Metal fuel tank materials?

[chris ballance]

Were the shells of most ww2 era internal fuel tanks made of carbon steel?

 

[FLYBOYJ]

Were the shells of most ww2 era internal fuel tanks made of carbon steel?

As far as I know most non-self sealing fuel tanks were made from aluminum

 

[chris ballance]

thanks, should have googled more for photos, and I would have found pictures like this of a B-17 and Blackburn Skua tanks, but I was searching for text.

 

[MiTasol]

Why would you use heavy carbon steel instead of light aluminium?

 

[chris ballance]

Not being a aerospace person, I have no idea how fuel tanks of the era were formed, what kind of joints, seals, were they designed for any real internal pressure?

 

[MiTasol]

Rule one was as light as possible so pre WWII was the period when "wet" wings were developed. A wet wing is one where the fuel tank consists of the upper and lower skins. wing ribs and other wing structure, usually spars, that are assembled with sealants so that the weight of the tank is little more than the weight of the sealants.

WWI vintage tanks were often steel because they could be soldered to make them leak proof but even by then the common method was weldable alloy which was riveted together then the seams and rivet heads welded to provide sealing.

They were typically pressurized to a very low pressure so that they could be leak tested but not usually pressurised in service as this would cause any minor defect anywhere in the system to spray fuel with the attendant fire and explosion risks. Some drop tanks were pressurised to force the fuel out and up to the engine or main tank(s). Many drop tanks were made of welded, or riveted and soldered, steel during WWII.

As welding procedures improved most manufacturers moved to purely welded tanks with no rivets.

Some "bullet proof" tanks were alloy tanks that were coated with multiple layers of compounds that would extrude across any small or medium size hole. Some where purely made of such material. Some were purely made of built up layers of leather and other materials.

 

[chris ballance]

Did the any WW2 era fuel tanks have inert gas injected as they emptied?

 

[pbehn]

Did the any WW2 era fuel tanks have inert gas injected as they emptied?

I think some used exhaust gases as a purge, not strictly speaking "inert". A big disadvantage to anything carbon steel is that they rust.

 

[Deleted member 68059]

The Germans made what was one of the first non-metallic bag-tanks, for the Bf109F. I.e a flexible skin of synthetic rubber and fabric housed in a metal frame to keep the shape.

Sadly for them, they found out after a while that their version of 100 octane fuel reacted to the synthetic rubber (Perduren and Perbunan) and the fuel then lost its detonation resistance,
destroying the engine. It was incredibly difficult to investigate as the reaction took from 2 to 4 weeks, so aicrcaft "just filled" showed no symptoms at all, and aircraft taken on only very short trips showed moderate symptoms as the fuel in the tank was always "slightly" degraded. It was always a problem to a certain degree as the engines were always near the knock limit, and rarely were the fuel tanks totally dry, as then you dont even make it home, so degraded residue built up.

 

[chris ballance]

I think some used exhaust gases as a purge, not strictly speaking "inert". A big disadvantage to anything carbon steel is that they rust.

Yes, but i surprised how many old cars had them, although Ford and other companies used stainless and aluminum in some cases.

 

[chris ballance]

The Germans made what was one of the first non-metallic bag-tanks, for the Bf109F. I.e a flexible skin of synthetic rubber and fabric housed in a metal frame to keep the shape.

Sadly for them, they found out after a while that their version of 100 octane fuel reacted to the synthetic rubber (Perduren and Perbunan) and the fuel then lost its detonation resistance,
destroying the engine. It was incredibly difficult to investigate as the reaction took from 2 to 4 weeks, so aicrcaft "just filled" showed no symptoms at all, and aircraft taken on only very short trips showed moderate symptoms as the fuel in the tank was always "slightly" degraded. It was always a problem to a certain degree as the engines were always near the knock limit, and rarely were the fuel tanks totally dry, as then you dont even make it home, so degraded residue built up.

wow, would not have thought about that chemical compatibility issue.

 

[Shortround6]

I think some used exhaust gases as a purge, not strictly speaking "inert". A big disadvantage to anything carbon steel is that they rust.

A few American planes carried a CO2 tank that could be used the fill an empty or part empty tank. The tanks had to vented in order to feed the fuel so a part empty tank could fill with new air as it emptied out but the mixed CO2 and air probably provided some protection.

Of course for combat planes this means you need a source of CO2 at the airfields to refill the tanks/cylinders.

 

[MiTasol]

I think some used exhaust gases as a purge, not strictly speaking "inert". A big disadvantage to anything carbon steel is that they rust.

but steel drop tanks are throw away so rust is not an issue and built in tanks were alloy or a flexible compound. or a mixture of both

 

[pbehn]

but steel drop tanks are throw away so rust is not an issue and built in tanks were alloy or a flexible compound. or a mixture of both

The OP stated internal tanks.

 

[GrauGeist]

Yes, but i surprised how many old cars had them, although Ford and other companies used stainless and aluminum in some cases.

Older automobiles had fuel tanks generally made of stamped tin, that were spot-welded together with the seams being soldered.
After this, they were coated in zinc or other materials to prevent corrosion.

 

[Snautzer01]

but steel drop tanks are throw away so rust is not an issue and built in tanks were alloy or a flexible compound. or a mixture of both

Not the german ones.

 

[MiTasol]

True but I don't think they recovered many dropped in the channel or over England

 

[Snautzer01]

True but I don't think they recovered many dropped in the channel or over England

Should have a return to sender sticker on it. Would be bad sport not to send it back then.

 

[chris ballance]

You wonder what would have happened to a steel drop tank hitting the water at +200 knots. Also what are the chances some random trawler gets hit with one? Probably ruin a good fishing trip.

 

[Snautzer01]

You wonder what would have happened to a steel drop tank hitting the water at +200 knots. Also what are the chances some random trawler gets hit with one? Probably ruin a good fishing trip.

I read some german accounts of allied droptanks hitting and even killing people and livestock. In all cases police would secure and german forces would take the things for scrap to the dedicated stelle for those gifts. Those stelle (work places for retriving valuable metals) Including the wrecks of bombers etc. I believe it was 1 of the reasons to go paper like drop tanks.