Stock parts, no mods, KSP v.0.24.
In case you're wondering: no, it does not use the schnazzy new monopropellant engines instead, though I suppose that option is both tenable and tempting. Nope, this craft is in fact an example of the miracles that can be performed through the combination of (in)glorious air hogging and thrust limiting. So come with me and rejoice! in the abhorrent splendor of perpetually abusing KSP physics.