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Post by ross128 on Oct 14, 2016 1:15:34 GMT
The main thing that hurts MPDs in my view is simply that they consume energy instead of producing it. A typical NTR puts out anywhere from 3 to 12 GW of power, which of course means even a 100% efficient MPD is going to suck down 3 to 12 GW if it wants to match that performance, out of a reactor that is maybe 20% efficient and has a giant thermocouple (and radiators) attached. They'd be great if we could stick them on a fusion or antimatter reactor.
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Post by nerd1000 on Oct 14, 2016 1:21:35 GMT
If we were using fusion or antimatter reactions for power it would make more sense to simply vent the resulting superheated plasma/exotic particles out the back through a magnetic nozzle. Isp would be even higher than a MPD thruster, with far less need for radiators.
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Post by wafflestoo on Oct 16, 2016 3:46:34 GMT
One way is to aggressively sling-shot around the sun. You start off with a tight hyperbolic orbit (not too tight of course, you'll probably cut inside Earth's orbit but not Venus'), then when you're at the point nearest the sun you burn retro to pull it into an ellipse that intersects Mars' orbit. Make sure you're orbiting the same direction Mars is of course, you won't be able to turn around. The real tricky part is timing and positioning it so that Mars is also close to the part of the orbit you're intersecting, so that you won't have to make too many adjustments after matching orbits. Tankers are useful, because this approach is still going to devour delta-V, it just spreads it out over several burns to set up a good place to match orbits. If you're good/lucky enough to nail Mars right at the intersection, you might even be able to do a circular insertion. That sounds about like the trajectory I used to complete the mission. If you time your burns right you only need about 13-14 km/s of dV. I haven't seen much use for MPDs so far as the scope of this game is concerned (unlike KSP where they were useful for delivering small probes here and there). That neptune one is a pain either way. I ended up making a special stripped-down siloship for it carrying a handful of extreme-dV nukes (was actually the origin of the Titan V Stationbuster, before I started trying to give it a bunker-buster warhead). Used a tanker and the ship's dV to at least get in the same plane with a roughly circular orbit retrograde to the station, then proceeded to lob missiles at it until it died (though Neptune's gravity really screwed with their targeting and ate quite a few missiles). The beauty of using nukes was that I could do a close circular insertion followed by a "match orbits" command, and the retrograde orbit would slam the missile into the station for free. You can use the default ships just fine using a bi-elliptic maneuver for the plane change maneuver. The trick is to refuel the combat ship after completing the plane change maneuver at the Apuranion and abandon the tanker in that orbit (presumably to rejoin the combat ship after the 'hit' is complete). You then make multiple burns at Peruranion to circularize your orbit (I think it took like three-or-four passes to complete), sync up with the station then intercept. That close to Uranus your orbital period is so short that you can afford to make several passes and still stay inside your time limit.
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