Manned, career Duna round trip

[Squidiness]

The title says it all, but I do have a few questions about manned Duna return missions:

1.) Should I do it Apollo style, leaving one guy in orbit with a crap ton of fuel and loading the other side onto a lander?

2.) I'm not good with docking, nor can I get mods, so can I do this in one launch?

3.) Should I bring an ISRU converter along with me? If so, where should I have it (in the lander or in the orbiter)?

Thanks in advance!

Edited January 6, 2017 by Squidiness
Extra question

[wumpus]

I'd assume that you are going to want an Apollo-style mission.  You don't really need "one guy in orbit" since you will have OCTO probes far beyond 1960s tech.  Remember, the only reason they docked in Apollo (and the Soviets planned this as well) was because their spacewalking tech wasn't up to Shuttle levels (although by then docking wouldn't be a problem either).  You can simply get close and spacewalk back to the mothership.

I'd recommend practicing by accepting kerbal rescue missions.  If you are in career mode, this gives a bit of a payout, a lot of rep, and FREE KERBALS.  If not, just start a career mode game, get into orbit and start accepting those missions (I think you can simply add plenty of science at the start to avoid any grind, hyperedit seems to be part of standard KSP now, not sure about on the consoles).

I was pretty tied to mechjeb for all my docking needs until I finally started accepting those missions, and learned to dock with ease that way.  Just expect to study a few "docking tutorials" harder than most KSP skills.  But if you learned to "move your prograde vector to the target" in landing, you should be all set for rendezvous/docking (and you only need to get as close as you need to rescue kerbals to perform an Apollo-style Duna mission with a spacewalk return).

[Tyko]

Agreed with @wumpus. If you're not good at docking, take the time to master it and consider that you're in good company - the US Gemini program spent a lot of time practicing docking before the launched Apollo. So, you'd be following history. If you want to learn from their methods, they launched the Agena target vehicle in LEO and then practiced rendezvous and docking with that

Here's a great video (there are many more too):

 

[Guest]

Do it however you want, no way is really better than any other. Oh sure, someone will come along talking about ~efficiency~ and whatever but in reality you decide how you play the game. Part of the game is exploring mission architecture, so just try something. If it doesn't work, try something different, and so on. Eventually you'll find a method you like for one or more reasons.

I've done Duna returns with a single vessel, Apollo-style, with refueling rigs, orbital depots, etc...

Edited January 6, 2017 by regex

[Aegolius13]

You definitely don't need to do Duna Apollo-style.  It's only a few hundred delta back to Kerbin if that's the end of your mission.   But as noted above,  you certainly can if you want. 

An ISRU is unlikely to be economical if your your craft not enormous - the several tons of converter and drill weight could probably be just add easily applied to extra fuel.   Though again,  it's definitely possible to do it that way if it sounds fun.   You could also add Ike as a destination if you wanted to do an extended,  ISRU supported mission. 

Edited January 6, 2017 by Aegolius13

[Snark]

Moving to Gameplay Questions.

How you do all this depends a lot on how ambitious your mission is.  Do you want to strip-mine Duna and Ike of all science, and hit all the biomes?  Or do you just want to touch down once on Duna and then fly home again?

If you want a big ambitious go-everywhere mission, then ISRU makes a lot of sense... do it on Ike, though, rather than Duna itself.  An ISRU miner/refiner/tanker, with a small lander that's basically like a Mun lander with a bit of extra dV and some parachutes.  The lander can handle anywhere on Duna or Ike.  It goes down, samples a biome, flies up to the orbiting tanker, repeat.

If you just want a simple touch-down-on-Duna-and-go-home, you don't need the ISRU, nor do you necessarily need an Apollo-style mission (though that can somewhat reduce the mass of the overall mission, depending on how you've designed it).  You can go either single-ship or Apollo-style, whichever suits your fancy.

[Aegolius13]

Forgot your last item.  Yes,  it's definitely possible to launch in one piece.  I don't really like docking,  and docked ships tend to be floppy, so I launch almost everything in one piece.   Fairings can be useful for attaching landers,  both for better aerodynamics and due to the new truss attachment nodes. 

There's not much advantage to launching in pieces,  unless you lack big enough engines or the assembled craft is extremely un-aerodynamic.  The rocket equation means it should cost the same to launch a given mass to orbit regardless of how you split it up.   And if anything,  the bigger engines tend to to be more efficient. 

