High delta V spacecraft

[Buzz light fear]

Just curious if any one has made a space craft that has ~ 20,000 m/second delta V because I am trying to do a mission to all of the larger prominent planets in ksp 1.1.2 any suggestions and I don't want refueling to be included

[DDE]

That's beyond the theoretical maximum capability of the stock nuke. Whatever it is, it's gonna have to be staged.

[Jarin]

Xenon can pull dV like that, but yeah, nuke with drop-tanks might be able to get into that range. Depends heavily on what your non-propulsive payload needs to be, too.

Edited June 8, 2016 by Jarin

[wumpus]

I was building a test design for an interstellar thread (basically just piling drop tanks on drop tanks to see how much delta-v I could get) and came up with the following notes.

Getting a mark 1 capsule to ~30km/s isn't that hard, but it will take nukes and several mk2 liquid fuel tanks (your mileage may vary).  Make sure you add nukes to various upper stages (where the mass of the engine is nearly insignificant) or you wind up with an hour-long burn to leave Kerbin.

Ions are obviously even more efficient, but with worse burn time issues.  One thing I ran into was that I couldn't get KE to work with staged ion engines (this might be long since corrected, I really don't play on this partition's copy of KSP).

I'd also make sure your kerbals do some harsh negotiation on what "refueling" means.  I'm pretty sure you don't want to land the main ~20km/s craft, and it is nearly as unlikely that you want to bring one lander/body.  I'd expect plenty of refueling from the main craft.  Once that is done, I'd expect other means of leaving fuel depots in places you are likely to backtrack over.

[ibanix]

Ion Engines with the maneuver node splitter mod may be your best bet.

[Streetwind]

@Buzz light fear - after seeing people tell you that only ion engines can do this without staging, you may be interested in learning about mass fractions. That will let you understand how exactly the amount of dV in any given stage is defined, and limited.

[Buzz light fear]

Thanks for the info I plan to make the ship a mothership with a reusable lander for a ton of different planets and moons and yes I do plan on having the mothership have staging with drop boosters and currently that total is 8 drop boosters and one center core though I do plan on using the liquid fuel oxidizer mixture rather than nukes. Also about the refueling I mean at the stops kerbin orbit refueling is just fine.

[X-SR71]

http://meithan.net/KSP/engines/

 

For 20000m/s dv, I see only Ion as a solution.

 

Perhaps you're better off with a simple ISRU setup and LV-N. You can make a small craft with the small ISRU, drills, ore tank, fuel cells, a single LV-N, have about 10m/s dv, and refuel in low gravity moons.

[Empiro]

On 6/8/2016 at 0:56 PM, Buzz light fear said:

Just curious if any one has made a space craft that has ~ 20,000 m/second delta V because I am trying to do a mission to all of the larger prominent planets in ksp 1.1.2 any suggestions and I don't want refueling to be included

It would be very difficult to reach that much delta-V without extremely long burn times. However, I don't think you need that much to merely orbit all the planets and moons. I'm not sure what's the best order to visit every planet for minimal overall delta-V, but that's something that can be worked out by using the delta-V calculators out there.

Another option is to simply ship refueling tanks around instead of carrying the fuel the entire way. For example, if your path takes you from Moho to Eve to Jool, why carry the fuel it takes you to get from Eve to Jool to Moho? Instead, send it directly to Eve, dock with it around Eve, and then head to Jool.

Edited June 10, 2016 by Empiro

[Buzz light fear]

On 6/10/2016 at 5:30 PM, Empiro said:

It would be very difficult to reach that much delta-V without extremely long burn times. However, I don't think you need that much to merely orbit all the planets and moons. I'm not sure what's the best order to visit every planet for minimal overall delta-V, but that's something that can be worked out by using the delta-V calculators out there.

Another option is to simply ship refueling tanks around instead of carrying the fuel the entire way. For example, if your path takes you from Moho to Eve to Jool, why carry the fuel it takes you to get from Eve to Jool to Moho? Instead, send it directly to Eve, dock with it around Eve, and then head to Jool.

Thanks for the input I may just use nukes with drop tanks

[foamyesque]

Pft. Just use stack staging; you can break upwards of 30000m/s of >1g acceleration. Of course, it's huge and probably not going to get you off Eve's surface, but you can go literally anywhere else, and nice and quickly

[Red Iron Crown]

On 6/10/2016 at 3:25 PM, X-SR71 said:

http://meithan.net/KSP/engines/

 

For 20000m/s dv, I see only Ion as a solution.

 

Perhaps you're better off with a simple ISRU setup and LV-N. You can make a small craft with the small ISRU, drills, ore tank, fuel cells, a single LV-N, have about 10m/s dv, and refuel in low gravity moons.

That tool only solves for a single stage. A staged nuclear rocket can hit 20km/s without too much trouble, and a staged chemical one can hit it but will be very, very large.

There is no theoretical limit on delta-V for staged designs, unlike single stages.

The usual techniques for maximizing dV apply, as always:

1. Use high specific impulse engines.
2. Eliminate every gram of unnecessary non-fuel mass, including engines.
3. Maximize the amount of fuel mass.
4. Arrange your tanks to empty one or two at a time, and drop them as they empty.

[foamyesque]

49 minutes ago, Red Iron Crown said:

There is no theoretical limit on delta-V for staged designs, unlike single stages.

No, but there are practical ones.

 

http://what-if.xkcd.com/24/

[Starman4308]

4 hours ago, Red Iron Crown said:

There is no theoretical limit on delta-V for staged designs, unlike single stages.

No, but there are real practical limits, and hilarious practical limits, such as "mass until space vehicle exceeds the Chandrasekhar limit and collapses", "number of parts until Unity engine gives up", "filled the VAB entirely with xenon drop tanks", "mass at which exhaust cannot reach escape velocity from vessel's gravitational field", "used every atom in the universe", etc.

For real-ish advice, Near Future Propulsion has some excellent ion engines, such as one with 12000 isp that I recently used to make a Moho transfer vehicle (for 6.4x) with.. ah... 20 km/sec of delta-V. Funny how that works.

[Magzimum]

I recommend that you first design the lander stages for all the planets/moons that you want to visit. Then you should put those together.

After you have overcome the shock how large the combined stages for all those planets has become (Eve requires a large lander), you can design the mothership, using NERVs with LF-drop tanks (shedding some NERVs along the way as well).

My Jool-5 mission had a similar build (although it was a little larger than strictly necessary because I wanted to bring a lot of Kerbals along).

Edited December 9, 2016 by Magzimum