexity and weight of the 'self-sealing' part).  It would also not be a surprise that BRM, with its strong links into British industry, would pioneer their use (which is what I think Charlieman is saying).

 

In-tank foam is used to reduce 'sloshing' of the fuel within the tank, and I believe that this has some advantages in a fire situation, but I am not sure just how that works.



#5 Wuzak

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Posted 28 February 2019 - 00:49

I believe that adding self-sealing also reduces the capacity of the tank a small amount.

 

For example, the first P-40s did not have self sealing tanks and had 180USG capacity, which went down to 160USG when self sealing was initially fitted.



#6 Kelpiecross

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Posted 28 February 2019 - 04:10

 I seem to recall that the present bag tanks were derived from Vietnam-era helicopter fuel tanks.  Rather than self sealing they were just very tough  - I recall seeing (on TV)  a bag tank being attacked by someone with an axe without doing it any damage.  A bit like attacking a car tyre with an axe - very tough.  



#7 Henri Greuter

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Posted 28 February 2019 - 08:18

After the catastrophic 2nd lap disaster at Indy '64 and the fire that eventually killed Dave MacDonald, USAC mandated the use of fuel tank technology as used in the Vietnam helicopters. They were not self sealing as far as I know. But they were effective. There have been no accidents with fires at the speedway anymore after a car crashed since then. The only serious fiery accident at Indy I do remember right now out of the top of my head is Rick mears refuelling disaster in 1981 and whatever other less dramatic refuelling accidents in later years.
At that time, ('65) USAC was way ahead in fuel tank technology instantly.

Eery....

When the 3 liter formula came along in F1 there were some fears for more fiery accidents from now on since the cars allo of a sudden had to carry at least twice as much, if not a bit more fuel on board than during the preceeding 1.5 liter era.
And that's indeed what happened....

#8 Nemo1965

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Posted 28 February 2019 - 09:58

After the catastrophic 2nd lap disaster at Indy '64 and the fire that eventually killed Dave MacDonald, USAC mandated the use of fuel tank technology as used in the Vietnam helicopters. They were not self sealing as far as I know. But they were effective. There have been no accidents with fires at the speedway anymore after a car crashed since then. The only serious fiery accident at Indy I do remember right now out of the top of my head is Rick mears refuelling disaster in 1981 and whatever other less dramatic refuelling accidents in later years.
At that time, ('65) USAC was way ahead in fuel tank technology instantly.

Eery....

When the 3 liter formula came along in F1 there were some fears for more fiery accidents from now on since the cars allo of a sudden had to carry at least twice as much, if not a bit more fuel on board than during the preceeding 1.5 liter era.
And that's indeed what happened....

 

What I find amazing is that safe fueltanks - self sealing or not - where so late introduced in F1 - considering the fact that British motorsport (and F1 was British, by and large) was so inspired and 'genetically' connected to fighter planes and fighter pilots. I remember David Purley saying (I am parafrasing here): 'Our fathers had war and fighter planes - we have races and race-cars.'

 

Furthermore, many F1-drives said they'd rather not wear safety-belts, because they prefered be thrown out of a car than being strapped to a burning one. So for me - with all the excellent posts above - I find it baffling that F1-engineers (apart from BRM) not said much, much sooner:   'You know... let us put fueltanks in the cars like the one we had in the 1942  Mk IX Spitfire.' (Or words to that effect). 

 

If I look at the Roger Williamson-accident at Zandvoort or that of Jacky Ickx in Jarama, it looked like the fueltank was nothing more than alloy-shell brimming with fuel, ready to bust open... or am I wrong about that? 


Edited by Nemo1965, 28 February 2019 - 11:41.


#9 Blue6ix

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Posted 28 February 2019 - 11:17

Interesting.

 

How about FT generations for fuel tank safety?

 

FTs like FT1, FT2 and FT3 and so forth were used starting from the early 1970s and then even made to mandatory one even though it wasn't really providing really good safety protection for the last few decade standards.

 

And even if things like fuel bladder, fuel bag and fuel cell itself within the tank was at times and for the late 1970s, safety enough, weren't the real reason for the accidents the use of multiple fuel tanks like main fuel tank and reserve tanks, adding the insult and injuries when having often quite a fiery crash?

 

If I'm not mistaken, they were prohibited starting from the 1978 season.

