Newbie Question

[alter5]

Im at a nice circular 600 km orbit around kerbin on my way to duna as soon as i get an encounter with the maneuver nodes and get that blue dot circle thingy on the navball it tells me that i have to burn acceptable 900m/s so far so good now if i move the vessel just a bit the blue dot becomes unstable and moves like crazy and gives me some weird values like 4000m/s etc. hope you can help thanks in advance.

Edited April 20, 2014 by alter5

[Taki117]

The reason that this is happening is that it's trying to calculate based on your current near circular orbit. What you want to do is align your ship to the maneuver node and perform a short Test Burn. (This will set your burn timer and give you a more accurate dV based on a now slightly less circular orbit) I'm mildly curious how you're getting 900m/s any way since the lowest I've ever seen is a little over 1k.

[Claw]

Do you have any mods installed?

The blue marker will sometimes jump around a bit. Especially once the dV for the burn gets to something small (around 5 m/s or less) or when you are maneuvering

Also, as you do the burn the dV should go down but will then go back up. So if you start chasing the blue marker around and you have a very powerful craft, you could find yourself burning past 0 m/s and it will start climbing.

Neither of those sound exactly like what you are describing though. If you could post a screenshot of your map screen that might help us understand what you are seeing. Press F1 in game and it will save a file to your KSP/Screenshots directory. Then you can upload that picture to someplace like http://imgur.com and link to it here in the forum.

[Robbii6]

How large is the vessel your moving? Very large ships can flex and cause fluctuations in dV due to the physics in the game.

[alter5]

hope you guys can take more info from the screen mods i am using are: Mechjeb, Engineer Redux and that cloud beautification mod^^

Edited April 20, 2014 by alter5

[Taki117]

Is that a docking port I see? That's the issue. I have a feeling what's happening is that that particular joint is flexing causing you all kinds of problems. Also, you are at 600km, NOT 600,000 km. (Big difference there)

[alter5]

Oh thank you gonna correct that asap^^ So the unstable connection aka my little docking port that is holding the 25 T Lander is not enough?

[Nemecle]

it mights be enough but because your spaceship is wibbly-wobbly its center of gravity move a bit and change a little the node : but if you turn gently and wait for the vessel to stabilize, you should be able to aim the blue marker

[Claw]

Is that a docking port I see? That's the issue. I have a feeling what's happening is that that particular joint is flexing causing you all kinds of problems. Also, you are at 600km, NOT 600,000 km. (Big difference there)

I would agree that the flex in the docking port might cause your blue marker to jump around. Although that still doesn't explain to me the change from 900 m/s to 4000 m/s on the dV requirement.

I think the 900 m/s comes from the fact that he's starting out so high already.

MechJeb and KER are somewhat redundant, but I don't think having them installed should cause issues like this.

If you're using MJ to develop nodes, you might have two nodes superimposed on top of eachother and when you're passing your 900 m/s node you're reaching the second node, which possibly requires 4000 m/s. If you're using MJ to develop the node, click on "Delete all nodes" first, before you have it create a new one.

Also, another reason there might be two nodes is if your departure date is early. I can't remember when the first (cheap) Duna transfer is, but I think it's day 58 or something. Of course that depends on which clock system you're using. But if you are way out on the phase, it's going to cost you a lot more to get there. If you have two nodes superimposed, it will seem like your first node is completely normal.

Edited April 20, 2014 by Claw

[Claw]

Oh thank you gonna correct that asap^^ So the unstable connection aka my little docking port that is holding the 25 T Lander is not enough?

A wobbly connection isn't really too big of a deal unless it's causing you actual steering problems. If you're unable to turn and aim at all, then you'll want to do something different. But like I said, that shouldn't cause a huge dV swing in the node. The node dV doesn't care about ship config.

[Sirrobert]

Did you test your entire rocket?

If you didn't, I suggest you quicksave, and stage through the entire thing. Pay special attention to the nuclear motors. (after the test quickload back offcourse)

Nuclear motors arranged like that with a decoupler around them have a nasty habit of blowing up when you stage them

[alter5]

If you're using MJ to develop nodes, you might have two nodes superimposed on top of eachother and when you're passing your 900 m/s node you're reaching the second node, which possibly requires 4000 m/s. If you're using MJ to develop the node, click on "Delete all nodes" first, before you have it create a new one.

Also, another reason there might be two nodes is if your departure date is early. I can't remember when the first (cheap) Duna transfer is, but I think it's day 58 or something. Of course that depends on which clock system you're using. But if you are way out on the phase, it's going to cost you a lot more to get there. If you have two nodes superimposed, it will seem like your first node is completely normal.

Well when i create the first Node with MJ it waits like 2 years or so before it starts the Burn so i suppose think(newbie^^) MJ is calculating the ideal phase too?

Edited April 20, 2014 by alter5

[Sirrobert]

Well when i create the first Node with MJ it waits like 2 years or so before it starts the Burn so i suppose think(newbie^^) MJ is calculating the ideal phase too?

Yes, if you tell mechjeb to make a transfer to another planet, it will do that at the next possible window.

However it's a little picky, and if the last window was 2 days ago (for example), it'll wait until the next window. Even though you can still have a pritty easy transfer 2 days after a window. The angle is still pritty much the same

[Claw]

Well when i create the first Node with MJ it waits like 2 years or so before it starts the Burn so i suppose think(newbie^^) MJ is calculating the ideal phase too?

Yeah, it might be trying. Although sometimes if you're too close to the transfer MJ gives wacky results. Just make sure all of the nodes are deleted before you set up your transfer node. Sometimes MJ will drop nodes off in random places and you won't even see them because they're off on another part of your craft's path.

[alter5]

Well thanks for your great help guys, see ya at Duna