tail-lander

Empress Eledíë-class explorer

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So, if you were following my G+, this is what I said this morning:

Well, since The Martian , and seeing their gorgeous model of Hermes , I’ve had a real urge to design the Empress Eledíë-class explorer, which one might be able to claim resembles its bigger, upteched, somewhat more Raygun Gothic cousin, but still from the same essential design school.

(This may slightly confuse people who’ve seen William Black‘s awesome rendering of the Drake-class frigate. The answer is that the Empire has multiple schools of spacecraft design: the Drake and its colleagues have their sleek, unitary look because the necessities of building starships that get shot at a lot, especially in the ‘can classes, mandate packing everything you can inside the well-braced armored shell.

The more commercial ships, the Cheneos-class and Kalantha-class freighters, for example, have a more industrial look that eschews the above for efficiency, although still with the Imperial eye for beauty.

And so the Imperial Exploratory Service’s vessels, the direct lineal inheritors of the scientific, research-oriented, modular tradition going all the way back to the Spaceflight Initiative, reflect that in every line of their design.)

So, yes, I’m mucking around with some preliminary sketches and numbers for that. Post at later.

Well, turns out that’s not stringently true, because I have yet to produce some sketches which satisfy me even to the level of the various dubious sketches posted here before. But what I can give you is a nice verbal sketch of the design layout, so here we go.

The Empress Eledíë (a class named after the founder of the Imperial Exploratory Service, if you were wondering), like the Hermes, is essentially a spinal design; it’s built around a long central passage-core, in this case a cylindrical axial passage and conduit space nested inside an octet truss, with internal handguide tracks for getting about the length of the ship quickly, and a matched pair of very long emergency ladders for those occasions on which it’s necessary to move about under thrust when the microgravity-sustaining space magic isn’t working. (This is not a recommended procedure.)

(To simplify matters in the following description, I’m going to use the standard IN nomenclature of defining cardinal directions perpendicular to the thrust axis as dorsal, starboard, ventral, and port. These are, of course, entirely arbitrary: the designers simply defined a 0° meridian and allocated names to directions at 90° angles therefrom. But they’re convenient for description.)

There are two places in the design where things aren’t simply hung off the spine, at the furthest extent of the bow and the stern. At the bow, this is the foreshield and the cargo pod. Like most sensible tail-lander designs – not that this class does or could ever land – this also includes the for’ard airlock, which is the starship’s primary airlock.

But you need a foreshield, or something to fulfill its function, when you’re going to go flying around on top of powerful drives. So at the bow, the spine expands into a support frame around the outside of the cargo pod, which in turn supports the foreshield. The axial passage runs through the cargo pod to the for’ard airlock. (Having the cargo pod right up here makes it nice and easy to move supplies in and out.) The pod includes vacuum-accessible cargo holds mounted on its surface at the cardinal directions, to store big items intended for use outside, like replacement probes and cutter modules.

The foreshield itself is a large convex plate divided into four quarter-circle segments, mounted at the 45° intervals onto the surface of the cargo pod by damn great motorized arms. When you need to use the for’ard airlock, these arms pull the plate segments out and back to expose it and let you dock, or something dock to you.

Moving aft, the next thing we encounter are the communications and sensor towers. The actual towers are to dorsal and ventral, and are designed to extend, raising the forest of antennae and telescopes and dishes and sensors at their tips to the point that they can look beyond the foreshield, when the ship’s not under hard burn. Lesser geodesics to port and starboard house the continuously operating navigational sensors.

A minor bulge a short distance behind them houses the working elements of the for’ard reaction control system.

Aft of those, four cylindrical-with-rounded-ends bitat pods, very similar but differentiated by minor features (the bridge has a cupola for visibility, for example, and the robot hotel has an airlock for the maintenance ‘bots to clamber up and down the spine), strapped onto the truss provide working space: the bridge from which the ship is navigated to dorsal, the sensory analysis center to ventral, and the robot hotel and some auxiliary engineering space to port and starboard, respectively.

Next up, the low power radiators (to port and starboard), for dissipating modest amounts of heat from life support and other auxiliary systems that aren’t the reactor and drive.

We now enter the pleasingly symmetrical central section of the ship, with the for’ard gravity wheel, the habitation wheel, which rotates clockwise on a four-spoked mount. It comes with crew quarters, the galley and mess, the gymnasium, the library, recreational areas, and various other your-home-in-space facilities.

Behind that is the docking cruciform, in which a symmetrical four-fold expansion of the spine hosts secondary airlocks. On an Empress Eledíë with its standard loadout, these carry the starship’s small craft – standard Élyn-class microcutters, capable of commuting to and from planetary surfaces. A supporting framework helps secure them while under thrust.

