Aerial Depth Charge Specs

[Balljoint]

I've been looking for the specs on and operation of 1944 aerial depth charges. It appears that they were fused for a set, rather shallow nonadjustable depth. Any details would be appreciated.

This relates to a "what if" as to whether the Taffy 3'Aerials TBFs could have been effective against capital ships.

 

[davebender]

USN CVEs had a limited supply of aerial torpedoes and armor piercing bombs. The first air strike should be no different then an air strike launched from Essex class CVs.

 

[vikingBerserker]

I thought the TBF's of Taffy 3 did drop bombs against capital ships?

 

[Balljoint]

I thought the TBF's of Taffy 3 did drop bombs against capital ships?[/QUOTE

Initially, being an anti-sub force, they were armed with depth charges which they bounced off the decks of the Japanese ship. There was an effort to rearm with torpedoes –particularly Taffy 2- but this was time consuming. I don't recall the torpedoes coming into the action until the Japanese broke off action. But by then the first Kamikaze attack of the war was underway.

Of course the "facts" depend on who's telling the story since there was a lot of disorganization and lost people and records.

 

[Tankworks]

MTBs in the channel took to rolling depth charges over the side as they passed coasters, the resultant underwater explosion would buckle their plates and send them down.
Aerial charges probably would not be a powerful enough weapon against a battleship however, but maybe better than rolling them across the deck although if they rolled over the side they would detonate very close to the hull and that would have had to have shaken them up a bit! I would not like to think about how near you would have to fly to a battleship to accomplish this.

 

[davebender]

Taffy 1.
CVE Sangamon
CVE Suwannee
CVE Santee
CVE Petrof Bay

Taffy 2.
CVE Natoma Bay
CVE Manila Bay
CVE Marcus Island
CVE Kadashan Bay
CVE Salvo Island
CVE Ommaney Bay

10 CVEs without counting Taffy 3 operating a total of about 280 aircraft. More carrier based aircraft then the USN had at Midway.

The IJN attack might have worked if they had struck at night. Once the sun came up IJN battleships and cruisers were just target practise for this large USN air force.

 

[vikingBerserker]

According to The Last Stand of the TIn Can Sailors by Hornfischer, the TMB's were armed with 500lb bombs, rockets, anti-personnel bombs.

Page 173:.."He (Lt Earl Archer) was among the few TBM pilots with a full weapons load: four five-hundred-pound bombs, eight rockets.."

It also makes numorous mentions of torpedo runs from the aircraft of Taffy 3, and I believe they only carried Wildcats Avengers.

 

[Balljoint]

Taffy 3 came to my attention several years ago while looking for a possible Evans with a CMoH. At the time there was an excellent site with detailed order of battle, timeline and even the course Taffy 3 course changes; but it appears to be taken down now. Since I couldn't fact check my source, I tried to avoid "facts".

That said, the Wildcats (FM-2s) and TBF/Ms were described as initially loaded for subs and were unable do anything to slow the attack other than harassment. The tincans greatly deterred the Japanese attack and actually torpedoed a cruiser though outgunned outranged 15-20 to 1.

My specific inquiry is obviously about a trivial point, but it's one of the exercises that are fun and sometimes turn up more interesting subjects –such as how I stumbled on the then little known Taffy 3 battle.

 

[davebender]

The Battle off Samar has a prominent place in most popular histories of WWII. If someone hasn't heard of it perhaps he has not read a single book about WWII in the Pacific.

 

[Shortround6]

There were about 7 different small airborne depth charges used By the USN during/after WW II. the first 6 went from 325lbs to 354lb n the MK 54 (used 30 years after the war) and explosive weights went from 227lbs to 252lbs. Most were filled with Torpex but a couple used TNT. Changes include round nose ( which ricocheted ) and flat nosed versions. They were pretty much interchangeable in use. there was also a larger series of about 625-650lbs but some versions were with drawn from use as they tended to destroy the dropping aircraft. In 1944 there was also a MK 64A1 GP bomb fitted with an athwartship hydrostatic fuse.

I have seen no mention of contact fuses ( which doesn't absolutely mean they were not fitted) so direct hits do seem to be out.

 

[Micdrow]

Try this, hope it helps.
View attachment Bombs for Aircraft 1944.pdf

 

[Balljoint]

I have seen no mention of contact fuses ( which doesn't absolutely mean they were not fitted) so direct hits do seem to be out.

Depth charges and torpedoes are much more effective with proximity fuses. The resulting "bubble" resonates and excites the ship's hull which in turn flexes and fails. At least that's what my wiki research teaches. A pure contact explosion might have a problem with a sub's pressure hull.

