[needed] US depth charges mod for the IJN campaign

[keltos01]

In its original form, it was not yet sufficently fast; modifications, such as lead ballast and different fins were applied, finally reaching the goal. It did, however, have to sacrifce explosive power and carried only 200lbs Torpex. Magnetic depth charges were also tried, but reliability problems precluded widespread use although the results obtained were outstanding.

Accordingly, a split version of the Y-gun, the K-gun, was developed - it could be mounted on the sides of the superstructure, firing one depth charge outboard.

Several of these could be and were mounted on each destroyer. They were the fleet destroyers' main and most effective ASW weapon, as those didn't receive Hegehog.


Mk 6 (Early War)

Weight: 338 kg / 745lbs

Charge: 272 kg / 600lbs Torpex

Sinking Speed: 2.4m/s / 8f/s later mods (mid-1942) 3.7m/s / 12f/s

Depth: 9 - 91m / 30 - 300ft later mods (mid-1942) up to 183m / 600ft



Mk 9 (Late War)

http://img410.imageshack.us/img410/7255/200pxdepthchargebd.jpg (http://img410.imageshack.us/i/200pxdepthchargebd.jpg/)


Mark IX Depth Charge used by U.S. Navy later in World War II. Unlike the cylindrical, barrel-shaped depth charge used earlier, the Mark IX is streamlined and equipped with canted fins to impart rotation on the depth charge, allowing it to fall in a straight trajectory (http://en.wikipedia.org/wiki/Trajectory) with less chance of drifting off target.

Weight: ????

Charge: 91 kg / 200lbs Torpex

Sinking Speed: 4.4m/s / 14.5f/s later mods(1944) 6.9m/s / 22.7f/s


Depth: 9 - 183m / 30 - 600ft


http://www.microworks.net/pacific/armament/depth_charges.htm

use :

The K-guns were often used together with stern racks to create patterns of six to ten charges. In all cases, the attacking ship needed to be moving above a certain speed or it would be damaged by the force of its own weapons.

For the reasons expressed above, the depth charge was generally replaced as an anti-submarine weapon. Initially, this was by ahead-throwing weapons such as the British-developed Hedgehog (http://en.wikipedia.org/wiki/Hedgehog_%28weapon%29) and later Squid (http://en.wikipedia.org/wiki/Squid_%28weapon%29). These weapons threw a pattern of warheads ahead of the attacking vessel to bracket a submerged contact. Hedgehog was contact fuzed (http://en.wikipedia.org/wiki/Fuse_%28explosives%29#Munition_fuzes), but Squid fired small depth-charges with hydrostatic arming. Later developments included the Mark 24 "Fido" (http://en.wikipedia.org/wiki/Mark_24_Mine) acoustic homing torpedo

The killing radius of a depth charge depends on the payload of the depth charge and the size and strength of the submarine hull. A depth charge of approximately 100 kg of TNT would normally have a killing radius (hull breach) of only 3-4 meters against a conventional 1000 ton submarine, while the disablement radius (where the submarine is not sunk but put out of commission) would be approximately 8-10 meters. A higher payload only increases the radius by a few meters due to the fact that the effect of an underwater explosion decreases with the distance cubed.

http://en.wikipedia.org/wiki/Depth_charge



here is the manual of the mark 6 depth charge from 1943 :

http://img24.imageshack.us/img24/3943/pg078a.jpg (http://img24.imageshack.us/i/pg078a.jpg/)

http://img30.imageshack.us/img30/5660/40562432.jpg (http://img30.imageshack.us/i/40562432.jpg/)

http://www.hnsa.org/doc/depthcharge6/index.htm

in game there is but one DC :

sim
http://img40.imageshack.us/img40/3402/25296749.jpg (http://img40.imageshack.us/i/25296749.jpg/)

DC /MK14
http://img40.imageshack.us/img40/207/81579101.jpg (http://img40.imageshack.us/i/81579101.jpg/) http://img40.imageshack.us/img40/7767/mk14.jpg (http://img40.imageshack.us/i/mk14.jpg/)

aren't those DCs overstrong ? look at the mk14 torpedo zon file to the right compared to the dc's to the left... Max radius of 40 meters (120 feet) you gotta be kidding me !


