Renewed Confidence

What, did you think I was just going to give up?

After my first tentative (and ultimately disastrous) steps into interstellar space with the K.S.S. Polymakria, I have a fuller appreciation for the challenges of such long-distance travel. We need a faster ship, and we need to never ever ever turn off time acceleration after leaving the system.

As I began constructing the Polymakria II, I reflected upon how ion engines are a huge pain in the arse for anything bigger than a tiny unmanned space probe. Sure, I gained a few km/s, but I lost a whole realtime day. So no ion propulsion this time. To maximize delta-v, then, the upper stages will be all-nuclear. The launch stages still have to be chemical, since they are the only rockets that can provide enough thrust to break free of a planet’s gravity from the surface.

The other thing I learned is that I should never forget heat sinks on NTRs. Running at 75% thrust instead of 100% was another annoyance that significantly increased the amount of time it was taking.

You might be looking at that picture and wondering what I’m going to do with a cargo bay. The answer is this:

Inside the bay we’ve got a couple of batteries, two RTGs for long-term power, some monopropellant, scientific instruments just in case space is all wonky, and a little detachable exploration vessel which has been nicknamed the “Scooty-Puff Jr.” Yes, all these things could be mounted on the outside of the ship. But where’s the fun in that? If I’m going to have Kerbals riding in this thing for several thousand years, they might as well ride in style.

Now we need a few more fuel tanks, because the first rule of rocketry is “more fuel = better”. (I think Tsiolkovsky would agree)

However, it’s not a rule of rocketry that five engines are better than one, so I guess this design reflects my impatience with the low thrust of nuclear rockets.

Next comes the in-system boost stage. If five engines are fun, then how about sixteen?

Oh… oh yeah. That’s what I’m talking about. Everything’s heat-sinked and covered in struts, as it should be, so now let’s get to adding the really big rockets.

First, a large upper chemical stage that should be sufficient to push the ship into orbit once given a kick by a truly monstrous first stage, and then the aforementioned monstrous first stage, and then…

Total height: slightly too tall to fit in the vehicle assembly building. Total weight: a lot. Total number of parts: my computer is crying.

I think we should take a moment to admire this beast.

Alright, anyone can make a ship that sits on the pad without exploding (note: this is sometimes a harder challenge than it may seem), but the real test is the launch. Does it have a high enough thrust-to-weight ratio to go up? Are there enough struts to keep it from falling apart? Is it going to be controllable at all? Well, there’s only one way to find out. Set thrust to maximum, check the staging one last time, hit that spacebar, and…

WE HAVE LIFTOFF!

I’m launching this right at sunset so I can skip getting it into orbit around Kerbin and just go straight for the heliocentric orbit.

The fuel in the first stage lasts a mere three minutes as it is guzzled by the thirty-two individual rocket nozzles (not counting the boosters). The thirty-engined N-1 ain’t got nothing on this.

Stage two has far fewer engines, but these ones are much larger. Four of them are sufficient to push the ship the rest of the way into orbit and begin its escape from Kerbin. Soon the chemical fuel will be expended and it will be time to light the nuclear rockets.

Once the ship is clear of debris, it’s time to throttle these babies up. Let’s see what this thing can do!

I knew that having 16 engines in fourfold symmetry like this would look good.

Once the solar apoapsis has been raised enough (~200,000,000 km), our brave crew (sadly not visible in the lower right of the screen due to some issue with the MK2 cockpit) shuts down the engines for the first long coast phase of the mission. Well, now’s a perfect chance to test the miniature exploration craft in the cargo bay. Matrey Kerman suits up and heads out.

He climbs onto the little seat and undocks, gently firing his thrusters to get clear of the cargo bay.

Oh, right, I forgot to put any sort of reaction wheel on this thing. And it’s unbalanced. So it is basically uncontrollable. After trying for a few minutes to put it back in the bay, I give up and leave it floating in space. Matrey’s main report, unsurprisingly, is that the “Scooty-Puff Junior suuuuuuuucks….”

With Matrey back aboard the ship, they close the cargo bay doors and get ready to fly for 11 years or so out to apoapsis. Once there, they swing the ship around and fire the engines again to bring the periapsis down to around 500,000 km…

At 2 hours from periapsis, we exit timewarp and begin the final thrust maneuver. Lightyear, here we come!