In which, as promised, I nerd out about the spacecraft you’ll be flying in the game from now on. I’ll get right to it and not talk much about the changes in this release, as you can look up the patch notes for that. However, there is one thing I’d like to quickly mention first!

Context!

I’ve added a codex screen to the game! You can open it from the title menu. It’s not much to look at, and it doesn’t have a lot of information in it yet. But I’ll be adding to that a little bit with every release from now on to start giving you a sense of the world in which this whole game actually takes place. There isn’t any real integration with the game yet, so you won’t be able to unlock entries and learn things as you play for now. But in time, I hope it will give some background information to fuel the imagination and make things a bit more interesting. In this release, there’s an article about the Great Lunacy, the first of a series of major events that will shape world from what it is to what it has become by the time the game starts.

Here comes Alex

Now, without further ado, let me introduce you all to the spacecraft you’ll be flying in-game for the foreseeable future! Here’s a shot of the ALLOX-Shana-F, more commonly called Alex (right-click and open image in new tab to see full resolution, itch doesn’t do lightboxes):

ALLOX is the name of its main engine, the ALLOX-100, after the aluminium-liquid oxygen mix it burns, utilizing a 100cm diameter fuel grain of foamed aluminium. Yes, it’s a solid-liquid hybrid.

Shana, meanwhile, is a reference to the crafts origins, which was the Shanabi light tug series which was very successful during the Great Lunacy. The Shanabi itself went through several iterations, and some joker thought it would be good marketing to call the next iterations Shana-C and Shana-D (there never was a Shana-A, for obvious reasons).

The Shana-D was the design the Alex was built on, or rather the spacecraft that were most commonly cannibalized to build the first couple spacecraft in the Alex series, which itself went through a rapid prototyping phase (the ALLOX-Shana-E) before arriving at the F design that finally saw major success during the busted years and is still built by the outer orbits to this day (that is, the day at which the game starts).

With resupplies from earth being cut off after the big bust, preserving the lunar water reserves for the human population and essential industries became the highest priority of the orbital communities. Using hydrogen as a propellant for rockets became unthinkable over night (though a majority of lunar inhabitants were already fighting the consumption of the limited lunar water by earth-based corporations before that). And yet, while that might have been good and well for the Moon, the stations in earth orbit needed a capable enough rocket to keep essential logistics between their population centers going. Aluminium and Oxygen are both abundant on the Moon, and solid aluminium rockets were already used in the majority of lunar launch systems apart from the mass drivers, so much of the industry to produce the propellant already existed. But they still had to make the hybrid engine work efficiently enough to be of use, which had never been done before. With the potential collapse of orbital logistics and the resulting thousands of deaths that would cause breathing down their necks, they made it work surprisingly fast. But while the ALLOX-100 represented a small and life-saving miracle, they could not achieve the impossible either. There’s just so much you can get out of an aluminium-oxygen hybrid, so compared to HydroLOX or MethaLOX rockets, Alex’ performance can be considered thouroughly unimpressive. But even now, with trade with earth having been going strong for a couple of decades, the cost and availability of ALLOX beats out upported Propellants for most purposes by a wide enough margin that there’s no end to its use in sight. The only thing that could break that advantage, short of magic antigravity, is asteroid-sourced hydrogen. It’s being worked on, but we’re not there yet…

There’s a slightly longer variant of the Alex that can carry a longer fuel grain for more Delta-V, though some of that is lost to additional LOX-tanks. That model is officially called the ALLOX-Shana-G, but more commonly referred to as “Long Lex”. When the ALLOX-150 engine was developed later on, a larger ALLOX using a 150 cm aluminium grain to provide more thrust, the Alex-Shana-H reached the market. The misnaming tradition continued, and the craft was called “Fat Lex” right out of the gate. While an Alex can be retrofitted to a Long Lex relatively easily, the Fat Lex shares almost none of its components with the earlier design except for the cargo cradle and the pressure cell.

