Round-trip ships.

[Vanamonde]

After building numerous individual rocket designs to deliver various payloads to various destinations, it occurred to me that an advanced space program would not re-invent the wheel for every new mission, and wouldn't be so wasteful as to throw the whole rocket away after each flight. Ever since, my primary goal while playing KSP has been to develop fully re-useable interplanetary ships to which various payloads can be docked for transportation. It's been a huge project because each time I have to design the ship in the VAB, break it down into components small enough to be launched, assemble them in orbit, and only then can I try to fly the thing to another planet to see if it works. Most of the time it doesn't, and I have to start over all the way from the beginning. However, after 6 months, I am closing in on my goal of having a fleet of designs that can access all the worlds in the game, and then come home to be refueled and sent out again. Here, for anyone who might be interested, is a brief history of my project.

My first ship was a test and proof of concept.

I cringe looking back on it. It had WAY too many parts because I threw in everything I thought a ship might need, and the proportion of fuel to payload was laughably small. It flew a successful test mission to deliver some probes to Minmus and back, and was then retired.

My second design actually reached Duna while carrying a considerable payload,

but didn't have anywhere near enough fuel for a return trip. Besides, it also had too many non-essential parts, and swayed around like it was dancing the hula when under thrust. The crew had to be rescued by a later mission.

My third ship delivered a cargo to Eve, and was my first ship to return to Kerbin (from another planet) after performing its mission.

But the flight revealed numerous flaws in the design, so I relucantly scapped the ship despite its successful first trip.

My fourth ship delivered 8 probes and a lander to the Jool system,

but once more didn't have enough fuel for a return. That crew is currently awaiting rescue on Bop.

And then, success!

My fifth ship made it to Duna and back, then Eve, then Dres, and then Duna twice more, and is still in use. It is my first truly successful, entirely re-useable interplanetary ship. I plan to build more of them, in improved versions, for use at those three worlds. However, it does not have the range to reach farther planets, so I continued with my project.

My sixth design was especially frustrating. After spending many hours making the thing in the VAB and assembling it in orbit,

the workaround I thought had found to have more than one secure docking link to the same parts didn't work, and the fuel tanks flopped around and couldn't get fuel to the engines anyway. That one was a total write-off.

My seventh design actually made it to Vall and back while delivering cargo,

but I was disappointed to learn, it was too big for the job. It came back with excess fuel, meaning it could be smaller and still make the trip to the Jool system. But the real problem was, the part count just about put my PC into a coma, and flying it to Vall was a terrible chore because the lag was so bad that the game was running at 1/4th real time. Sadly, even though this ship worked in the sense that it performed the mission, I had to retire the design.

But now, I'm pleased to be able to report that my 8th ship

has delivered cargo to Tylo and returned,

and Eeloo and back.

(Okay, that last one was actually my 9th ship after my 8th ship suffered a mishap. Pilot error. Don't ask.)

However, it came back with an alarmingly small fuel reserve, so I don't believe it can reach Moho, at least on a round-trip.

So right now, Moho is the only world that I still can't reach with a fully re-useable ship, and that will be the next and final phase of this project I've given myself.

So I'm sure I'm not the only one building round-trip vessels, but I don't recall seeing any posted on the forum. Who else is doing this, and what do your ships look like? (No offense, but I'm only interested in stock designs so that I can compare/contrast with my own.)

Edited July 1, 2013 by Vanamonde

[Mach56]

What did you do to the 8th ship:cool:?

[SDIR]

I'm interested. Are there any .craft download links?

[Yuming]

Do you aerobrake those monsters when going to jool, or just burn retrograde? I see it can make it to Eeloo, so i guess fuel is not a problem for those missions.

[Vanamonde]

What did you do to the 8th ship?

I thought of a way to make it better and decided to discard and replace the engine segment. Which was really dumb, because I forgot that you should always launch the most awkward ship segment first and then dock the easier-to-fly segments to it while it sits still. So when I launched the replacement engine segment, it had teething problems because this is still a new design I'm perfecting, it flipped around wildly, and by the time I got it flying straight again and went to map view, I found it was on a 45 degree inclined orbit. In short, I realized it would be easier to build a whole new ship starting with the improved engine section than to try to rendezvous and dock a new engine section to the existing ship. So much for making the 8th ship better.

Are there any .craft download links?

