Well, firing up DuckDuckGo, the San Francisco Maritime Museum has an original Navy Mk 13 detailed description https://maritime.org/doc/torpedomk13/torp009.htmon line that is dated from June 1942 and still lists the warhead as 400 lbs of TNT. So that would be the warhead through summer of 1942.
At the Navweapons site I noted above, there is a cover article on US torpedoes that discusses various topics on US torpedoes. According to that in late 1942, the US introduced TPX as a warhead explosive. The TPX was a blend of TNT, RDX and powdered aluminum. The RDX increased the explosive power relative to pure TNT and the powdered aluminum burned a little slower so the bubble of the expanding gas of the explosion would last a little longer. Empirical testing indicated that this would increase the damage of detonation by about 50%. The bad bit about TPX was that it was not as stable as TNT, but there was a war on.
The main Mk 13 page talks about the poor running performance extending into 1943 but everything getting sorted out by the Leyte Gulf, fall of '44. It's not clear when along the way, the warhead size was increased to 600 lbs.
The most complete text appears to be in an official history from the Bureau of Ordnance. See http://www.ibiblio.org/hyperwar/USN/Admin-Hist/BuOrd/BuOrd-6.html. This is by far the most complete discussion. The Mark 13 material is after a long detailed discussion on the submarine torpedo fiasco and fixes. Much of the other sources' text seems to paraphrase the language here.
Performance slightly improved in 1943 (only 70% dud rate) from even more abysmal values in 1942, but the incremental improvements (mostly with the shroud ring/pickle barrel) started to reach the fleet in 1944. Those worked spectacularly well so the Model 10 was standardized with the bigger TPX charge and shroud ring assemblies were manufactured and shipped out to the fleet so the older torpedoes in inventory could be retrofitted to Model 10 standards.
So if I was king, the most detail I include is:
- Model 1, 90% dud rate at start, 404 lb TNT warhead.
- Model 2: 70% dud rate July, 42, 404 lb TNT warhead.
- Model 2A 70% dud rate, October, 42, 404 lb TPX warhead (606 value)
- Model 10, 10% dud rate, September 44, 606 lb TPX warhead, (909 value)
One thing I don't know is if upgrades on ordnance pass through to torpedoes afloat in magazines. My reading of the source material is autumn is broadly operational timing so moving that intro date up a month to give carriers a chance to resupply with torpedoes might be appropriate.
Since the dud rates are hard coded, you can drop the Model 2 at no loss. If there was a good source to justify quicker implementation of the bigger warhead that might included, but it is pretty clear that the Model 10 is where the bulk of the improvements had been achieved. Increasing the drop height of the torpedoes from 100 feet to 5000 feet might be well documented historically, but I don't know how to get that into AE.
BTW, I agree that the IJN TB should be restricted to the Type 91 Mod 3, but I think the heavier Mod 7 should be available to the Francis and Peggy as well as the Betty.
< Message edited by engineer -- 7/27/2019 12:44:01 AM >