actual attacks with IJN torpedoes :

http://img5.imageshack.us/img5/492/data3.jpg


http://www.defence.gov.au/sydneyii/EXP/EXP.001.0029.pdf


keltos

explosives data :


TNT
Trinitrotoluene, commonly known as TNT, is a constituent of many explosives, such as Amatol, Pentolite, Tetrytol, Torpex, Tritonal, Picratol, Ednatol, and Composition-B. It has been used under such names as Triton, Trotyl, Trilite, Trinol, and Tritolo.

Formulag/ccmKj/KgPower*
C7H5N3O / 61.64 / 870 / 1

Torpex
TORPedo EXplosive aka TPX. A mixture of 37-41% TNT, 41- 45% RDX (Cyclonite, Cyclomethylene Trinitramine), 18% aluminium.
Torpex is attractive because of the increased explosive energy and higher detonation velocity of RDX as compared to TNT and the prolongation of the pressure wave by the aluminium. On a weight basis, Torpex is conservatively estimated to be about 50% more effective than TNT as an underwater explosive against ships. However, Torpex is more sensitive than TNT and RDX is expensive and difficult to make safely.
Formulag/ccmKj/KgPower*
? / 1.81 / ? / 1.61




In the late 1940s Torpex was replaced by HBX, then H-6 in the 1960s and by PBX in the 1970s.?1.81?1.61Wet gun-cottonWet gun-cotton is not affected by shock, failing to explode when penetrated by rifle bullets, or when loaded in shells, upon shock of discharge; is comparatively insensible to sympathetic explosion, and is not exploded by heat.???0.5




http://www.dutchsubmarines.com/speci...MineExplosives

Warheads
The second major development, new warheads, involved the switch from TNT to Torpex as the high explosive. Torpex is a mixture rather than a pure chemical compound as TNT is. The components are TNT 41%, RDX (Cyclonite, Hexogen) 41% and aluminum powder 18%8. Torpex is attractive because of the increased explosive energy and higher detonation velocity of RDX as compared to TNT and the prolongation of the pressure wave by the aluminum. On a weight basis, Torpex is conservatively about 50% more effective than TNT as an underwater explosive against ships. Torpex is, however, more sensitive than TNT and RDX was expensive and difficult to make safely. The process of converting to Torpex torpedo warheads (and depth charge loadings) began with an order for 20 million pounds in early 19429. The first Torpex loaded warheads10 followed late the same year. The 640 pounds of Torpex in a Mk.14 warhead was at least the equivalent of 960 pounds of TNT11 almost twice the destructive power of the original Mk.14.


The reaction of the submariners to Torpex is apparent from an entry for 19 March 1943 in the fourth war patrol report of USS Wahoo: "0515H; Fired one torpex torpedo at medium sized freighter identified as KANKA MARU, 4,065 tons, range 750 yards, 120 port track, speed 9 knots. Hit. After part of ship disintegrated and the forward part sank in two minutes, and 26 seconds. These Torpex heads carry a [sic] awful wallop."

____________________
7 Quoted in Theodore Roscoe "United States Submarine Operations in World War II", Annapolis: US Naval Institute Press, 1949 p.262. In addition to these problems Westinghouse seems, albeit with Navy concurrence, prematurely to have turned their attention to the all electric Mk.19 and allowed the Mk.18 to languish.
8 Torpex ranges from 45% TNT, 37% RDX, 18% Al to 41% TNT, 41% RDX, 18% Al
9 Interestingly, the US Army was willing to produce cyclonite, RDX, for the Navy's use in Torpex, but was reluctant to use it for Army munitions because of safety concerns.
10 Torpex and TNT warheads were interchangeable. If there was a substantial change in weight, some adjustment to the depth gear was required.
11 Comparisons with Japanese torpedoes often neglect the difference in high explosives. Japanese torpedoes used Type 97 high explosive, which is not significantly more powerful as an underwater explosive than TNT.

http://www.geocities.com/Pentagon/1592/ustorp3.htm


tomas : Generally speaking, RDX, explosive mixed with TNT to form Torpex, is rated by itself as giving a detonation wave of 8700m/s, while TNT yields 6900m/s. By itself, RDX is therefore about 21% more powerful than TNT.Adding aluminium powder to the explosive increases the generation of heat and increases the brisance by allowing the explosive to convert itself into gas pressure more rapidly. Brisance is the ability of the explosive through heat, shock and pressure to destroy structures it is in contact with.

