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

[Timppa]

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)

 

[FLYBOYJ]

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

 

[Timppa]

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.

 

[stona]

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

 

[FLYBOYJ]

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.

 

[Shortround6]

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.

 

[swampyankee]

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.

 

[drgondog]

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

 

[davebender]

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.

 

[stona]

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

 

[davebender]

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).

 

[Njaco]

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.

 

[stona]

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

 

[davebender]

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.

 

[stona]

That sounds reasonable, thanks
Steve

 

[Shortround6]

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.

 

[Tante Ju]

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

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.

 

[razor1uk]

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.

 

[drgondog]

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.

 

[Timppa]

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.