Edited January 6, 2017 by Aegolius13

[Tyko]

1 hour ago, Aegolius13 said:

Forgot your last item.  Yes,  it's definitely possible to launch in one piece.  I don't really like docking,  and docked ships tend to be floppy, so I launch almost everything in one piece.   Fairings can be useful for attaching landers,  both for better aerodynamics and due to the new truss attachment nodes. 

There's not much advantage to launching in pieces,  unless you lack big enough engines or the assembled craft is extremely un-aerodynamic.  The rocket equation means it should cost the same to launch a given mass to orbit regardless of how you split it up.   And if anything,  the bigger engines tend to to be more efficient. 

Just FYI - with Auto-Strutting docking clamps are no longer wobbly. The trick is to set the auto-strutting on all your docking clamps before you actually dock. If you do it after you've docked and the craft is wobbling at all the Auto-Strut can actually lock it when it's in mid-wobble and your craft will be bent. 

[Guest]

Also, I'm looking at this question and it states "career Duna round trip" but that doesn't really mean much. Here again is the problem: everyone plays differently. For instance, where one player would try to do it as cheaply as possible using SSTOs to build the mission piecemeal I would go full-disposable single launch and not care about the funds (aside from "do I have some?") "Career" says nothing. What are your goals?

Efficiency/Expediency

Safety/OSHA Violation

Saving/Expending Funds

Fun/Frustrating

And more.

And then there's considerations like where in the tech tree you are. I usually do a Duna return about mid tech tree which means ISRU isn't an option at all. But here you suggest you have access to that sort of gear based on your questions so I can assume you're fairly high up the tree, giving you access to many more parts.

If you want a serious suggestion you should be specific about how you intend to accomplish the mission. Otherwise, just try something out, go to Duna. Asking vague questions is just going to end up with someone imposing their playstyle on you.

Edited January 6, 2017 by regex

[Squidiness]

8 hours ago, regex said:

Do it however you want, no way is really better than any other. Oh sure, someone will come along talking about ~efficiency~ and whatever but in reality you decide how you play the game. Part of the game is exploring mission architecture, so just try something. If it doesn't work, try something different, and so on. Eventually you'll find a method you like for one or more reasons.

I've done Duna returns with a single vessel, Apollo-style, with refueling rigs, orbital depots, etc...

I did it exactly how I thought it would work: I would send up two ships to be docked Apollo-Style in LKO, and simply head of to Duna

I can't begin to tell you how proud I was of this tiny station, but I grossly underestimated the amount of fuel required to get to Duna, and note how the big stage is nearly empty, so the ship turned out to be hardly Minmus-capable. Long story short, I just completely gave up on it and reloaded another quicksave. Can anyone post a screenshot of a minimal, Manned, and Duna-round-trip-capable rocket just so I can get an idea of how much fuel I need? Because ^this thing obviously didn't make the cut. I almost always overestimate the amount of fuel required to get somewhere — even if it's by a little bit — but never have I underestimated fuel the requirements of a specific mission

 

EDIT: I see what you mean, but I don't have the patience nor time to experiment for hours on end, sorry if that came off as rude

Edited January 7, 2017 by Squidiness
Just more stuff

[Guest]

1 minute ago, Squidiness said:

I did it exactly how I thought it would work: I would send up two ships to be docked Apollo-Style in LKO, and simply head of to DunaI can't begin to tell you how proud I was of this tiny station, but I grossly underestimated the amount of fuel required to get to Duna, 

If you can get it to Mun orbit, add about half again more fuel for the transfer stage, maybe. Couldn't tell you without doing some actual math and designing a ship since I rely on the numbers rather than looking at parts (and nowadays you just need a calculator because they've added all the mass readouts in the VAB).

Make sure you're making a good transfer too, that's critical.

[Squidiness]

5 minutes ago, regex said:

If you can get it to Mun orbit, add about half again more fuel for the transfer stage, maybe. Couldn't tell you without doing some actual math and designing a ship since I rely on the numbers rather than looking at parts (and nowadays you just need a calculator because they've added all the mass readouts in the VAB).

Make sure you're making a good transfer too, that's critical.

Well, I can get to Duna just fine, but what I meant to say was that it would be a one-way trip, pretty much kissing Jeb, Bill, Danuki (my go-to guys for any mission; Bob and Valentina both died in a space station catastrophe) and all of their science goodbye, for good. I'm also pretty bad with interplanetary encounters when it comes to efficiency, so I prefer to bring along a lot of spare fuel just in case, so I really don't get very concerned about efficiency, that is, if a round trip wasn't what I was planning, thanks for the advice anyway!, though

[Snark]

So, just eyeballing your ship, I'm guessing it's ~60ish tons when fully-fueled in LKO, yes? If that's approximately right, then the 24 tons of fuel in the big stage at left should give you around 1600 m/s of dV.

