Issue with decoupler

[space_explorer]

Hi all,

I recently bought this game and I love it! I followed the various tutorials and  made some successful launches (yeah!).

Now I'm trying to build a custom rocket to make a space station.

However, I'm having an issue with the decouplers. Esssentially, if I use a motor smaller in diameter than the fuel tank right above the motor, the decoupler will cover only the motor and I will see gap in the profile of the fuselage. I'm adding a couple of pictures to show what I mean:

Here is the last stage with the motor mounted: https://imagebin.ca/v/4l5vWwjeFdOd

And here the decoupler attached at the bottom of the engine: https://imagebin.ca/v/4l5vj7g82QRP (the red and yellow lines show the difference I'm talking about).

Is there any way to prevent this?

Sorry if my  language is not technical enough, I'm just learning.

 

Thank you.

 

[James Kerman]

Welcome to the forum @space_explorer.

I have moved your topic to Gameplay Questions.

[Snark]

Hello, and welcome to the forums!

3 minutes ago, space_explorer said:

Esssentially, if I use a motor smaller in diameter than the fuel tank right above the motor, the decoupler will cover only the motor and I will see gap in the profile of the fuselage.

Yes. This is happening because you're using an engine that's smaller in diameter than the fuel tank above it.

Note that the cylindrical thing around the engine that you're looking at has nothing whatsoever to do with the decoupler. It's not part of the decoupler.

It's part of the *engine* and is called a "shroud". And it's the same size as the engine because it's part of the engine.

7 minutes ago, space_explorer said:

Is there any way to prevent this? 

Yes. Use an engine that's the same size as the fuel tank above it.

Or, if you have the Making History expansion installed, there's a set of parts called "engine plates" that can allow you to do what you want.

Or there are various free mods available that include engine plate parts.

[space_explorer]

Hi, thank you for your reply.

I got it.

 

[4x4cheesecake]

Welcome to the forum

Yep, the engine shroud is part of the engine so it will always be the same size, regardless of the size of the decoupler underneath it. Since you bought the Making History DLC, you can use an engine plate to work around this. Place the engine plate at the bottom of the tank, set it to a single node and attach the engine to this node. The engine plate provides an attachment node which can be used to attach more tanks and other stuff, the shroud will be created by the plate in this case und will fit the diameter.

You can also create an interstage fairing: put a small decoupler at the bottom of the engine (you can disable the engine shroud if you want) and then add a fairing base with the correct diameter underneath it. The fairing can be closed on the edges of the tank on top of the engine and cover the engine

[Geschosskopf]

Welcome to KSP, @space_explorer!

If using the MH engine plates, be aware that they have built-in decouplers, but these are between the engine and the tank above it, which that engine is intended to use.  This is normally a bad thing So, if using an engine plate merely to get a shroud the size of the tank around a smaller engine, be sure to right-click on the engine plate and disable its staging.  Otherwise, you risk jettisoning the upper stage engine along with the spent lower stage and leaving the now-useless upper stage tank in place.

The engine plate decouplers are nice in a few somewhat non-standard applications, but this is not one of those.

 

[Geonovast]

11 minutes ago, Geschosskopf said:

Welcome to KSP, @space_explorer!

If using the MH engine plates, be aware that they have built-in decouplers, but these are between the engine and the tank above it, which that engine is intended to use.  This is normally a bad thing So, if using an engine plate merely to get a shroud the size of the tank around a smaller engine, be sure to right-click on the engine plate and disable its staging.  Otherwise, you risk jettisoning the upper stage engine along with the spent lower stage and leaving the now-useless upper stage tank in place.

The engine plate decouplers are nice in a few somewhat non-standard applications, but this is not one of those.

 

That's.. what?  Could you elaborate?  I'm not quite following.

That's not how the engine plates work.  The engine plate is exactly what the OP is needing.  The engine plates have a single decoupler for the bottom-most node, which is what activates the shroud.   The engine nodes don't decouple. 

 

[Geonovast]

1. Attach Engine Plate to bottom of tank.  Notice the node floating at the bottom.  That's your decoupler.

2. Attach Engine

3. Attach Tank to the bottom node.  You don't even need an actual decoupler.

4. Shroud will appear.

5. Toggle Shroud off, adjust height using the variant switcher, then toggle the Shroud back on.  This is done in the PAW by right clicking on the Engine Plate.

 

6. While launching (NOTE: I did this by F12-ing the thing to orbit first.), just stage the engine and plate normally, as if you were using a decoupler.

@space_explorer

As a side note, since I can't see what's inside your fairing, what's going on with the decoupler directly underneath the fairing?  Are you keeping the fairing plate in space?

Edited June 21, 2019 by Geonovast
gbus I can't spell today.

[Geschosskopf]

1 hour ago, Geonovast said:

That's.. what?  Could you elaborate?  I'm not quite following.

That's not how the engine plates work.  The engine plate is exactly what the OP is needing.  The engine plates have a single decoupler for the bottom-most node, which is what activates the shroud.   The engine nodes don't decouple. 

Hmm.  Well, maybe I put it on upside down.  I did lose the upper stage engine when I staged it once.  But I do drink a bit....  So, the engine plate is actually a strange type of decoupler that mounts above the engine instead of below, but which acts below instead of above.  Nice to know.  I've been turning off the engine plate's staging and using a normal decoupler below.