I was wondering, since I play "the other side" how accurate were the damage/hitpoints settings of the US depth charges and their behavior (sink rate, duds...) in SH4 ?


I would like to be absolutely sure that the ones we implement for the IJN campaign "Climb Mount Niitaka" are historically accurate. I was DC by a DD dropping 12 DC each and everytime... still looking as to how many they had...

this in turn reflects on my IBDM...

a movie :

http://www.wpafilmlibrary.com/detail/u_s_navy_destroyer_fires_depth_charges/4729338d-cc77-5648-fe7e-ad20b99fb749.html

keltos

[keltos01]

IJN campaign US DC mod v 1.0

in the .sim :

reduced sink rate to 1.5 m /s or 5 feet/s as the above data says

reduced the max range to 20 m from 40 m, even though data says 8-10 m max.

in the zon :

Mark 14:

643 lbs TNT warhead.

Damage points 120 to 180.

DC

272 kg torpex = 405 kg TNT =810 lbs = 1.25 times more powerful explosion than mk14

1.25 * 120 = 150
1.25 * 180 = 225



tbd

keltos

[keltos01]

IJN campaign US DC mod v 1.0


new values set according to historical data on explosive power and sinkrate.
http://www.navweaps.com/Weapons/WAMUS_ASW.htm



download :

http://www.mediafire.com/file/zjoyzq4zzyo/IJN campaign US DC mod v 1.0.rar


keltos

[peabody]

DC /MK14
http://img40.imageshack.us/img40/207/81579101.jpg (http://img40.imageshack.us/i/81579101.jpg/) http://img40.imageshack.us/img40/7767/mk14.jpg (http://img40.imageshack.us/i/mk14.jpg/)

aren't those DCs overstrong ? look at the mk14 torpedo zon file to the right compared to the dc's to the left... Max radius of 40 meters (120 feet) you gotta be kidding me !



keltos


You can't really compare the DC to a torp with damage radius, the torp hits the ship, the DC does not. (sometimes ;)) So if you set the max raduis of a DC to 7, any DC more than 7 meters from the sub would have no effect. If I interpret the data correctly. I know your uboat would definately feel a DC going off at more than 7 meters. I would also think that the amount of damage it causes would decrease the farther away it was.

Peabody

[keltos01]

You can't really compare the DC to a torp with damage radius, the torp hits the ship, the DC does not. (sometimes ;)) So if you set the max raduis of a DC to 7, any DC more than 7 meters from the sub would have no effect. If I interpret the data correctly. I know your uboat would definately feel a DC going off at more than 7 meters. I would also think that the amount of damage it causes would decrease the farther away it was.

Peabody


as stated in the first post :

The killing radius of a depth charge depends on the payload of the depth charge and the size and strength of the submarine hull.

A depth charge of approximately 100 kg of TNT would normally have a killing radius (hull breach) of only 3-4 meters against a conventional 1000 ton submarine,

while the disablement radius (where the submarine is not sunk but put out of commission) would be approximately 8-10 meters.

A higher payload only increases the radius by a few meters due to the fact that the effect of an underwater explosion decreases with the distance cubed.



USN ASW effectiveness during World War II
In the first few months of the war only 5 percent of all depth charge attacks were successful. Normal combat conditions reduced that figure to 3 percent. Combat records showed that in early 1942 the lethal probability of a single depth charge pattern (barrage) was about 3 percent and five attacks would raise the chance of a kill to about 10 percent. The possibility of inflicting significant damage to a submarine was about 30 percent after five attacks. By the end of 1943, better weapons and tactics had improved these figures such that about 30 percent of all detected submarines suffered at least some damage and 20 percent were killed. By the last year of the war, at least 35 percent of all submarines attacked were being damaged while 30 percent were killed. In mid-1944, the USN was claiming an 8 percent kill rate with a single Hedgehog pattern. By the middle of 1945, that figure had risen to 10 percent.