A contraption of aluminium, hemp, and vicious necessity

Now that I’ve divulged a bit of the spacecraft’s history, let’s have a closer look at the actual spacecraft itself:

1. Cargo cradle, operated by winches and ropes.
2. Payload dock (optional)
3. Main docking port
4. Pressure cell, 3.5m x 1.5m diameter, though quite a bit of that space is taken up by the life support systems and electronics. The Alex may not be entirely claustrophobic, but definitely not comfortable if you’re stuck in it for a few days.
5. Main electrical systems like batteries, transformers, main bus etc.
6. The “plug”, A simple construction that is inserted into the front of the fuel grain.
7. Ropes pulling the plug (and with it the grain) back against the pressure of the combustion chamber.
8. Foamed aluminium fuel grain, 10.5m x 1m diameter.
9. Guides keeping the fuel grain in place while maneuvering.
10. Main truss. The backbone of the Alex, holding all its parts up against the acceleration of the craft.
11. Manually disengageable cuffs allowing the bottom of the truss to fold down for inserting the fuel grain.
12. 4 LOX tanks, 2m in diameter, for a total of 14.1 tons of (mostly) liquid oxygen, kept at an equilibrium pressure of 12 bar. The two left-side tanks are removed from the picture for better visibility.
13. Electric winches to pull the fuel grain into the combustion chamber.
14. Combustion chamber, where the LOX is injected to burn with the porous aluminium grain. Operating at a nominal pressure of 7 bars for a maximum of 290 kN of thrust.
15. LOX-injection, pressure regulators and thermal control of the combustion chamber (one unit on each side).
16. RCS thrusters.
17. Exhaust nozzle, ejecting up to 110 kg/s of Al2O3 at a velocity of up to 2650 m/s.

Specs

• Dry mass: 8500 kg
• Maximum remass: 30 tons (15.9 tons aluminium, 14.1 tons LOX)
• thrust: 290 kN
• exhaust velocity: 2650 m/s
• Maximum Delta-V without payload: 4000 m/s

A few fun facts:

• Hemp is actually a common crop on the moon and the outer orbits, by virtue of almost every bit of the plant being usable for something. Most clothing is made of Hemp, as cotton is a horribly wasteful plant when you need to maintain a closed ecosystem. And of course it makes for excellent rope, which is useful in a lot of applications.
• The fuel winches don’t have to pull the entire mass of the fuel grain. As the craft accelerates, the grain “falls” into the combustion chamber partly on its own, as it is not clamped down. A full grain would do so even against the chamber pressure. This would however be too slow to sustain the 3.6 cm/s velocity by which it needs to be fed into the chamber to sustain the proper massflow at full thrust.
• The LOX is fed into the combustion chamber by tank pressure, maintaining an equilibrium temperature to vaporize parts of it to maintain the pressure. Apart from the thermal control of the combustion chamber and nozzle (also using a part of the liquid oxygen in a “pre-heat for cooling” stage before injection) the system and plumbing responsible for this is the most complex part of an Alex, and somewhat more prone to developing issues than the rest of the craft. A solution with another gas with a lower boiling point would have been much preferred, but the moon doesn’t have many gases to spare apart from oxygen. With renewed trade with earth, some pilots retrofit their Alex to use such a system to increase reliability despite the higher operating costs. It doesn’t take much, after all, and most is reusable.
• Not yet depicted in these illustrations is the RMS which is usually attached to the right side of the craft right beside the pressure cell (between the RCS thrusters), and the suit port on the left side in the same position, where an EMU can be docked to. The EMU never enters the pressure cell, rather a pilot enters the EMU through this specialised airlock.
• There is no front docking port by default, the main docking port of the craft is at the top of the pressure cell. However, a front dock port connecting to the pressure cell can be installed to enable interfacing with pressurized payloads, allowing the Alex to ferry passengers or providing more ample living space for exceptionally long trips, though at the cost of other payload.
• The truss couldn’t hold the mass of the full LOX tanks (most of it hanging from the front of the truss by ropes) at maximum acceleration, but since the craft can’t reach that acceleration with full LOX tanks, the point is moot.
• It is an old joke among Alex pilots that if it ever happens that both electric winches for the fuel grain fail at the same time, “you’ll have to get out and push”.

