Strange CoT problem (bug?)

[Floule]

Hello guys!

Since several days I have a problem with some strange CoT issue which stops me from building my first mun base.

Here is a screenshot: Link

As you can see, the section with the nuclear engines is seperated from the upper part. But the CoT ignores this, and combines the nuclear engines with the two in the upper section.

Flight behavior is as expected with this CoT, completely unflyable.

May be relevant: I created the upper part in the SPH, and transferred it to the VAB(Yes, I did change the "type=VAB"). I then proceeded to add the nuclear engine section.

Is this a known bug? Is there a workaround?

Edited September 29, 2014 by Floule
embedded image

[Alshain]

If I'm seeing this right, your staging has the LV-909's decoupling at the same time as they are activated. If you notice, even Engineer isn't reading that stage.

Edited September 23, 2014 by Alshain

[Floule]

Thanks for the fast reply!

But no, thats not the problem, I tested it right now, and proper staging makes no difference.

[Alshain]

Well, that may just be the way it is. I can't say I've ever tried building a rocket like that. What's holding the LV909 engines on?

[Laie]

If the editor disregards staging while displaying the CoT, you must temporarily replace the LV909s with something of similar size and weight that is not an engine. Like, a stack of six 1x1 panels attached to a docking port (perfect weight, not so sure about the CoM). Or a FLT-100 Tank, with 31.5 fuel / 55 oxi, would come pretty close at 495kg.

You don't have to get it 100% right -- on a 30ton vessel, 10 kilos barely matter; nor does a slightly off-center CoT. It will suffice if you get it good enough so that SAS can handle the rest.

[cakepie]

You can temporarily tweak the thrust limiter on the LV909s to zero, that should give you the COT without their contribution.

Just remember to turn them back on when you're done!

[Rhomphaia]

For building assymetric craft I would suggest RCS Build Aid.

I would also suggest that after placing the fuel tanks that the engines are mounted on with symmetry, add the engines one at a time. that way you can tweak the trust of each one to compensate for the asymmetry.

[Laie]

thrust limiter

*facepalm*

[Claw]

Yeah, this isn't really a bug so much as how the editor is built. It always shows the composite CoT regardless of staging.

As was suggested, if you want to see the thrust vectors separately, you need to tweak the limiters to zero. Just don't forget to put them back.

Cheers,

~Claw

[Floule]

Yeah, this isn't really a bug so much as how the editor is built. It always shows the composite CoT regardless of staging.

As was suggested, if you want to see the thrust vectors separately, you need to tweak the limiters to zero. Just don't forget to put them back.

Cheers,

~Claw

Okay, thanks for that. Looks like I wasn't clear enough about my main problem.

When I try to fly with this craft, it acts like not only the nuclear engines are burning, but also the upper two engines. Of course, the upper two engines aren't fired up, but somehow the craft acts like they are. Any ideas about that?

[cakepie]

Probably because of your asymmetrical design. Looks like there's more stuff on the girder side of your upper stage, which could mean:

1. Are you sure CoM is perfectly centered? It's hard to tell from your screenshot. If your nuke stage CoT isn't lined up nicely behind the CoM, it would lead to asymmetrical thrust. Since you describe the craft to be turning as though the LV909s are firing, this suggests that your CoM is off toward the girder side.

2. May be a drag issue as well, with more things sticking out on the girder side slowing it down, causing craft to apparently turn toward that side.

[Floule]

Probably because of your asymmetrical design. Looks like there's more stuff on the girder side of your upper stage' date=' which could mean:

1. Are you sure CoM is perfectly centered? It's hard to tell from your screenshot. If your nuke stage CoT isn't lined up nicely behind the CoM, it would lead to asymmetrical thrust. Since you describe the craft to be turning as though the LV909s are firing, this suggests that your CoM is off toward the girder side.

2. May be a drag issue as well, with more things sticking out on the girder side slowing it down, causing craft to apparently turn toward that side.[/quote']

I can't play and try it out right now, but looks like I'm a complete idiot. This is most likely the problem. Sorry for the fuss about it, I was really confused about the whole thing. Thanks a lot for dealing with another idiot who blames the game for his mistakes

[Claw]

Thanks a lot for dealing with another idiot who blames the game for his mistakes

It's not like that. The community exists to help anyone and everyone enjoy the game.

Cheers,

~Claw

[Pecan]

Yeah - because almost every single one of us has made the same mistakes or only avoided them because someone asked just before we got it all wrong.

[Heagar]

There is a solution for all your problems at the same time:

I see a docking port in the front near the center of your payload. Use this as a mountpoint! You can either use a (flipped) second docking port on your final stage or a normal decopler. Then strutify the payload for the needed stability.

BTW: You don't need to manipulate your craft file to switch it to VAB or SPH. Simply put it in the subassembly, from witch you can load it in both locations.

Edited September 25, 2014 by Heagar