Theory:
This units works as a it sounds, a structure that can house, repair and rearm aircraft, and a large number of them. Rearming an repair is done at a MUCH slower rate than a traditional airpad.
It would have limited storage, and take time to launch aircraft (time dependent on type: fighters launch faster than bombers, swifts being the fastest, likhos slowest).
It would also run auto-defense, acting as a sort of mini-AI in that it would launch interceptors to hit incoming bombers and use scouting data to micro the interceptors away from AA.
Reason for this unit:
Honestly, I hate having 20+ planes circling around my air fac, and it would be nice to have a place to store and hide planes (from scouting and damage) for future use without having to land them in a massive cloak field.
Second reason is that micro managing fighters is a complete pain in the ass when they decide that chasing down 1 enemy fighter is a great idea, and then all die to AA.
Cost: 800M
HP: ~ 6000-8000
Repair and Rearm Rate: .25E
Max Storage: 40 Planes
Negatives: Destroys or captures all planes inside if destroyed or captured, respectively.
Practice:
I don't know if it is actually possible for the Spring Engine to store units in a "vault" akin to Age of Empires 2
Yes I know this is an incredibly stupid idea . . .