 

Even though fuel tank from the last 41 years in F1 cars is a single cell, some of them actually do or at least had that little compartment/shelf thing which can contain somewhat more fuel than which was added to the main tank mostly.

 

Most notably that was seen and done up within the early 1990s because of the mostly non-refuel rules.

 

It was sometimes like in times of the early to mid 1970s, crucial for surviving to the finish line.

 

Had it not for those shelf fuel/compartment fuel, retirements could have been even more common than what they even were before.


Edited by Blue6ix, 28 February 2019 - 11:23.


#10 JtP2

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Posted 28 February 2019 - 14:34

Thought bag tanks were mandatory from the1970 season. The reason Brabham went monocoque. I seem to remember Brabham's comment " if you got to use a bag tank inside an aluminium shell, you might as well make the aluminium shell the car" In fact, I think foam filled bag tanks were mandatory for any international event, have a friend who had to buy one to do a televised rallycross for the 70/71 season. Btw, I still have it after buying it when the international date ran out.

 

There is of course a big difference between a bag tank and a self sealing tank.



#11 Claudio Navonne

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Posted 01 March 2019 - 08:42

I think I read that Vanwall suffered some retirements in 1956 races because the fuel broke down the sponge inside the tank and clogged the injectors' pipes. I always thought it was because they were testing with self-sealing tanks. The problem was that the fuel of the cars (free until December 31, 1957) was very different (corrosive) to the gasoline or kerosene used by the airplanes.



#12 Lee Nicolle

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Posted 17 March 2019 - 00:41

It is well known that many WW2 warplanes had self sealing tanks. Though far from all.

Speedway were using bag tanks well before F1.

F1 has never been a leader. As they were a decade later to use seat belts as well!

Fuel tank foam reduces capacity by about 10% and is also anti spray as well as anti surge.

These days for most budget racers a lot use plastic tanks. Far stronger than an alloy tank and a similar weight. I have seen one recently [in a hotrod roadcar] that was squished up badly but did not split unlike a steel or alloy one. It actually blew the hose off the vent fitting as the air had to go somewhere, luckily on top. Ford Australia used plastic in their cars from 79 on, underslung on the boot floor. 

When I crashed my Sports Sedan backwards into a tyre wall the alloy tank simply folded  up and tore open. Luckily for me no fire but  full 40 litres of Avgas onto the ground. I salvaged a couple of fittings as well as the foam. 



#13 Lee Nicolle

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Posted 17 March 2019 - 00:49

I think I read that Vanwall suffered some retirements in 1956 races because the fuel broke down the sponge inside the tank and clogged the injectors' pipes. I always thought it was because they were testing with self-sealing tanks. The problem was that the fuel of the cars (free until December 31, 1957) was very different (corrosive) to the gasoline or kerosene used by the airplanes.

Fuel tank foam has a finite life and will be very allergic to different fuels. 

Recently I have gone to E85 on the tintop I dabble with and had to change the foam for one compatible with the ethanol. 

I had a tank that had been fabricated in an airforce shop and the foam just turned to a gluggy mess in a short period. And clogged the fuel filter totally. This a Z9 oil filter and using Avgas. Luckily very little got forward of the filter.

I presume and hope it was for jetfuel only as a avgas fueled plane would be falling out of the sky!



#14 Charlieman

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Posted 30 March 2019 - 14:19

I came across these notes in Doug Nye's book about Cooper (I think it may be in the BRM books too). The author is Tony Rudd, comparing a 1960 BRM P48 MkII and a 1958 Cooper F1/F2 (Cooper used the same same chassis for F1 and F2 racing, and the basic concept was similar in 1960).

 

Cooper fuel tank, 20 SWG aluminium welded with retaining straps, baffles and filler system. Capacity 14 gallons, weight 17 lb.

 

BRM "fireproof bag". Capacity 15 gallons, weight 6 lb. Add a bit for a retention box, which comprised part of the BRM overall bodywork weight, and for a filler. However the BRM total bodywork weighed less than that of the Cooper. 

 

So the bag tank feature -- fireproof ability undetermined -- weighed less or about the same as an aluminium welded tank circa 1960.

 

The Indy 500 Cooper of 1961 had aluminium fuel tanks with a glass fibre layer (on the lower side?) to protect them.



#15 mariner

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Posted 01 April 2019 - 14:28

Why did it take so long? 

 

One word I would suggest MONEY 

 

Budgets in aerospace and wartime  may not be unlimited but they come from tax raising and debt borrowing governments. Nobody in 1960's F1 etc had any real money.