Alex vs. Reality

It is inevitable that any hard science fiction design will eventually get deconstructed by some space nerd that will present a couple of flaws that would make the whole design completely unfeasible in reality. This is because authors are usually not multi-disciplinary teams of engineers spending years designing each individual component of the system. Me, I’m no engineer at all. I’m doing the work of a software engineer for almost 10 years now, but I never had the education of one, and as Don McMillan once pointed out “Software engineers don’t count!”. In fact, I’m not even an author. I’m just some dude making things up, and on top of that, I have significant deficiencies in practical thinking, as my wife keeps reminding me off. In short, I’m not the guy you’d want to come up with elegant solutions to complex engineering problems under severe resource constraints.

But I am a space nerd, and occasionally I do deconstruct science fiction concepts and present a couple of flaws that make them completely unfeasible in reality. So let me help you along and do the preliminary analysis of the design right away so you can pick it up from there and rip this thing apart. Some of your input might even go into improving the design in the future!

Performance: We are already using aluminium in solid rocket fuels, but a throttleable aluminium/lox hybrid has never been built. There is one paper around that documents an experiment with powdered aluminium and gaseous oxygen, and the results are thoroughly underwhelming. However, this was just an experiment, not a serious attempt at designing and optimising an actual engine. The current ISP is theoretically possible, or so I’m told, but highly optimistic. It is highly questionable if an engine with this performance could actually be built.

Dry mass: The dry mass of this thing is highly optimistic! It is in fact significantly lighter than the Apollo capsule with CSM. I ran some calculations to make sure that pressure cell and the LOX tanks capable of holding the pressure wouldn’t completely blow the budget apart, and to my surprise they didn’t, but in the end it’s mostly guesswork in which the most unknown component is the engine. I have no idea how much that thing would really weigh and not really any means of finding out other than some ballpark scaling from existing engines. In the end, I picked something that wasn’t completely impossible but still kept the game playable.

Reaction control system: This one part is kind of magic right now. It’s envisioned to work with powdered aluminium injected by gaseous oxygen that would at the same time be the oxidizer, with each thruster being a self-contained unit, but right now you’d be right to ask where the hell the thrusters store their propellant. The RCS was very much an afterthought and in the end I had to get to doing other things, so I just slapped a couple of thrusters on. Also, the front thrusters would actually be blocked by the payload, which I only realized while looking at my render when writing up this article. Maybe I’ll get around to revisiting that at some point in the future. At least, replacing the RCS with something more powerful and convenient working on upported Monopropellants from earth is a point on the upgrade tree I have currently on the drawing board.

Pressurizing liquid oxygen with gaseous oxygen: I have it on good authority that this is possible. But it’s not trivial. What would the thermal control system look like that reliably keeps the equilibrium temperature, especially in a vacuum? No idea. However, given the power a pump would require to push the LOX into the combustion chamber (about 80 kW with a halfways reasonable efficiency of 50%), I figured our future lunar engineers, undoubtedly orders of magnitude more capable than me, would be ingenious enough to make it work, given the alternative involves massive batteries, the raw resources for which are hard to come by on the Moon, or a separate gas for pressurization, which would possibly be even harder to come by.

Foamed aluminium… on the Moon? It’s really hard to burn a solid chunk of aluminium. The more pores it has, the better, since that increases the surface area that can react, so foamed aluminium seems a much better choice. Making foamed aluminium in and of itself is not a problem, but its production requires enclosing some gas to make it porous. Preferably you’d take an inert gas for that, but good luck finding those on the moon (I mean, they’re there, but in amounts that would make homeopaths scratch their heads). The only gas really abundant is oxygen, which famously is all but inert. Enclosing oxygen would lead to oxidization in the pores, which means some part of the aluminium wouldn’t burn anymore and be dead mass. How large a part? I don’t know. What other gas could a lunar industry use in an economical mass-production process? Hydrogen would be nice and possibly even slightly increase the efficiency, but that again means throwing away the future in small bits. How much would that bit actually matter, given unavoidable losses in water recycling and industrial processes? I don’t know. Is it thinkable to design a process equivalent to foaming but using no gas in zero-G? I don’t know. I decided to stop my thoughts at that point and get on with it.

