Armor Plate and Self Sealing Tanks

[syscom3]

Many people (myself included) talk about the following. But you know, maybe we really don't understand it. I know its different from airplane to airplane, but its probably similar to one degree or another.

For armor protection for the cockpit seats, just how much weight does the armor weigh, and what type of ballistic protection does it afford [like how much weight would the Zero gain if they used armor seat protection]?

What other parts of an aircraft also gets armor protection? Linkages? Fuel line junctions?

For self sealing fuel tanks, just what exactly is the weight and volume penalty?

 

[drgondog]

Many people (myself included) talk about the following. But you know, maybe we really don't understand it. I know its different from airplane to airplane, but its probably similar to one degree or another.

For armor protection for the cockpit seats, just how much weight does the armor weigh, and what type of ballistic protection does it afford [like how much weight would the Zero gain if they used armor seat protection]?

What other parts of an aircraft also gets armor protection? Linkages? Fuel line junctions?

For self sealing fuel tanks, just what exactly is the weight and volume penalty?

The fighter armor plate doctrines were all over the place and weight penalties ranged from ~ 45 pounds in a P-51 (1/4" to 5/16" hardened steel aft of seat - only) to 260 pounds for the later model P-39D's. The P-63 cut it down to ~120 pounds. The P-47 was around the 60 pound - all aft of seat.

The Spit (most) had 8mm armor and all aft at about 60 pounds. The IL-2 was at top extreme and the FW 190A-8 had back/side/front armor plus 30mm glass on front windshield (and behind head aft of seat?) This ship also had some cowl armor to provide additional protection to the engine from head on 50 cal fire

The LW doctrine IIRC was geared to stopping a 50 caliber round at 200 yards to protect the pilot

Self sealing tanks usually had a single layer (later a double layer) of rubber/neoprene type lining on outside of cell - usually targeted to withstand a 12.7 ball/api hit.

None of the self sealing tanks were very effective against an explosive 20mm in context of rupture.

 

[comiso90]

I imagine that when the self sealing tanks took hits, they were drained and properly patched after the mission. The self sealing feature was effective enough to get the pilot home but was not considered an actual seal.. correct?

.

 

[syscom3]

How much volume in the fuel tank is devoted to the compounds that made it self sealing?

 

[drgondog]

How much volume in the fuel tank is devoted to the compounds that made it self sealing?

The only one example I have looked at was about 1/4" thick layer of what seemed to be two laminates (hard to see)

 

[renrich]

According to Dean, "America's Hundred Thousand" the Wildcat held 160 gallons of internal fuel in unprotected tanks and 147 gallons in protected tanks. In the F4F3 the armor weighed 155 pounds, F4F4, 165 pounds and FM2, 223 pounds.

 

[syscom3]

It doesn't seem that armor plate for the cockpit doesn't add to much weight. Ditto with the self sealing tanks.

I wonder why the Japanese came to different conclusions.

 

[BombTaxi]

I think the Japanese were perhaps hoping to outrun or out-turn anything heavily-armed enough to shoot them down - a bit like the battlecruiser vs battleship debate at sea. This certainly seemed to work for them in the very earliest days in the war, but they obviously didn't think about what would happen when the enemy sussed thier tactics and developed their own responses...

A further thought - at the time the Zero was designed, most a/c were packing 2-8 rifle calibre MGs. 50s and 20mm cannon were rare, so perhaps the Japanese incorrectly anticpated the kind of punishment the Zero et al. would receive?

 

[Soren]

The Japanese were on to something if they could but have kept the speed climb rate of their a/c to either the same level or higher than that of their enemies.

The Ki-84 was approaching this, and with better built engines, fuels and better trained pilots it could've proven superior to most Allied fighters.

 

[BombTaxi]

The lack of trained pilots later in the war really showed up the deficiencies of Japanese aircraft. The Marianas Turkey Shoot was just one example of how easy it was for poorly trained pilots in substandard aircraft to be butchered by better aircraft flown with greater skill...

 

[FLYBOYJ]

It doesn't seem that armor plate for the cockpit doesn't add to much weight. Ditto with the self sealing tanks.

