Medusa Grand Tour Architecture. Go where you please!

[m4rt14n]

How do you get it so it doesnt wobble all over the place when hitting the thrusters? My mothership is wobbling even in LKO.

[Captain Sierra]

How do you get it so it doesnt wobble all over the place when hitting the thrusters? My mothership is wobbling even in LKO.

In my case, a few well placed struts and KJR, and senior docking ports. Rune uses juniors and multidock. How's that work for ya Rune?

The other thing to note is the tow configuration (just make sure to disable gimbal!). It's far more stable and anti-flex than a push configuration if you shut off gimballing, as KSP does not support center of thrust above center of mass. The gimbal will not reverse and it becomes self destructing instead of self correcting.

[Rune]

How do you get it so it doesnt wobble all over the place when hitting the thrusters? My mothership is wobbling even in LKO.

Well, a lot of thinking mostly! As Captain Sierra says, a very important thing to note is the tractor configuration. Think of it as towing a noodle instead of pushing it, every small deviation will create torque forces both times, but in this case those forces end up trying to bend the noodle/ship back to its original position, while in a pusher design they tend to bend it further away. You could say that in this case the pendulum fallacy is not a fallacy after all. That is because the pendulum fallacy applies to rigid objects!

But apart from that, the structure of the ship is also intended to be as rigid as I could make it. Not counting the side tanks, there are only two dock connections on the main axis of the ship, heatshield to fuel tanks, and fuel tanks to spine, both Sr. docking ports that can take a bit of flex. And the fuel tank section has most the mass in it, so it kind of works as the center of mass, so I only worry about bending moment for relatively small masses (the Tylo lander on the back is left to dangle as it wants, mostly). Now inside the fuel section, I use a double docking with Jr. ports, also as Sierra says. Each port is wobbly as hell by itself, but as I put two on opposing ends of the longest fuel tank, I end up with very little flex around the longitudinal direction, which is the important part. I haven't yet tried, but if you put also tanks in the corners, you should get a much, much more rigid assembly by taking out the last degree of freedom they have, which is to swing like a door around the line the two docking ports make. Still, that slight oscillation is minimal and doesn't affect the direction of thrust in the slightest, so, who cares... besides, barrel rolls are for planes

And last but not least, in the end every port is, at most, under the stress a single nuke can give out. And believe me, that ain't much. Low T/W can let you get by with very low structural rigidity! But I strongly suspect in this case, I could mount much more powerful engines, and I would still be able to point where I want, because I thought a bit about how the forces would distribute around my spacecraft., and placed my connections strategically. As a result, she may turn slowly because she is massive, but the only things that wobble slightly are the payloads, and once you turn on the engines everything settles into a rigid position hanging from its anchor points. Plus,. the engines plumes get slightly deflected outwards, which looks cool and impact very little the effective thrust.

Rune. Having studied several subjects on structural engineering in uni also helps, I guess. ^^'

[Top8]

Just a shout out - I liked your Medusa so much it inspired me in this desgin: http://forum.kerbalspaceprogram.com/threads/67002-Visions-of-2070/page5

[Patupi]

How do you get it so it doesnt wobble all over the place when hitting the thrusters? My mothership is wobbling even in LKO.

As Rune said, good planning... OK, in my case it was accidentally planned, sort of. I shipped my spare tanks up on the top of a rather long rocket and so it had a large ASAS unit on top. This means that EVERY drop tank in that design has it's own torque. This evens things out a little, so things don't wobble quite as much. True, turning it is a git, and incredibly slow, but it does turn with surprisingly little distortion in the overall shape.

[Alewx]

I like it, it really Looks like it could be a real spaceship for space travel.

But is it really completely absolutly stock parts? If so then i will get it and try it out, maybe modify it for my own Inspiration, ist awesome .

[Rune]

I like it, it really Looks like it could be a real spaceship for space travel.

But is it really completely absolutly stock parts? If so then i will get it and try it out, maybe modify it for my own Inspiration, ist awesome .

Completely, absolutely, cross-my-heart and all that jazz. Otherwise, let me know so I can fix the mistake! And enjoy your travels!