 

When Lotus built the 25 they had to use riveting as the chassis was a mixed aluminium and steel fabrication. Also they knew from direct aircraft experience that  nearly all aluminium aircraft were welded and non  welding alloys could be stronger. 

 

So with an assurance of leaks from a riveted chassis,  bag tanks had to be afforded.


Edited by mariner, 01 April 2019 - 14:29.


#16 rms

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Posted 04 April 2019 - 03:47

Why did it take so long? 

 

One word I would suggest MONEY 

 

Budgets in aerospace and wartime  may not be unlimited but they come from tax raising and debt borrowing governments. Nobody in 1960's F1 etc had any real money.

 

When Lotus built the 25 they had to use riveting as the chassis was a mixed aluminium and steel fabrication. Also they knew from direct aircraft experience that  nearly all aluminium aircraft were welded and non  welding alloys could be stronger. 

 

So with an assurance of leaks from a riveted chassis,  bag tanks had to be afforded.

 

Your saying "nearly all aluminium aircraft were welded" requires some evidence to back it up. 

 

Stress bearing welded aluminium structures are extremely prone to cracks and structural failure. I seem to remember Porsche having a couple of problems and Frank Gardner would park the car and walk home.

 

That is a bit hard to do at 10,000 feet !



#17 Wuzak

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Posted 04 April 2019 - 10:23

Looks a lot like rivets

 

http://www.b-domke.d...antom/7366.html



#18 JtP2

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Posted 04 April 2019 - 11:59

The only WW2 aircraft that I can remember being welded was an F6F Hellcat which had the skins spot welded. Last big metal flying bus I was on seemed to have a lot of rivets holding it together.



#19 cpbell

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Posted 08 April 2019 - 10:08

This subject was covered in part in the following thread:

https://forums.autos...ed-regulations/

 

From that, you'll note that most F1 accident-related fires post-Spanish GP 1973, when the deformable structure requirement came into effect, were failures of connectors between tanks rather than failure of the tanks themselves. 



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#20 mariner

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Posted 11 April 2019 - 01:51

Your saying "nearly all aluminium aircraft were welded" requires some evidence to back it up. 

 

Stress bearing welded aluminium structures are extremely prone to cracks and structural failure. I seem to remember Porsche having a couple of problems and Frank Gardner would park the car and walk home.

 

That is a bit hard to do at 10,000 feet !

 

 

I have been away and just realised a big OOPS! I meant to say aircaft were " not welded" but that tiny word "not" got left out - sorry



#21 bigleagueslider

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Posted 17 April 2019 - 07:00

The fuel cells commonly used in racing are a bit different than the self-sealing (ballistic) fuel tanks used in military vehicles.

 

Racing fuel cells use a fabric reinforced rubber bladder inside a metal (or composite) housing, often with internal foam baffling and self-sealing breakaway fluid fittings. http://atlinc.com/racing.html

 

The self-sealing ballistic fuel tanks used on military vehicles have a vulcanized rubber coating applied outside a metal/composite tank, often with internal foam baffling to minimize sloshing and the potential for explosion. http://atlinc.com/ballistictank.html



#22 gruntguru

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Posted 17 April 2019 - 21:59

Welcome back stranger.



#23 7MGTEsup

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Posted 18 April 2019 - 10:52

After the catastrophic 2nd lap disaster at Indy '64 and the fire that eventually killed Dave MacDonald, USAC mandated the use of fuel tank technology as used in the Vietnam helicopters. They were not self sealing as far as I know. But they were effective. There have been no accidents with fires at the speedway anymore after a car crashed since then. The only serious fiery accident at Indy I do remember right now out of the top of my head is Rick mears refuelling disaster in 1981 and whatever other less dramatic refuelling accidents in later years.
At that time, ('65) USAC was way ahead in fuel tank technology instantly.

Eery....

When the 3 liter formula came along in F1 there were some fears for more fiery accidents from now on since the cars allo of a sudden had to carry at least twice as much, if not a bit more fuel on board than during the preceeding 1.5 liter era.
And that's indeed what happened....

 

I thought it was the banning of gasoline and the maximum fuel capacity that stopped a repeat of 64?. There have been a few fiery crashes since (Salt Walther and Swede Savage both in 1973) but they didn't look anywhere near as spectacular because of the alcohol burning with a much dimmer flame and no smoke.