Going to Duna from LKO, with a good transfer window, takes about 1050 m/s.  If you use aerobraking on arrival, that puts you in Duna orbit with a few hundred m/s of dV to spare.  Do the landing-and-return thing with your lander.  Then, from low Duna orbit back to Kerbin takes a smidge over 600 m/s of dV, which your ship should easily be able to do once it dumps the spent big tank.

In short:  that ship should totally be able to go to Duna, do a landing, and then come back. 

One suggestion:  it's carrying far more monopropellant than it needs.  By a lot.  I'd suggest dropping all the monoprop tanks from the lander (the lander can carries plenty to handle docking), and all but maybe two of the monoprop tanks from the big ship.

38 minutes ago, Squidiness said:

I'm also pretty bad with interplanetary encounters when it comes to efficiency

If you need help with planning your interplanetary transfer, there are various tools out there to help with that.  My personal favorite is http://ksp.olex.biz ... simple and easy to use, nice graphical interface.

 

 

[Squidiness]

1 hour ago, Snark said:

So, just eyeballing your ship, I'm guessing it's ~60ish tons when fully-fueled in LKO, yes? If that's approximately right, then the 24 tons of fuel in the big stage at left should give you around 1600 m/s of dV.

Going to Duna from LKO, with a good transfer window, takes about 1050 m/s.  If you use aerobraking on arrival, that puts you in Duna orbit with a few hundred m/s of dV to spare.  Do the landing-and-return thing with your lander.  Then, from low Duna orbit back to Kerbin takes a smidge over 600 m/s of dV, which your ship should easily be able to do once it dumps the spent big tank.

In short:  that ship should totally be able to go to Duna, do a landing, and then come back. 

One suggestion:  it's carrying far more monopropellant than it needs.  By a lot.  I'd suggest dropping all the monoprop tanks from the lander (the lander can carries plenty to handle docking), and all but maybe two of the monoprop tanks from the big ship.

If you need help with planning your interplanetary transfer, there are various tools out there to help with that.  My personal favorite is http://ksp.olex.biz ... simple and easy to use, nice graphical interface.

 

 

FYI, The big stage with the skipper is nearly empty, so I hardly skimmed Duna's atmosphere before running out of fuel

[Snark]

 

15 minutes ago, Squidiness said:

FYI, The big stage with the skipper is nearly empty, so I hardly skimmed Duna's atmosphere before running out of fuel

Ah. Well, yes, that would be a problem, then.

The answer seems straightforward enough, though... once you've parked your mission in LKO, just send up a tanker to fill it up before you depart for Duna.

Looks like you've engineered a pretty decent Duna mission; all you need to do is to make sure it's got a full tank before departure.

If docking is a problem, then a couple of options... 1. practice docking ... or 2. put it on a bigger set of booster stages so that you can lift the pictured ship to LKO with full tanks.

[Squidiness]

6 minutes ago, Snark said:

 

Ah. Well, yes, that would be a problem, then.

The answer seems straightforward enough, though... once you've parked your mission in LKO, just send up a tanker to fill it up before you depart for Duna.

Looks like you've engineered a pretty decent Duna mission; all you need to do is to make sure it's got a full tank before departure.

I just heard about this thing called "asparagus staging", and it seems to work like a charm! I'll attempt this mission again, except I'll use staging that makes your pee smell weird, since I'm pretty sure I could have gotten away with that big stage you see to the far left being completely full in LKO if only I used asparagus stagingn

Edited January 7, 2017 by Squidiness
nacho business

[Snark]

Asparagus can be a useful technique-- best of luck! There are other options, too.

If you get to the point where you could use additional advice, a shot of your ship on the launchpad would be helpful.

[Palaceviking]

1-yes

2-rcs balancer then practice practice practice. It's an essential part of piloting and I'd recommend mastering it before doing duna, but hey this will be practice. 

3-no need. Maybe on future missions to setup logistics systems but don't overcomplicate things on your first interplanetary voyage.

4-land safe.

[Squidiness]

1 hour ago, Palaceviking said:

1-yes

2-rcs balancer then practice practice practice. It's an essential part of piloting and I'd recommend mastering it before doing duna, but hey this will be practice. 

