XPlane2Blender is the official exporter for the X-Plane ecosystem. Its scripts can be used to import or export scenery or cockpits from Blender to X-Plane.
Download Blender 2.78 or 2.79 then grab the latest non-beta version of the scripts here. An installation guide is available as well.
Introduction to XPlane2Blender Video
This tutorial shows how to setup Blender and the X-Plane .OBJ exporter XPlane2Blender. These are the first steps in the process of creating your own custom objects for X-Plane 11.
The particle_tutorial.zip file contains a sample project with an internal document on how to experiment with particles, and 5 different types to choose from.