Board Thread:Questions and Answers/@comment-29666298-20160913153732/@comment-232062-20160913161107

What you're talking about is commonly refered to as "improvement inheritance" or something similar. It is a thing and though I haven't seen it done or done it myself for every plane, I have done it for converting maxed 21(skilled) into maxed 52(skilled). There is no real reason to belive that it wouldn't work for other conversions..

The bonus AA comes from the Improvements .2 AA per improvement star. Like all improvements this does not alter the displayed AA value. When maxed, your plane will still say 12AA but will count as 14AA.

The reason people do this inheritance thing is because of the screw cost per improvement and the planes consumed during improvement, for example - improving a T21 (skilled) consumes the basic T21 fighter plane and improving a T52 (skilled) consumes basic T52's... 21's are a bit easier to get either/cheaper as stock equipment or through development. If you use your monthly quest Quests you can take advantage of the chearper to improve 21(s) and then convert it into a 52(s) while retaining your stars.