Bill Jurens :Also, keep in mind that due to scaling laws, even a relatively large difference in charge weight only increases the damage radius a relatively small amount. In air, the radius of equivalent overpressure is proportional to the cube root of the charge weight, so doubling the damage radius (using overpressure as a measuring stick) requires multiplying the charge weight by eight. The situation in water is much more complex, but basically quite similar. In a nutshell, changes of even 15%-20% in charge weight tend to have relatively little effect on the amount of damage observed.


The Type 89 torpedo is equal in explosive weight to the Type 92 : 300 kg, but the one uses type 91 explosive, the second type 97 explosive.

Obviously only two torpedoes are necessary to sink a 10000T+ ship.

Since the Type 95 mod 1 has 405 kg Type 97, and the Type 96 has 550 kg Type 97, I would expect them to be a one torpedo kill shot most of the time.

What could be the result of only 60% hits out of fired torpedoes I wonder ?

keltos

blast radius
 

Having found out that the blast radius=cubicroot of explosive weight :

Type 95 :
x = cubroot of 405 kg = 7,398 m

Kaiten :
x = cubroot of 1550 kg = 11,572

way less than I first thought..

keltos

cubic root calculated here :
http://www.csgnetwork.com/cuberootcubecalc.html

New Formula
 

http://img183.imageshack.us/img183/4...wertorpijn.jpg
The numbers in italic are the new ones made according to the formula here below, the ones under the torpedo name are the same but not divided by the Torpex to TNT ratio of 1,5 :



New formula for the IJN torpedoes explosive power :


weight of torpedo warhead IJN / weight of torpedo warhead US
------------------------------------------------------------- * 1,07 (Type 97 ratio vs TNT) * 120 (MK14's game explosive power min)
1,5 (torpex ratio)


405/292
-------- *1,07 * 120 = 118,726
1,5


what do you think ?

I still am not sure that I have to divide the explosive power of the IJN torpedoes by 1.5 as per the Torpex ratio, since I don't know if the game designer based their numbers on torpex (post 1942) or TNT (pre-1942)

keltos

Torpedo zon files - two Yields
 

Two different zon files, one according to the torpex explosive being 1.5 times stronger than type 97 explosive, the other one assuming the game based the early mk14 as loaded with TNT, thus being more or less equal to the Type 97 explosive.

Rename the one you prefer to Torpedo.zon and slip into the library folder of the IJN torpedo mod.

Low Yield has a base value for the Type 92 of :
min 88
max 132
ap 73

rg min 2,2
rg max 6,7

High Yield has a base value for the Type 92 of :

min 123
max 184
ap 103

rg min 2,2
rg max 6,7



Now they need testing. I also need info on the explosive power of the Type 91 explosive % TNT or Type 97 explosive, because the type 89 torpedo had such a warhead.

[edit]
low yield :Nevada BB took four Type 92s and one Type 95 to finish it off, 10 k tanker still afloat after 2 Type 95 hits. Liberty ship 2 type 92 hits, still afloat, Submarine Tender 3 type 95 hits, still afloat.

high yield : 2 Type 95 into a T3 tanker - still afloat - 3rd Type 95 sinks it. Liberty class : one Type 89, one Type 95 hit - lists heavily to port -Submarine Tender 4 type 92 hits, still afloat. Troop transport : 2 Type 95 hits - lists to port -

