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human
[Star Wars] How does an Astromech Droid fit into the sockets of the Aethersprite- and Actis-class Starfighters?

Seriously. Their entire lower half just disappears, and I doubt they just take-apart and re-assemble the droid just to make it fit.
gpt
In terms of the original Aethersprite, they didn't.  The fighter could not accommodate a full sized astromech, so they commonly used truncated astromechs wired directly into the figher's systems.  Later, the Delta-7B was introduced which made room for a full sized droid socket.  
The Actis was designed for a full astromech from the get-go, so the full socket is there. The wing shape is deceptive, but if you take a look at the underside, the hull is plenty deep enough for the droid to fit.