Shinano Aircraft Carrier Conversion

[Scott Kenny]

What is not understandable about disassembled aircrafts? They stored as fuselage with wings next to them, empty fuel tanks and likely no ammo, some might even lacks engines. To make them fly that requires like 30-60 minutes or even more of preparation time, not ideal for a strike carrier.

Longer than that, attaching wings and rigging the control cables (and all the fuel and electrical connections) is a 4-8 hour job for at least 2 people. Per plane.

While I'm no expert, I'd guess you probably want to take it for a spin around the traffic pattern afterwards to make sure it flies right, as well. Probably not the best plan in the middle of combat operations.

Yes, that's also required. And there will probably be some adjustments needed as well, just because that specific airplane is a little different. (I am a licensed A&P mechanic.)

 

[EwenS]

Shinano would had carried 3x 2.774ton triple 46cm turrets, 2x triple 190ton 15,5cm turrets and 6 twin 34,5ton 10cm turrets totalling 8.909 say 9.000tons of armament plus ammo and barbette armour, I doubt she would had any issues with stability even with a double hanger deck layout.
The problem is the Japanese wanted carriers as fast as they could get them and creating another hanger deck would cause a later construction date, more materials, and design workhours for calculations.

Stability may or may not have been an issue. It is not simply a case of the weight but the height at which it is carried.

As a battleship much of the weight of the armour, armament, munitions etc is placed low in the ship. In a carrier with an armoured flight deck like Shinano much more of it is carried much higher in the ship.

It is also worth noting that Shinano had her main belt side armour halved in thickness during conversion. And yet as completed her full load displacement remained about the same as the Yamato class battleships (c72,000 tons full load). Her draught was also about a foot greater than that of the battleships. So despite losing all the kit mentioned a lot of other stuff including the armoured flight deck, aircraft ordnance, aviation fuel etc had to go in.

The practice in the armoured carriers of Britain, the USA and Japan in the case of Taiho, was that the flight deck armour covered the hangar area between the lifts. So with a hangar 164m long and with a width of 18-34m (from the drawing in an earlier post most of it looks nearer the latter than the former) that is an area of somewhere between 2,952-5576 square metres of flight deck to be armoured. Shinano had 3" of armour on her flight deck but that was AIUI laid on a backing of 1" of ordinary steel as in the Taiho. So that is a total of 4" of metal to be supported at some height above the main deck. At a rough estimate that is somewhere between 2,300-4,300 tons of metal depending on the hangar width being covered. Given my above comments about hangar width probably nearer the latter.

Then the question of hangar height. The hangars in Taiho were designed to operate the same types of aircraft as Shinano, had a clear height of 5m. That means that the c4,000 tons of flight deck in Shinano was carried 5m + the depth of the substantial beams to support its weight above the battleship upper deck.

Add a second hangar into the ship and you have to carry that c4,000 tons of armour another 5+ metres higher still. That has to have some effect on her overall stability.

Whether that extra hangar would be enough to destabilse her altogether I don't know as I'm not a naval architect. But it demonstrates that the matter is not as simple as looking at the weights.

 

[Tzoli]

I doubt that if two hanger levels were to be adopted then there would be two armoured layers. Only the flight deck would had been armoured in my opinion. Also note that two hanger levels does not meant two equal sized hangers, the lower hanger most likely would had been smaller.
Indeed Shinano's belt armour was halved from 41cm (original design was 40cm) to 20cm but this was only covered the machinery spaces to my knowledge, the magazine spaces still had the 40cm belt armour. As for deck armour eg the original Battleship deck armour according to sources remained at 190mm and these armour was very heavy.

Indeed the armoured flight deck would had been at a much higher level but note no other battleship was as wide as Yamato increasing stability and there is still the possible addition of extra torpedo bulges which would further increase stability.

 

[EwenS]

I doubt that if two hanger levels were to be adopted then there would be two armoured layers. Only the flight deck would had been armoured in my opinion. Also note that two hanger levels does not meant two equal sized hangers, the lower hanger most likely would had been smaller.
Indeed Shinano's belt armour was halved from 41cm (original design was 40cm) to 20cm but this was only covered the machinery spaces to my knowledge, the magazine spaces still had the 40cm belt armour. As for deck armour eg the original Battleship deck armour according to sources remained at 190mm and these armour was very heavy.

Indeed the armoured flight deck would had been at a much higher level but note no other battleship was as wide as Yamato increasing stability and there is still the possible addition of extra torpedo bulges which would further increase stability.

I think you have misunderstood me. I wasn't thinking of two armoured decks, just raising the armoured flight deck up that 5+m. and creating a new second hangar space underneath. What I omitted to mention was the added weight necessary to provide that second hangar. Steel for the sides of the new second hangar and a new hangar roof/floor between those two hangars, plus all the structure to support that.

Yes bulges could be added but that would slow the ship. Her max speed of 27 knots was already much lower than the usual Japanese fleet carrier standard of 33-34 knots that had been applied from Soryu onwards. (And yes I am aware of the lowere speeds of the various light carrier conversions & Hiyo, Junyo etc).

My point was simly that the matter of adding a second hangar would not necessarily as easy as you liked to portray. There is as they say no such thing as a free lunch.

 

[Pirate Pete]

One reason for a single hangar might be to do with the Japanese’s experience with the light carrier Ryujo. Originally designed with a single hanger (and also attempting to ‘beat the treaty limits) in that she was less than 10,000 tons (originally at least), but, they decided to add a second hanger to increase aircraft capacity, and she wasn’t armoured like Shinano. Lesson learned possibly of trying to squeeze a quart into a pint pot?
Or…Remember the Tomozuru!

 

[EwenS]

One reason for a single hangar might be to do with the Japanese’s experience with the light carrier Ryujo. Originally designed with a single hanger (and also attempting to ‘beat the treaty limits) in that she was less than 10,000 tons (originally at least), but, they decided to add a second hanger to increase aircraft capacity, and she wasn’t armoured like Shinano. Lesson learned possibly of trying to squeeze a quart into a pint pot?
Or…Remember the Tomozuru!

They undoubtedly learned the lesson about topweight, amongst other things, with Ryujo and other incidents around the same time. But the successors to the Ryujo designed from the outset as carriers were all given double hangars - Soryu, Hiryu, Shokaku, Zuikaku , Taiho and Unryu class. Even the Hiyo & Junyo converted from merchant hulls while on the slips were able to be given given double hangars. The only carriers that weren't given double hangars other than Shinano were the conversions from ships originally designed for other purposes - Zuiho, Shoho, Ryuho, Chitose, Chiyoda & Ibuki which were all broadly comparable with the Ryujo - bit longer but with similar beams. Stability was certainly an issue when Ibuki was redesigned.