Step 1: Play as Saudi Arabia (or probably any nation that doesn't start with planes)
Step 2: Research and manufacture an interwar small airframe with two bomb locks and level 1 engine.
Step 3: At an airport, open the deployment window (where you select the type of airplane to deploy)
Step 4: Select your interwar CAS plane, game crashes.
Playing latest beta version on latest game version.
Other airplanes don't causing crashing, but this series of steps consistently crashes.