Rune. The guys at R-SUV love postcards, BTW

[Patupi]

Just a quick note to say my attempt at a Grand Tour has died still birthed along with my computer. The HD was apparently dead, at least as far as I can get, so if I attempt this again I'm going to have to start from scratch again *sigh* Now I wish I'd uploaded the craft files somewhere so I could try again! The darned thing was parked in Kerbin orbit for weeks while I did other things... and then BOOM! All gone

Well, when I get my new computer I'll give it another go maybe, but I doubt it'll look quite the same.

[Alewx]

Hey Rune,

finally i got the time to get back into KSP, so I try to construct my own kind of Deep Space Ship, and i wanted to rebuild your Heat Shield.

But, omg that is ****ing annoying with the Rotation and Placement and symetry, how did you get your to work that well? i get frustrated now after one hour of non working tries to place the Panels in a nice order.

[Rune]

Just a quick note to say my attempt at a Grand Tour has died still birthed along with my computer. The HD was apparently dead, at least as far as I can get, so if I attempt this again I'm going to have to start from scratch again *sigh* Now I wish I'd uploaded the craft files somewhere so I could try again! The darned thing was parked in Kerbin orbit for weeks while I did other things... and then BOOM! All gone

Well, when I get my new computer I'll give it another go maybe, but I doubt it'll look quite the same.

Sad to hear! Another machine sacrificed in the altar of gaming. SSD drive giving out?

Hey Rune,

finally i got the time to get back into KSP, so I try to construct my own kind of Deep Space Ship, and i wanted to rebuild your Heat Shield.

But, omg that is ****ing annoying with the Rotation and Placement and symetry, how did you get your to work that well? i get frustrated now after one hour of non working tries to place the Panels in a nice order.

Oh, that, like many other things in my builds, comes very easily courtesy of the Editor Extensions mod, that allows you symmetry settings of up to x100. Among many other things! But be sure to check the guide for the keyboards shortcuts, it takes a while to get used to, but later you can make KSP parts sing while marching off neatly into place.

Rune. Never gets his posts right the first time.

Edited March 29, 2014 by Rune

[Alewx]

Thanks for the Info, cool.

Did anyone suggest to integrate it into the regular game; sounds and Looks like a really cool enhancement.

[problemecium]

I like the meteoroid shields you have there ^^ I recently started putting those on my own ships, so it's nice to see I'm not alone.

[Camaron]

My Grand Tour ship is really just a first-gen, experimental type of thing, but it works great, and has very similar design principle to the OP. One of my biggest concerns is parts count, so you will see there is very little wasted parts. The "Giga Grappler" is a simple, throwaway heavy maneuvering device, and doesn't stay with the ship after construction. It's maximum config is Equivalent to 19 Orange tanks, and is designed to shed 16 of them during a long range trip.

It only takes two launches to build the ship, plus a few more for fuel carriers since the tanks are installed empty.

I have lots of ideas for a gen 2.

Edited March 30, 2014 by Camaron

[Alewx]

Hey Rune,

I feel Kind of stupid, to ask but how did you convince KSP to use more than just a single Docking port to dock the tanks at medusa? The radial Junior Docking ports are the thing, I use a similar setup on my own ship but the tanks i wanted to rigid this way are ignoring the second port totally.

@Camaron

Nice ship, but is the single nuclearengine in the centre of the ship not a bit underpowered for the mass?

Edit: As soon as the tank docking problem is solved i will show pics of it.

Edited April 4, 2014 by Alewx

[Majorjim!]

Hi Rune,

Impressive looking machine there. Can you list the places it can go to and return from?

MJ

[Rune]

Hey Rune,

I feel Kind of stupid, to ask but how did you convince KSP to use more than just a single Docking port to dock the tanks at medusa? The radial Junior Docking ports are the thing, I use a similar setup on my own ship but the tanks i wanted to rigid this way are ignoring the second port totally.

@Camaron

Nice ship, but is the single nuclearengine in the centre of the ship not a bit underpowered for the mass?

Edit: As soon as the tank docking problem is solved i will show pics of it.

That's multidock. It is doable, but tricky. See, the thing is the docking ports only work between different crafts, so you can't connect the second one once the first have docked. But you can dock them both at the same time! You need a lot of precision, of course, and having them perfectly aligned. If you miss the first try and only one locks, you have to undock and go at it again, I'm afraid. Navyfish's docking alignment indicator is invaluable for that, but I have been able to do a pentadock without it, by far the trickiest docking I have ever done:

(That is a previous version of a Grand Tour ship)

Hi Rune,

Impressive looking machine there. Can you list the places it can go to and return from?

