This is smaller plane, maximum takeoff load is about 20 tons, and it probably wasn't fully loaded, full semi-truck can be about 35 tons so it isn't that impossible, aluminium is super light material.
Honestly if you want best free cad program there is nothing close to FreeCAD, sure UI isn't super modern but as someone who had to use CATIA in high school it looks amazing, just slap dark theme on it so it doesn't hurt your eyes. If you are up for paid version there is BricsCAD but price is spicy, not sure if it is possible to find pirated version for linux or if you are even interested in fucking with that.
Hopefully last mission will be washing emperor on the throne.