3-no need. Maybe on future missions to setup logistics systems but don't overcomplicate things on your first interplanetary voyage.

4-land safe.

I'm sorry, what do these numbers mean?

[Palaceviking]

22 hours ago, Squidiness said:

The title says it all, but I do have a few questions about manned Duna return missions:

1.) Should I do it Apollo style, leaving one guy in orbit with a crap ton of fuel and loading the other side onto a lander?

2.) I'm not good with docking, nor can I get mods, so can I do this in one launch?

3.) Should I bring an ISRU converter along with me? If so, where should I have it (in the lander or in the orbiter)?

Thanks in advance!

How the hell do i know? They're you're numbers!!

oh ok. Maybe not 4

[Squidiness]

5 minutes ago, Palaceviking said:

How the hell do i know? They're you're numbers!!

oh ok. Maybe not 4

I forgot I even had those

[Squidiness]

On 1/7/2017 at 9:17 AM, Palaceviking said:

1-yes

2-rcs balancer then practice practice practice. It's an essential part of piloting and I'd recommend mastering it before doing duna, but hey this will be practice. 

3-no need. Maybe on future missions to setup logistics systems but don't overcomplicate things on your first interplanetary voyage.

4-land safe.

Do you think this is Duna-capable?

[Garrett Kerman]

3 hours ago, Squidiness said:

{snip}

Do you think this is Duna-capable?

Yes. You might want to disable one set of engines, or else you aren't going anywhere. A couple of sugguestions:

1. Only one set of engines is needed. This is the 'propulsion module' (fancy language for a few fuel tanks and an engine). This should be launched and docked to the rest of your ship. You may want to launch a refueling mission to fill up it's tanks.

2. Get rid of that IRSU. With a ship of that size, it is absolutley pointless and only acts as a deadweight. Also, four drills is huge overkill. If you really want the IRSU, bring the 1.25 meter one, two small drills, and two radial ore tanks. Those two you're bringing are too big for your needs. Also, make sure to bring lots of power and some radiators too if you want the IRSU and the drills to work. Really, just don't bring any of that. All it is is deadweight.

3. Pack efficent engines. Get rid of those thuds. They are inefficent and not very helpful. Replace that skipper engine with a poodle engine. The poodle is more efficent, and therefore requires you to pack less fuel.

4. Pack parachutes. Duna has an atmosphere, so you should use it. Parachutes can slow down your lander quickly, meaning you use less fuel on your decent. 

5. Rid yourself of half the monoprop. If you split four tanks between the lander and the crew module, you should be in good shape. All that extra propellant won't be used and will only become deadweight.

If anything was confusing, feel free to ask me for clarification.

[Palaceviking]

3 hours ago, Squidiness said:

Do you think this is Duna-capable?

It's edge case, I'd have to do the math,.

[AeroGav]

As others have said,  if it's a Duna only mission than ISRU isn't necessary (though setting up a fuel station is useful long term).

Also full Apollo style, with separate lander and ascent stages makes no sense, given how heavy rocket engines are in KSP (why carry 2 rocket engines down to the surface?).

If you really want, have the science stuff , legs, chutes and tanks for the landing fuel on a radial decoupler (or two) so you can leave it behind.

You could save a little bit of delta v by separating the tank with the duna -> kerbin return fuel in low duna orbit before descending to the surface.  It means you're not carrying that kerbin transfer fuel down there and lifting it back to orbit again, however the Kerbin return burn isn't all that big, so it's a lot of effort for not much reward.

The only remaining question is whether to go nuclear or chemical.    A small lander, with mk1 parts, would have adequate TWR with a single LV-N engine.   @GoSlash27 has a spreadsheet i think which can calculate whether you get a lower total fuel + engine mass with a 0.5t Terrier burning LFO at 345ISP or with a 3ton nuke burning LF only, 800 ISP.     The more delta V you need for 

1. completion of insertion into LKO (upper stage burn)
2. interplanetary transfer
3. landing and ascent

 

... the more the maths ends up favouring the nuke.      

If your vessel was both large and nuclear powered, you could perhaps make a case for having a low twr nuclear powered transfer stage and a chemically fuelled (spark?) lander, but i think that's more for visits to places far off with high grav like Tylo.

Just keep it simple really, i'm pretty sure you could make a success with size 1 parts and nothing more than a Terrier and a Reliant or two.