Home Island AA Defences
Obviously, if a bombing attack is at the stage where AA has to fire, things are going bad. However, Japan in the late-game has to accept that the Allies will send bombers where they want: the goal then changes to make the Allies lose as many bombers as possible.
So, in a fit of mad planning, I've organized the placement of AA units within the Home Islands. My method focused on a concentration of defences at the top ten or so heavy and light industry centers in the Home Islands, essentially leading to the abandonment of almost every other base in Japan.
My reasons for this are two-fold. First, supply always seems to be the critical factor for end-game Japan rather than engines, airframes or HI/Armaments points. Secondly, manpower attacks (and the resulting firestorms) seem to do far more damage than pinpoint attacks against a specific factory - it is no conincidence that the top manpower bases are also top HI/LI bases: two birds with one stone.
The Statistics
Let's consider the weapons that Japan has to defend her skies come 1944-45. I'll disregard smaller weapons that likely won't be in play.
IJA Anti-Aircraft Weapons
The bulk of AA weapons can be found in the dedicated IJA AA units.
Gun - Range - Effect - Pen - Acc - Ceiling (Comments)
8cm/40 Type 88 AA gun - 4 - 26 - 28 - 34 - 23000 (most common IJ AA gun. Decent accuracy and good ceiling)
8cm T99 AA gun - 11 - 26 - 28 - 35 - 27500 (used in the Home Islands AA units, minor improvements over the Type 88)
10cm/40 Type 14 AA gun- 17 - 34 - 45 - 38 - 31000 (bigger, heavier, more accurate. Used by Independant Gun Coys)
12cm/56 Type 03 AA gun - 22 - 45 - 53 - 53 - 36500 (hits hard, hits often, hits high. The 10cm Type 14 upgrades to this monster in 9/43, and some "Air Defence" units in Japan undergo a TOE upgrade in mid 44 that gives them these monsters.)
As you can see, the bigger the gun, the better it is. Japanese flak isn't anywhere as good as the Allied devices, so it's important to make the most of what you have. Sadly, the bulk AA units will be stuck with the Type 88 or 99 for most of the war, with only some units upgrading to the 12cm weapons.
IJN Dual-Purpose Weapons
Interestingly, the IJA doesn't have a monopoly on air defences in the Home Islands. Quite a few bases in Japan have dedicated IJN base forces, and these bases have some dual-purpose weapons that can supliment the IJA's AA weapons.
8cm/40 Type 88 DP gun - 4 - 26 - 28 - 34 - 23000 (exact same stats as AA version above, most common DP gun)
8cm/40 Type 41 DP gun - 12 -13 - 28 - 33 -19000 (much poorer version of the Type 88)
10cm/65 Type 98 DP gun - 21 - 29 - 45 - 58 - 41000 (great gun, but only 20 guns in 5 static fortress units)
12cm/45 10YT DP gun - 17 - 45 - 52 - 45 - 32800 (good gun, mostly used in fortress units)
12.7cm 3YT DP gun - 18 - 51 - 58 - 55 - 38900 (fantastic gun, accurate, packs a punch and can hit just about anything. Best gun that Japan has for bomber killing!)
However, all of these weapons are used in small numbers by dispersed base forces, so it's impossible to effectively concentrate them.
Thanks to the wonder of TOE upgrades, however, they can be concentrated. Various other Japanese units undergo TOE upgrades, giving them small numbers of these weapons. The only TOE upgrades that give large numbers of DP guns are as follows:
Kure Naval Base Force - Has a TOE upgrade in Jan '44 giving it 54 (!) 12.7cm guns.
Yokosuka Naval Base Force - Has a TOE upgrade in Jan '44 giving it 96 (!!!) 12.7cm guns.
The Plan
My AA defence is centered around the following cities, in order of importance:
- Tokyo
- Osaka/Kyoto
- Yokohama/Yokosuka (come Jan 44, the Naval Base Force can defend this city alone)
- Nagoya
- Kobe
- Hiroshima/Kure (come Jan 44, the Naval Base Force can defend this city with the help of a few IJA AA units)
- Nagasaki/Sasebo
Tokyo
4 AA Regiments
3 AA Battalions
4 Independant Gun Co's
Total: 88 8cm Type 99 guns, 16 10cm Type 14 guns.
Osaka/Kyoto
2 AA Regiments
1 Feild AA Gun Co
3 Independant Gun Co's
Total: 36 8cm Type 99 guns, 12 10cm Type 14 guns.
As AA units arrive as reinforcements in the Home Islands, they'll be centered on Osaka/Kyoto till there's about 100 guns.
Yokohama/Yokosuka
Nothing at present. If Allied bombers are in range before the Base Force TOE upgrades come into effect, defences will be stripped from Nagasaki/Sasebo to cover this base.
Nagoya
3 AA Regiments
1 Independant Gun Co.
Total: 46 8cm Type 99 guns, 4 10cm Type 14 guns.
Kobe
3 AA battalions
2 Indepdnant Gun Co's
Total: 24 8cm Type 99 guns, 8 10cm Type 14 guns.
Later reinforcements will be sent here to bring the total number of guns to about 60.
Hiroshima/Kure
1 AA Regiment
1 Independant Gun Co.
Total: 16 8cm Type 99 guns, 4 10cm Type 14 guns.
This will be suplemented by the TOE upgrade to the Kure Naval Base Force.
Nagasaki/Sasebo
2 AA Regiments
1 Independant Gun Co.
Total: 32 8cm Type 99 guns, 4 10cm Type 14 guns.
[center]
Crew of a Type 88 Gun in a training exercise.[/center]