In the middle of this section, a bigger cylindrical pod which wraps around the axis, is the ship’s park. The central part of that is exactly what it says on the tin, an open microgravity space that functions as a park and greenhouse, serving both to freshen the air and replenish the food supply, and to provide some open space to help people from going space crazy on long missions. Tankage for life support and spare water and so forth is wrapped around the outside, which lets it double pretty effectively as a caisson, in case of solar flares that the regular shielding can’t manage.

Aft of that is the laboratory cruciform. These aren’t the main labs, however: the cruciform structure itself is basically identical to the docking cruciform. In the standard loadout, though, it holds the hot labs, which are Bigelow-style inflatable habitats used for additional microgravity lab space. With the advantages of being isolated by the airlocks, and readily detached from the rest of the starship in the event of some artifactual oops.

And at the aft end of the symmetrical section, the aft gravity wheel, the laboratory wheel, which has a similar four-spoked mount to the habitation wheel, but rotates anticlockwise, thus cancelling out the gyroscopic effect of all this spin gravity as much as possible. It contains laboratories, workshops, and other research-oriented facilities. Most importantly, it contains a segment that’s offset to the outboard, whose “floor” opens up; this is the probe garage, so designed to allow probes to simply be dropped through the floor and centrifugal force to carry them outward and away from the starship, clear of the shielding and to safety range, before engine ignition.

Aft of this, finally, we now reach the drive and engineering section. First, of course, we reach the propellant tanks, multiple layers of D/He3 tanks strapped onto the truss serving in their double role as fuel bunkerage and radiation shadow shield, and right behind them, at the 45° intervals, the four high power radiators to carry away the heat from the reactors and the drive. The pressurized axial passage within the truss ends at this point in a heavily shielded airlock: it’s mostly the ship’s mechs that climb further back down the truss, and even when sophonts do, they go outside to do so.

Beyond this point the spine begins to broaden into the drive-supporting thrust frame through which’s volume the various high-power engineering machinery is fixed, including the power reactors, the vector-control core, and so forth, and on top of which is surface-mounted the clusters of the aft reaction control system,

And then, at its base, the clustered fusion torch drive that pushes the whole starship along.

(Keep well clear.)

Starships Are Not Boats

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As explained here…

(In short, down, when under thrust, is determined by the direction of your drive axis, and specifically, is the direction your engine is in – because it’s pushing you the other way.)

I feel somewhat bad, sometimes, for violating this one here and there, sometimes quite egregiously, but there’s a reason for that, and it has to do with the fiction in my science fiction. Specifically, the inertial dampers that I talked about here. See, way back in the day before those were invented, from the Phoenix stack on up, spacecraft and then starship design was indeed constrained this way; virtually all designs were tail-landers, with the decks perpendicular to the drive axis, and the only exceptions to that rule being belly-landing vehicles intended to operate in atmosphere and/or land planetside, in which case the need to deal with the planetary gravity field took precedence and those aboard pretty much had to suck it up and deal with the inconvenience when in space and under thrust.

(We omit, for the moment, the complexities of spin gravity and the combination of spin and thrust “gravity” that gave the world terms like thrustdown and spindown and realdown and lots of rather complex gimballing mechanisms.)

But then the inertial damper was invented, thus ensuring that the interiors of starships equipped with it were under microgravity all the time, even when they were under thrust, and naval architects almost immediately split three ways:

  1. The traditionalist school, who had been building tail-landers for a millennium and dammit, were going to keep on building tail-landers, because that’s how spacecraft ought to look, and for that matter, it’s kind of nice to still be able to fire up the drive if your inertial dampers break down, isn’t it?
  2. The convenientist school, who countered that people had been complaining about what a pain in the ass ladders, companionways and elevators were for getting about inside spacecraft for most of that millennium, especially if you’re not under thrust most of the time, that long corridors are much nicer, and that it’s good not to have large pieces of equipment split between a half-dozen decks, and so now that they could build starships as belly-landers, dammit, they were going to.
  3. And the spacer school, who pointed out that if there’s one thing that you could learn from modular and beehive habitat design over all that time, it’s that “down” is a strictly local phenomenon and one only useful under a few circumstances anyway, and that in a microgravity environment not only can you arrange your decks any damn way you please, but you don’t even have to be consistent in doing so, and proceeded to arrange their designs’ interiors in whatever way they felt was useful at the time and place.

In what I think of as the modern era, the spacer school has essentially won the argument, although examples of the other two schools do still show up. (After all, planet-landing craft have to be consistent one way or the other, what with that planetary field to contend with.) Among people who have the relevant technology, at least – the constraint still exists, and applies in full to anyone who doesn’t have fancy ontotechnological physics-editing tech to play with.