Space Engineers: How to Balance Thrust with Gravity

Good Morning from my Robotics Lab! This is Shadow_8472, and today, I have been working on a ship in Space Engineers. Let’s get started!

Space Engineers is a game where you mine resources on planets, moons, and asteroids to build bases and ships. Over my time playing it so far, I’ve noticed many simplifications, like just how step rough terrain can be before my character slips, or the peculiar arrangement of planetary ore. The physics of moving things around, on the other hand, remains more true to life.

Early Game

For context, I’ve been playing “survival” mode: that is to say I started in the Solar System map on the Earthlike planet. It took me a couple tries before I got a self-sufficient base, but I have successfully made my in-game home in the mountains at a high elevation.

Early on, ore is carried by hand in a backpack. I eventually built a little flying truck and taught myself how to fly by trial and error. Without enough downward thrust when fully loaded, I involuntarily go bumping along the ground, and landing gear explodes, leaving scrap metal behind.

I quickly outgrew my little golf cart, so I built my first ship with an interior and equipped it with mining drills. Each time I rearranged its insides, a little more character became permanent features on the hull. I installed multiple systems I didn’t strictly need, like a Hydrogen tank and engines to generate power from an ice splitter. The trickiest of all was making the whole thing airtight and pumping in Oxygen from a tank.

My finished product was about twice as long as I expected, and quite a bit wider. In practice, I have to make multiple passes at the same area, slowly opening it up until I can reach in and get what I’m after. I’m prone to bumps and nicks, and if I drill too far in, I will catch on something, twist on my axis, and start losing control.

Just as important to an individual ship’s success is the ground station’s work. I did the math once, and found my eight little engines could hardly keep up with the power output of one of my batteries. Left to itself, in theory, it can fly roughly 1 minute for every 5 it spends recharging from an on board Hydrogen supply. If it has to split the ice itself, I could be looking at a quarter of the productivity. A well equipped base can generally top the batteries off in three minutes when I tell them to recharge.

New Ship: Concept

The game has two “grid” sizes for building: large and small. Coorisponding blocks take more components to build on larger grids. Storage blocks have much more volume; the biggest coming not quite to half a million Liters of capacity on a large grid. I want to fill one with a small grid ship. At the same time, I’m remembering when that little shovel of a vehicle I built turned upside down on me because it was overloaded. I want to fly the first time without any accidents due to skipping the math, because this ship will be a lot harder to “just unload.”

How Many Thrusters?

The actual number pulled from in-game is 421,875 L. Small grid large containers are 15,625 L, an 27 (or three cubed) fold increase. I spent some time designing a cargo bay with these numbers, and came up with a repeating design with 7 segments of 4 where I can access each container by hand if need be, leaving me with 28 containers and a cargo capacity of 437,500 L.

My experience to date is only on the Earthlike planet, so that’s where I’ll be designing it to operate. Ores can be really deep in the ground, so I’ll want enough reverse thrust to hover when pointing straight down under full load so I can back out of a hole I’m digging. The densest (and only) density among all the ores is .37 L/kg. Paying close attention to the units, I divided my earlier capacity by the density, coming up with a total cargo weight of 1,182,432.432 kg!

The real Earth has a gravitational accelleration of 9.8 M/s/s. Multiplying the weight of the cargo, I get 11,587,837.838 KgM/s/s. Force from the engines are given in Kilonewtons, but conversion is simple if counterintuitive: the Newton is equivalent to the mess of units already present and the decimal just needs to move over. A little rounding lands at 11,588 kN. The thrusters I’ll be using provide 576 kN. From here, it’s a simple matter of division to find I need a hair over 20 thrusters just to lift the payload.

Ship Layout

For this craft, I started with the cargo hold. I stuffed as many batteries as would fit in the gaps and calculated that I’d need the full output of at least 15 batteries. I already have more than that, though I may want additional units for longer battery life.

Moving forward, I have a habitation section. When building, I like to pretend there’s more going on than is mechanically present, so a living space is in order. The cargo hold was tall enough that I had enough space for a second deck, where I added an airlock for entering and exiting the ship, as well as a few ship’s systems: fuel tank, ice splitter for Oxygen and Hydrogen, Oxygen tank, several large Hydrogen tanks. I was having trouble deciding how long to make the habitation section until I took a cue from the length of the big tanks I installed for future space travel, assuming I don’t make yet another one before I blast off.

The third pressurized section is a long neck leading to the cockpit. I’m following the same general idea for a floor plan as my last ship, and this was where my batteries ended up. In this design though, it’s just there to look cool, but in theory should afford a little more leeway when digging. I’ve also included two conduit lines for moving ore back to the cargo hold in case one side gets damaged.

Up in the front is the “spherical” cockpit with a crazy number of drill heads poking out on both the top and bottom. When I took a break for my write up, I was figuring out windows for it, but they’re being a pane to put in without provision for corner blocks that aren’t just a 2D slice. I’m also looking to have redundant ship’s systems below deck. In the case I come under heavy enemy fire (I’m on peaceful for all I know) and the neck snaps, the surviving part can escape to safety and undergo repairs.

All the way in the back, I’m planning on a redundant command center. In the case I’m backing out of a hole I’ve dug or the more dire scenario discussed above, the ship won’t be without a command seat. If I’m going to have Hydrogen powered generators, here is where I’d stack them. I also need a place to stash a whole lot of gyroscopes for rotation control. The overall ship’s design is practically begging for a set of wings, and I’ve read about a so-called gravity drive I can design and build. I’ll be sure to include some connectors to attach such an apparatus if they don’t double for unloading cargo.

Takeaway

Planning a ship is serious business. I’m far from done –probably another couple full days out– but when I checked the weight from the command chair, the dry mass is lumbering in the direction of my earlier ship’s fully loaded mass of about 300,000 kg. I plugged that figure into my spreadsheet, and it told me to expect to need at least 26 engines for neutral lift capability. I’ll of course want to plug the actual number in when I get there, but such is the nature of iterative design: enough extra engines will call for more batteries, etc.

I still have much to learn, like how I’m going to automate that airlock so I don’t vent Oxygen when I go to space, or how to unload all those cargo containers when I dock with home base.

Special thanks go to my father who was there for reviewing simple Newtonian physics.

Final Question

This week was supposed to be a Raspberry Pi week, but I’m out of SD cards, and the cards on order are lost in the mail. What was the last thing the post misplaced for you?

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