I was cruising around the help file and look what I found this paragraph in the perk points section:
The perk system is a way for HTC to introduce some interesting but otherwise unbalancing planes on a limited basis but the benefits go deeper than that. Perk planes (and vehicles) would be things like Me 262s, Ta 152s, Tempests, B-29s, Ar 234s, Tiger IIs, etc.
b-29, tigerII. This probably means that HTC originally had some intention to include the b-29.