Bigger LOX tanks? I thought the Gotland was really clever when I first read of the joint exercise. But now I'm convinced that the German (fuel cell) technology is potentially better. It eliminates the necessity of dumping the combustion products of the Stirling engines' heater out of the pressure hull. It also reduces the moving parts count to a minimum.
Both the Swedish and German boats are very small and can offer only limited storage space for torpedoes and/or missiles. The Gotland was ferried to San Diego with a surface ship. It appears that these "pocket" subs are best suited to coastal defense and may have problems with "blue water" sailing. Our best defense may be to just stand off in deeper water with our missile boats.
Regards,
GtG
PS The Swedish boat is co-ed. What red blooded sewer pipe sailor could resist that duty?
The Siemens fuel cells are also safer.The biggest problem with AIP now is that subs cannot go beyond 5-7 knots to achieve endurance.So the Stirlings can give you 15 days but at a speed of 3-5 knots.
Being only about 1,600 tonnes,they can hold only about 20 weapons,which is small by American standards(though a US boat weighs nearly 4 times that much for less than twice the weaponry!!!).Anyway,The Russians recently unveiled a conceptual version of their Amur-1650 class AIP submarine for the Indian navy which had an 8 cell VLS for long range cruise missiles in addition to 18 torpedo tube weapons.That's a pretty novel concept if you ask me.