Multiple ship interplanetary transfers vs single ship interstellar transfer

[Seeker89]

I'm have been doing a lot of thinking when as I plan my trip to Duna. This will be my first without cheating... lol.

I want to know if it would be better to send more than one ship to Duna just after each other or launch all the parts into space, dock them and then send it to Duna in a massive ship.

Edit: corrected title... sorry

Edited June 14, 2015 by Seeker89

[Snark]

It totally depends on what you want to do at Duna. For example, do you just want to do "go there, land, grab science, return"? Or do you want to do a more ambitious get-it-all-in-one-go, where you totally strip-mine the Duna system of all available science? (e.g. do multiple landings, hit all the biomes, go to Ike too and hit all of its biomes, and come back with the whole enchilada)

For a simple single-landing scenario, you don't really need to have multiple ships, or even a particularly big ship; it takes more dV to go to Duna and back than it does to the Mun, but not insanely more dV. It requires trickier navigation and attention to launch windows, but the design of the ship isn't hugely harder, and doesn't require higher tech than a Mun mission.

If you want to go the get-it-all approach, then you'll need a bigger mission (either because you need to send lots of fuel, or else you need to send lots of heavy ISRU mining equipment). You could do that with multiple ships, or one big ship. Personally, I prefer the one-big-ship approach (either launched in one piece, or multiple ships docked together) because it involves less fiddling around for me to do-- I only have to navigate once, and don't have to waste any fuel on arrival in getting the various ships together.

The fun part of Duna is that it's a fairly easy target as interplanetary missions go, which gives you a lot of latitude in designing your mission. There are lots of different ways to do it, so you can go for the mission that suits your play style. For harder targets that "push the envelope" a lot more (like landing on Moho or Eve-- both difficult, but for different reasons), the options are somewhat more constrained.

Edited June 12, 2015 by Snark

[waterlubber]

DeltaV wise, it would be more efficient for multiple trips because you wouldn't need docking ports, etc. Then again, you would need batteries and utilities on every ship, and life support if you did that. However, time wise, one big ship is easer. Due what Apollo did: DEO. Launch a single ship consisting of a lander and a transfer stage. Launch to Duna. Land the lander. Return. Dock. Return again. Win.

[xtoro]

I'm a multiple ship guy now. I currently have a probe going to eve, and 2 Landers and a probe going to duna/ike. I'm about to send a science rover to duna so they can drive around.

[Orbital Vagabond]

I also prefer multiple ships. Multiple vessels means lighter individual payloads, which makes it easier to engineer vessels to have good TWR, in turn allowing more precise transfer burns.

[A35K]

The way I did my first Duna trip, was by sending a huge 3.75m tank powered by 8 nukes as the interplanetary stage, with a lander and rover for Duna and another pair for Ike on top. The Duna lander used a 3 man pod, while the Ike lander had a 1 man pod. After the mission, the landers got back to the mothership in low Duna orbit and returned home. So I recommend sending it to Duna as one ship, do any docking in LKO.

[Geschosskopf]

I'm have been doing a lot of thinking when as I plan my trip to Duna. This will be my first without cheating... lol.

I want to know if it would be better to send more than one ship to Duna just after each other or launch all the parts into space, dock them and then send it to Duna in a massive ship.

If all you want to do on the trip is plant a flag, then a single ship is the way to go. Getting to and from Duna is just a pinch more dV than going to and from Minmus, so the only difference being you need a bigger lander due to more gravity at Duna. IOW, doing a flag-plant on Duna is hardly any different from putting one on Minmus so you don't need anything really huge (unless you worry about life support, crew elbow room during the trip, etc.) For anything more involved, however, IMHO it's always better to send a flotilla of small-medium ships than 1 huge monster.

I wrote a tutorial on doing flotillas if you need some pointers. See the link in my sig.

[ajburges]

It's a tradeoff.

Flotillas allow for less complicated ships. Each one will be smaller, easier to controll, and less susceptible to wobbles. If they can dock, you also have more abort modes if you run low on fuel for crew and sample return.

On the downside you need to duplicate more parts and efficiency tends to be higher as you go bigger due to the mass tradeoff of nukes calling on 10t+ payloads for real dV/mass gain. You also need to manage multiple launches per window which can be an issue.

If your craft run missions that require separate orbits, you should definitely have them arrive separately for dV savings. Separating at course correction may not give you the needed difference in arrival time for efficient capture burns, so separate launches may make sense.

Also if you plan too leave a station/base behind, don't complicate its design by integrating it with the return craft.

Edit: ninja'd by Geschosskopf I second the advice to read his flotilla tutorial. It's the perfect read for your question.

Edited June 12, 2015 by ajburges

[Seeker89]

It would pretty much be an all in one, Mining base, lander, some scan sats and a way to get some home. I play with EPL and MKS so that would be a apart of it too. Of course with EPL I could just build most stuff there. I'm also not the best at docking either. Duna is just the next one coming up, what about other worlds?

[Red Iron Crown]

I prefer to send a single ship. Less clutter in map view, only one set of burns to get right, never end up with two ships aerobraking at the same time, and I enjoy docking so orbital assembly isn't really a chore for me.

[Peder]

Actual I have my self created a big ship in orbit og kerbin that is about to embark to duna and it have everything such as /crew quaters/capsul/lander/rover/research facility and the weight is abou 400-500tons i think.

