Best Interplanetary ship

[Nabiscovinco]

So, I've decided it is time to explore something other than the Mun, and have plans to make a ship to Duna. But I have some questions.

(FYI: I have decided on 8 nuclear engines -have no idea if that is overkill- and plan on bringing at minimum one manned lander, one sat, and one probe to land on the surface. Also, I plan on doing a test run to the Mun to see if stuff breaks)

Would the best engine arrangement be having all eight at the back, all eight at the front, or four in the front and four in the back?

Oh, and if you all decide to include tips for a Duna land/takeoff lander that would be awesome

Edited July 30, 2013 by Nabiscovinco

[Swifty]

If your hauling out a very large payload it's best to have a puller design with all engines at the front, it reduces wobble massively.

As for the number of engines - more engines = faster burn but more weight so more fuel needed. I send my 200tn+ inter planetary beast out with only 4 nuclear engines. Duna transfer requires a 10 min burn, which is best done in a number of passes to ensure accuracy of ejection angle (makes a huge difference getting that right).

As for landing on duna, it's like a easy Kerbin. Aerobraking starts at about 13km so aiming for a periaps of about 11km should put you into a nice orbit.

Parachutes can be used for landing but pack more than you would take for landing on Kerbin due to the thinner atmosphere.

[strongest_2hu]

Remember that the game doesn't understand gimbals when it comes to engines in the "tractor" (pulling) configuration, it tries to gimbal them the way they should go if they're pushing, so it winds up going the wrong direction. You will need to disable engine gimbals in a tractor configuration (if the engines have them).

[Immashift]

Puller designs are the most stable, and imo easier to launch. Here's my grand tour ship - it does use Kethane, but you can get to and return from any one planet without it. Lander is meant for Tylo, and so can tackle anything but Eve (LKO in a single stage, though it spends all its fuel to do so).

This whole rig put together has something like 10k DV.

The guy above me is correct. Have to disable all engine gimbaling if you do a puller design. This thing ends up drifting a lot if you don't, which matters when doing 22 minute burns....

My advice if you do a puller, or a pusher actually, is transfer as much fuel as you can into the aft of the craft. It makes it more stable and less prone to wobbling around.

For the record, you don't need to make super massive ships to do this sort of stuff. They're just fun to make and play with.

I used a single half-tank and poodle power for Duna - with perfect phase angles and a lot of tiny adjustments before leaving Kerbin SOI, as well as aggressive aerobraking, you can do it without much fuel at all:

Also, 8 nuke engines is a tiny bit overkill. I used 3 with an orange tank for Eve to push a lander there and back, I think.

Edited July 30, 2013 by Immashift

[Vanamonde]

You can find some IP ship configurations in this thread: http://forum.kerbalspaceprogram.com/showthread.php/37952-Round-trip-ships

[Rosco P. Coltrane]

I don't know exactly why, but more engines = less dV. An orange thank with 2 atomic engines (plus probe core and stuff) = 11k dV. 3 engines = 10k, 8 engines = 6,5k.

So, as you can see, more engines mean less burn time, but also less dV. I guess because of the weight. The same thing happens with fuel. More fueld, less dV per "gallon" (or whatever unit Kerbals use).

My advice is that you install some mod that gives you those numbers (Mechjeb, Kerbal Engineer Redux) and try for your self.

[Nabiscovinco]

Hmm.. Ok. So I'm thinking of reducing the number to six engines. I would need to work on bringing the fuel tanks/engines up, but that can be worked on.

As for the lander, would it just be a Mun lander, but with more fuel/parachutes so it can go through atmosphere? I only ask because my landers are awful.

[allmhuran]

The number of engines you'll need depends on how big your payloads are. If you want to transport an entire base in one trip and don't want to sit around performing a burn that's an hour long, you'll need to scale up your propulsion system, both fuel and engines.

As far as geometry goes, I like to put the engines right in the middle for very large ships, and in a 4x symmetry or higher orientation. As mentioned by previous posters, this means half the mass is being pulled which helps alleviate stress. But it also allows you to configure the engines into action groups to assist with turning: relying on RCS or, absurdly, pure module torque to move huge ships around requires truly insane levels of patience.