http://www.navweaps.com/Weapons/WAMUS_ASW.htm

I set the damage radius to 20, half stock's, because I believe that the DC were doing more damage than they really should have, especially when you read the data here above from navweaps.com


keltos


download :

http://www.mediafire.com/file/zjoyzq4zzyo/IJN campaign US DC mod v 1.0.rar

[peabody]

Keltos,

I am not disputing your data only your conclusions as it applies to the stock game. Now there are a lot of Damage Models around that change some data. But as it applies to the stock info:

In your post you are stating distances for "Hull Breach" and "out of commission", I am talking doing damage. Even thought the Max range is 40 meters it does not do 100% of it's damage at 40 meters. I have never had a hull breach at 40 meters. Also the game uses hitpoints so it is totally different than RL.
At 40 meters you may get a .03 damage to a component on the sub, you are not going to get a "hull breach" only minor damage if any at all.
You also state "the attacking ship needed to be moving above a certain speed or it would be damaged by the force of its own weapons." Now I realize the hull of a submarine is built to withstand more "pressure" than the bottom of a DD but that DC is not exploding at 10 meters.

To put it is perspective, your subs are 100 meters long, so if a DC went off at the nose you wouldn't feel it in the conning tower (50 meters away)?

I am NOT saying hull breach only that you would feel it and the effect could cause things to break at 40 meters in my opinion.

Put on your diving gear and we will put you 40 meters away and drop a DC, see if you get a headache.:har:

So basically all I am saying in that the data is giving distances for "hull breach" and "disabled", I am talking damage. The article you quote is talking sinking a sub, not damage to components that gets fixed by the men on board.

Peabody

[keltos01]

quote=peabody;

Keltos,

I am not disputing your data only your conclusions as it applies to the stock game. Now there are a lot of Damage Models around that change some data. But as it applies to the stock info:

In your post you are stating distances for "Hull Breach" and "out of commission",
yes I do

I am talking doing damage.ok

Even thought the Max range is 40 meters it does not do 100% of it's damage at 40 meters. I have never had a hull breach at 40 meters. Also the game uses hitpoints so it is totally different than RL.

:damn:

At 40 meters you may get a .03 damage to a component on the sub, you are not going to get a "hull breach" only minor damage if any at all.ok

You also state "the attacking ship needed to be moving above a certain speed or it would be damaged by the force of its own weapons." Now I realize the hull of a submarine is built to withstand more "pressure" than the bottom of a DD but that DC is not exploding at 10 meters.

ok

To put it is perspective, your subs are 100 meters long, so if a DC went off at the nose you wouldn't feel it in the conning tower (50 meters away)?

yet they do damage the tower in that case...


I am NOT saying hull breach only that you would feel it and the effect could cause things to break at 40 meters in my opinion.

Put on your diving gear and we will put you 40 meters away and drop a DC, see if you get a headache.:har:

ha ha ha:rotfl2:a hand grenade would suffice...

So basically all I am saying in that the data is giving distances for "hull breach" and "disabled", I am talking damage. The article you quote is talking sinking a sub, not damage to components that gets fixed by the men on board.

Peabody

so you think the DC were well set from the start?

keltos

[keltos01]

http://img693.imageshack.us/img693/2743/dmdcmod.jpg (http://img693.imageshack.us/i/dmdcmod.jpg/)

http://img412.imageshack.us/img412/1787/46386507.jpg (http://img412.imageshack.us/i/46386507.jpg/)

maybe for the damage I'll agree with you Peabody..

but they fell too fast : now when a DD closes and drops DC you go to falnk and turn and get a chance to avoid the DCs whereas before you were a sitting duck...

also I found a smaller version of the hedgehog with only 4 rockets for small ships... :D Maddy ???

keltos

[peabody]

also I found a smaller version of the hedgehog with only 4 rockets for small ships... :D Maddy ???

keltos

Those hedgehogs will definitely wake you up if you get caught at periscope depth and don't know the ship is carrying them. :o:o

Peabody

[keltos01]

hedgehog :

http://img24.imageshack.us/img24/5606/wamushedgehogmk1115pic.jpg (http://img24.imageshack.us/i/wamushedgehogmk1115pic.jpg/)

Missiles were fired in pairs with an interval of either 0.1 or 0.2 seconds between pairs. The order was such that the missiles with the highest trajectories were fired first while those with the flattest trajectories were fired last. This allowed all missiles to hit the water at about the same time. Reload time was 3 minutes. When aimed to impact at 200 yards (180 m) from the firing ship, it took about 17 seconds from the time the missiles were fired until they sank to a depth of 200 feet (61 m).


