Interplanetary Cruiseliner

[ximrm]

I started to build an interplanetary spaceship.The first part is aestheically pleasing and was easy to get into orbit.

Its basically a cockpit,with crew compartments and docking hub in the middle and a detachable fuel&engine part.

My plan was to add the rest by docking it at the hub,just like my KSS(should have named it KISS). It's a nice solid body.

However,my concern is that after seeing my other ship,the moho-1(the number should be at least 15) losing a few struts and bending like a boiled noodle, I have no idea how to add the rest via the hub and not ending up in a dozen parts floating around after accelerating.

Now, is there any wayto add stabilizing parts ,after it was launched into space?

Or how do I build such a long range cruiser?(Kind of a Queen Mary in space,not the exact design)

Optional question: which kind ofengine is the most efficient?(Ion engines seem too slow to me,despite of their hunger for electricity)

I want some speed but not carry around kilotons of fuel if possible. Currently it has three large nuclear engines(not the one that need a generator) which I haven't used yet.(I thought it was harder to get it into orbit,but my boosters and substages did very well.)

Edited May 23, 2014 by ximrm

[KerbMav]

Now, is there any wayto add stabilizing parts ,after it was launched into space?

Or how do I build such a long range cruiser?(Kind of a Queen Mary in space,not the exact design)

Use the attachable struts from KAS or turn on/off Quantum Struts (either magical force beams or solid metal ones).

Optional question: which kind ofengine is the most efficient?(Ion engines seem too slow to me,despite of their hunger for electricity)

I want some speed but not carry around kilotons of fuel if possible. Currently it has three large nuclear engines(not the one that need a generator) which I haven't used yet.(I thought it was harder to get it into orbit,but my boosters and substages did very well.)

You wont get any more efficient than the ISP 800 of the nukes - 390 is the next highest for e.g. Toroidal Aerospikes.

[cantab]

For rigidity, use senior docking ports, and use multiple docking ports if need be (though that makes design and docking harder). Also, try not to have big pieces sticking out sideways, or if you must consider putting engines on them so the thrust is spread out instead of all in one place. If you do have one main engine section, try and have "control from here" set on a part close to it, either a probe core placed for the purpose or else the docking point that joins it to the module in front, that way SAS responds to the motion of the engine section and ignores the rest of the ship flexing. For long slender ships, pulling can be more stable than pushing, but remember to lock the gimbal on puller engines because SAS gets confused by them. And watch your reaction wheel placement, and consider disabling wheels on your payloads that you don't need when doing the transfer. (This is especially likely to be an issue with asteroid tugs since they need lots of torque.)

Or, as mentioned, use KAS or Quantum Struts to place struts in flight.

If all else fails, you may have to reduce thrust.

As for the engines for your transfers, for medium and large ships the nuclear engines (LV-N) are the go-to choice, being much more efficient than any of the chemical engines, and more powerful than the ion engines. Using a cluster of ion engines on a big ship is perfectly possible but results in a high part count since the stock ion parts are so tiny. For small ships making short journeys, say to the Mun, though a lighter chemical engine like the LV-909 or Rockomax 48-7S can work out better, while for small ships making longer journeys the ion engines are very viable, just watch out for darkness stopping your burns. For very large ships or impatient people, the KR-2L can be a good choice due to its high thrust.

[michaelhester07]

Efficiency of engines from best to worst (imo)

Ion thrusters

Nuke rockets (NERVA)

Liquid Fuel Booster

Kerbodyne single bell (KR-2L) -Best capital cruiser engine IMO

//below this point your mileage may vary and you may think one engine is better than another and thats OK

Rocomax small single thruster (forgot the designation but it's the one that weighs .1 tons) -Best engine for small non-planetary landers

Rocomax Poodle -third best lander engine... for when your lander is huge

Rocomax Skipper

Lv 909 -second best lander engine behind the rocomax above

Lv T30

Lv T45

Kerbodyne 4-bell

Rocomax Mainsail

Wonder why you see those Thrust to Weight ratios in Kerbal Engineer for other planets/moons? That's because you need to beat that TWR to get off that planet/moon. In space there is no TWR but having a high TMR (which is roughly equivalent to what you see on kerbin) means you can stack more fuel to use it up and result in higher deltaV than before.

