Thankyou to damienreave for posting a link to the file. I had difficulty finding it.
Following are my observations in implementing this: (programing and general geek-noob here)
After saving file to desktop I had to re-read mappleaf and shockrift posts to figure what to do with it.
A) In mods folder, drop the file in the main folder for Companion Drone mod. This is easy enough dealing with a zip on a Mac, been a while since I've done it on a PC.
B) Modify "line 428" of some file, somehow...
The file is for the mod, not the game. It is "data.lua" in the main Companion Drone folder in the mod folder.
In that file modify line 428 to read:
filename = "companion-drones/10-jet-flame.png",
This is in a section that starts:
table.insert(layers, 1,
Maybe I'm just a big dummy and it took a few days for me to try, then a few hours to figure it out.
Hope this helps