The principle disadvantage of Hedgehog was its 40 ton recoil force, which precluded it being used on small warships. This led to the development of Mousetrap, as described below.


It should be noted that the USN considered that the Hedgehog projectiles to be missiles, not rockets, as the propelling charge was entirely used up prior to the projectile leaving the spigot.


Mousetrap :


http://img197.imageshack.us/img197/2366/wamusmousetrappic.jpg (http://img197.imageshack.us/i/wamusmousetrappic.jpg/)


Mousetrap rocket projector with four rails. This weapon was originally classified as a Rocket Launcher and retained its original Mark number when reclassified as an ASW projector. This weapon was developed to take the place of Hedgehog for smaller ships such as patrol craft which could not withstand the recoil forces generated by that weapon. An 85 lbs. (39 kg) warhead was originally fitted, but this was too heavy to man-handle in rough seas. The warhead was changed to the lighter one of the Hedgehog (see above), which had the added benefit of simplifying logistics. The mountings were usually fitted in pairs and could not be compensated for rolling. Not considered to be as effective as Hedgehog, but did give those smaller ships an ahead-firing weapon.

Mark 22
A Mousetrap projector similar to the Mark 20, but with eight rails, organized as four over four. Fired a pattern of about 80 yards wide (73 m) at a range of about 300 yards (274 m). 100 of these weapons were in service by November 1942. In addition to smaller craft, twelve Benson (DD-421) class and Gleaves (DD-423) class destroyers were each fitted with three of these projectors on the forecastle forward of the first 5"/38 (12.7 cm) mount (http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm).

http://www.navweaps.com/Weapons/WAMUS_ASW.htm

[keltos01]

DC /MK14/air DC
http://img40.imageshack.us/img40/207/81579101.jpg (http://img40.imageshack.us/i/81579101.jpg/) http://img40.imageshack.us/img40/7767/mk14.jpg (http://img40.imageshack.us/i/mk14.jpg/)http://img14.imageshack.us/img14/6828/airdcb.jpg (http://img14.imageshack.us/i/airdcb.jpg/)

the air dc is more like it !

and btw the Hedgehog model ingame sucks...

anyone build me a working Mousetrap I'll throw in the model !

keltos

[Ducimus]

DC's are one of those things where, you have, what's in the text books, and then, how it acutally works in game, and the two, don't always cooperate with each other.

For the most part, the Min and max damage on a depth charge is fine. It, along with torpedo damage, is one of the few things that, out of the stock game work correctly and there's little point in changing them, though if you have a "block buster" of a DC aside from normal DC's, then clone that puppy!

Realize however, that Min and Max radius, is under a rule of diminishing returns.

In other words, lets say your DC explodes to the tune of 200 damage. This damage is then applied to the radius. If the min radius is 4.5, then from 0 to 4.5 meters, the full 200 points of damage is applied. From 4.5 meters, on out to the max radius (stock is 40 i think), then how much damage is applied becomes less and less the farther you are away from the min explosion radius of 4.5. At 40 meters, very little damage is being applied.

Depth percision is an important variable. It's basically saying, "detonate randomly at this variance" if the AI sets the charge to explode at 150 meters, and you specify a depth percision of 5, then the charge will explode randomly between 145 and 155 meters.

Detonation depth doesnt seem to work. You can't force the DC to explode within a historical depth parameter. The AI tends to set these and it seems to override this variable. BTW, you can force hedgehogs to detonate by a certain depth. Just not DC.s

Explosion impulse is fun. Put some really large numbers in there and watch what happends. :D Basically, its the shockwave.

Fall speed works.

Feel free to use the DC settings from TMO as a baseline to expand from. The settings therein are from months of trial and error in SH3 and seem to work well in SH4. Most of your major mods will have similar settings.