Welcome to Nation-Wars. The help file is a new edition and it's not even close to being full of help yet. The manual will help you understand things better. But the best thing is to join a nation where people can help you understand things better.
Flying Discs, or level 12 jets as we call them are not an upgradable unit. You get them by random as we already discussed. Granted the name could be a different but we all kinda liked them.
In time I'm sure you will find other things you don't like about the game but if you stick with it you will find yourself addicted.. It seriously grows on you
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Things are always changing as the game grows so if you have suggestions for things you would like to see or changed, make a post in the suggestions section.
Good luck and thank for playing!