Ninety-Three

Plaid goes so fast that it blows through Kerbin's atmosphere in a single frame. At this point, changing the decoupler count produces a corresponding linear change in speed. The only thing stopping you from exceeding the speed of light is your computer's ability to render the decouplers. Putting aside the physics of whether Plaid would burrow or explode, it's not actually that bad. Theoretically Plaid should be massless, but F = ma gives us 0.00508 t. I have no idea where that comes from, as it's not strut count or the RCS flair block. Using this mass, Plaid impacts the Mun with 1.86 * 10^12 J of kinetic energy, or 450 tons of TNT. That said, you can (say, to Duna), which will have significantly more mass.

Well of course not, it's 6.6!

Putting a bit more work into the engineering of it, the same trajectory could be used to get almost the same time with Sepratrons, landing completely intact. You'll notice that I bubble-wrapped my ship in landing gear, with an impact tolerance of 80 you can slam into the VAB pretty hard and survive. Edit: You could probably also manage an intact landing using exactly that ship, and adding some excellent timing on pre-igniting the SRBs before unclamping. That would get pretty precise, but once you bubble-wrap the SRBs, I bet it would land intact too.

Ignoring the points, I built a maximum efficiency model that is theoretically sound, and weighs in at under 620 kg, manned. It's currently in orbit and awaiting me to be struck by the fit of patience required to set up a Minmus intercept that coincides with good solar power, I'll probably have photos in by the end of the day.

Pft, math. Eyeball it! I present to you: Six seconds (or seven, if you insist upon a clear view). On the launch pad. Decouple the first set of boosters and engage the second. Decouple the second stage and drop to ground. In this screenshot, I'm landed, though the blast from my second stage hitting ground obscures it. Look, the lander! Clear view. I didn't bother to, but since the entirety of your input to this design is pressing space twice after launch, it should be pretty easy to do this in IVA mode, once you practice a bit to get the timing down.

I'm not sure I like the idea of awarding more points per ton instead of the usual challenge style of rewarding efficiency, it's going to lead to the challenge winner being whoever's computer can handle the three thousand solar panels that it takes to power their hundred ton ship. Despite my reservations, I've had a lot of fun messing around with solar panels on Minmus, so I'll be signing up. A clarification: The 75 points for "no return stage", am I right in reading that as "Single stage ion vehicle"?

If you allow RCS, I can get to Duna and back.

That would be me! I sent an SRB ship to Duna, and back with only solids (plus RCS for course correction). It doesn't technically qualify for this challenge, but for those interested, here's the mission report.

Oh, I got well over 100 m/s on Minmus (airplane wheels, not rover parts). You pretty much lose the ability to turn, but you can continue to accelerate at least. If you hit the slightest bump at those speeds, you'll go flying madly, which is why I'm looking for flat Munar ground. What I'm looking to do is less about turning and more about "Munar land speed record", I didn't have high hopes, but I figured it was worth checking for the presence of some perfectly flat terrain.

A while ago I had great fun playing with a rover on the Minmus salt flats, using the wide open spaces to get up to some really good speeds. I've been trying to recreate this on the Mun, but so far the rover has a tendency to lose control the first time it hits a bump going much more than 40 m/s. Does the Mun have any large ultraflat surfaces for rover racing like Minmus does?

To the people having trouble launching Plaid, it occasionally fails to launch correctly when I run it. There doesn't seem to be any technique, the game just isn't too fond of sixty million Gs, I suggest simply giving it another try, it works more often than not (though a warning, decoupler stacking is not fond of the "Restart Flight" button, so you should go back to the Space Center first). I will mention that pressing escape isn't a necessary part of the launch, it just helps you get the re-entry screenshots.

By popular request, I've taken Plaid on a new journey. Yeah, we're going into the sun. Hurray!

Like I said, the ship launches the same regardless of which, if any decoration you use. The ten times lighter solar panel and nothing also yield 0.0508 t.

It really is just decoration. In the early designs I had a few theories on it being helpful, but they fell through. I kept it around because I thought it looked nice. The ship launches the same if you use a much lighter solar panel, or no decoration at all. F = ma tells me it's inheriting 0.0508 t from somewhere, and I'm not sure where. Current theories include a hardcoded amount of mass added to all ships, and "Weightlessness is glitching it hard, and the speed it spits out just happens to be very close to a nice round number", but that theory's a bit weak because I've observed that my maximum speed scales very linearly with decoupler count.

Look at the mission report I linked, it's all explained.