Napalm for anti-shipping

[Thumpalumpacus]

The USAAF were using a form of napalm on Japanese defenses on some of the islands.
They were literally 55 gallon drums with plywood fins - worked exceptionally well.

The original barrel-bombs.

I remember reading that the original-composition napalm burned very quickly, while to concoction we used in Vietnam (and maybe Korea? Memory fails me) would take a few minutes to expend itself. Much better for setting things on fire.

 

[tyrodtom]

We mixed our own napalm at NKP Thailand, plus we also had premixed napalm already filled from Dupont.
The pilots preferred our mix.
It was a big hopper, like a grain hopper, that metered gas thru while we pored a powder in the top.
The powder was from one of the food companies, can't remember which.
Depending on the temperature, if you opened the top hatch of the bomb within the first half hour, you'd see something that had the consistency of apples butter.
In about 3-4 hours, it would look like thick honey.
In about 10-12 hours it looked like jello .

We assembled 66 and 100 gallon bombs from kits, like making a small aircraft fuselage , but with a real thick skin, with 2 internal framers where the lugs went, with big o-ringed end caps, all aluminum.
Me and one other guy, and a 5 Thai crew sometime built and filled 50-60 a day.

We always used MoGas, about 80 octane then.
One time the supply of Mogas was low, so we had to use 115/145 which we had for the A-26s, A1s etc
The pilots was waiting at our front gate the next morning wanting to strip some hide off our butts for the weak napalm we had mixed .

 

[ThomasP]

re:"Fleet oiler aside, the best target for napalm would be the IJN's matchstick aircraft carriers."

US and IJN carriers were built in a similar manner as far as basic structure (ie wood* flight deck surface over thin steel 5/16"-1/2" underlayer). The main ship's hull structures were of similar ruggedness (in terms of sea keeping), with the benefit of any doubt going to the Japanese. The main difference was in damage control capability.

I may be wrong on this, but I think that if you leave out the fires caused by aircraft, fuel/fumes, ammunition, etc, the primary cause of the spread of shipboard fires was the ship's paint. There were sometimes fires caused by ignited topside hamper, but these were usually easy to put out. Even as late as the Vietnam War there were instances of fires spreading on US ships where the spread was mostly due to the heavy/multiple layers of paint.

On US and IJN carriers, aircraft (at least some) were often left with fuel onboard when in the hangar, and sometimes (often/usually?) some were fueled/refueled/armed/rearmed when in the hangar. The British almost always defueled their aircraft as soon as possible after recovery (either on-deck or in the hangar), depending on what was going on. There were exceptions to this, on all sides, but these seem to have been the mode. Late-war for example, if the British felt secure from attack, they would sometimes fuel and arm aircraft in the hangar. I would appreciate hearing from anyone with better information.

*edit: Changed "teak" to "wood" as better information was provided further down thread, thanks to R Leonard.

 

[The Basket]

With a bomb you can near miss and still blow things up.

Cause damage.

So there is that. On American ships there certainly exposed flak gunners. But setting fire to a ship is not necessarily sinking a ship.

maybe napalm on a naval carrier is bad mojo because if you have a store of napalm on your carrier and it goes up then may the lord have mercy on your soul

 

[Snautzer01]

The USAAF were using a form of napalm on Japanese defenses on some of the islands.
They were literally 55 gallon drums with plywood fins - worked exceptionally well.

Unusual bomb

 

[stona]

Napalm is perfect for static, land-based situations where the target has a controlled environment: pillboxes, buildings, fortresses, etc. where the need to roast the defenders will benefit the offensive.
.

What napalm did was to drive defenders INTO the fortifications allowing attacking infantry to flank or otherwise close with and neutralise the fortifications.

As just one example, a report by the US 117th Infantry Regiment, from October 1944 stated that the napalm bombs dropped by the 9th AF,

"...had a tremendous psychological and physical effect upon the enemy troops occupying the defenses outside the pill-boxes. These outer defences were given up because of the napalm attack, forcing the enemy troops into the pill-boxes. This enabled our attacking troops to get to the rear of these fortifications, use pole charges and seize the pill-boxes... POWs stated that napalm did not bother them while they were in pill-boxes; however, the demoralizing effect was great and fear of further attack by 'fire bombs' persuaded them to stay inside their pill- boxes."

It could also have the reverse effect, making the makeshift defensive positions in the rubble left by more conventional attacks untenable. As the 9th AF's own ORS noted,

"...the enemy must utilize masses of rubble and smashed houses as defense positions. Napalm, upon the devastated area, renders these temporary emplacements untenable, causes fires to take hold in the wreckage, and drives the enemy into the open."

 

[R Leonard]

Not to be pedantic, though I usually am, and but while I'm not sure what wood was used on Japanese flight decks, USN flight decks were of Douglas Fir overlaid on steel. Before anyone jumps up and shouts "NO! They were Teak!" I'd suggest checking the building plans, where once can find specific notations on flight deck composition, "Douglas Fir".

