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Join Date: Dec 2007
03-28-2012, 11:28 AM
Originally Posted by
Gravitational slingshot only works if the object you're using is also moving in the approximate direction you're trying to go, and you need to start from outside it's gravitational influence (these two combine so that you're "falling" much longer than you're "rising" after perigee so you get a net gain). If you start from an orbit around the object, getting back out to that distance will rob you of what speed you gained. That's why probes don't slingshot out of earth orbit, they use boosters and slingshot on a second pass.
I would have to go back and recheck some things, but as I recall a fusion ram jet becomes viable at about .5c and .5 c can be obtained by using an Orion project typr of propulsion system.
Or forget the ramjet and go Orion Project all the way. A nuclear warhaed in the 1 megaton range can release about 4.184 petajoules, which is about 4.184x10^15, and there are much higher yielding devices than that.