Just noticed today the exp inbalance of the KM submarine line. Everything in each tier costs the same for every nation, whether that be straight ship research cost, or made up for in module research.
The KM sub tree has two tiers that other trees do not. Tier 6 and tier 10. It is the only sub tree that requires those to get the next one up. Fine and dandy, except that credits and exp are now being earned and spent towards the next tier, say the tier 6 from the 5. For the three other nations, they get to save all that exp and those credits earned to skip to the tier 7.
The cost of the tier 7 for all nations is rather high probably due to it skipping a tier 6. This is still the case of KM, but now you have to spend ~61k exp and 63k credits on the tier 6 before you can progress to the tier 7.
Calculations are as follows:
From the T5 sub to the t11 sub, in terms of exp/credits(purchasing modules along the way) required:
IJN:
5->7 = 139,080xp / 99,260cred total
9->11 = 5,286,150xp / 1,839,650cred total
5->11 = 5,425,230xp / 1,938,910cred
US:
5->7 = 139,080xp / 99,260cred total
9->11 = 5,286,150xp / 1,839,650cred total
5->11 = 5,425,230xp / 1,938,910cred
UK:
5->7 = 139,080xp / 99,260cred total
9->11 = 5,286,150xp / 1,839,650cred total
5->11 = 5,425,230xp / 1,938,910cred
KM:
5->6 (61,300xp / 62,940cred)->7 (139,330xp / 104260cred) = 200,630xp / 167,200cred total
9->10 (2,054,190xp / 894,690cred)->11 (5,488,670xp / 1,652,390cred) = 7,542,860xp / 2,547,080cred total
5->11 = 7,743,490xp / 2,714,280cred
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The cost to go from just KM t10 to t11 is higher than the total cost from 5->11 for all the other nations...
You can see the numbers calculated unlocking and purchasing only the required modules to get to the next ship. The point behind working through the tiers is unlocking the next ship. This does not work for KM subs if the prices of going up 1 tier vs skipping that tier entirely are the same. Granted, you get to play a tier 6 and tier 10 that other nations lack, but because subs are pretty much the same if not worse at higher tiers (only slightly more air per tier, and all slower), this does not make up for it. Not to mention that the KM T7, T8, and T9 are exactly the same sub model.
KM costs over 1.3mil xp and over 800k credits more to get to end tier sub, vs all other nations. It definitely should not be so. It should work out to the same roughly for everyone, with KM getting different xp requirements working through those ships. If this is not fixed, there is no reason to level KM subs over a different nation.
Solution: Reduce xp requirements on the KM 5>6, 6>7, 9>10, and 10>11. KM should be cheaper to advance through the single tiers, where as UK, IJN, and US should cost more than KM to unlock the T7 from the T5 because they are skipping a tier entirely.
Input and arguments are welcome.