Refuelling question

[Triangular]

Hi all,

I'm new here, have been playing this amazing game for a couple of days and can't seem to stop!

So far my greatest achievement is that I have made my own Mun lander, landed it, and got the crew safely back to Kerbin.

I'm thinking about other stuff I can do next. A mission to Minmus beckons, as does the construction of a refuelling port in orbit around Kerbin.

This leads me to my question - I'm aware that a refuelling port basically needs a couple of big fuel tanks, a pod, some solar power, a small engine of its own and at least one docking port, but I was wondering: does the docking port have to be attached to the end of the fuel tanks? or what could go between fuel tanks and a docking port so that refuelling could still take place? Presumably you can't separate them with just anything - eg struts/girders won't convey the fuel? So what can you use here?

Thanks in advance for any help.

[Limited Infinity]

So far I've found docking to any port will allow fuel transfer. Doesn't even need to be one from the fuel portion of a station. For example a station with a fuel portion, a crew portion and a solar portion in that order would still be able to transfer fuel to a craft docked to the solar portion.

[ComradeGoat]

As long as everything in-between is fuel crossfeed capable, it should work fine. Nearly everything is.

[Sol_Rokks_Teddy]

The only parts in the game that are not "fuel crossfeed capable" are the decouplers, and even with those i am pretty sure you can still manualy tranfer fuel (alt+left click)

[katateochi]

For refuelling is does not matter where the port is. Even if it is connected to something that is not "fuel crossfeed capable" the menu driven transfer of fuel will work between any tank on any part of a connected craft.

It only needs considering if you building a multipart craft that needs to use fuel from connected tanks as it travels. But as already said, most parts aside from decouplers are crossfeed capable.

[magnemoe]

The only parts in the game that are not "fuel crossfeed capable" are the decouplers, and even with those i am pretty sure you can still manualy tranfer fuel (alt+left click)

You can without problems. they only stop the automatic transfer to running engines.

[Cby]

Actually, you don't need to worry about cross feed when your refuelling a ship. Just alt-click on two fuel tanks and select in or out. Then, the magic fuel starts disappearing from one tank and reappears in the other. If you want to add fuel tanks to a spaceship your building in orbit, then you would need cross feed compatible parts, or just keep transferring fuel, which is annoying, but irrelevant to your question.

[Triangular]

Thanks for the info guys. Seems you can even refuel through girders then..!

Now I'm trying to launch the first part of my refuelling station, the rocket keeps falling apart - usually a structural failure on linkage between Rockomax Jumbo-64 Fuel tank and the neighbouring part (either another identical fuel tank or the Rockomax adaptor). Is this a common problem? Any solutions? I've tried strengthening the joins with beams and stuff but can't seem to get it into orbit. Any thoughts?

[Specialist290]

The only parts in the game that are not "fuel crossfeed capable" are the decouplers, and even with those i am pretty sure you can still manualy tranfer fuel (alt+left click)

I can personally attest that at least one of the I-beam segments is also not fuel crossfeed capable.

On a related note, if you ever want a challenge, try landing a Mun lander that has two radially-mounted engines, but only one of them is hooked up to the central fuel tank with fuel ducts because you forgot to turn symmetry back on while you were placing them in the VAB. "Fun" times.

[Titus Jeb Worshipper]

I had also been wondering about this, just hadn't gotten round to posting the question yet, for some reason I keep forgetting about how amazingly helpful this community is, takes some getting used to I guess. Anyway time to commence building, attempting to launch and sploding spectacularly. Now thats fun times

[Triangular]

OOf. Sounds like quite the party...

Finally got the station up. In the end I separated the 2 jumbo fuel tanks with the "Structural Fuselage" part because it is described as "more solid due to reinforcements" and although it looked like it shouldn't it seemed to work:

I got 1 x Jumbo tank's worth of fuel up, was hoping for more but kept dropping the size of the payload to try and get it in the air. Would appreciate some tips on how to get more fuel into orbit if anyone has any?

[Limited Infinity]

I'm no rocket engineer, but here's my largest lifter:

It's a pain to fly and took me forever to get it to work, but it can carry 4 large fuel tanks with 4 large monpropellent with plenty of fuel for orbital maneuvers.

It's hanging out at only 300K, but had mor than 75% of it's fuel left. It took two trips to stock my station. One to bring the four perpendicular tanks up and refill the shuttles. The second to park for future orbits. My hope is that it'll be an interplanetary fuel tanker.

If you want the craft file I'll post it somewhere, but like I said it's a pain to fly. I shot myself in the foot using the covered docking ports. I think they're cool but I had to lift entirely with radial support

Veterans don't laugh. She's ugly and inefficient, but I got her off the ground with only an asparagus tutorial for help

[Triangular]

What a beast! I've been working on similar looking things but only using the jumbo tanks, I see you separated yours with smaller tanks- does that stop the structural linkage problem from happening so much?

