Excessively Large Ships

[workerbee]

http://imgur.com/9HH5p6Y My massive interplanetary: 20 nuclear, 60K LFO, 8400 DV, 900+ tons. 2 small landers, 1 large lander, 1 station core, 2 sats, 7k mono, science pod, fuel ferry, rover, etc etc.

EDIT: One more pic with just the station core attached at the end, mid build: http://imgur.com/ttErZ7B

I built this based off of a craft file (see here: http://forum.kerbalspaceprogram.com/threads/97152-My-reusable-stock-ships-visit-Jool-and-Duna) that user Vanamonde made.

Now that it is built, I am having a hard time with the long burns, timing of those burns, turning of the ship, etc etc...I was wondering if you all might share some of your experiences captaining the largest ships out there.

I have resorted to shorter burns, only at and near periapsis, in order to be as efficient as possible to leave Kerbin SOI but I must say, it is incredibly time consuming and tedious, and even Mechjeb can't save me.

Edited December 16, 2014 by workerbee

[Motokid600]

Good... God man what are you using for engines in that first pic I can't tell... Are those SRB's? .14 twr ... Honestly I wouldn't be able to stand it. I'd actually make a larger transfer stage just to bring up that twr. Yea MJ will do you no good because it'll just want to burn through the planet. You'd have to greatly increase the height of your parking orbit if you wanna do it in one burn.

Edited December 17, 2014 by Motokid600

[workerbee]

Yeah I realize now that I should have started with a higher park but I was worried I would lose advantage of the Oberth...can anyone confirm?

[Crimson Sunrise]

I believe the Oberth effect burn has to be executed manually.

[Vanamonde]

This is more of a how-to kind of question, and so, moved to gameplay questions.

Oh, and thanks for plugging my ship.

[LethalDose]

Yeah I realize now that I should have started with a higher park but I was worried I would lose advantage of the Oberth...can anyone confirm?

Uh... help? Don't build things so big?

If the long burns are a problem, you can use periapsis kicks. Basically burn where you want to exit until you're too far past the point, then orbit around, and burn in the same place (your new periapsis) again until you're too fare past the point where you want to burn...

Then go around, again...

and burn, again...

See how this works?

Evenutally you'll break orbit and be on your way. If you're going somewhere other than Duna or Eve, though, you're probably gonna want to make your transfer burn in solar orbit, which is gonna cost ya dV.

Just looked at that craft... yeah, that things a monster. I think you're learning bigger isn't better.

[zekes]

I just let it sit.... sometimes burns take a while

also, I tend to make a laucher slightly bigger than the payload needs to get to LKO, so the upper stage can boost it out of orbit - because the upper stage has a TWR of about 2, while the transfer stage is about 0.2

Edited December 17, 2014 by zekes

[thereaverofdarkness]

You can take full advantage of the Oberth Effect and also have a very low TWR if you have a lot of time to make the transfer, and space to extend the apoapsis. You can simply extend it partway, then wait an orbit and go a little further when you come back to periapsis. If you don't have any moons that will mess up your orbit, you can simply begin raising the apoapsis long before your transfer window opens up, then wait with the apoapsis barely inside the local SOI until time to make the final transfer burn.

[Janos1986]

Turning around things that long and slim must be a pain in the bottom, I can picture them flopping and wobbling about at every RCS thrust.

Humble advice: try to develop a big ship in 3 dimensions, by expanding both radially and longitudinally. Just sayin'.

[workerbee]

You can take full advantage of the Oberth Effect and also have a very low TWR if you have a lot of time to make the transfer, and space to extend the apoapsis. You can simply extend it partway, then wait an orbit and go a little further when you come back to periapsis. If you don't have any moons that will mess up your orbit, you can simply begin raising the apoapsis long before your transfer window opens up, then wait with the apoapsis barely inside the local SOI until time to make the final transfer burn.

I like this method but if you're waiting for a transfer that is a few weeks or months out, it is very likely that your orbit will eventually become disrupted by Mun or Minimus. After having tried several methods for my burn with this beast, I have decided to do 3 or 4 shorter burns at and near peri...it's not the most efficient burn ever, especially since my ship is so long and wobbly, but I am fairly certain it will end up working (doing the burn now, cross fingers).

[panzer1b]

In terms of truning, ive more or less completely switched from long-slender to more short-fat, as well as cramming all the fuel in the middle, so that then i actually have a method for the reaction wheels (i still use 50 or so react wheels for larger craft). Personally, id love for teh game to add larger and way more powerful reaction wheels, as well as some to fit the MK-2 and MK-3 fuselage, and maybee one to fit the 3.75m rockets.

As for burn times, either make your orbit high enough that you can do it in 1 burn, or as someone here mentioned, do it in multiple burns, so you have a AP thats more or less near the max height it can be without breaking orbit. This is ofc very annoying with any bodies nearby (forget doing this near jool, and kerbin's mun seems to be rather notorious at getting in the way as well, but with some luck/reloading game saves, you can get past this complication). Its best to do this burn quite late, as the longer you wait, the higher the probability something will block your orbit. Another possibility is using agravity assist, but those are very tough to set up, difficult to execute, and still require quite a bit of burning. personally for longer burn times (above 10 minutes), i just raise the orbit to 100km, or if its super long, i make a new ship, as im not patient enough to deal with any burns that are more then around 20 minutes, even if i use x4 time compression.

I like this method but if you're waiting for a transfer that is a few weeks or months out, it is very likely that your orbit will eventually become disrupted by Mun or Minimus. After having tried several methods for my burn with this beast, I have decided to do 3 or 4 shorter burns at and near peri...it's not the most efficient burn ever, especially since my ship is so long and wobbly, but I am fairly certain it will end up working (doing the burn now, cross fingers).

there is also one method to COUNTER this problem, but it is in my opinion an exploit. You can time warp fast enough past the intercept that the game never has time to calculate what the body did to your orbit. This can also be done to avoid collisions (you will phase thru the planet if you warp fast enough), but again, i dont use this personally as it is defenetely cheating (heck, at this point ill use Hedit to save the ship, or just let it crash like its suppost to)

Edited December 18, 2014 by panzer1b

[workerbee]

I truly wish that larger crafts did not have so much joint movement...perhaps a different, more circular design is in order...sort of like the craft they use in the movie Interstellar. I think for my next build, it will be something, as you said, shorter and fatter...and maybe rounder.