In-flight mechanic
In some levels there are little tank-like units that remain stationary. These are the 
units that shoot out the lightning and repair structures. They cannot move on their 
own, but you can pick them up to place them anywhere and they will slowly repair 
any nearby units or structures. If you pick one up and fly around with it, whenever 
you take on damage it will fix your ship. Be careful though, because any enemies 
that may shoot at you from below could hit it, and they cannot repair themselves. 
However, sometimes it better to leave them near your base so they will repair 
things as needed. 


In-flight artillery
If you need a little extra firepower for your ship, look for a tank and pick it up. As 
long as you are holding the tank, it will act like a rotating turret for your ship and 
fire upon any enemy units that get within its range. The tank's cannons will rotate 
360 degrees so it can attack enemies all around you. This is very useful if you do 
not want to deal with having to make constant maneuvers to avoid being hit by an 
enemy that is tailing you.