# What was the the best location of fuel tanks in WW2 single seat fighters



## Timppa (Aug 22, 2013)

What was the the best location of fuel tanks in WW2 single seat fighters ?

1. In front of the pilot (Spitfire, Hurricane, Tempest, F4U)
2. Below the pilot (F6F, Fw190)
3. Rear fuselage (Bf109)
4. Inside the wings (Yaks, P-51)


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## FLYBOYJ (Aug 22, 2013)

I guess it’s a matter of what location gave the best CG location while mitigating combat risk.


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## Timppa (Aug 22, 2013)

FLYBOYJ said:


> I guess it’s a matter of what location gave the best CG location while mitigating combat risk.



My intention is that you play the designer here, with all pros and cons you know.


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## stona (Aug 22, 2013)

FLYBOYJ said:


> I guess it’s a matter of what location gave the best CG location while mitigating combat risk.



I agree.
They had to put it somewhere and I'm not convinced that any one place was much less vulnerable than another. From the pilots' point of view I reckon the Spitfire/Hurricane solution must be the worst.
I quite like the Fw 190 self sealing fuel cell(s) position, but then the pilot was sitting on it.
Cheers
Steve


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## FLYBOYJ (Aug 22, 2013)

Timppa said:


> My intention is that you play the designer here, with all pros and cons you know.


There would be a lot more information needed. MAC location, C/G limits, aircraft size, structural considerations. If the wing was a continuous spar forming a large wing box within the fuselage under the pilot I would say that would be the optimum location.


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## Shortround6 (Aug 22, 2013)

Under the pilot makes for a fat fuselage, perhaps not so important with radial engines? 

amount of fuel is another *BIG* consideration. 400 liters like a 109 or 1400 liters like a late P-47D.


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## swampyankee (Aug 23, 2013)

Shortround6 said:


> Under the pilot makes for a fat fuselage, perhaps not so important with radial engines?
> 
> amount of fuel is another *BIG* consideration. 400 liters like a 109 or 1400 liters like a late P-47D.



For subsonic aircraft, like WW2 era fighters, the optimum fineness ratio was about 7 or 8 to 1. Wetted area was, overall, more important than fineness for aircraft in this speed range; the most important consideration is to prevent separation from occurring on the rear part of the fuselage. 

Leaving that aside, I think the best place for the fuel in a single-engined fighter of the era would be in tanks beneath the pilot. The worst place would be in tanks behind the pilot, as these would tend to be destabilizing when full, as was the case with the P-51. Part of the reason that the Corsair was not considered acceptable for USN carrier service was because the tanks forward of the pilot made landing visibility quite poor.

Of course, as flyboy said, more information is needed. Single seat fighters had a lot of stuff crammed into the fuselage: big engine, pilot, radio, fuel (the big engine will need lots), maybe armament, landing gear, etc.


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## drgondog (Aug 23, 2013)

The mission priorities have to be known to make a value judgment on approach to fuel requirements.

A point defense interceptor will have a lower emphasis placed on fuel storage as a priority, stripping 'excess fuel' in favor of better performance with less weight by sacrificing fue.

Cost is a factor as greater fuel storage implies greater wetted area (and implied greater drag) as well - to accommodate higher end fuel storage and internal armament. Most US fighters were huge(GW and wetted area) in contrast to European and Japanese and Soviet counterparts. One component of 'huge' was the R-2800 and the other was stuffing fuel in the wings.

Range is always important to Tactical footprint and extension of power beyond the Battlefield - whether naval avaiation or strategic bombardment/tactical interdiction.

For US doctrine, WWII s/e recips, I favor wings and fuselage for fuel storage. Given GW maximums with full fuel, the mission can be changed to swap external payload for equivalent fuel load to perform CAS or other bombing missions. This capability is well represented philosophically with F6F, F4U, P-38, P-47 and P-51 in contrast to say, Me 109 or Yak 3 or A6M, etc


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## davebender (Aug 24, 2013)

I disagree. Fuselage tank is less likely to be hit and easier to protect with armor then any wing mounted fuel tank. An armored fuselage tank can also serve as part of aircrew protection.

However you need enough fuel for the combat role and adequate space in the fuselage. So bomber and transport fuel tanks will probably be in wings for lack of any other reasonable option.


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## stona (Aug 24, 2013)

davebender said:


> I disagree. Fuselage tank is less likely to be hit and easier to protect with armor then any wing mounted fuel tank. An armored fuselage tank can also serve as part of aircrew protection.



