Decoupling stages at the wrong time

[SagansSpace]

Hello guys,

I am new to KSP and I got strange problems with decoupling parts.

 

I am building my rocket, everythings looks fine. Liftoff and  decoupling works until I am on a Kerbin orbit. While the rocket is flying orbital, I got enough power, flight controls (controlled from Kerbin) and my antennas are working fine aswell. Now I am trying to decouple so I can use the next engine for leaving the orbit. But instead of burning the next engine, the rocket disconnects the top coupler, located under a fairing. I am loosing a complete stage and I am forced to use the satellite engine (trying to bring that one to mun) to leave the orbit.

The stage order should be correct, I tried to google my problem, without succsess. Here are some screens:

 

https://picload.org/view/dladadlr/20180725202104_1.jpg.html

https://picload.org/view/dladadol/20180725202111_1.jpg.html

https://picload.org/view/dladadaw/20180725202105_1.jpg.html

 

Thank you all

 

 

[4x4cheesecake]

Welcome to the forum

Usually, this is a staging error, so you should double and tripple check your staging Lets take a look at your screens:

Stage 4 ist your transfer stage to the Mun? By looking at the shroud, I guess it is a rhino?
So stage 6 is the one you want to decouple via the decoupler in stage 5 so you can use the rhino in stage 4 to fly to the Mun. But instead of stage 5, your staging 'jumps' to stage 3 and decouples the whole transfer stage, is that correct?

It might sound silly but your stage 6 looks pretty massive so maybe it just stays in place even though it is already decoupled. Is it possible that you just pressed your staging key a few times more because it looks like the stage does not decouple? Which numbers are displayed during your flight on the 'stage counter' in the lower left corner? Does it skip stage 4?

If you can provide a .craft file (upload it to dropbox, onedrive or whatever) so we can take a closer look on our own, that would be really helpful as well

[Superfluous J]

If you hover your mouse over the events in the stages, the parts that will do that thing will highlight. This is how I troubleshoot any and all staging problems. Works in flight and in the VAB.

[SagansSpace]

Hey,

thanks guys. I already know this horseman, but even thank you for helping.

Its just exactly like you wrote it cheesecake. I wasnt able to check the stage control indication to this point of time, but I already uploaded the .craft file.

https://www.file-upload.net/download-13246064/Beyond.craft.html

 

Maybe, I fortgot some information. After decoupling the "middle" stage, I have to change the vehicle, which is controlled, by using the map. Maybe KSP recognizes the top stage, as an independant spacecraft.

 

Thank you

[4x4cheesecake]

2 hours ago, SagansSpace said:

Maybe, I fortgot some information. After decoupling the "middle" stage, I have to change the vehicle, which is controlled, by using the map. Maybe KSP recognizes the top stage, as an independant spacecraft.

That's an imporant information and it happens to me as well. Fotunately, there is an easy solution for both issues

Just use the 're-root' tool on the top probe core (the one placed below the resource scanner). It is a bit strange to use...select the tool, click the probe core once, move your courser away from the core and click the core again. Now, you picked up the whole craft and the top probe core is the new root part. Click again to drop the craft and your done. Everything should work fine now  

I'll try to explain it to you:

You actually made one mistake while creating your rocket: You build it from the bottom to the top. Your root part (the very first part you placed) is the central 'Twin Boar' engine in the first stage (first stage mean in this case 'the first stage that burn', not stage #1!). As soon as you decouple the first stage, your rocket will loose the root part but there must be one root part for every craft. So KSP will fix that for you and pick a part new part to be the new root of your craft. Usually, KSP will pick command modules or probe cores (or the next one in the 'tree' structure? Not quiet sure though but the result keeps the same^^). And that's the point: You got at least 2 probe cores in your rocket and the next one, when moving from the bottom to the top, is in stage #6.

As soon as you decouple stuff, most of it will be marked as 'debris' and nobody cares about. But if there is a command module or probe core on the decoupled stage, it will become a new vessel and if there is a command module or probe core on both sides of the decoupler, you basically split one vessel into two vessels. Now, KSP has to decide which vessel will be focused and it will always be the one, which contains the root part of the original vessel. The 'new created' vessel will pick a different part as root (you remember, every vessel needs one). In your case, you will keep the focus on stage #6 so you have to switch to the other vessel you actually want to fly. The same thing happens as soon as you decouple the next stage: New root part will be selected on the new created vessel and the focus stays on the one with the root part of the original vessel, in your case this is stage #5. This pattern keeps going on until you reach the top probe core.

By seletecting the top probe core as root for the whole rocket, you avoid this behaviour since your focus will always stay on the part of the rocket you actually want to fly.

I would like to recommen to you, to start building your rockets from the top, to the bottom. This will prevent issues like this one and KSP actually expect you to build your rocket in this direction. Start with your payload, put all the other stages below and you should be fine in the future

Btw.: Your rocket design remindes me of the house of edith fintch...I like it, really extravagant  

edit: I haven't mentioned it explicit so: Your staging works fine as soon as you use the top probe core as root part for the rocket

Edited July 26, 2018 by 4x4cheesecake

[SagansSpace]

Ok, thank you. I were able to fix the problems with your help 

I also started building my new rockets from the top now -> no more staging problems.

Nice to hear you like the design, I think extravagent is the best descritption for it.

Thank you again, topic could be closed