self sealing gas tanks

[renrich]

When did British and German ac start using self sealing gas tanks?

 

[renrich]

I have been rereading Peter Townsend's book about the BOB and he keeps mentioning instances where a hit in the gas tank on both Hurricanes and Spits causes the AC to catch on fire. Does anyone know for sure that the British and German AC in the BOB were equipped with self sealing gas tanks? I do know the early F4F3 DID NOT have self sealing gas tanks.

 

[Glider]

My understanding was that they started to be fitted during the Battle of France when it quickly became obvious that they were a must have addition. It was a rolling programme fitting them to existing A/C but new builds had them fitted.
I believe (bute certainly cold be wrong) that by the BOB all front line aircraft had them but it should be remembered that they had their limitations. A 20mm in the tank would be almost certain to set it alight.

 

[mad_max]

I'm not an expert; but in the books I have about the Spitfire, the Spit I's didn't have
self sealing tanks. When the Spit II's came out with the Merlin XII installed the Brits
added more armour and self sealing tanks. The first one to roll of the assembly lines
was in June 1940 and operational use began August 1940 with No 611 Sqn.

This is what I found. Disclaimer is someone may find different/better facts.

 

[pbfoot]

Self sealing tanks according to Spitfire the History by eric Morgan and Edward Shacklady indicate fitting selfsealing on to lower fuel tank on the MK1 27/7/40 I'm still searching for more info. I assume the upper drained into lower tank and probably most of the fuel in the upper was used while taking off and climbing to altitude

 

[renrich]

It sounds like to me that self sealing tanks were not all that prevelant during the BOB and that explains the easy flaming of the Hurricanes and Spits. Churchill should at the least be censured and possibly impeached for that.

 

[HoHun]

Hi Pbfoot,

>I assume the upper drained into lower tank and probably most of the fuel in the upper was used while taking off and climbing to altitude

I'm not sure whether it was the top tank or slow sealing on the low tank, but it's my impression that the front tanks remained a combat hazard during the Battle of Britain. I recently read a book titled "Guinea Pigs" (or similar), written by a fighter pilot who was one of the founding members of the Guinea Pig Club. He describes his first encounter with the brilliant surgeon Archibald McIndoe, who - after looking at the pilot's burns - simply asked "Hurricane or Spitfire?"

Apparently, the heavy facial burns were so typical for fighter pilots that McIndoe did not need to ask for any general information on cause of the injuries ...

(As so often, McIndoe worked wonders in the treatment of the author of "Guinea Pigs". Wish I'd remember the name - unfortunately, I have mislaid the book. It really made a deep impression on me.)

Regards,

Henning (HoHun)

 

[comiso90]

It sounds like to me that self sealing tanks were not all that prevelant during the BOB and that explains the easy flaming of the Hurricanes and Spits. Churchill should at the least be censured and possibly impeached for that.

Why? Because he's the Prime Minister?

If that's true then Roosevelt should have the same punishment for the abysmal performance of American torpedoes early in the war...

____

How much extra weight did self-sealers add? What was the effect on performance?

.

 

[Glider]

It sounds like to me that self sealing tanks were not all that prevelant during the BOB and that explains the easy flaming of the Hurricanes and Spits. Churchill should at the least be censured and possibly impeached for that.

Be fair, no one else had them as standard at the time. Both the UK and Germany were fitting them as quickly as possible and when a war starts, you have to fight with what you have. The USA had the huge benefit of being able to learn from the European battles before December 1941 and they were by no means common in the USA at that time.

 

[pbfoot]

I'm reading this tome to find more info and came upon this item
"but the more serious problem was pilot protection from fire from the bottom tank. Sholto Douglas said that the tank could not have self sealing covering owing to insufficient clearance between it and the fuselage skin. A metal bulkhead had been designed for installation between the tank and the cockpit for this , it was suggested , would allow the pilot sufficient time to vacate the aircraft in the event of a fire . This modification took months to reachproduction aircraft and retrofitting was necessary . working parties had to go on 24 hr shift systemto clear the backlog and each Spitfire took 40 hours to modify ."
this was on the MKV around 11 june 41 this seem to contradict the previous info posted by me and it's from same book

 

[Hop]

The Spitfire II pilot manual, dated July 1940, says:

"The lower fuel tank is covered with self sealing rubber".

The Spitfire V manual I have doesn't mention the sealing on the tanks directly (as far as I can see), but does say that the tanks can be pressurised for operation at high altitude, but that this hinders the self sealing tanks.

The Spitfire IX manual I have is post war and says:

"Fuel is carried in two tanks mounted one above the other (the lower one is self sealing) forward of the cockpit".

 

[pbfoot]

This book I'm getting the ref from is 650 pages of microscopic print I has to hunt down my glasses I bought 3 years ago and never use. I'm heading out to the hanger tommorrow and will look through the extensive library on the Spit to see what I can find. And maybe the engine covers will be off on the IX and I can look

 

[Marshall_Stack]

Just curious..

How does a self-sealing tank work? Is it simply a tank lined with a rubber that melts at the area that it is leaking and seals itself?

Also, don't some airplanes have Co2 that they can inject into the tanks? I think it was to purge gas vapors out of an empty tank. Could that be used to combat a fire?

 

[renrich]

I was being facetious when I made the remark about Churchill being censured. It seems like every bad thing that happens lately is Bush's fault.

 

[FLYBOYJ]

Just curious..

How does a self-sealing tank work? Is it simply a tank lined with a rubber that melts at the area that it is leaking and seals itself?

Also, don't some airplanes have Co2 that they can inject into the tanks? I think it was to purge gas vapors out of an empty tank. Could that be used to combat a fire?