Which single seat fighters in the ETO had armoured rather than self-sealing fuel tanks? I'm not counting something like the sheet of aluminium optimistically termed "deflection armour" above the Spitfire's upper tank. I mean some serious, heavy, 5mm or thicker, armour plate around the fuel tank.
Cheers
Steve


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## davebender (Aug 24, 2013)

Test of Me-109 G-2.
Kurfürst - No. 209 Group : TEST OF ME.109G-2 (TROP).


> Armour.
> 
> 21. This is almost identical to the Me.109F-4 and consists of one flat and one curved 10 m.m. plate protecting the back and top of the pilot's head. Three plates, the upper one 8 m.m. and the lower 24 m.m. [Note: This must be two 4 m.m. thick plates as noted elsewhere] protect the pilot's back. A 63 m.m. bullet proof glass shield set at approx. 60° is mounted 13 m.m. behind the 8 m.m. plexiglass windshield. A dural bulkhead consisting of 30 layers of 0.8 m.m. sheet bolted together is fitted to the lower 2/3 of the fuselage cross section.



Me-109 fuel tank was in front of the dural armor bulkhead. Hence tank and pilot were protected from rear attack (i.e. preferred attack position).


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## Njaco (Aug 24, 2013)

My understanding is that the fuel tanks on the P-51 affected the CoG to the extent that pilots had to use one tank over others or taking off would be troublesome even dangerous.


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## stona (Aug 24, 2013)

That could be construed as an "armored fuselage tank" at a stretch I suppose. It's not exactly what I understand by the term. It is more a tank with some protection. It's certainly not some serious armour plate _around_ the tank.

I'm not sure what a 24mm composite of aluminium alloy would actually stop, assuming it was fired from more or less directly behind and would therefore strike the armour before the tank. I'd be interested if anyone knows, having seen footage of a few Bf 109s burst into flames when hit.

Cheers
Steve


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## davebender (Aug 24, 2013)

M113 APC solid aluminum armor was 38mm thick. It was designed to protect against 7.62mm AP rounds.

I've got to assume laminating the Me-109 armor increases protection level. Otherwise RLM would have specified 24mm of less expensive solid armor. So my best wild guess would be protection similar to the M113 APC.


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## stona (Aug 24, 2013)

That sounds reasonable, thanks
Steve


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## Shortround6 (Aug 24, 2013)

Good Aluminium armor protects on level _close_ to the _same weight_ of steel armor. 

The advantage in light armored vehicles (and some aircraft?) is that the much thicker aluminium is better able to act as "structure" and eliminate the need for framing/structural support. An M113 is sort of a monocoque APC  No real frame work.


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## Tante Ju (Aug 25, 2013)

stona said:


> That could be construed as an "armored fuselage tank" at a stretch I suppose. It's not exactly what I understand by the term. It is more a tank with some protection. It's certainly not some serious armour plate _around_ the tank.
> 
> I'm not sure what a 24mm composite of aluminium alloy would actually stop, assuming it was fired from more or less directly behind and would therefore strike the armour before the tank. I'd be interested if anyone knows, having seen footage of a few Bf 109s burst into flames when hit.
> 
> ...


 
It was effective at stopping .303 rounds from penetrating into the fuel tank from astern attacks, and the laminations probably served to render incendiary rounds ineffective as they passed through the layers. It also rendered early US .50 incendiary rounds ineffective, then the US copied the Russian .50 round, which remained effective. Earlier, the Emils mounted a 8 mm steel plate in the same place, it protected the tank all well but this was both pilot and tank armor and given its rear location, it could be more easily bypassed by rounds coming at an angle, and hitting the pilot. So they moved the pilot armor to the pilots back, and then a bit later they added this laminated bulkhead again,

The laminated bulkhead, with the the round having to pass through the fuel tank (and the fuel inside) before hitting the 8 mm back armor of the pilot also protected the pilot well from .50 AP rounds, which could only pass through the pilot armor if they hit the tank above the fuel line - quite unlikely, given that the 109 tank was full at the beginning of the engagement when drop tanks were carried.


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## razor1uk (Aug 27, 2013)

I for my 2 pfennigs worth, I would have thought that the rearest laminated/composite armour of the 109 rear fuz. was like some of the Wermachts carriage weapons shields - two thinner sheets of metal spaced apart, thus creating a total thickness of metal equivalent to the stated number, but perhaps with an air gap to increase the chance of incendiary rounds (if using tracer ignition) fizzling out and post penetrated rounds that are tumbling to ricochet off the second layer. ...but I'm most likely wrong and so reserve that right.


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## drgondog (Aug 27, 2013)

Njaco said:


> My understanding is that the fuel tanks on the P-51 affected the CoG to the extent that pilots had to use one tank over others or taking off would be troublesome even dangerous.



