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Posted: 9/9/2004 9:12:04 PM EDT
So I'm watching the History channel and they are talking about the japanese Zero not have self sealing fuel tanks. How does a self sealing tank work?
Link Posted: 9/9/2004 9:13:35 PM EDT
Made of rubber?
Link Posted: 9/9/2004 9:17:12 PM EDT
[Last Edit: 9/9/2004 9:18:19 PM EDT by dpmmn]
Rubber lined and foam filled bladder inside of the fuel tank
Link Posted: 9/9/2004 9:18:15 PM EDT
but how does the rubber seal itself?
Link Posted: 9/9/2004 9:19:13 PM EDT

Originally Posted By twonami:
but how does the rubber seal itself?

Ever shoot a tire?
Link Posted: 9/9/2004 9:22:29 PM EDT
[Last Edit: 9/9/2004 9:22:47 PM EDT by twonami]

Originally Posted By Fat_McNasty:

Originally Posted By twonami:
but how does the rubber seal itself?

Ever shoot a tire?

no, but I've seen the Firestone? self sealing tire display
Link Posted: 9/9/2004 9:22:34 PM EDT
Link Posted: 9/9/2004 9:25:00 PM EDT
sort of get it, a non reactive soft rubber compound fills in the hole
Link Posted: 9/9/2004 9:25:03 PM EDT

Originally Posted By twonami:
but how does the rubber seal itself?

The rubber is elastic enough that the projectile will not really punch a circular hole in the liner. The result will generally be a slit. The hydrostatic pressure of the fluid in the tank will push the rubber back down, and the slit will, for the most part, close back up. Now, you poke enough holes in the liner and you won't have any real integrity to the membrane. But one or two holes will be survivable. There may be some seepage through the slit, but the fuel won't go pouring out. Modern specialized self-sealing tanks employ a foam between the liner and the skin which further helps seal the puncture.
Link Posted: 9/9/2004 9:26:06 PM EDT
cool. thanks for the explanation
Link Posted: 9/9/2004 9:31:29 PM EDT
[Last Edit: 9/9/2004 9:33:27 PM EDT by luger355]
i understand the idea but i dont know exactly what they did.

Im thinking what was done is to have a smaller tank inside a larger tank.
The space in between the two was (i guessing) filled with some sort of semi liquid material under pressuse. When a hole is put into the tank the material under pressure is pushed out, turns hard and seals the leak.

Similar to putting a can of fix a flat in a tire and running over a nail.

If that makes any sense.....

edite to say i didnt read dzl's post
Link Posted: 9/9/2004 10:22:02 PM EDT
[Last Edit: 9/9/2004 10:23:20 PM EDT by KA3B]
This only comes from my experince working with Naval aircraft for 20 years....

Self-sealing fuel cells for military aircraft, not a fuel tank, (a fuel tank is a part of the structure of the aircraft, IE wet wings, there is no "fuel cell") are a Goodyear patented product.

Self-Sealing Fuel Cells
A self-sealing cell is a fuel container that automatically seals small holes or damage caused during combat operations.

A self-sealing cell is not bulletproof, merely puncture sealing.

As illustrated in figure 3-31, the bullet penetrates the outside wall of the cell, and the sticky, elastic sealing material surrounds the bullet.
As the bullet passes through the cell wall into the cell, the sealant springs together quickly and closes the hole.
Now some of the fuel in the tank comes in contact with the sealant and makes it swell, completing the seal.
In this application, the natural stickiness of rubber and the basic qualities of rubber and petroleum seal the hole.

This sealing action reduces the fire hazard brought about by leaking fuel.

It keeps the aircraft’s fuel intact so the aircraft may continue operating and return to its base.

The most commonly used types of self-sealing fuel cells are the standard construction type and the type that uses a bladder along with the self-sealing cell.

Of the two, the standard construction cell is used the most.

It is a semiflexible cell, made up of numerous plies of material.

The combination bladder and self-sealing cell is made up of two parts.
One part is a bladder-type cell, and the other part is identical to the standard construction cell.
It is designed to self-seal holes or damage in the bottom and the lower portions of the side areas.
The bladder part of the cell (nonself-sealing) is usually restricted to the upper portion.
This type of cell is also semi flexible.

There are four primary layers of materials used in the construction of a self-sealing cell. These layers are the inner liner, nylon fuel barrier, sealant, and retainer.

All self-sealing fuel cells now in service contain these four primary layers of materials.

If additional plies are used in the construction of the cell, they will be related to one of the primary plies.

The inner liner material is the material used inside the cell.
It is constructed of Buna N synthetic rubber. I
ts purpose is to contain the fuel and prevent it from coming in contact with the sealant. This will prevent premature swelling or deterioration of the sealant.
Buna rubber is an artificial substitute for crude or natural rubber.
It is produced from butadiene and sodium, and is made in two types, Buna S and Buna N.

The Buna S is the most common type of synthetic rubber.
It is unsuitable for use as inner liner material in fuel cells.
It causes the petroleum fuels used in aircraft to swell and eventually dissolve.

The Buna N is not affected by petroleum fuels, making it ideal for this application.

However, the Buna N is slightly porous, making it necessary to use a nylon barrier to prevent the fuel from contacting the sealant.
The nylon fuel barrier is an unbroken film of nylon.

The purpose of the nylon fuel barrier is to prevent the fuel from diffusing farther into the cell. The nylon is brushed, swabbed, or sprayed in three or four hot coats to the outer surface of the inner liner during construction.

The sealant material is the next material used in fuel cell construction.
It remains dormant in the fuel cell until the cell is ruptured or penetrated by a projectile.
It is the function of the sealant to seal the ruptured area.
This will keep the fuel from flowing through to the exterior of the fuel cell

The mechanical reaction results because rubber, both natural and synthetic, will “give” under the shock of impact.
This will limit damage to a small hole in the fuel cell.

The fuel cell materials will allow the projectile to enter or leave the cell, and then the materials will return to their original position.
This mechanical reaction is almost instantaneous.

The chemical reaction takes place as soon as fuel vapors penetrate through the inner liner material and reach the sealant.

The sealant, upon contact with fuel vapors, will extend or swell to several times its normal size. This effectively closes the rupture and prevents the fuel from escaping.
The sealant is made from natural gum rubber.

The retainer material is the next material used in fuel cell construction.
The purpose of the retainer is to provide strength and support.
It also increases the efficiency of the mechanical action by returning the fuel cell to its original shape when punctured.
It is made of cotton or nylon cord fabric impregnated with Buna N rubber.

Link Posted: 9/9/2004 10:26:00 PM EDT
very cool explanation, you learn something new on ARFCOM everyday
Link Posted: 9/9/2004 10:30:16 PM EDT
the knowledge base here consistently floors me...
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