If I understand correctly what you want, there are two possible ways: 1. If your aircraft already has a texture map assigned to it, you can edit the map in Photoshop and add the lettering at the place you need 2. If there is no other texturing, edit the texture of the appropriate part with the material editor. You can assign the the file with your letters in the basic editor (color map tab) but you'll need the advanced editor to scale and  position.   I attached a picture of the function editor. The map is connected to the color node and to the transparency node (so that you get just the letters without the white background.  You need to set the repeat to 'none' and adjust the offset (and scale?) so it is situated in the right place. You can adjust the position and scale of the letters in the advanced editor, color tab, without using the function editor, but I dont know how to do adjustments for the transparency without the function editor. Maybe there are easier ways - I'm not the greatest expert - but this should work, (If you have your letters in a png file with transparent background you may not need to worry about transparancy adjustments in vue - try it) I hope it works

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