Also Douglas Fir was the preferred USN solution because
(1) it was a readily available - home grown, if you will - making it a strategic resource
(2) one might ask where the most plentiful supply of quality Teak could be found . . . Southeast Asia is the answer and Southeast Asia was controlled by whom? I don't think the Japanese were in the business of selling Teak to the USN.
(3) the characteristics of Douglas Fir were superior to Teak for the repeated abuse of aircraft landings. Teak did not have as much "give" (this discovered through its initial use on the Lexington Class in the 1920s) as Douglas Fir and had a tendency to splinter to a greater degree.

On non carrier type warships, it was a standard wartime precaution to remove wood covered decks, leaving bare metal, then painted over. A simple precaution, just like removing years of built up paint in a ships interior. Navy's tend to know a little about fire hazards, as they say, "a fire at sea can ruin your entire day."

 

[Koopernic]

With a bomb you can near miss and still blow things up.

Cause damage.

So there is that. On American ships there certainly exposed flak gunners. But setting fire to a ship is not necessarily sinking a ship.

maybe napalm on a naval carrier is bad mojo because if you have a store of napalm on your carrier and it goes up then may the lord have mercy on your soul

The Skip bombing method certainly often involved strafing a ship with a solid nose B-25 to kill the defensive gunners followed by skip bombing. I'm not sure of fusing but I immagine there would be a hard impact fuse plus a soft fuse to detonate after about 5 seconds of the first skip.

The Luftwaffe's "Turnip Planting Method" involved aiming the bomb ahead of the waterline with a 5.3 second delay. The bomb would sink to about 20m and detonate under the ship and break it in two. Obviously a direct hit would have an desirable effect as well.

A hit on the waterline by napalm is likely to do nothing.

 

[ThomasP]

Hey R Leonard,

Thanks for the info on the type of wood used on US flight decks. I have edited my original post from "teak" to "wood".

 

[Tom17]

What would a napalm fire being sucked into the boiler intakes do?
Tom

 

[Tkdog]

Burn along with the fuel oil I assume.

 

[Tom17]

I'm wondering if no air gets to the boilers ('cos the napalm's using/blocking it) they'd go out?
Tom

 

[Thumpalumpacus]

I'm wondering if no air gets to the boilers ('cos the napalm's using/blocking it) they'd go out?
Tom

I would imagine this would be the case at least momentarily while the napalm burns and sucks up the inflow. Or perhaps the boilers might just have a hiccup.

I have no idea how long the effect might last, or how long it might take to restart a boiler if it should get snuffed in this manner.

 

[GrauGeist]

It takes a considerable effort to shut down a boiler and they don't go out instantly unless the boiler is damaged by combat.
Much like a wood stove that has red-hot embers - shutting down the draft and damper sees the embers slowly banking back but the moment you open the draft & damper, they come back to life.
The white-hot coals in the boiler's fire-box will do the same.

 

[Tkdog]

You aren't going to get enough gasoline in the intake to impact the boiler. Not even if you are Luke Skywalker. Dumping burning gasoline on a metal ship is just not going to be that effective. Which is why it was not done.

 

[gumbyk]

You aren't going to get enough gasoline in the intake to impact the boiler. Not even if you are Luke Skywalker. Dumping burning gasoline on a metal ship is just not going to be that effective. Which is why it was not done.

Not at sinking the ship, but its a hell of a distraction to AA gunners...

 

[tyrodtom]

It takes a considerable effort to shut down a boiler and they don't go out instantly unless the boiler is damaged by combat.
Much like a wood stove that has red-hot embers - shutting down the draft and damper sees the embers slowly banking back but the moment you open the draft & damper, they come back to life.
The white-hot coals in the boiler's fire-box will do the same.

Didn't most, if not all, WW2 era naval vessels have oil fired boilers, not coal ?

 

[GrauGeist]

Didn't most, if not all, WW2 era naval vessels have oil fired boilers, not coal ?

Ahh yeah, this is true - coal-burners had been phased out.
However, the heat retained in the oil-burner's firebox means a quick restart if the oil-burner is snuffed out.
We've seen examples of this when warships had their boilers knocked out in combat, but were able to relight them and get the ship underway in a short time.
Cold boilers take an eternity to build up a head of steam (as seen during the Pearl Harbor attack).

 

[tyrodtom]

If you used up enough oxygen to put out the fire in the boiler, what would happen to the the engine room crew ?

 

[ThomasP]

I believe most WWII ships with high pressure boilers (over ~200 psi) used forced air supply for the boilers in order to ensure enough air, sort of like big fans pulling in air from the intakes and pushing/drawing it into/through the boiler.

An explosion could and sometimes did blow out the fires in the boilers.

Napalm would not have any substantial effect unless there was a lot of it dumped right into the intakes, but since most intakes were protected (in one way or another) from liquids (eg torrential rains or heavy seas) and solids (eg birds) falling into the intakes from above it would be unlikely that the napalm could get into the forced air system.

Ships sometimes had their boiler fires put out when enough water made it into the intakes, usually when the ship had rolled enough that a large wave could dump water in into the intakes.