How to build Stage and half spacecraft like American Mercury-Atlas using only stock parts?

[Pawelk198604]

How to build Stage and half spacecraft like American Mercury-Atlas using only stock parts?

[Gargamel]

Moved to gameplay questions. 

[Aerodynamic Kerbal]

I think you might do it with enough offset.

If you add a radially attached attachment point, put on a decoupler and a structural tube with the right diameter, then offset it so that the stage 1 engine is covered up and then finally add 2 fuel tanks on the sides.

Of course there is an easier way but I can't think of such

[jimmymcgoochie]

Atlas-style staging requires hollow parts, which stock KSP doesn’t really have. If you have the Making History DLC then you might be able to use structural tubes and/or engine plates, otherwise your best bet would probably be a fairing with the additional attach nodes on, which you’ll need advanced tweakables enabled in the main menu settings to activate, and a well-placed decoupler for the skirt to decouple and some fuel lines to feed the engines.

It’s a lot easier to just do liquid-fuelled boosters and fuel lines, or solid boosters with fuel tanks on top and decouplers with crossfeed turned on.

Edited August 15, 2022 by jimmymcgoochie

[Stamp20]

1 hour ago, Aerodynamic Kerbal said:

If you add a radially attached attachment point, put on a decoupler and a structural tube with the right diameter,

Rather than a radial attachment point, you could use an engine plate with the shroud disabled then attach a structural tube like Aerodynamic Kerbal said. The engines on the half stage will only use the fuel tanks on the half stage without fuel lines.

Something like this:

[DeadJohn]

@Pawelk198604Attach the sustainer engine directly to the bottom node of your fuel tank. Then surface attach cubic struts + optional cosmetic parts + decouplers (enable crossfeed) + booster engines in symmetry mode. Use the offset and rotate tools to get a look you like.

Image 1 below shows the basic concept. Image 2 adds additional parts to improve the appearance (booster engines have already been staged away in this shot). I have visual mods but only used stock parts.