Also those struts at the top: i presume they are connected via decouplers?

Craft file would be handy if you could post. TY

[Limited Infinity]

I'm trying to get the .craft file up on Spaceport, but it doesn't show yet. If that doesn't work I'll try some thing else.

I do find the smaller tanks struted helps some with linkage, but does add a little more wobble. Mainsails on the jumbotanks also overheat faster. I saw a youtube video by AddMeGamers with the mainsail firing connected to different tanks and it seemed I liked the X200-32 the best.

All those struts will go away when the tanks are decoupled. I am not certain what the part count is, but the first 5 stages or so will bring a frame rate to a crawl.

Edit: O.K. I don't know what's going on with space port, but here it is.

https://www.dropbox.com/s/amb75txilh5sppk/Bactrian%20MkII.craft

I warn you, frame rates will crawl when you try to fly it. Here are the flight instructions. Sorry for the wall of text, but she's a bit touchy and may 'splode if you don't handle her right.

Action Groups

1 Activate forward engines / Shutdown aft engines

2 shutdown forward engines / Activate aft engines

3 Toggle forward docking ports

4 Toggle aft docking ports

5 Toggle Gimbal for all engines except central engines

Launch Schedule

Pre-Launch:

Toggle Gimbal (Action Group 5) - This usually takes two presses. I suggest right clicking on an engine so you can see the Gimbal option. Then hit 5 twice so you see the Lock Gimbal option switch to the Free Gimbal option. This will lock the Gimbal for all the engines except for the center Mainsails for steering, reducing wobble.

Activate SAS (T) (Optional) - You can keep SAS on the whole flight except for gravity turn and completing the orbit (when you obviously need to turn ) or you can fly manually.

Thrust Engines to Full (Shift) - Don't worry about heat on the lifter. I have lift throttle at full through the whole launch and have not lost a engine to heat.

Launch (Space) - Only the free Lifter engines fire. I wanted to save the crafts engines and fuel for space since it is a tanker. It seems foolish to have to fuel a tanker.

Stage 10 (Space) - Around 2600 m Drops for tanks. Just getting rid of weight. Get ready for stage 9. It comes quick.

Stage 9 (Space) - Around 3200 m SRB separation.

Stage 8 (Space) - Around 7K Drops outer Tank. More weight dropped. A little rotation by this point, but manageable

Gravity Turn - 13.5 K Here's where things get a little tricky. If you're better with orbits then I am, you might know a better way. Turn off SAS if you are using it. I go straight for 45 degrees on 90 (east). You can use RCS to assist the turn. You want to make sure your well out of the thickest stuff (at least 13K) before turning as you have lost a lot of stabilizing struts have been dropped in previous stages. Stage 7 can creep up on you if you do not nail the turn. If the stage get's real close. I'll stop my turn anywhere on 90, even out, and turn SAS back on. Stage and then continue turn. You can turn SAS back on after the turn is complete.

Stage 7 (Space) - Around 22K Drops lower middle Tank. Here's where things get really delicate. We've lost a lot of our stabilizing struts and you'll start to get some shaking. I have lost some tanks at this point, but it seems like as long as I just hold her straight, she holds together.

Stage 6 (5 Space) - Around 39K (your gravity turn may alter this) At this point we're just shooting for an Apoapsis of 70K. We won't hit this at this stage, but we have to plan a little. We'll be dropping the lower center rocket with our Gimbal, because our upper rockets have more struts keeping the craft stable. As you near the stage right click one of the upper mainsails for the menu so you can see when Gimbal is activated. As soon as the lower rockets empty, press 5 to reactivate Gimbal and then space to stage. Those orange garbage cans have had a lot of shaking at this point. Be gentle. they can still fall off.

Complete Orbit - Around 48K (a lot can affect this, but this where I am as I write this) At this point we're preparing to burn horizontally at 0. We're going to start a little early, because the LV-N's need a lot of time before Apoapsis to be effective. When the Apoapsis gets to about 65K cut thrust (x or ctrl all the way). Gently maneuver to 0 degrees on 90 (East). RCS may be used. I like to keep 30 seconds to 1 minute 30 seconds in front of my Apoapsis. We'll be finishing with the LV-N's. As I'm writing this I crept past my Apoapsis, but was able to push it ahead by bringing my heading up to 30 degrees on 90. Let's try to get our Periapsis to 60K.

Stage 5 (Space) Final launch separation. I have the separation in it's own stage, because it forces me to stop and think and keeps my for and aft engines separate. If you want to combine stages 5 and 4 feel free, but realize it will reduce all previous stages by 1. At this point, The final engines are either heading back to Kerbin, or have a Periapsis below 65 K and can be de-orbited at your leisure, or stuck at a stable orbit. They are drones with small docking ports so they can be refueled and de-orbited later if you're stickler for such things.