However it turned out to be a bad idea to couple 3 crafts together since the docking ports I have avaliable in my career game, is not strong enough and when i apply power then all 3 ships twist and bend in various directions making it impossible to control.

It does also not help the 3 crafts have different weight so I had to adjust and fine tune every engine so they more or less are balanced to be stable. ( the 3 ships are docked sideways next to each other )

To make a long story short I have given up trying to get the 3 ships to duna when they are docked together due to stability issues so they have to go by them self and then dock when they reach duna instead.

However I have been thinking about using "kas kerbal attachment system and have an engineer place some strut connectors to bind the crafts together, then my big ships should become much more stable so I avoid using fuel/rcs to dock when I arrive at duna. ;-)

Well you can create one big ship and go to duna, but you need to have a good design..

It might just be more "easy" if every ship go to duna by it self and then dock with the others in orbit... BUT be aware that all ships arrive at duna in the same orbit angle so you avoid using fuel to adjust your orbit as little as possible.

[xtoro]

Actual I have my self created a big ship in orbit og kerbin that is about to embark to duna and it have everything such as /crew quaters/capsul/lander/rover/research facility and the weight is abou 400-500tons i think.

However it turned out to be a bad idea to couple 3 crafts together since the docking ports I have avaliable in my career game, is not strong enough and when i apply power then all 3 ships twist and bend in various directions making it impossible to control.

It does also not help the 3 crafts have different weight so I had to adjust and fine tune every engine so they more or less are balanced to be stable. ( the 3 ships are docked sideways next to each other )

To make a long story short I have given up trying to get the 3 ships to duna when they are docked together due to stability issues so they have to go by them self and then dock when they reach duna instead.

However I have been thinking about using "kas kerbal attachment system and have an engineer place some strut connectors to bind the crafts together, then my big ships should become much more stable so I avoid using fuel/rcs to dock when I arrive at duna. ;-)

Well you can create one big ship and go to duna, but you need to have a good design..

It might just be more "easy" if every ship go to duna by it self and then dock with the others in orbit... BUT be aware that all ships arrive at duna in the same orbit angle so you avoid using fuel to adjust your orbit as little as possible.

Use KJR together with Quantum Struts and you'll be golden. QS reattach when you dock up, comes in handy.

[magnemoe]

For me this is an matter of design and part count, you also have to survive the aerobraking, this adds design challenges.

Gilly base in orbit releasing scanprobe.

Scanner moved to the small probe after doing Gilly scan and contract, then scan probe is used as as science module on tug, tug has an hitchhiker module who was needed for getting Eve science data.

It will also be used for servicing eve landers, taking them to gilly orbit for refueling, taking them bak to low eve orbit, crew transfer and so on.

Jool mission, same template, launched earlier, lander is to small for Vall so I sent an docking tank in followup mission.

Followup mission 2 will be multi ship, also as stuff like the Layte spaceplane and Tylo lander can go on own engines. Laythe base will look like the Gilly base but with fuel cells and rcs rather than solar panels.

Purpose is science and servicing the laythe spaceplane.

[Superfluous J]

10 ships each with their own engines have the same TWR/Isp/dV/etc as 1 ship that is 10 times the size, with 10 engines.

The former is easier to construct and each piece may be easier to fly, but the latter - once you've got it down - is quicker and easier to maintain during the mission. Also, you likely don't need that 1 ship to be 10 times the size, nor does it likely need all 10 engines.

[pandaman]

I did an 8 ship anomaly exploration of Duna as my first interplanetary manned venture. 6 2-man crewed landing missions (one crew for each anomaly and 3 spare crews) and 2 service vessels (1 and a spare) to return all crews home.

Turns out it was a good plan. I lost 2 crews to the kraken on arriving at Duna soi, and stuffed up my orbit insertion with one service vessel and burnt most it's fuel. The remaining crews got home safely, but one had an 'entertaining' return to orbit resulting in one kerbal having to return to the surface to await rescue from the surviving spare lander and the other getting stranded in orbit on EVA and out of fuel that had to be rescued by the nearly out of fuel service vessel to be transferred to the full one for the journey home.

Multi vessel missions can be fiddly to operate, but it can give you a vital safety margin.

[HvP]

Both approaches certainly have their advantages, but if you're going to send multiple launches within the same window then I would highly recommend the Kerbal Alarm Clock mod. It will give you a heads up when any planned maneuver is upcoming and can even stop time acceleration when any ship is approaching a burn or SOI change whether they are focused or not. It greatly relieves the stress of checking in on which ship needs attention next.

Personally, I prefer to run with at most a mothership for orbit that launches a probe or lander and maybe a fuel supply ship following up.

[Seeker89]

So most people would dock the ships in space and launch it as one?

[WOODY01]

I started off doing missions with one larger design and for several reasons I now do multiple ships.

- Forgetting a part or a design flaw I failed to catch during testing

- Found it better to put ships in different inclinations for different task or going to a planets moons. Scanning planet, targeted landing, refueling, dropping probes, going to a planet's moon.

- multiple chances to make the encounter, so if you encounter a bug or make an error the mission can continue

- Can refuel from other ships if you miscalculate dv needed for one of the craft or decide to expand the mission and go more places than planned.

My missions usually include a scanning/communication probes for planet and it's muns, drop probes(maybe carried on scanning probes), either a refueling station or drill with refinery, manned lander, unmanned rover, manned rover, orbital station, maybe a surface base.