While you could get 8k delta V from a stack of NERVAS you could get 12k from a stack of KR2Ls and enough gas in front of them. Here are some of my high deltaV motor designs

KR-2L and that huge kerbodyne tank: 5k dV for a modest payload and a decent TWR. You could potentially see 8k with 2 of the huge tanks if you don't care how fast you get to where you're going. This design can single move up to a class C asteroid with 800 deltaV attached.

LV909 and FL800: comes in at around 4k deltaV and stacks easily under the tri-stack adapter. You can go to Duna, land on Ike, and get back with these as a transfer stage.

FL200 + Rocomax single small thruster: coming in at 3.5k for a modest probe with small experiments on it + 1 materials experiment. This is best used for a science scout probe to be carried on a mothership.

FL100 + RSST: For a one way lander on any non atmospheric body.

tri stack FL800 + nervas: one of the better transfer stage designs. Don't expect it to burn fast though.

The way it works out is that your engine's mass works against it's thrust to reduce the effective thrust it can put out. This is why you see the LV909 having the same ISP as the LV T45 but about 3x more delta V when you mount it.

Edited May 22, 2014 by michaelhester07
spelling and some content

[ximrm]

Tanks you for your answers.

One more question remains.

Are claws an option?

[ProjectGemini]

Tanks you for your answers.

One more question remains.

Are claws an option?

Probably not. Claws are pretty unstable.

[michaelhester07]

for space tugs to move heavy machinery (like nuke rocket pods) yes. For permanently attached parts? no.

[ximrm]

I don't know why, but the quantum struts have vanished from my inventory,reinstalled the file,moved to parts folder,reinstalled ksp completely(there was an other issue, but still no guns.)

I think I'll stick to the pulling method,the docking should be easier and i think i can build a long ship this way.

After all, I lost all my vessels.Time to start something new.

[ximrm]

Also I could use the docking washer from the servo parts plugin.

That'd make attachment to more ports easier.

[Northstar1989]

You wont get any more efficient than the ISP 800 of the nukes - 390 is the next highest for e.g. Toroidal Aerospikes.

False. Using KSP-Interstellar's plasma thrusters (they are basically scaleable electric engines, and are based off real-life technology that has never been polished as we currently have no way to realistically power it on our spacecraft without nuclear reactors), and fusion reactors or beamed microwave power. You can get ISP's into the thousands with low, but usable thrust. (higher than stock ion engines, at least, with enough electricity)

Mod, I know, but so is KAS.

Regards,

Northstar

Edited May 23, 2014 by Northstar1989

[cantab]

Near Future Technologies (formerly near Future Propulsion) is also good for nuclear electric and solar electric propulsion. A simpler and more focussed mod than Interstellar I believe.

Of course in NFT and I assume KSPI, even if the engines have nominally high Isp the benefits may be undone by the weight of the ancilliaries like the reactors. Generally speaking the more delta-V you need the more important Isp and the less important drive system mass are.

[technion]

Efficiency of engines from best to worst (imo)

Rocomax Poodle -third best lander engine... for when your lander is huge

ISP aside, this is almost never a good idea for a lander - it's too heavy. If your lander is that huge, use multiple engines.

The largest landers out there (Eve ascent vehicles) would never work with skippers.

[Northstar1989]

Near Future Technologies (formerly near Future Propulsion) is also good for nuclear electric and solar electric propulsion. A simpler and more focussed mod than Interstellar I believe.

Ahhh yes, but does NearFuture provide In-Situ Resource Utilization capabilities? Nope...

Of course in NFT and I assume KSPI, even if the engines have nominally high Isp the benefits may be undone by the weight of the ancilliaries like the reactors. Generally speaking the more delta-V you need the more important Isp and the less important drive system mass are.

KSP-Interstellar offers the EXCELLENT option of beaming your power to a lightweight Microwave Beamed Power Receiver on board your spacecraft to get around that issue. There is some loss in the transmission, of course, but since the power is sent as a relatively tight beam, it's a lot less than you might expect... Like many other technologies in KSP-Interstellar, including the fission reactors and the ISRU options, it's closely modeled and balanced after real-world technologies...

Regards,

Northstar

[ximrm]

What about solar sails?

Haven't tried them yet, but after some time,they should have some speed facing the outer solar system.

For the voyage home I would then use electrical engines.

btw: Does anyone know how long it would take for a certain acceleration ,with let's say 8 sails,pulling 500tons?I(f 8 are enough)

Or a way to calculate that?

Edited May 24, 2014 by ximrm