Example:

[Geschosskopf]

In 0.21, docking ports are much less wobbly than before so engine placement isn't as critical.

While it's rather cool to build some massive ship in orbit so you can take an entire expedition at once, expect to spend LOTS of time reverting and restarting from quicksaves. Unlike a 1-shot rocket, you never know how a multi-part ship will work until you've got it all put together after however many launches of parts and then tankers to top up the tanks. Will it wobble too much? Will it hold together? Is it so imbalanced that it won't fly straight? Does it have enough delta-V? Will the burn times be measured in months or years? It'll probably take several attempts to answer each of these questions, and each attempt will likely involve multiple launches of parts and tankers, with redesigns between.

The alternative is to launch a flotilla of smaller ships, maybe with the intent to connect them at the destination, maybe keep them separate. Smaller ships require less tweaking so fewer mulligans and the mulligans are less complex. The downside, however, is to have no more ships than you can handle at once, mostly meaning they arrive at different enough times that you can deal with them individually. This tends to work out pretty well by itself; a few hours difference in departure time at Kerbin gets amplified to days or weeks the further away you go.

[allmhuran]

The downside, however, is to have no more ships than you can handle at once

True. But the real downside, as you said, is that it's not nearly as awesome.

[Nabiscovinco]

Ok, I believe I have a ship design in mind, but about the manned lander. (as stated before) is it just a beefed up Mun lander? That's all I WAS thinking of doing, but I can always just check Youtube.

[njd80]

If you can manage to land using only parachutes - you can actually carry a little less d/v than a Mun lander. This was mine from 0.20.

When fully loaded with fuel, it could depart from an orbital station at 100km, land using parachutes, then take off and return to the same station using appox. 1500 d/v.

[Geschosskopf]

If you can manage to land using only parachutes - you can actually carry a little less d/v than a Mun lander.

Be sure to have enough parachutes, though. Use this handy-dandy calculator to figure out how many you need:

http://ksp.freeiz.com/

Also, if you plan on using the lander more than once (like to land at different easter eggs), be sure to provide ladders so the Kerbals can climb up to each parachute. Once close enough to the parachute, you can right-click it and get the option to repack it. Need to do that before you take off again .

[njd80]

Need to do that before you take off again .

They definitely need re-packed before the lander is re-used, but it isn't necessary before you take off again.

Using this lander, I would always repack them while on EVA after I had taken off and docked with the station.

EDIT: I can see the safety benefits of repacking them before takeoff - an ascent failure could result in an emergency landing.

Edited July 30, 2013 by njd80

[WillThe84th]

On 7/30/2013 at 10:19 AM, njd80 said:

EDIT: I can see the safety benefits of repacking them before takeoff - an ascent failure could result in an emergency landing.

The kerbals might be screwed either way though.

[max_creative]

NUKES!!! AND MK3 PARTS!!! AND VERNORS!!! AND SEVERAL TONS OF STRUTS ON THE LAUNCHER!!! 

I mean it when I say several tons of struts on the launcher. 

I mostly use one stage LV-N ships, and drag a lander behind it. I have a lot of them in my mission report. 

When I have really big things (For example Jool 5 or the ultimate challenge) I use big tugs with docking ports on the front and back, so that they can be stacked on top of each other and maybe put payloads in between. The tugs are usually flat, with a bunch of arms sticking out. On the end are one or two LV-Ns. Or I maybe might make it look like a squid.

I've seen a lot of good interplanetary ships. Usually the ones that work well don't look so nice, and the ones that look nice aren't as practical. I'm kinda am in between. Mk3 parts already look nice and are definitely practical holding all the liquid fuel! Using Mk3 adapters, C7 2.5 to 1.25 adapters, and nose cones it awesome! It looks nice, and it stores liquid fuel and oxidizer! Very useful for storing fuel for your Vernors! 

Also, Look at some SciFi spaceships. It actually works sometimes. I have a Duna X-Wing! Ok, it doesn't fly in an atmosphere, but it does get there about 50% of the time!

I hope this is helpful and not just a waste of ten minutes typing.

[Rocket In My Pocket]

Be forewarned.

This thread is originally from 2013 and may contain some seriously out dated info.

[Vanamonde]

In fact, it seems to contain little that isn't outdated. Time to put it out to pasture.