Author Topic: self sealing fuel tanks  (Read 1908 times)

Offline Matrix

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self sealing fuel tanks
« on: March 14, 2010, 09:09:29 AM »
I watched the show Air combat the other day that pitted the P47 against the FW190.  One of the things that struck me was the mention of self sealing fuel tanks in the P47.  So i started pondering how the aircraft are modeled in AH, if planes did in fact have this technology why do we see fuel leaks in the game from them or the fire ball?

*******************************   GOT THIS INFO OFF WIKIPEDIA***************************************************
World War II
In the newer generations of pre-war and early-war aircraft, self-sealing tanks were tanks used to minimize the potential damage from leaking or burning fuel. A conventional fuel tank, when hit by enemy fire, could leak fuel rapidly; this would not only reduce the aircraft's effective range, but was also a significant fire hazard. Damaged fuel tanks could also rupture, destroying the airframe or critically affecting flight characteristics.

It was realised early on that it was not practical for weight reasons to add armour plate to aero fuel tanks, hence a way of stopping fuel leaking from damaged tanks was necessary.

Early attempts at protecting fuel tanks consisted of using metal tanks, covered inside or outside by a material that expanded after being pierced. Research revealed that the exit of the projectile, rather than the entry, was the greater problem, as it often tumbled, thus creating a large exit hole. Amongst the earliest versions of these types of tanks were those manufactured in the United Kingdom at Portsmouth airport by Fireproof Tanks Ltd. These tanks were first installed in the Fairey Battle with other versions installed in Supermarine Spitfires, Hawker Hurricanes and larger aircraft such as the Avro Lancaster.

 
Manufacture of self-sealing gas tanks at Goodyear (1941)Goodyear chemist James Merrill was awarded a patent in 1941 for refining and successfully testing his method for manufacturing self-sealing tanks using a two-layer system of rubber compounds encased in a metal outer shell or the wing lining of the aircraft.[1] In 1942, he received a War Production Board citation from President Roosevelt and the Goodyear tanks were subsequently placed in service in Goodyear-produced Corsair fighters, as well as other aircraft. By 1942 Fireproof Tanks had developed the first flexible fuel bladders as range extender tanks for the MkIX Spitfire. These tanks were flexible containers, made of a laminated self-sealing material like vulcanized rubber and with as few seams as possible to minimise leak paths.

As early tests showed that impact could overpressure a fuel tank, the self-sealing fuel cell is suspended, allowing it to absorb shocks without rupture. U.S. Navy fuel tanks during the war were able to withstand .50 caliber (12.7 mm) bullets and, on occasion, 20 mm cannon shells.

Not all fighters were fitted with the relatively new invention; self-sealing tanks tended to be heavier with lower capacity than non-sealed tanks. Nonetheless, aircraft that were fitted with self-sealing tanks regularly took more punishment than those without. Combat experience in the Pacific showed that the heavily protected American aircraft could sustain far more damage than the lightly armored Japanese designs without self-sealing fuel tanks (for instance, the Mitsubishi Zero).

Offline Krusty

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Re: self sealing fuel tanks
« Reply #1 on: March 14, 2010, 09:16:01 AM »
Because they only seal "N" % of the time, and they only seal against smaller rounds. Try blowing a foot-wide hole in it with a 20mm cannon round, and it's not going to seal it shut!

Offline Shifty

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Re: self sealing fuel tanks
« Reply #2 on: March 14, 2010, 09:35:59 AM »
You'll notice you see more fireballs on certain aircraft than you do on others. Last week when flying in the no icons Midway setup in the AVA if you saw a fireball in the distance it was almost always a Japanese aircraft. If I killed a zeke it usually caught fire. If I killed an F4F or P-40 it usually came apart with no fire. So I assume this is programed into the games aircraft to represent self sealing tanks. Krusty has a point the protection can only go so far. The A-10 Thundebolt II had what we called ballistic foam around the areas of the self sealing fuel cells. After Desert Storm we had a couple of aircraft come back to squadron from the war that had to have both replaced because of heavy battle damage. In fact these aircraft were brought back to us by C-5s. You can only take so much damage no matter how good a system you have.

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Offline Matrix

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Re: self sealing fuel tanks
« Reply #3 on: March 14, 2010, 10:18:30 AM »
 sure Krusty has a good point, but to that point when in the arena how many times do you see a con bleeding fuel or does your a/c bleed fuel after being hit?  was self sealing fuel tanks taken into consideration when modeling AH a/c? 

 IE: "U.S. Navy fuel tanks during the war were able to withstand .50 caliber (12.7 mm) bullets and, on occasion, 20 mm cannon shells"

are these small caliber rounds??? 

Offline Krusty

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Re: self sealing fuel tanks
« Reply #4 on: March 14, 2010, 10:56:19 AM »
How many times have you seen a fuel leak in planes with self-sealing tanks? Plenty....

How many times WOULD you see them, if they were not self-sealing? Tons more.

You ever take hits on your wing in a P-51 with no damage? There ya go, your tanks didn't leak. How about taken a ton of hits in your F4u's fuselage? There ya go, you didn't leak.

