Great work! love the designs. Obviously the people complaining about newtons laws are correct but reading over the entire thread definitely indicates these are from the future. Funny thing is in a couple hundred years this could be possible. Go back to the roman days and ask them about plutonium fission bombs :P they will say its never going to be possible, but here we are.
Ok i made an account to ask one question :P. among the parts B9 offers the y adapter (protective cap) and if you select the sub part battery it has a ludicris volum of 512,000 capacity. so i think this is way overpowered. I nerfed my own part by changing the base volume from 36 to 6 giving it 12,000 volume. It makes any fuels useless but lets be real here a 512k battery for 30 kerbal dollars is kind of overpowered . i dont know if there is anything you could do to make it balanced either : (