# Can we use the planets and Sun to fling out a craft at relativistic speeds? [duplicate]

E.g. The Voyager crafts took various assists from the planets. Sun being much more massive, wouldn't a spacecraft gain much more energy from such a flyby on the correct trajectory? If so then what fraction of $c$ could we achieve?

• Voting to close, sorry, this is a duplicate of physics.stackexchange.com/q/128356 also related to physics.stackexchange.com/q/134473 – user81619 Nov 3 '15 at 13:38
• @count_to_10 I agree. Shall I delete this? – iceman Nov 3 '15 at 13:43
• Sorry about that, been there myself, imo yes, but it takes 5 votes so it's up to you. – user81619 Nov 3 '15 at 13:44