[MOD/CAREER] How to build spaceship with more than 20000 m/s of DV?

The best method where you are is to make a ship in orbit with several launches. Make fuel tanks, science ships and engines all on seperate crafts and then dock them in low kerbin orbit.

You could use a large 2.75m fission reactor (the green one lasts far longer without refueling) with some plasma engines, since those are very efficient.

Tex · May 25, 2014

I'd have to agree with SirusKing, the best way to do it would be a multi-piece mothership. Make sure to have sets of LV-Ns on there, to make the most of the fuel you can bring.

raxo2222 · May 25, 2014

Hmm, I think I could build it in 3 launches: First lander, then main module and at last fuel tanks with nuclear generator and plasma engine.

I never built ships like that yet, as I got 64 bit system just recently.

thescientist · May 25, 2014

20000 m/s of DV?

Are you planning a grand tour?

Anyway, as said before I think that multiple launches and/or special staging are the only way to achieve all this DV keeping your part count below insanity level (or, better, lag level)

Edited May 25, 2014 by thescientist

raxo2222 · May 25, 2014

I found nice DV map here:

http://forum.kerbalspaceprogram.com/threads/40413-Reading-dV-map

Here and back + landing/return to starship. Launch from Kerbin - 4550.

Mun 2680 + 1700

Minmus 2270 + 520

Moho 7900 + 2800

Eve 4920 + 12000

Gilly 8640 + 70

Duna 3180 + 1380

Ike 3940 + 1070

Dres 5100 + 1110

Jool 9640 + 22000

Laythe 11200 + 2800

Vall 11220 + 2360

Tylo 11520 + 6140

Bop 11540 + 552

Pol 11440 + 360

Eeloo 8740 + 1680

So 13000 m/s of DV should be enough for starship, when leaving from orbit, and 3000 m/s of DV for lander, if we don't go to Tylo (6140 m/s), land on Eve (12000 m/s) or fly into Jools atmosphere for science (22000 m/s).

And 20000 m/s of DV is enough for full Grand Tour? o.o

Edited May 25, 2014 by raxo2222

merendel · May 26, 2014

You can get quite far on very little dV if you do it right and are willing to spend time orbiting waiting for ideal windows. Send a mothership with a lander docked to it. Always leave the mother ship in the most ecentric orbit you can and send the lighter lander in to do landings and then return to the ship. Going to eve for example you can aerobreak to just bairly capture and spend a few dV to raise your PE out of the atmosphere and wait for a gilly incounter and send your lander to gilly. you might have to spend a few hundred dV on the lander but the same fuel will only be the equivelent of a few dozen on the mothership. return to the mothership and wait for an opertunity to do a burn at eve PE that will kick you down to moho.

Agian ecentric orbit and land with the lander to save fuel. After moho do an eve flyby and get a gravity kick up to duna's orbit. After duna/ike swing by dres then up to jool. Agian gravity assists are your friend in jool, you can bounce up and down the gravity well on a handful of dV geting kicks off tylo or aerobreaks off laythe/jool itself. After your Joolian adventures get one more kick off tylo to throw yourself onto an encounter with eeloo. Say hi to eeloo and then head back to kerbin and aerobreak to capture and do your minmus/mun visits.

Take along a lab on the mothership to reset materials/goo. Also since you have kethane bring along a scanner and some ship cappable of mining kethane and returning it ot the mothership for refining. with that you dont need to bring a huge amount of fuel as you'll easily be able to refuel along the way. Gilly, Ike, and the smaller jool moons make exelent pit stops

Streetwind · May 30, 2014

The key to having lots of dV is high Isp, and staging. I know, shocking, isn't it?

It's more relevant than you think, though, because of reasons of math and fuel/mass fractions. It doesn't matter how much fuel you add, your fuel/mass fraction will never exceed (or even reach) 1. Ergo, there is not only a hard limit to the dV a single stage can afford you (regardless of fuel amount), but also massive diminishing returns as you approach that point. Someone did the math, and as it turns out, you'll never be getting more than 22x Isp worth of dV per stage, period. If you want to be realistic, you're never going to get more than 20x, and if you want a vessel that actually has useful payload, you're probably not going to get more than 15x without jumping through tons of hoops. Any vessel with more than 10x Isp worth of dV is starting to see noticable diminishing returns.

With the LV-N sitting at 800 Isp, you're essentially confined to staying below 16,000 dV per stage no matter what you do. The only means to reach 20,000 Isp, then, is to either a.) have multiple stages, for example two stages with 10,000 each; or b.) get an engine with a higher Isp, for example the PB-Ion. At 4200 Isp, it can go over 80,000 dV per single stage if you really push it.

Now, since you have more mods than crazy cat ladies have cats, I'm sure you can find an engine which satisfies your needs. if not, though, I can recommend Near Future Technologies, which gives you a good number of high-Isp electric propulsion choices, some with almost as much TWR as the LV-N.

One final option would be to simply not have 20,000 dV, but to refuel during the trip via locally sourced kethane.

raxo2222 · May 30, 2014

I unlocked mod engines with 800 ISP. I have somewhere around 9000 of dv on last stage now

maltesh · May 30, 2014

I found nice DV map here:
http://forum.kerbalspaceprogram.com/threads/40413-Reading-dV-map
Here and back + landing/return to starship. Launch from Kerbin - 4550.
Mun 2680 + 1700
Minmus 2270 + 520
Moho 7900 + 2800
Eve 4920 + 12000
Gilly 8640 + 70
Duna 3180 + 1380
Ike 3940 + 1070
Dres 5100 + 1110
Jool 9640 + 22000
Laythe 11200 + 2800
Vall 11220 + 2360
Tylo 11520 + 6140
Bop 11540 + 552
Pol 11440 + 360
Eeloo 8740 + 1680
So 13000 m/s of DV should be enough for starship, when leaving from orbit, and 3000 m/s of DV for lander, if we don't go to Tylo (6140 m/s), land on Eve (12000 m/s) or fly into Jools atmosphere for science (22000 m/s).
And 20000 m/s of DV is enough for full Grand Tour? o.o

It should be noted that the map you've linked assumes that the player, when going to a moon of a planet from Kebin, will brake into a low circular orbit around the target planet, and then do a Hohmann transfer from that low circular orbit to the moon in question.

As a result, it significantly overestimates the delta-V necessary to reach Ike, and drastically overestimates the delta-V needed to reach Gilly or any of the moons of Jool.

raxo2222 · June 1, 2014

It should be noted that the map you've linked assumes that the player, when going to a moon of a planet from Kebin, will brake into a low circular orbit around the target planet, and then do a Hohmann transfer from that low circular orbit to the moon in question.
As a result, it significantly overestimates the delta-V necessary to reach Ike, and drastically overestimates the delta-V needed to reach Gilly or any of the moons of Jool.

So what would be correct values for moons?

---

Okay I unlocked everything. Now I have access to top notch technology.

So I can just warp anywhere from Kerbins orbit.

Now how to build Interstellar lander with all scientific instruments, that can return from Laythe/Eve/Jool atmosphere to my orbiter?

---

Is pair of DT Vistas/plasma engines good combo, for atmospheric lander? Generator is upgraded antimatter - I get its initial supply from ship manifest, when I launch rocket.

First two parts of my starship are good enough.

Edited June 1, 2014 by raxo2222

[MOD/CAREER] How to build spaceship with more than 20000 m/s of DV?

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