I recently saw a documentary about the Japanese I-400 subs. Monster subs, way ahead of their time in WWII. They had an aircraft hanger inside and could deploy aircraft after surfacing. It’s a shame none survived after the U.S. scuttled them off Hawaii to keep the technology out of Russian hands. The Chinese are seventy years late on a big sub and still can’t match what the Japanese accomplished so many years ago.
On the plus side they had enough fuel to circle the globe 1.5 times and three torpedo aircraft.
On the minus side they had a huge radar signature, took almost a full minute to dive and then only had a test depth of 300’. They fact that they could travel 30,000 miles was offset by the fact that there was no cold refrigeration stores or AC. The crew would have died of disease and malnutrition long before needing a fill up. They were slow and slow to turn and the offset hanger deck hull caused a serious pull to port.
Still they were pretty amazing craft. I am not sure why we thought needed keep them from the Russians, it is not like the Russians couldn't figure out how to do it on their own.