I'm so happy I found this thread. Of note for Windows 10 users is to copy the file, edit it, then reinsert it into the directory to circumvent the "You Don’t Have Permission to Save in This Location" issue, which authorizing user rights doesn't seem to fix. Also, make sure you go into Folder Options and deselect "Hide extensions for known file types", so that you can remove the hidden .txt file name extension created after changing the file with a text editor, returning it to .lua so the game recognizes it.
I've done this for each of my WW2 aircraft, cept the Spitfire, which I can't seem to locate the propeller value in. Thank you everyone!