For the P-51B/C/D/K the 85 gallon fuselage tank addition limited the Mustang's maneuverability with the full tank, but burning down to ~ 25-30 gallons made the 'stability' issue go away. The P-51H put 205 in the wings (vs 184 gallons for B-D) and 50 in the fuse tank, lengthened the fuselage aft of the fuselage fuel tank - and dramatically improved both stability and take off management.

That 85 gallon tank meant nearly 220 more radius miles of range. The difference between barely making Berlin and easily making east of Munich to Posnan Poland.

ALL of the fighters with very long range - except the Zero- had wing fuel tanks, and the Zero made its capability by sacrificing pilot protection and G loads with an ultra light fighter.


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## Timppa (Sep 1, 2013)

Fire was and is the biggest fear for the pilot from the days of WW1. Mannock became obsessed about the possibility of being burned to death if his plane was shot down. As a result, he began carrying a pistol with him with the intention of shooting himself if his plane ever caught fire. Clostermann and Bloemerz wrote very graphic descriptions of these incidents.

From this perspective. from the best to worst:

1. Wings
+Farthest away from the pilot
+Little or no CoG shift.

2. Below the cockpit
+Little or no CoG shift
+Slipstream presses the burning fuel away from the cockpit.
+Fuel tanks give some protection to the pilot
- Burning fuel inside will reach the cockpit, especially when inverted.

3. Behind of the pilot
+Slipstream presses the burning fuel away from the cockpit.
+Fuel tanks give some protection to the pilot
- Burning fuel inside will reach the cockpit, especially when diving/inverted.
- Big CoG shift

4. Front
+Little or no CoG shift
- Slipstream presses the burning fuel directly to the cockpit.
- Cockpit is pushed aft, reducing the forward view, especially important in carrier aircraft.


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## FLYBOYJ (Sep 1, 2013)

Consider that fuel in the wings offer a huge target area, sealed or not....


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## drgondog (Sep 2, 2013)

FLYBOYJ said:


> Consider that fuel in the wings offer a huge target area, sealed or not....



Agreed Joe - but the object of getting the legs is to make the other guy the target.. the 51 and F4U obviously qualified on that score more often than not.

I suspect that if you added the scores of the US fighters with Fuel in the wings, 51/F4U/P-47D-25 and P-38 the victory credits far exceed the fuselage 'only' fighters..


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## davebender (Sep 6, 2013)

It's a good thing these aircraft arrived during 1944. Otherwise European air forces would not have learned they had been fighting improperly for the previous five years.


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## swampyankee (Sep 7, 2013)

davebender said:


> It's a good thing these aircraft arrived during 1944. Otherwise European air forces would not have learned they had been fighting improperly for the previous five years.



Well, the Germans certainly found out that their fighters weren't the best thing since sliced bread.


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## drgondog (Sep 15, 2013)

davebender said:


> It's a good thing these aircraft arrived during 1944. Otherwise European air forces would not have learned they had been fighting improperly for the previous five years.



The aircraft (P-38 and P-51) 'arrived' in combat ops 1942. The P-47D didn't have a wing tank version until mid 1944 and cut out of long range ops until then... Neither the Brits nor the Germans contemplated long range fighter operations - which shaped their tactics and mix of aircraft and one would argue, limited their options to stretch their enemies.

Neither approach is right or wrong until you ask the questions "what missions do we need to be most effective at?"


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## tomo pauk (Sep 15, 2013)

Bill- a nitpick: the P-47 received wing tanks with the -N variant. The late Ds featured enlarged fuselage tank, bringing tankage to 370 gals.


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## bob44 (Sep 15, 2013)

drgondog said:


> For the P-51B/C/D/K the 85 gallon fuselage tank addition limited the Mustang's maneuverability with the full tank, but burning down to ~ 25-30 gallons made the 'stability' issue go away. The P-51H put 205 in the wings (vs 184 gallons for B-D) and 50 in the fuse tank, lengthened the fuselage aft of the fuselage fuel tank - and dramatically improved both stability and take off management.
> 
> That 85 gallon tank meant nearly 220 more radius miles of range. The difference between barely making Berlin and easily making east of Munich to Posnan Poland.
> 
> ALL of the fighters with very long range - except the Zero- had wing fuel tanks, and the Zero made its capability by sacrificing pilot protection and G loads with an ultra light fighter.



I believe, with the aft tank, taking off was not so much of a problem as was combat maneuvers especially pulling out of a dive.


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## bob44 (Sep 15, 2013)

swampyankee said:


> Well, the Germans certainly found out that their fighters weren't the best thing since sliced bread.



