You said set the direction and forget it! That is so far from reality of jet propelled space crafts.
Gravity? It is zero 4+ light years away.
You must be reading too many space novels. I worked with real physics throughout my career as mechanical engineer designing highest impact in the world machines (cold extrusion of steel).
I will end this discussion by saying no earth spacecraft can make it to another solar system. I am willing bet money where my mouth is. If it was possible, we would have alien visitors constantly visiting earth because there are many older solar systems than ours, and therefore good chance of being more advanced.
The lack of alien visitors is no proof that crossing between solar systems is impossible. "It's never been done before, therefore it's impossible."
And there is nothing that states that an older solar system is more likely to host life capable of launching spacecraft. We might be not just in the right location but in the right time.