The Midways, closer in weight, would make even better comparison with the Shinano. Shinano wouldn't even be a real carrier; her official designation was something like an accomodation carrier, a carrier/fleet tender/repair/hospital ship of some sort. The AC it carried was quite minor when in proportion with her size. The cause was the rarity of aircrews towards the end of the war. Even battleship Ise, converted into a seaplane battleship, didn't have enough crew to operate her miserable aircraft facilities. The whole Japanese war machine aimed for a quick victory in the Pacific. It certainly wasn't geared for the long run. I question their battleship design teams in particular, having skipped a whole generation of fast, carrier group-able ships to produce useless prestige leviathans, relics that Yamamoto compared to katanas on a modern battlefield. There was also too much variation in the carriers, and the Japanese failed to come up with a worthy Zero successor as war advanced. Their cruisers and destroyers, however, were the bane of the Allied navies, owing much to the "Long Lance" oxygen torpedo.
I concur, the Shinano was not primarily intended to be used as an attack aircraft carrier but as a carrier group support ship. Just think how much aviation gas and fuel oil the Sinano could carry. It's like the Iowa's BB's, they don't need oilers following them around, the Iowa's carried so much fuel they were able to refuel it's escorts at sea.
In my opinion the Shinano was basically a platform without a mission. They basically put her together because the third Yamato hull was too valuable (in their view) to simply scrap and they realized they didn't need a third Yamato anyway.
Wow, really? Are you aware that there was a 4th Yamato class Battleship under construction? Yamato Class Hull 111 was 30% complete when the scarcity of materials led them to make the decision to break her up in 1942. The materials recovered from the hull were then used to convert the 2 Ise class Battleships into aircraft carrier - battleship hybrids. After Midway they even considered converting all Battleships into carrier-battleship hybrids. It was only lack of materials that prevented this from happening. And the Ise class ships were rather impressive in their own right. A total of 6 twin turrets, for a total of 12 14" main guns. For the conversion the rear 2 gun mounts were removed, leaving her with 8 14" guns. To offset the weight the flight deck was probably the most sturdy ever built. 8" of concrete and 6" of steel armor were added to the 4" of deck armor already in place to offset the weight of guns that were removed. When planes and pilots became scace later in the war their catapaults were removed and they were used primarily as troop transports and cargo vessels. At the end each were anchored and used as massive off-shore gun and anti-aircraft batteries. It took at least 22 bombs to sink the Ise, 10 to sink the Hyūga. You say a platform without a mission. The only problem with that statement, is that if you look at the IJNs plans for carrier-battleship conversions, they would have essentially all been like those of the Ise class. Gunpowder rear-facing catapaults, capable of launching conventional aircraft for one-way missions, or launching sea planes and recovering them with a crane (these ships had no capability for carrier deck recovery). And if the war had held off another 6-9 months, the construction of Hull 797 "Super Yamato" would have started. This would have been a lighter and faster ship then the original Yamato class, with greatly improved AA capability over the original ships of her class.