MJ

Well, considering it's built to do a Grand Tour, I'd say any place in the kerbol system (Eve's surface excluded without developing a new lander). There is a table of delta-v's without dropping tanks or landers for the various tank configurations in the OP, and the big ones give you 9.8km/s, that should give you an idea. But the smallest, single tank configuration is already capable of a Jool transfer.

Rune. It's bit enough to go interplanetary on RSS, actually... it could do Mars roundtrips.

[Alewx]

That's multidock. It is doable, but tricky. See, the thing is the docking ports only work between different crafts, so you can't connect the second one once the first have docked. But you can dock them both at the same time! You need a lot of precision, of course, and having them perfectly aligned. If you miss the first try and only one locks, you have to undock and go at it again, I'm afraid. Navyfish's docking alignment indicator is invaluable for that, but I have been able to do a pentadock without it, by far the trickiest docking I have ever done:

http://i.imgur.com/6LCTuFz.jpg

(That is a previous version of a Grand Tour ship)

Well that sounds like a real problem for me. My Docking manuevers are anything from aligned, and take almost one hour for just getting into my LKO 105km for Assembling stuff. having to be aligned that two ports are precise at unknown limit is something that looks impossible for me.

The single port Docking is core feature? Or is there any mod out that is cappable of enabling multiport docking without beeing perfectionist and expert?

Sorry for the bad spelling but IE11 is playing tricks on me

[Majorjim!]

Ok so with around 9.5k mps that's mostly one way trips right?

Which bodies have you been to and returned from

With this ship?

[Rune]

Well that sounds like a real problem for me. My Docking manuevers are anything from aligned, and take almost one hour for just getting into my LKO 105km for Assembling stuff. having to be aligned that two ports are precise at unknown limit is something that looks impossible for me.

The single port Docking is core feature? Or is there any mod out that is cappable of enabling multiport docking without beeing perfectionist and expert?

Sorry for the bad spelling but IE11 is playing tricks on me

I'm sorry, I think the docking behaviour is a core part of the game, you just can't make real connections between different parts of the same ship. I do, however, manage to dock ports while loading the ship on the runway/launchpad (I think it's upon physics load), so perhaps a quicksave/quickload might do the trick, I dunno. You will still have to have the ports correctly aligned, though, even if it works. Still, once you dock bad the first time, undocking and backing away 1.5m (so the magnetism resets) makes for a much easier second try, since you are already aligned in two axis.

It takes a lot of practice, but rendezvous and docking is one of those things where skill is just a matter of hours devoted to it, and the once you have spent them, then it becomes real easy.

Some other hints that may help you:

- Lock the camera on chase mode (through the "V" key), so you can make sense in your head where up down and such are in relation to your ship.

- Control without getting into docking mode, left hand controls orientation through WASD and QE, right hand controls translation through IJKL and HN. Forget the mouse, it just gets in the way. Takes a bit of getting used to, but you also had to learn to play FPS once, right?

- Learn how the prograde/retrograde vectors work in your navball, and learn to go first to it for information, then you can start trying to make sense of the situation with eyes. Ditto for the target markers.

- If you still have problems (and it's likely), I very much recommend NavyFish's Docking alignment indicator, and once you get the hang of how that works then go for 100% instrument dockings and just don't look at the rest of the screen (basically, line the orange lines with the white ones, and the velocity vector with the green lines, and watch closing speed and angle).

Rune. It's also a very gratifying skill once you have it, it opens up the way to big LEGO in space!

Edited April 4, 2014 by Rune

[Alewx]

I'm sorry, I think the docking behaviour is a core part of the game, you just can't make real connections between different parts of the same ship. I do, however, manage to dock ports while loading the ship on the runway/launchpad (I think it's upon physics load), so perhaps a quicksave/quickload might do the trick, I dunno. You will still have to have the ports correctly aligned, though, even if it works. Still, once you dock bad the first time, undocking and backing away 1.5m (so the magnetism resets) makes for a much easier second try, since you are already aligned in two axis.

It takes a lot of practice, but rendezvous and docking is one of those things where skill is just a matter of hours devoted to it, and the once you have spent them, then it becomes real easy.