I do plan to share the designs eventually, but I don't like to post anything until I'm sure it will be smooth for other players to use, and right now I'm just trying to get the things to work, and not even trying to make them easy to fly. The bridge section of that last ship, for example, is a real kludge. It takes off on Mainsails to get its bulk off the ground, but they waste a lot of fuel so on the way up I pump the fuel into the ship segment itself and ejected the big engines, then it flies most of the way to the other parts of the ship for assembly, then it ejects the engine on the rear to free up the docking ring and flies backward to the dock with a tiny engine just temporarily stuck on the nose. The really successful ship that's made several trips, the fifth one, also needs to be reworked to use the new, big docking rings, which will reduce its part count significantly.

I've aerobraked wherever I can, at Eve, Duna, and Kerbin, and Jool's atmosphere was a big help in reaching Vall and Tylo. It's a big fuel savings, which is the main reason I don't think either of these ships could make a Moho trip, even stripped down without cargo.

Edited June 27, 2013 by Vanamonde

[Xaiier]

I've been doing a similar line, but I'm only on the third one. I really like these. Do you have data on D/V and TWR? I would like to know what it took to get to Eeloo.

[Vanamonde]

Do you have data on D/V and TWR? I would like to know what it took to get to Eeloo.

I can only give you rough figures because, of course, the mass changes as the bits of payload are deployed, and some of the original fuel total goes with them, and different payloads vary in mass. The Eeloo ship has a thrust of 720kn (12 LV-Ns) and masses 369.33 tons when fully fueled without cargo, and massed 401.45 tons with the Eeloo cargo of small station,

2 mini-rovers,

with their deploying landers,

and 2 satellites.

When fully loaded, these ships accelerate at about 1/3rdG, and here you can see the total fuel capacity of the ship itself (not counting cargo's tanks) vs. what was left after the Eeloo trip.

I hope this is helpful.

[narhiril]

I decided to take a crack at a similar project.

Here's the Halcyon Planetary Explorer above Duna. It carries a crew of 11 comfortably and has an Altus MkIII lander docked on the front port in this picture. It went from Kerbin to Duna, moved into an orbit around Ike, and rendezvoused with an unmanned ship in Ike's orbit. The unmanned ship was carrying another lander, which was used to land on Ike and return to orbit. The Halcyon then transferred to a low orbit around Duna, where the Altus lander successfully landed and returned. The crew was transferred back to the Halcyon and the lander was left parked in orbit.

Here are a couple more shots from that mission.

Assembly:

Transfer to Duna:

Rendezvous with Ike lander:

Ike landing:

The Halcyon in orbit over Duna, seen from the Altus MkIII lander:

Duna Landing:

Waiting for transfer window back to Kerbin. Ike can be seen on the left, with the silhouette of Duna on the right:

[Vanamonde]

So really? Only a couple of us are doing this? I thought there would be more.

By the way, as much as I dislike cheats and try to avoid mods, flying 4 to 7 fuel tankers to refuel my ship between every flight is getting really tiresome. How could I just wave a magic wand and make its tanks full?

[katateochi]

Very nice to see the evolution of your IP transporters. Those are some MEGA craft!! What is the weight of the payloads that your most recent one can carry? Could you make it to Moho if you carried less cargo but took some extra fuel instead?

I've not built anything this versatile, I tend to build different transport craft that are bespoke for the cargo (and of course mine all use mod parts).

If you're wanting a magic wand to wave and fill the tanks there are several ways.

- Edit your persistence file, find the craft in it and then find all its tanks and edit fuel levels manually like that. Thou that can be tedious and time consuming.

- Use hyper edit. Yes hyper-editing fuel is cheating, but as you have a tanker craft that can carry fuel to it and you obviously have the skill to fly said tanker to the ship to refuel it, then hyper-editing it is just a way to skip round some major boring and time consuming maintenance processes. You could also time warp for about as long as that process would normally take if you care about keeping it "real".

- A halfway hack would be to fly the tanker into orbit. Edit your persistence file and copy the tanker craft into another txt file. Then rendezvous, transfer fuel and then deorbit or end the flight of the tanker. Then go back to edit your persistence file and paste the tanker in again. This just cuts out having to launch it each time but you still have to do the rendezvous and transfer operation. (it should in theory work fine, just take a backup of your persistence file before incase it screws things up). You could also, when pasting the tanker back in, take the position info from the target ship and set the tanker to that (just with a slight change so they don't appear inside each other).

