Okay I admit it is not a totally original concept. But in Book 5 of Orion’s Spur, crazy Debbie has to race between the Perseus arm of the galaxy to the Sagittarius arm of the galaxy in the Sara. To continue accelerating she sling shots off of multiple stars along her path, going faster after each swing.
I was not surprised, but delighted to see an article today about this same concept being put to practice by NASA. They are doing a multiple sling shot using first the Moon, and then Earth to send a spacecraft to Venus, and then on to Jupiter cutting across the Solar System using a shortcut. My only disappointment is that they didn’t also use Venus as yet another speed accelerator along the way.
The article is a good and short read: https://www.yahoo.com/news/spacecraft-slingshot-around-earth-moon-203913638.html