Some other hints that may help you:

- Lock the camera on chase mode (through the "V" key), so you can make sense in your head where up down and such are in relation to your ship.

- Control without getting into docking mode, left hand controls orientation through WASD and QE, right hand controls translation through IJKL and HN. Forget the mouse, it just gets in the way. Takes a bit of getting used to, but you also had to learn to play FPS once, right?

- Learn how the prograde/retrograde vectors work in your navball, and learn to go first to it for information, then you can start trying to make sense of the situation with eyes. Ditto for the target markers.

- If you still have problems (and it's likely), I very much recommend NavyFish's Docking alignment indicator, and once you get the hang of how that works then go for 100% instrument dockings and just don't look at the rest of the screen (basically, line the orange lines with the white ones, and the velocity vector with the green lines, and watch closing speed and angle).

Rune. It's also a very gratifying skill once you have it, it opens up the way to big LEGO in space!

Actually I never docked in Docking mode. The chasecamera is ok but I get just confused, but I will try harder. That means I get a busy Weekend.

Did you ever manage to dock something at 4 dockingports that are in 120 degree directions? So what I mean is, having instead of 2 symmetry axis at the medusa build one with 3 axis.

[Alewx]

Sorry for double post but that is somekind of answer to my question before.

I found out that there is a dirty way of multiport Docking.

in the persistent.sfs file of the savegame are all the parts of all ships including the Docking ports.

Every Docking port has 3 states that are possible: Ready, that means there is nothing docked; Docked (docker), this means it is docked to another port and also tells somekind of direction maybe for physics; Docked (dockee), that is the port that is docked to the otherone and slaved to ist movement, as far as I understand it.

So it might be possible to just dock the things in Orbit with mutliple ports, and then manually fix them in a Texteditor, but that is highly experimental.

[rottielover]

Hi Rune, I downloaded all these, wonderful. I have but one thing, the RCS isn't quite balanced, which is OK, but makes for some hairy docking, especially the nuke engine modules.

I took the liberty of a slight re-design, and though it's ugly, I think it has two benefits. 1) the RCS is balanced across the COM, should make lining these up perfectly easier. 2) I used "lower tech" parts. The octo probe core earlier in the tree and included small solar panels, more rcs fuel and a small battery (to replace the RTG). It did increase the weight by 1 ton (3.6 to 4.4) but it would allow for people to send out this mission to Jool sooner in the tech tree, when it's more relevant.

I'll share a pic here, if you want the craft file I'll send it to you privately. I plan to comb over the rest of the ships and parts and "tech them down" a bit. Would be nice to send this out say around Tier 6-7 in the tech tree, before you have ALL nodes unlocked, but far enough that a Jool mission would be possible anyway.

Thoughts?

[Camaron]

Wow, this thread lit up all of a sudden.

@ Alex - Yes, A single nuclear is the most efficient config, but is indeed, painfully slow. Its a modular ship though, So I could tack on new engines whenever I want.

However, I've restarted a new career for 23.5 and it's new parts pretty much made this ship totally obsolete, considering a big asteroid tug I launched earlier achieved 135km orbit at 1,015 tons. "Big" got an overhaul in this update.

[Rune]

Ok so with around 9.5k mps that's mostly one way trips right?

Which bodies have you been to and returned from

With this ship?

Srry, didn't see that. 9,5kps is enogh for a return from lots of places! In fact, anywhere but moho, and I have my doubts, you could get fancy with gravity assists. And if that is not enough, you can effectively stage the design by dropping tanks. Also, consider the landers get counted as payload, but they get used and also lighten the ship.

Alex, what you are talking about might perhaps be doable, but the coordinates of the parts or their alignment angles wouldn't match, so expect a visit by the kraken if you try and back up your file... he might not approve!

And Rottielover, feeling honored, imitation and flattery and all that. By all means go ahead! If you convert the design, you could post links here and I would put them in the OP (with due credit of course) so that people can have a go at them. Also, I know about the misaligned RCS, but I suffer both from a lot of experience docking (which makes me radically underestimate the difficulty), and heavy use of the docking alignment indicator, which makes it even easier. Plus, its prettier!

Rune. And I'm going to drop the phone and stop posting now, because this is a bar and the beer on the table is calling me. Cheers!

[LABHOUSE]

Can I download this to work in the demo version?