RE: combat submarines
Torpedoes have long been debated, and the information is readily available in various threads. The physics are incredibly difficult, and the expense, if it is possible, is simply not justified, compared to the cost and simplicity of the current system. Remember, the current system has had 30-40 years of development, with almost everything else mentioned lately tried by numerous people over the years and determined to be inferiosr or impractical.
Feel free to try and develop something. I would strongly suggest, however, that you join a combat club and get some experience with the parameters involved and what you are needing to accomplish. Real life experience will help a lot. I would wager that you could put a decent battleship or two on the water with less time and expense than trying to develop a "new and improved" torpedo system.
Cheers,
Wreno