here are some ideas for you:

1. perhaps you can have a research facility that allows you to produce research points in a few fields with which the player can buy upgrades to his units and facilities. Perhaps there can be an upgrad that allows the supply cannisters to throw more resources out per second.

2. it may be a better idea for you to make this "invisible radar-like resource transmission thing" over-ground and underground pipes or something like that that can transport supplies. Perhaps you could have an upgrade that cloaks these pipes and makes them impossible to see, therefore almost making it like these invisible radar beams you have ideas regarding.

3. You may want to include the option to have units run out of ammunition in-game and need a supply truck to come and deliver supplies to them. This could add a very interesting dynamic to gameplay. In a war of attrition, this would be fairly easy to do, but if you get surrounded, you wouldn''t have a chance. Perhaps later in the game you can paradrop resources to troupes, or use helicopters.

I had considered the physical supply lines idea, but I think I''ll stick with transmitted resource for now. Having a physical supply line I think makes it a little too vulnerable - there would be too much to protect, I think.

And also, for now, the craft will slowly replenish their ammo and hull. Needing to repair and rearm using other vehicles may complicate the game too much.

But thanks for the suggestions! I''m keeping most everything in mind. Perhaps ultimately the games can be that customizable, so players can decide for themselves just how complicated they want the management to be.

Researchable upgrades are a definite possibility, most likely a necessity for fun factor. I haven''t gotten that far in the design yet, though.