DB, perhaps I should have said little known to me. Prior to the History channel and Tincan Sailors, no one in my circle seemed to know of it. When I came across it 6-8 years ago, it was new to me though I had some knowledge of the sub, BB and PT successes against the other prongs of the Japanese effort, as well as the collecting of the decoy carriers

 

[johnbr]

Hope this helps you.

 

[Balljoint]

I found the lost site: it's a work-in-progress and has a new format. I would recommend it as a good read if Taffy 3 is of interest.

Book Index - BOSAMAR.COM

 

[Shortround6]

Depth charges and torpedoes are much more effective with proximity fuses. The resulting "bubble" resonates and excites the ship's hull which in turn flexes and fails. At least that's what my wiki research teaches. A pure contact explosion might have a problem with a sub's pressure hull.

Reading through the manual provided Micdrow it appears that contact fuses were available although it does not say in what numbers and it appears that the fuses have to be fitted when the plane is armed/loaded. I understand the principle behind the " proximity" fuse for a depth charge or a torpedo. It is just that the smaller, much more common 325-350lb depth charges have a fairly small "Kill" radius against a sub and a very small damage radius against the large ship hull. The explosive weight is 1/2 to 1/3 of most normal torpedoes for one thing. Another is the fact the magnetic exploders (proximity fuse?) for torpedoes were supposed to explode the charge under the hull, not along side it. The resulting "bubble" if amidships, would result in the bow and stern supported buy the water and middle of the ship hanging in "air" breaking the back of the ship.

A contact explosion has absolutely no trouble with a submarine hull, see hedgehog and mouse trap anti-submarine weapons. The Problem is hitting the hitting the narrow submarine hull in the first place. A 30ft "kill" radius triples the likely hood of a single charge killing or damaging the submarine and measn you need a lot fewer charges to get a lethal pattern.
The Problem is almost reversed against a ship like a battleship. If you are using a hydrostatic fuse it may fail to function on impact with the 100ft wide ship with the depth charge breaking up on impact meaning even if the detonator goes off a fraction of a second late the explosive may no longer be in contact with the detonator. You now have a 30 foot wide "band" on each side of the 100ft wide ship to land the charge in to get any effect. Against battleships such a charge placement would only have a minimal effect. The Sub is one compartment wide. any breach/leak in the hull will flood the sub for part of it's length from one side to the other. A battleship is many compartments wide and any battleship built after about 1890 has a row of compartments down each side specifically to reduce the effect and contain the damage from under water explosions. Cruisers are narrower and do not have these special compartments although they may have a double bottom the curves part way up the side. They do have multiple campartments across the hull for much of their length ( boiler rooms sometimes excepted.)

While 325-350lb depth charges will not penetrate the armored decks of battleships or cruisers even if fitted with contact fuses the explosion of such charges topsides could knock out AA guns and secondary guns, gun directors, radar, radios, bridge personnel, damage funnels causing loss of draft and speed and so on. While not fatal blows they could reduce the ships ability to fight considerably and the target area of the ship is larger than the narrow strip of water on each side.

 

[Balljoint]

Shortround6, thanks, I pretty much agree with your assessment. The Yamoto had over 1000 compartments. Multiple torpedoes did take her down, though there is a fairly strong opinion that she self-scuttled.

U-505 was captured in the Caribbean with planes marking the location with gun fire. I assume they didn't drop charges because the detonation depth was too shallow but the clear water allowed visual tracking.

More on point, I suspect a depth charge might annoy a BB if placed below it, but wouldn't do serious harm unless near the screws or rudder

 

[Shortround6]

A US aerial torpedo had about 2-2.4 times the amount of explosive a 325-350lb depth charge did. A torpedo explosion has several things going on at once but the pressure of the explosion, a main part of the force, is looking to expand rapidly in all directions. Water is pretty much incompressible although it can be put under great pressure. The explosion can either move aside the water or the steel of the ships side or both. The deeper the explosion the more water on top ( sides and bottom of the explosion could be infinite) of the explosion and the more force will try to escape through the ships side. A torpedo running at 20 feet will be more effective than one running at 3-5 feet. While a depth charge going off 15 ft from the ships side will not exactly be "cushioned" by the water the water will spread the force of the explosion over a greater area of the ships side. This may create more damage or a lot less depending on the ship sides's strength. A weak hull may have more plates twisted and seams split around the hole while a strong hull may suffer bent plates and leaking seams rather than a large hole. To sink a sub ( or force it to the surface) you just need a big enough leak that the pumps cannot over come it. Even a big WW II Sub was around 1/10 the size of even a good WW I battleship. and 1/3-1/4 the size of a good cruiser. If you want to sink a big surface ship fast you not only need a hole in the side rather than a a big leak but you need to have multiple leaks leading further into the ship, fore or aft of the main hole or inboard/across the ship.