Cargo cradle: The cargo cradle seems simple enough on the outset, and that’s what I thought too. But it’s actually quite a headache. Currently there’s two winches per beam, one pulling “up” and one pulling “down”. Due to the center being taken up by the payload docking port, I’ve found no way how to make it close beyond that radius, but decided that it might not be necessary. Even so, the top beam extending quite a bit above the pressure cell is quite impractical in combination with the main docking port. You need to rely on the docking target providing a narrow enough extension, and with so little clearance getting the beam caught during a docking maneuver would be a major danger which most probably would be considered unacceptable under pretty much any circumstances. I thought about making a kind of forklift system, but then could not figure out what such a system would look like if you don’t have gravity to pull it down again (did I mention that I’m not much of a practical thinker?). Right now the entire cargo cradle kinda looks cool, but is a highly questionable arrangement.

Gameplay effects

Before ending this already considerably long post, let me just shortly address what the introduction of Alex’ specs means in terms of actual gameplay. While Alex is a very optimistic aluminium-LOX hybrid, the specs I had in there before was a highly optimistic Hydrolox craft that seems to have mostly been made out of thin air (since I really didn’t put much effort into designing a spacecraft at that point). It was a lot more capable and even had even less dry mass than Alex. As a result, Alex can no longer make it from the inner-most station to the outermost in one go, even without any payload at all.

Payload sizes in general are smaller. I’ve mostly addressed that problem by boosting the base cargo rate. Before, a rate of about 400 moneys (since the in-game currency still has no name) for a 10-ton payload was about break-even. Now it’s 900 moneys for 5 tons. Just goes to show what impact a bit of technology has on an economy, I guess. Since I wisely have not implemented any actual economic systems yet, the only thing I need to worry about right now is keeping the game playable, so I just boosted up that rate without having to think about what this change would do to prices of imported every day items. I’ll do stuff like that much later in development. So for delivery jobs, the major change you’ll see is that you tend to get around less, and that long-hauls tend to be less profitable because you can carry less payload. For example, the maximum payload that Alex can carry over the “big gap” between Empyrean Core and Argosy Colony is 10 tons.

Maintenance and Recovery jobs are somewhat less affected, though I had to redefine quite a bit what being near something means. This is actually a problem that has been around since the introduction of orbital mechanics, since two objects being too close to each other resulted in ridiculous synodic periods especially in the outer orbits, where it could happen that you’d spend weeks out there simply because of the Hohmann window (and the current incapability of the system to calculate anything but that unless you’re already on an eccentric orbit). So I had to see that things are a reasonable distance apart, but that also means that they’re a bit more difficult to reach for the Alex. As a result, especially for recovery jobs it can happen more frequently that you get jobs offered for which you do not have enough DV.

However, one fun side effect of the reduced capabilities of the Alex means that remass scales a lot worse. I.e. the more remass you load, the more remass you burn to transport that remass. This is of course true for any rocket engine, but with Alex’ much lower ISP it starts to kick in really heavily. As a result, stopping somewhere in-between and remassing now becomes an economic option for heavy payloads if you have the time! This is because doing two shorter hops, even with the additional burns for rendezvous required, might together end up using less total remass than doing one big hop with much more mass to accelerate during the initial burn. And so, it seems I just got a freeby in terms of fun planning options. However, I’ll also need to put in a couple of fuel depots at strategic places to make it really useful. I haven’t done that yet, but I’ll be looking into it. These will mostly be small placeholder locations for now for which I won’t start making up any backstories just yet. They’ll really only be there to give you more options.

What’s next?

Last month has largely been spent on the drawing board. Designing the alex, starting to design its upgrade tree and from there a specification for what the actual upgrade system in the code must be capable of handling, and of course making the model for the Alex and coming up with a post-processing pipeline to result in the kinda 50ies/60ies looking style that you see in the image. I’ve come reasonably close to what I wanted it to feel like, and could finally decide that yes, that art style would work for the actual game. Right now, however, the systems are missing from the game to actually accommodate any graphics. And since I’ve already started, and since I’ll need to push out a background image for a station each month if I want to hit my goal of being ready for a more representable demo next year, this is the perfect time to put those systems in. For the next update, which I hope will be next month, you can expect an initial overhaul of how non-focused challenges are currently presented, so I’ll actually have some screen area free to even put graphics there, and so they’ll blend with the future background images of the “scene” better. That in itself will not be that exciting, but once I have that I’ll have the capability of presenting them more like menu options integrated into the graphic, a bit liket the good old “Archimedean Dynasty” presented its menu options in stations.