Realistic fast Interstellar Propulsion Methods

[stefan r]

... REALLY big fuel tank...

... your five-million metric ton spacecraft ...

This measure of "big" is disappointing IMO. If your puny economy ride was parked by Neptune L5 it would need to be 50 km just to be detectable. Need to up that by 5 to 7 orders of magnitude

 

[sbrothy]

I've probably mentioned this before but the most "realistic" option we have now seems to be Dr. Zubrin's Nuclear Salt Water Rocket.

To quote Atomic Rockets:

"[...]. Zubrin then goes on to speculate about a more advanced version of the NSWR, suitable for insterstellar travel. Say that the 2% uranium bromide solution used uranium enriched to 90% U235 instead of only 20%. Assume that the fission yield was 90% instead of 0.1%. And assume a nozzle efficency of 0.9 instead of 0.8.

That would result in an exhaust velocity of a whopping 4,725,000 m/s (about 1.575% c, a specific impulse of 482,140 seconds). In a ship with a mass ratio of 10, it would have a delta V of 3.63% c. Now you're talkin..."

Also Wiki on the NSWR.