[Vanamonde]

What is the weight of the payloads that your most recent one can carry? Could you make it to Moho if you carried less cargo but took some extra fuel instead?

The Tylo mission carried 72 tons of payload and came home with just a trickle of fuel left, but the fuel efficiency was reduced by the fact that I launched a bit late for the outgoing window and had a devil of a time trying to plot a return directly from Tylo orbit to Kerbin, and finally had to use the really sloppy but conceptually easier method of launching from Jool orbit, matching orbits with Kerbin, and waiting about 1.3 kerbin years for an intercept. So I'm sure that ship could get to Moho with a reduced cargo, but it might have to be a REALLY reduced cargo because of the difficulty introduced by Moho's inclination.

Thanks for the refuelling options, of which hyperedit sounds like the tidiest.

[Rocket Farmer]

It's interesting to see all the different methods used. I run stock with no mods.

I only started in 0.20 so I haven't been accomplished enough to build a monster like yours and I haven't tried a rendezvous in space either.

I have built a solid 100 tonne lifter. It has got me up to manned landings on eeloo with a decent rover and a return for the kerbal to kerbin (in a much smaller vessel than yours as the ride home is a kerbal, a can, some fuel and a nuke). I am using my 2nd mun lander design (can you say it was overbuilt for a mun landing).

Also I was surprised to see you use only 12 nukes for a 400 tonne craft. I am running 8 on my 100 tonne and would consider less tough.

I can land and return that unit from anywhere other than Moho, tylo and eve (I can land on them but not return).

Currently I am expanding my lifter to 200 tonne to ensure a Moho and tylo return (it is much harder than 2x to design).

After that I'm thinking a jool 5 moon mission with separate landing craft/rovers/satellites for each

[Vanamonde]

I was surprised to see you use only 12 nukes for a 400 tonne craft.

Interplanetary travel is all about the fuel efficiency, and while long, low-acceleration burns are less precise, they are fuel efficient. Could we see some pics of your ship?

[Rocket Farmer]

Sure. I'll figure out how to post some in the next day or two.

It's a pretty simple design. I figure it out in excel first before building so I know my delta v's and twr at each stage and can very quickly try variations before building.

Stage 1 is an ugly 5x5 pancake of skipper rockets each with 45 tonnes of fuel. Each has a further lift (above its fuel) of about 4 tonnes. They burn in a single stage and get me into orbit (I have to circularize with my nuke transfer stage). It pushes 115 tonnes close to orbit. The skippers meant it was much easier to build than using mainsails (much less chance of failure).

Stage 2 (transfer) is 8 Nukes with 4.5 tonne tanks around a 36 tonne tank. It is pushing 43 tonnes of payload.

Between this and my lander I have a 2 tonne rover. It sits under the lander and is dropped cost hanger style after landing.

Stage 3 (lander) has the large tank body with a lander can on top with 2 nukes mounted in close and 2 lower ones mounted out wide. It also has the landing gear spread wide so the rover can drive out.

Stage 4 (return) drops the landing gear, bottom tank and bottom wide nukes leaving only 2 nukes, one 9 tonne tank, 2 4.5 tonne tanks and the lander can.

It's DV is around 17,000 all in getting me too and from Duna, Dres, any jool moon but tylo, and eeloo.

Lastly excel tells me that including another kerbal habitat reduces my DV by 1,200 in this design.

[unwisemonk]

You aren't the only ones working on this. I'm on vacation right now so I can't show you, but I'm assembling a large ship. It will be used first for sending mapping satellites to the 3 large Joolian moons. Also I'm bringing an SSTO for Laythe and a rover for Vall. Using the remote tech mod I attached many com sats to leave in orbit of Laythe and Vall. I know I'm using mods but only utilities. (Remote tech, and the mapping sat mod)

Edited July 4, 2013 by unwisemonk

[Oddbin]

I am at my second try at a round trip cargo ship. V1.x was lost when I swapped to steam. Decided to start fresh. Will see if I can find a picture but basically 8 nuclear engines in two's held on pontoons made from the smaller but longer fuels tanks that are attached to an orange tank with a connector or the rear. I am using the puller method.