Not so much melts, but the rubber in a self sealing tank is just very pliable and is able to fill the void left by a bullet. Mind you if the hole is too big or a portion of the tank is torn away, it will not work.

Co2 was used as a fire retardant - I never heard of it being pumped into a tank.

 

[renrich]

The F4U1 had wing tanks that were not selfsealing as the fuselage tank was. There was a CO2 bottle in the cockpit, unfortunately next to the CO2 bottle used to blow down the landing gear in an emergency. When going into combat the pilot could use the gas tank CO2 bottle to purge the wing tanks of gasoline and fumes. I say unfortunately because one Navy pilot when going into combat, chose the wrong bottle and blew down his gear thus leaving him a sitting duck and resulting in his demise. Admiral Connolly jumped all over Boone Guyton about this design deficiency and one of the bottles was moved to a new location.

 

[Marshall_Stack]

I read that the last version of the mighty Brewster Buffalo had the same feature (Co2 to purge the wing tanks).

 

[Cub Driver]

The USA had the huge benefit of being able to learn from the European battles before December 1941 and they were by no means common in the USA at that time.

Here's the experience of Curtiss-Wright: the plain vanilla P-40 (what ought to have been called P-40A) was without self-sealing tanks. Export models were sold to France, and Britain took these over as the Tomahawk I. The RAF asked for self-sealing tanks and two more thirty-caliber guns in the wings. Curtiss built these and Britain adopted them as the Tomahawk II, later called IIA. This was in the fall and early winter of 1940. Curtiss built essentially the same airplane for the U.S. Army as the P-40B.

These tanks has an exterior rubber membrane. An interior membrane was more effective, and Curtiss put this airplane into construction in the early months of 1941. To the RAF, this was the Tomahawk IIB. With a few modifications (notably a bracket for a centerline fuel tank) the same plane became the P-40C. (Tomahawk IIBs were also supplied to China for the American Volunteer Group, though apparently Curtiss retrofitted them with P-40B-type fuel tanks, and there were other anomalies.)

I'd always assumed that the rubber simply closed over the bullet hole by mechanical action, but more recently I've been told that there was a chemical reaction with the gasoline, causing the membrane actually to swell. In any event, an interior membrane was more effective than an exterior one, though it cut down on the gasoline the plane could carry (160 US gallons in the P-40B, 135 gallons in the P-40C).

First delivery of the Tomahawk IIA was October 1940. However, these planes weren't used in the BoB, and in the end all RAF Tomahawks went to North Africa or were seconded to Russia (and China!).

Blue skies! -- Dan Ford

Coming August 21: Flying Tigers: Claire Chennault and His American Volunteers, 1941-1942

 

[HoHun]

Hi Renrich,

>When did British and German ac start using self sealing gas tanks?

On German self-sealing tanks, you can find pages of interesting information here:

http://www.ww2aircraft.net/forum/other-mechanical-systems-tech/bf-110-analysis-6399.html

(File Me 110 part 1, page 90 and following.)

In short, Vultee analyzed a captured Me 110 and found that the self-sealing tanks were of limited use, not as good as "current" US tanks but as good as US tanks of the same period (1939/1940). The installation of the tanks was considered superior to US installations as it was designed to reduce sparking, shrapnel generation and hydrostatic shock as far as possible (and facilitating maintenance at the same time).

12.7 mm bullets were considerably more effective than rifle calibre bullets in causing leaks, though the self-sealing capabilities only closed one half to two-thirds of the leaks caused by rifle-calibre fire in the test. (Against 12.7 mm, I'd say the tanks were only marginally effective.)

The Vultee article credits the Germans with being the first to introduce self-sealing tanks, but as this is wartime information, it might be inaccurate. The fuel tanks on the Me 110 are stamped May 1940, but I imagine that it might be possible to find out the aircraft's Werk-Nr., which usually enables the experts to deduce its production date. (I'd say from the description of the installation, the self-sealing tanks are unlikely to be a retrofit, so the production date would be good data for our timeline.)

Regards,

Henning (HoHun)

 

[JoeB]

The F4U1 had wing tanks that were not selfsealing as the fuselage tank was. There was a CO2 bottle in the cockpit, unfortunately next to the CO2 bottle used to blow down the landing gear in an emergency. When going into combat the pilot could use the gas tank CO2 bottle to purge the wing tanks of gasoline and fumes.

I've read that some Corsairs also had an exhaust gas inerting system, exhaust gas rich in CO2 (but mostly inert nitrogen, just like the intake air), recirulated to the fuel tanks. Soviet Lavochkin fighters definitely featured such a system, and I half remember mention of the same system in late P-51D's, from a pilot's manual I used to have (but don't have now, could be misrecalling that). It's essentially what modern oil tankers do to ensure a non-explosive atmosphere in their cargo tanks in all phases of operation.

Bottled gas systems have also been used in a/c for tank inerting, regulators having been going back and forth on a rule that all airliners have this since the TWA Flight 800 disaster, apparently from an explosive atmosphere in a fuel tank and source of spark from malfunctioning deepwell pump. US carriers had similar systems, using CO2, even at the beginning of WWII.

The problems with tank inerting to protect against fire from combat damage are two 1) in many circumstances the fuel mixture in the tank is too rich to support combustion, so the system is overkill as far an explosion strictly inside the tank but 2) the systems don't help that much once the gas gets outside the tank from a hole shot in it, and either forms an explosive mixture within a wing or fuselage structure, or just destroys the plane by fire. Therefore self sealing systems to try to prevent tank leakage, were more to the point.

However USN figures for period Sep '44-Aug '45, with great majority of tanks in combat self sealing, were that only 11% of a/c hit in the fuel system recovered safely. Self sealing tanks seemed to mainly benefit pilot rather than plane survival.

Joe