Stage 4 (1 or Space) Main thrusters activated. Action Group 1 also activates thrusters, so at this time we can lock stages and just use 1 and 2 to switch between thrusters. I find the LV-N's don't have a lot of Gimbal for this whale of a beast. Feel free to use RCS as there's a ton (possibly literally ) but with a little patience it is not necessary. With forward and aft engines, you won't need to do any crazy 180's.

Now we're at one of three positions. First and worst case our Periapsis is below 60K. If this is so burn those LV-N's as high as you can with out heat. These will over heat quite quickly at full throttle. Bring your nose out maybe to 10 degrees at 90 to avoid over taking your Apoapsis. Go ahead and throw RCS forward with H key if you need to. If you pass your Apoapsis and your orbit is shrinking, I'm sorry, but it's time to abort.

Second, your Periapsis is between 60 and 70 K. This is where I usually fall often on purpose to make sure my last stage can be de-orbited. As long as you are more than 30 seconds in front of your Apoapsis you should have no problem burning at 0 degrees to finish your orbit, other wise see above.

Third, your Periapsis is over 70k.

Congratulations. You are now in space with a stable orbit and well over 19000 fuel and 6500 monopropellent. As I write this I'm at 19406 Liquid, 23718 Oxidizer, 6601 MonoPropellent. That should get you to most Kerbin orbits with 4 full jumbo-64's and 4 full FL-R1's

Note's on final stages: These are if you ever want to de-orbit the craft.

Stage 4 - Forward Engines At this stage 1 key and 2 key can switch the action groups for forward or aft engines saving 180 degree turns. I just like to keep the the engine groups visually separated in the stage list.

Stage 3 - Aft Engines. At this stage 1 key and 2 key can switch the action groups for forward or aft engines saving 180 degree turns. I just like to keep the the engine groups visually separated in the stage list.

Stage 2 - Decouples the body from the module. I keep this separate from the parachutes to give the module a chance to get away from the body.

Stage 1 - Parachutes.

Again sorry for the wall of text. Enjoy

Edited May 15, 2013 by Limited Infinity

[Triangular]

This is really helpful, thanks!

I'll have a go at using this, but really just wanted to look at it to see how to stop stuff falling apart all the time. Most of the fun of this game so far is in designing my own stuff - but it can be frustrating when you get the same crash report again and again... "structural linkage" etc... So far experience tells me to rely on strut connectors rather that the seemingly pretty useless beams.

I just managed to double the amount of fuel I could get up in the air since yesterday so, getting better.

One more question: sometimes its really hard to place strut connectors - they seem to disappear immediately on placement - does this happen to everyone and is there a workaround?

Thanks again for all your help, amazing response. I'm now going to try to teach myself how to dock, wish me luck. I hear using this newfangled mechjeb device is frowned upon...

[Limited Infinity]

I have had the struts seemingly blend into other pieces. If you can zoom inside of the piece with shift scroll or middle click you can sometimes find them when the reverse polygons aren't rendered. I also find this helpful for alining struts. Zoom in right be hind them and aim where you want to connect right above. This should give you a nice straight strut.

I learned docking the old fashion way with tutorials and a lot of practice. I know some people frown on mods, but I say what ever makes the game fun. I see mods as breathing new life in a game that may be getting a little stale. I like to get as much as I can out of vanilla and once I've done that use mods to add longevity to the game.

[Scotius]

How well your computer can handle two big ships near each other? If you get lag when they are close, you might simply NEED MechJeb to dock. I ran into this very problem when my space station reached certain part count. Lag was theoretically minimal, but it nonetheless rendered manual docking impossible - mere puff of RCS sent docking ship into a tumble, or it did nothing at all. MechJeb so far managed to handle all my dockings reliably, though it uses ridiculous amounts of monopropellant

[Triangular]

Thanks for the heads up scotius. I'm still watching tutorials before I give it a try. I'm running an AMD Phenom X4 at 3.40 GHz, 8GB RAM and an NVIDIA GeForce GTX 460 with 4GB onboard memory. Not exactly top spec but it's handled the game pretty good so far. We'll see what happens when I try to dock...!

[Triangular]

Not docked yet, but I have managed to make a very reliable and efficient lifter - gets 3.5 Jumbo tanks into a nice 100km orbit, and doesn't fall apart!

I had read about asparagus staging before but was surprised by the difference it makes in terms of efficiency!

[Reavermyst]

As long as the station and ship are connected via docking ports, you should be able to refuel from there. If you want to be fancy, you can get a couple mods like KAS or Quantum fuel. I got both, but I like the idea of dragging a hose to the ship and hooking it up to refuel it. Feels like a space Chevron!

[Limited Infinity]

Well that looks a quite a bit more stable than the one I built. How does she fly?