[brutt]

Locomotive can harvest energy and matter from Sun and then use it to orbit around Sun, slowly gaining speed, until it will no longer will be able to compensate сentrifugal force. Then it can reach high orbit passively, pickup pilots on high orbit, and be ready to flight, with full tanks. Or it can dump fuel, and do another dive to Sun, for more fuel.

If it will survive Sun radiation at low orbit, then it may also survive interstellar travel at high % of C.