Vertically launched space planes

[Ruskiwaffle1991]

So I have the X-20 mod and I really wanna try using it but the problem is I don't know how to create a proper launch platform for it. I don't wanna install another gigantic set of mods for this and I don't have the making history DLC so I wouldn't really know how to make a stable enough rocket that is also capable of getting the plane to orbit or just suborbital. 

[Vanamonde]

Build it like any other rocket, though you may want to preserve the aircraft shape by linking it to the launch stack by the belly rather than the rear, like the space shuttle. The only real problem is that the lifting surfaces the aircraft needs will strongly draw the rocket "upwards," and you'll need to account for that. Give the ship lots of control authority and maybe rotate it so that this trend works in your favor and helps make the gravity turn. Or you can use the really messy fix  of making the craft symmetrical by copying the plane part on each side.

[Ruskiwaffle1991]

Yeah, but like I'm playing on career and I barely have any good control parts. Trying the space shuttle method didn't work out.

[Vanamonde]

I suppose you could put wings on the launch stack to counter-act the wings on the plane. Terribly inefficient but perhaps workable. 

[miklkit]

Or you could not use a rocket at all.  Using a decoupler, you could stick it on the nose of a big airplane and let it take you to altitude, decouple, and go.

[jimmymcgoochie]

The X-20 was meant to be launched on a rocket with really big fins on the bottom to keep it stable, see link below to the image because I can’t get it to embed right now.

https://images.app.goo.gl/m5GNPFeA6QbXE3wU8

Build a normal rocket that has the required delta-V to reach orbit, add an extra 10-20% margin to account for the higher drag and then stick some wing panels to the bottom - no need for control surfaces, engine gimbal and passive stability should be enough. You could also disable the control surfaces on the X-20 itself during the launch as they’ll probably do more harm than good and destabilise the rocket.

And if you haven’t already, enable advanced tweakables in the main menu settings and autostrut everything to stop it wobbling itself to pieces.