I think they found this out during the BOB.
But the incoming FW190 and later 109's with better tactics helped for awhile till better Allied fighters, better tactics and in numbers doomed the LF.


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## Aozora (Sep 24, 2013)

Shortround6 said:


> Good Aluminium armor protects on level _close_ to the _same weight_ of steel armor.
> 
> The advantage in light armored vehicles (and some aircraft?) is that the much thicker aluminium is better able to act as "structure" and eliminate the need for framing/structural support. An M113 is sort of a monocoque APC  No real frame work.



The type of fuel tank installed can also help, as can the use of an inert gas pumped into the tank as the fuel level goes down - the Russians used cooled exhaust gases (carbon monoxide), although this apparently degraded the self-sealing.

The WWII Fighter Gun Debate: Fighter Armour


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## MiTasol (Aug 9, 2014)

Sir Archibald MacIndoe (Archibald McIndoe - Wikipedia, the free encyclopedia) and (Guinea Pig Club - Wikipedia, the free encyclopedia) treated hundreds of Spitfire and Hurricane pilots who had suffered horrific burns as a result of the fuel being immediately in front of them and then leaking all over the pilots legs and cockpit floor as a result of bullets and other damage.
Fuel under the pilot in the wings does not normally enter the cockpit when the aircraft is shot.
Mosleys 1962 book "Faces from the Fire: The biography of Sir Archibald McIndoe" is most enlightening and Richard Hillary's 1941 book "The Last Enemy" (about his experiences as a burn victim) plus Geoffrey Page's two books ("Tale of a Guinea Pig: Exploits of a World War II Fighter Pilot" and "Shot Down in Flames: A WW2 Fighter Pilot's Remarkable Take of Survival") provide more evidence of the gross stupidity of putting avgas in front of a pilot in a combat aircraft


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## MiTasol (Aug 10, 2014)

To Quote page 48 on the Airlife publication on the Hurricane 
"Tom Gleave's extensive burns to face, hands, arms and legs - 'standard Hurricane burns' - were to require many months of surgery and treatment at the Queen Victoria Hospital, East Grinstead, as a patient of Sir Archibald McIndoe, the New Zealand-born consultant in plastic surgery"


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## stona (Aug 10, 2014)

MiTasol said:


> To Quote page 48 on the Airlife publication on the Hurricane
> "Tom Gleave's extensive burns to face, hands, arms and legs - 'standard Hurricane burns' - were to require many months of surgery and treatment at the Queen Victoria Hospital, East Grinstead, as a patient of Sir Archibald McIndoe, the New Zealand-born consultant in plastic surgery"



Yes, and many thought these were caused by the wing tanks. The fire was drawn into the cockpit as there was no bulkhead/firewall or other obstruction between these tanks and the cockpit. The relatively small tank in front of the pilot was a much smaller and harder to hit target and most likely not the major culprit in the infliction of the aptly named 'Hurricane burns'.

Cheers

Steve


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## Glider (Aug 10, 2014)

Fairly soon in the war additional plates were installed on the Hurricane to reduce the chances of flames being sucked into the cockpit, giving the pilot a few more precious seconds to get out. I am afraid I don't have access to my papers on that but maybe someone else can help?


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## stona (Aug 10, 2014)

Glider said:


> Fairly soon in the war additional plates were installed on the Hurricane to reduce the chances of flames being sucked into the cockpit, giving the pilot a few more precious seconds to get out. I am afraid I don't have access to my papers on that but maybe someone else can help?



From the wings? I am unaware of such a modification. I know it was suggested in late 1940, but considered too time consuming, involving considerable redesign, to be done. The smaller header tank was at least made self sealing and the modification retro fitted quickly to Hurricanes already in service. That was a wise decision. Though the tank was considered a difficult target there is little between it and the pilot apart from the instrument panel.
I too am away from home so can't access anything not already on my lap top.

I'm not sure that there is a 'best' position for large quantities of petrol in a WW2 fighter. All of them were prone to fire and _little or more often no consideration was given to protecting the fuel tanks or cells in the design of the aircraft._ All the protection, be it armour or the various self sealing solutions were more or less retro-active. Even the engine was considered as 'armour' for fuel tanks in some aircraft though the fact that it was bolted to the front of the machine had nothing to do with shielding the fuel tanks and its protective role seems not to be by design but by coincidence 

Cheers

Steve


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## MiTasol (Aug 13, 2014)