With luck this link should like to my gdrive where there's a picture. If not I will upload later to a hoster and repost.

https://docs.google.com/file/d/0B8PgAZ0oJ7MoWEFUZEN0cWtjN00/edit?usp=docslist_api

Edited July 4, 2013 by Oddbin

[Pershonkey]

Those ships look very nice! I've been mainly doing 1 launch ships with lots of armor (The latest of which only have about 8k dV), designed for military/logistical use, although I'm currently designing modules for an interplanetary ship constructed in orbit. I might have to revisit my designs, because I find myself packing more of the non essentials than I need onto every module. Two questions: How (If at all) did you manage the ASAS? What I've been doing to avoid multiple on my ship is putting one in the bridge module (Often the second sent up after the engines) and putting ASAS on spare docking ports so they can be jettisoned after joining. Second question: What is your opinion on SAS? None at all, spread it out through the parts, or just have one mega stabilizer module?

[Vanamonde]

Oddbin, I don't have permission to see your pic. Could you upload it to a free service like Imgur.com, and then use their BBCode link in your post?

Pershonkey, each segment that I launch must (of course) be a functioning ship with all the necessary parts, but I eject all the additional SAS-tyoe parts with the delivery stages and only have one ASAS module on the assembled ship. That's really all a large interplanetary ship needs anyway. The sheer mass of the thing helps it resist rotations, engine gimballing holds it on course during acceleration, and there are no forces to induce rotations while you're in free fall. In fact, I leave SAS mode off at all times to avoid shivering, and only turn it on to hold attitude during burns. The position of the ASAS part within the ship doesn't matter, so I put it as far as I can toward the front of the ship so that less force is put upon it during accelerations, because they can be kind of fragile. (It is, after all, a guidance computer rather than a load-bearing part.)

　

　

Oh, as you can see in the pics of my earlier ships, I was trying a different concept then. Each segment of the ship remained capable of independent maneuvering on RCS, with the idea that I could rearrange the ship's cofiguration during a mission. However, 1) I never found any need to do that, and 2) the duplicate components quickly drove the part count to unmanageable levels as my ships got larger. So I stopped building them that way.

Edited July 5, 2013 by Vanamonde

[Streiger]

There are some adventureous designs here.

I always have problems using multiple shipparts docked together. Accelerating sometimes breaks the docking ports or the ASAS rippes the whole structure apart.

I'm quite new to this forum but i have one quite large craft myself which would actually be able to travel to other planets but not land on them.

It could transport some stuff there like small landeres or sattelites.

I always try to design more really spaceship like stuff which can move about and go through the solar system.

This is one design:

I already posted that here in the forum.

It weighs about 200 tons and is powered by 12 atomic engines, but you could strip away the armor and save alot of weight but it looks like a mess inside of it.

But one thing just came to my mind. I had ASAS installed on all parts of the multipartship. Does that work against each other ASAS from the other parts or why is it so unstable when activated?

[Oddbin]

That was one of two variants. The boom tail on this one had a bunch of solar panels as it had a payload of 8 small satellites and 4 small landers. Wanted to make sure nothing ran out of power. Another had a tail that had bunch of docking ports along it that I used for Larger Satellites and then put 3 large landers on the end.

I made a variant of the ship with half the engines and only 2 sponsons, and no docking ports on the front, that I used to haul stuff to Mun/Munimus including a tug that I used to assemble a small base. It also carried a Munnar Surface to Orbit craft.

[Vanamonde]

Streiger, multiple ASAS units do not fight each other, but they do not help each other, either. The reason your ship is unstable with ASAS turned on is that we are able to build much larger ships as new versions of the game give us bigger parts, but the ASAS parts themselves have not been updated to properly control the larger ships that are now possible. But that is going to be fixed in the very next update, as the SAS system is getting entirely rebuilt.

Oddbin, what did your ship look like with cargo embarked, and how much is it able to haul?

[Torque]

[Vanamonde]

Where did that go, Torque?

[Torque]

This is my first attempt at sending heavy payloads on interplanetary round trips. Its currently on its way to Eve, however I left it on its own for now while I design a lander for eeloo.

[Oddbin]

I never maxed it out before I wiped the game. I will find out this weekend on the current version though.

Cargo wise it was a cluster on the opposite end from the drive section. The idea was I could swap out the tail/boom section and attach a train of fuel tanks or parts of a station if needed.