Hi Jay, looks great! You can't use capacitors alone to increase voltage. You can make a circuit using a coil, a FET, and capacitor, which is called a DC boost converter. Or you can try increase the rpm to get more voltage. Once you get 13.5 voltage you are good to charge a 12V battery.
What generator are you using? Your problem is typically of projects which use a car alternator or other high rpm motor as a generator.
To make it turn downwind, try reversing the blades, and removing the tail - that alone might do it.