Agreed Steve, the Hurricane cockpit tank was "relatively small" but exactly the same burns occurred to Spitfire pilots which is a clear indication that the self sealing tanks did not work as predicted.
I must say however the definition of "relatively small" is rather important.
The wing tanks were 33 gallons each and cockpit tank 28 gallons which means this "small" tank actually held 28/94 = 29.8% of the total fuel load.
The cockpit tank is the same width and height as the instrument panel - over 75cm/30in wide (twice as wide as the pilot) and 45cm/18in high
As far as being hard to hit you must remember that it was immediately forward of the instrument panel and was less than one metre in front of the prime target (the pilot). That means it was far closer to the prime target than the wing tanks and was inside the cone of projectiles aimed at the pilot. From the 180 degree arc from behind an instrument panel has no armour properties. The very small armour behind the pilot would only protect the tank for a stern attack and those were not common. For above and behind the pilot armour did not protect the fuel tank at all.
In frontal attacks the fuel tank was again well inside the cone of projectiles.
Another minor consideration is the fuel lines in the cockpit, small target but very fragile


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## stona (Aug 13, 2014)

The majority of successful attacks made on RAF fighters during the BoB were made from within 15 degrees of dead astern. Successful was deemed an attack in which the RAF fighter was hit at least once, giving the researchers something to measure. I have the report and figures somewhere, but not with me here in Budapest! 
It wasn't me but the RAF that considered the header tank in front of the pilot to be a relatively difficult target _compared with the wing tanks_ on a Hurricane. It isn't so much the volume of a fuel tank as the area exposed to attack. From 15 degrees off the wing tanks offer a much better target.
The lack of successful attacks from larger angles off is probably a reflection of the inability of most Luftwaffe pilots, like their RAF contemporaries, to estimate angle off (and range) accurately and consequently be rather bad at deflection shooting.
Cheers
Steve


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## Ivan1GFP (Aug 18, 2014)

The F4U Corsair and P-47 Thunderbolt also had rather large fuel tanks in front of the pilot and both aircraft were known for pretty good durability. I don't believe the location results in an obvious vulnerability. Bottom line is that fuel ANYWHERE is vulnerable.

The choice depends a LOT on the size of the aircraft and the amount of fuel required. What works for 100 gallons in a P-39 or Me 109 would not work for 300 gallons for a P-47 or Corsair. The bottom line is that with fuel and ammunition being disposable loads, it MUST be placed near the CoG to avoid a drastic shift. Ideally the pilot should also be near the CoG. This is not because s/he is disposable but more because differing weight pilots should not change the aircraft trim or require ballast to compensate.

With that stated, my choice for MOST aircraft would be to put the main tanks into the wing roots for reasonably small quantities and in the fuselage over the wings for a larger quantity. The 184 gallons in the P-51 fit in the wing roots under the pilot without making the fuselage overly fat. The Macchi fighters and P-40 (Reserve Tank) mostly used the same location though with less quantity.

Some of the choices in this poll really describe the same thing. The Reserve and Main tanks on a P-40 are at least:
Under the Cockpit,
In the Wings,
Forward of the Cockpit.

- Ivan.


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## parsifal (Aug 18, 2014)

I found this cutaway, which provides an indication of the fuel stowage positions of the Zeke. Zekes were flying torch basically, but they also possessed phenomenal range for an early war aircraft, not really eclipsed until the P-51s arrived. and range was all important at the beginning of the Pacific war


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## Ivan1GFP (Aug 19, 2014)

The reason for the A6M Type Zero being so easy to burn wasn't because of its fuel tank locations;
It was because of the fuel tank construction.

Unlike most WW2 fighters, the A6M series had simple aluminum tanks rather than bags suspended by straps.
This made for better capacity, but when they were hit, the hydrostatic shock would usually rupture the tank which made for a LOT of leaking fuel to ignite.

Interestingly enough, surviving warbirds typically are equipped with aluminum fuel tanks again. 
I suppose they aren't terribly concerned about getting shot at.

= Ivan.


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## parsifal (Aug 19, 2014)

I agree, however it had a lot of fuel to burn and a lot of places that an incendiary round could inginte the aircraft. its hard to know which tank position was the most likley to catch fire, though anecdotally ive read it was the wing mounted tanks that were hit most often


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## stona (Aug 21, 2014)

parsifal said:


> anecdotally ive read it was the wing mounted tanks that were hit most often



I have too. I think they were more exposed and offered a larger target in the most successful attack profiles. RAF pilots certainly thought so. I'd be surprised if some research into this wasn't done, maybe at Orfordness, but I've never seen the results anywhere. 

In a related matter there must be a reason why the Luftwaffe sought to provide armoured protection for ammunition stored in the wings/wing roots of Fw 190s. The plates were positioned to protect the ammunition from return fire from bombers, rather than from a fighter attack, but it must have been considered vulnerable

Cheers

Steve


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