I wonder why the Japanese came to different conclusions.

You'd be surprised how much 150 - 300 pounds affects performance.

 

[renrich]

FB nailed it. In an AC like the early A6Ms, with less than 1000 HP, a few hundred pounds was a big factor on performance. An AC like the Wildcat, with around 1200 Hp, when armor, self sealing tanks, folding wings and extra guns were added had it's performance substantially degraded. Later in the war, the A6M got more HP, which degraded it's range, but bigger MGs, SS tanks and armor kept the airplane from achieving better performance.

 

[tomo pauk]

I think the Japanese were perhaps hoping to outrun or out-turn anything heavily-armed enough to shoot them down - a bit like the battlecruiser vs battleship debate at sea. This certainly seemed to work for them in the very earliest days in the war, but they obviously didn't think about what would happen when the enemy sussed thier tactics and developed their own responses...

A further thought - at the time the Zero was designed, most a/c were packing 2-8 rifle calibre MGs. 50s and 20mm cannon were rare, so perhaps the Japanese incorrectly anticpated the kind of punishment the Zero et al. would receive?

Hi,
A humble disagreement about the anticipated threats. The P. 24, I-16, Ms-406, P-38, P-39, Whirlwind, Bf-110, Fw-187 and Bf-109E-3 carried canons, and were widely advertised as such.

And the 2 LMGs were destroying bombers, let alone the fighters. At least above Poland.

 

[syscom3]

...... An AC like the Wildcat, with around 1200 Hp, when armor, self sealing tanks, folding wings and extra guns were added had it's performance substantially degraded. .....

How much additional weight did that take?

For the Zero, I dont think the addition of a 100 pound armor slab behind the seat would make much difference.

 

[renrich]

The empty weight of the F4F3 was 5426 pounds, the F4F4 was 5778.9 pounds. The armor in the F4F4 was 7.5 pounds more than the F4F3. I would think that the SS tanks would not weigh more than the unprotected when they were full because of the gasoline displaced. The 352 pounds difference must have been mostly the folding wings and the two extra MGs. The early F4F3 lacked armor which weighed 155 pounds, so the startling difference in performance can be chalked up to a difference in weight of around 500 pounds.

 

[syscom3]

The empty weight of the F4F3 was 5426 pounds, the F4F4 was 5778.9 pounds. The armor in the F4F4 was 7.5 pounds more than the F4F3. I would think that the SS tanks would not weigh more than the unprotected when they were full because of the gasoline displaced. The 352 pounds difference must have been mostly the folding wings and the two extra MGs. The early F4F3 lacked armor which weighed 155 pounds, so the startling difference in performance can be chalked up to a difference in weight of around 500 pounds.

Thanks Renrich.

Did that weight figure include the 2 additional guns AND the additional ammo?

 

[renrich]

The weight given is empty weight for both which would not include ammo but I believe tha ammo weight would be almost the same for F4F3 and 4 since the F4F3 carried 400 RPG and the F4F4 carried 240 RPG.

 

[renrich]

Sys, I have been studying these tables in Dean on the F4F and it is a little confusing. I think the bottom line is that the F4F4 loaded for the same mission weighed around 350 pounds more than an F4F3, which would have armor and protected tanks. The FM2 weighed pretty much the same as the F4F3. It went back to the four guns and it's performance was similar to the F4F3's. There was also a F4F3A which served with the F4F3. The F4F3A weighed around 200 pounds less than the F4F3 because it had a different engine supercharger combination and did not have as good a high altitude performance. According to Lundstrom, there were times, early war, that the 3A and 3 served in the same squadrons off of carriers. That probably complicated matters because of the different performance at different altitudes but the Navy was desperately short of fighters in those days.

 

[syscom3]

So only 350 pounds of weight changed the performance that much?

 

[renrich]

I believe that is the bottom line. The gross weight of the F4F3 in fighter configuration was 7150.5, the F4F4 was 7426. In overload fighter it was 7543 and 7972 respectively. You can see that difference in weights vary some according to mission. I suspect that most times in the Pacific battles the Wildcat took off with all the ammo and fuel they could stuff in it. These figures are from Dean but are Navair numbers.