The thing is you're saying "I see them not working a lot" -- but the other side of it is, when they DO work you don't see anything at all.

Then you sneeze at a zero, it bursts into flames, and you realize what it would be like if no planes had self-sealing tanks at all!


P.S. Self-sealing has to do with swelling or some other function, where it closes a hole by a round. Multiple rounds in the same spot (a solid burst) will seriously degrade its ability to "swell up and plug the hole" -- the entire system just wasn't made with "swiss cheese" in mind, it was designed for the odd puncture here or there.

Offline Motherland

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Re: self sealing fuel tanks
« Reply #5 on: March 14, 2010, 11:58:27 AM »
sure Krusty has a good point, but to that point when in the arena how many times do you see a con bleeding fuel or does your a/c bleed fuel after being hit?  was self sealing fuel tanks taken into consideration when modeling AH a/c? 

 IE: "U.S. Navy fuel tanks during the war were able to withstand .50 caliber (12.7 mm) bullets and, on occasion, 20 mm cannon shells"

are these small caliber rounds??? 
You take a lot more hits to your fuel tanks than you realize.

The next time you're fighting a zeke (I think that it's pretty much the only fighter in the game without self sealing fuel tanks), especially with a .50 cal or .30 cal bird, take note of the damage it takes... even if you don't take a wing off (which is a hard thing not to do against a zeke) you're going to puncture a fuel tank (or set it on fire). With almost every shot. That's how your jug, what have you would react if it didn't have self sealing fuel tanks.

Offline USCH

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Re: self sealing fuel tanks
« Reply #6 on: March 14, 2010, 02:38:21 PM »
In Fighter ace we had self sealing tanks but they only worked if you flew level until the leak sealed itself.... it seemed to work fine and I for one liked it..

i don't like flying the blue aircraft for the simple reason they only have one tank and when it is hit it becomes an instant ditch...

i feel it would be simple enough to code in a programme in witch aircraft with SSFT's could have them like in FA... If you keep turning and burning the tank keeps leaking.. if you level off and allow the sealant to work you get to save some gas (and have a chance of making it home)

Offline Krusty

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Re: self sealing fuel tanks
« Reply #7 on: March 14, 2010, 03:26:31 PM »
That's absurdly ludicrous....

It makes no difference what orientation the tank is. Most times the rubber (or whatever used) material gets wet as the gas leaks out, and expands from the contact, swelling to the point it cuts off the leak.

"flying level" has diddly squat to do with it, IMO. That's just really poor code choices on FA's part.

Offline USCH

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Re: self sealing fuel tanks
« Reply #8 on: March 14, 2010, 04:25:55 PM »
I totally understand your point but what it does is force the guy to disengage and fly level to save his butt. It doesn't allow him to keep fighting as if nothing is wrong. Witch IMO is better than no sealing at all.

Understaning my point of veiw? Not looking for a fight here, just giving out a my experience.

Offline Motherland

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Re: self sealing fuel tanks
« Reply #9 on: March 14, 2010, 04:27:37 PM »
I totally understand your point but what it does is force the guy to disengage and fly level to save his butt. It doesn't allow him to keep fighting as if nothing is wrong. Witch IMO is better than no sealing at all.
What's wrong with having SSFT's that don't force you to disengage?

Offline Ruler2

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Re: self sealing fuel tanks
« Reply #10 on: March 14, 2010, 04:28:35 PM »
Another thing to notice, when you DO get a fuel leak on a plane with self-sealing fuel tanks, look at how SLOW the fuel drains! That is because although the fuel is leaking, it is being held to a minimum by the tank itself. Whereas on an A6M or other plane with no self-sealing tanks, the fuel gauge moves faster than the Roadrunner!

Offline whiteman

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Re: self sealing fuel tanks
« Reply #11 on: March 14, 2010, 04:53:05 PM »
Don't want to get holes in your Blue Birds, fly smarter. I've been flying them since i started and running out of fuel from a hit is rare for me. If I'm going to fly a blue plane into ack on purpose I'll have a drop tank or I'll keep fuel in the wings on the F4U-1 and -1A.

Offline SIK1

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Re: self sealing fuel tanks
« Reply #12 on: March 14, 2010, 07:56:51 PM »
Yep in the -1, and -1A I leave the RW tank as a reserve, burning the LW first then the main.
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Offline kingcobradude

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Re: self sealing fuel tanks
« Reply #13 on: March 14, 2010, 08:14:56 PM »
the self sealing tanks are modeled here. Ive had some of my birds take loads of punishment in the fuel tank area and nit have leaks. thet=y are made for the occasional puncture, not a 88mm flak round shredding it
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Offline Stoney

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Re: self sealing fuel tanks
« Reply #14 on: March 14, 2010, 09:37:30 PM »
The only problem I have with the fuel fires in the P-47 is, given the location of the main tank, it would be almost impossible to hit it from any type of rear aspect shot.  Almost all of my fuel fires in the Jug come from a rear aspect shot.  However, for now, I'll push the "I believe" button and wait to see how the new damage model changes this.

"Can we be incorrect at times, absolutely, but I do believe 15 years of experience does deserve a little more credence and respect than you have given from your very first post."

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