Keltos

http://img15.imageshack.us/img15/3151/data2k.jpg
http://www.fischer-tropsch.org/primary_documents/gvt_reports/USNAVY/USNTMJ%20Reports/USNTMJ-200D-0022-0469%20Report%200-01-1.pdf



The Germans and the Japanese used hexanitrodiphenylamine in admixture with TNT in torpedoes, sea mines, depth charges, and bombs. Commercially this explosive was used in compositions called Neurodits. The Swedish used it in compositions called Novit. The Germans mixed it with aluminum powder in compositions called Schieewolle 18, and it was also used in German skip bombs. The Japanese used it in compositions called Seigata (aka Type 97), and Otsu-B.
http://www.roguesci.org/chemlab/ener...enylamine.html

Type 91 : 6600 m/s

TNT : 6940 m/s

Type 97 : 7100 m/S

Otsu-B : ???? m/s (60% TNT 24% HND 16% aluminium powder)

Torpex : 8570 m/s (42% RDX, 40% TNT and 18% aluminium)

http://stason.org/TULARC/science-eng...xplosives.html


I read that in her fifth war patrol, Wahoo had both TNT and Torpex warheads on board :
http://www.warfish.com/report5.html

So I wonder how the SH4 Devs chose the hitpoints ?

Keltos

It's funny how I seem to be making the questions and the answers here :har: :wah:

New formula for the IJN torpedoes explosive power :


weight of torpedo warhead IJN / weight of torpedo warhead US
------------------------------------------------------------- * 1,07 (Type 97 ratio vs TNT) * 120 (MK14's game explosive power min)
1 (TNT)


405/292
-------- *1,07 * 120 = 178,089


Well, here's what I understand :

German Hexanite isn't much better than TNT.

in game German T1 and Te and TIII torpedoes have these values :

MinEF=120
MaxEF=180
AP=100
Minradius=3
Maxradius=7

the homing ones have less, taking into account the homing device :

MinEF=80
MaxEF=160
AP=100
Minradius=3
Maxradius=7

the US mk14 has the same values as the T1a !!!!! :

MinEF=120
MaxEF=180
AP=100
Minradius=3
Maxradius=7

So the Mk14 they modded here represents the early war mk14 with a TNT warhead.

Then the Type 97 explosive warhead should have 1.07 times that value as per same warhead weight.

cqfd


Keltos



download :

IJN torpedo mod version 3.8 :
http://files.filefront.com/v+38+IJN+.../fileinfo.html

new zon file download link :
http://files.filefront.com/Torpedozo.../fileinfo.html

Keltos,

Where again is the leap of faith jump off point?

The early war MK 14?

mk14 had TNT warheads untill 1943.

since in game the T1a (300 kg) has the same hit power as the stock mk14 they must have based it on TNT, not Torpex.

I think what is missing is to have two types of mk14 to choose from : one with TNT warheads and one with Torpex warheads like Wahoo during her fifth patrol between April and May 1943 :

http://www.warfish.com/report5.html

maybe mod one of the unrealistic ones into a Torpex mk14 ?

Keltos

how does anyone really?

this is a topic i have disagreed about often.

contrary to popular opinion, there is no real true record of what was "needed" to sink a ship.

when you look at sinking reports, many logs say how many torps were used and the result but my problem with such reports is they dont keep track of what was actually "needed" to sink a ship as much as tracking how many were used to sink it.

in real life you want to overdo it so you dont miss the oportunity to get the sinking so no respectable sub commander would send one torp at a time to measure only what was needed to sink each ship.

because of this it is my contention if 2 torps were needed to sink a ship they still used 4 or 5 and recorded it took 5 torps to sink. no one could or should have accurately used just enough torps to sink a ship because a dud or some other factor can cause a missed oportunity for the kill.

the only thing you can do is guestimate based on damage repair records after being torpedoed at that varies greatly based on hit locations, quality of construction, age and condition of ship, and the angle the torpedo hits at.

so no matter how much you look at records there is no true record you can use, you can only guess based on averages and unknown factors.