What industrial exoplanet machine would serve as the best escape vehicle from a remote secure stronghold?

Question

My world has 18th century society norms with steampunk tech. I have added a scene from the story to the end of this question, just fill in the blank. Some characters become impressed into service with pirates and taken to their isolated remote stronghold. This is an alien world with a hostile atmosphere which is navigated exclusively by airship. The planet has no free oxygen so there is no powered heavier-than-air flight. Likewise, heat engines do not use combustion, they use chemical heat reaction for power. So they use fuel tanks.

The planet is dead so the only activities outside of a city would be either transportation, energy generation, heavy construction, or resource mining.

The enclave likewise has to do some degree of industry, they can’t live as complete parasites. 18th century pirates could at least fish and grow livestock after all.

Details of how the society actually works or uses resources are not part of the story, so I can’t state what gasses, ores, or compounds they utilize - whatever makes the story work. But industry obviously happens, and my character escapes this allegedly inescapable hideout by slightly modifying some apparatus or machine which permits them to bust out and escape into the wilderness (not without danger nor into the safety of a city, mind you).

In my mind I am thinking of how Ridley used the walking lift to battle the alien queen in Aliens. Having a walking cargo lift in the world allowed Ridley to fight that epic battle. Well, I have an epic escape scene with one character crashing through a wall and running/flying “out of the pot and into the fire,” into the hostile atmosphere of a dead planet.

Given that the world has no real specific resource vital to the plot, the spectrum of contraptions should be wide enough to find an escape vehicle.

The tech level is 19th century steampunk. There are no computers, no RADAR tech, no spacecraft, and no transportation infrastructure (at the location of the escape at least)

Specs for the vehicle:

1. Has or can be easily configured with airtight “cabin” of minimal accommodation.

2. Already designed to work in the outside environment.

3. Is not ridiculously slow (or can be readily modified to be quick or nimble)

4. It’s a tool or equipment that pirates logically would have stolen/acquired for their own use (rather than for hawk - items with trade value trade are more protected and harder to explain how he accessed it)

5. In the scene he will weaken the wall before breaking out. Either with charges or a fire. So the machine doesn’t need to be a battering ram.

6. He will almost certainly make the escape by improvised flight, which means he will be hanging from some spare ballonnets and using something for directional motion. Probably won’t have time to rig control surfaces and none need to be in the donor vehicle. Just brute force propulsion.

7. If flight, then Elevation control will be stolen from a prize vessel in their yard. He’ll have some levers in the cab to actuate some ducts.

8. Walking equipment seems the most probable donor, but the legs may get sacrificed or repurposed.

9. Aside from mining, outside activities include wind harvesting, stone cutting, and ship handling (known as yellow gear today). Various equipment or vehicles are likely associated with those operations; again - likely no wheels.

10. Weight is the enemy. Something logically lightweight or easily lightened.

While I think stealing the Captain’s prized yacht would make a spectacular story, it’s not the way my story goes. That’s why I want this piece of industrial junk to beat the odds and show off my character’s ingenuity. Sort of like the sparring robot turned champion in Real Steel

NOTE: My story is not about the vehicle; it’s about the character and his ingenuity. This is a disposable prop in the world, like Anakin Skywalker’s racing pod.

The stronghold itself is the same one referenced here.

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A Scene from the story:

I am miles into the deadlands in a stolen __________, and my chamber is leaking. I do not know how much longer my coolant can do combat with the hellish air outside this hull of metal, pervading insidiously upon my cockpit. How long I might maintain vitality systems is unknown and unknowable in my claustrophobic dark prison, having only the tangerine glow of the Geissler tubes to give any purpose to my eyes or comprehension to my pen. But a sense of urgency has failed to conquer me yet. This oblivion has rendered me absolutely feckless. I am fully under its enchantment: Not knowing if such a serenity as this might ever again come to my ears, is perhaps even more fearful than the certainty of death that approaches. I also put down the lamps, to gather whatever I may of what lay beyond my small window. I stand in complete harmony with my world—and—that is precisely it, is it not? It was my world, after all. Who else would take claim of it? What use is it to entertain a botheration when in the entertainment of it I could make no purchase of another day; another hour; another minute, unto my end? It is no longer utter blackness, with my lamp now low; but—in fact; beautiful. It is nothing if it is not a poetic end that blesses mine eyes, and I feel it a sin to not share it.

Beyond the ochre-green swelling hills of the badland rose the mighty slopes of craggy basalt spires up to the lofty steeps of the Carpathians themselves. I know this now; what was unknowable only yesterday in my uncharted captivity—that these are without question the mightiest range in known lands. I do sit as an ant at the feet of the Carpathians. Before me they towered in a glow from tangerine riverlets dividing the forevermore darkened sky into shifting vaporous continents, ranges, and islands, hanging impossibly above me in the heavens, eternally shifting into a new and wondrous map whose only purpose is to be forgotten and redrawn again. The bath of luminous mists pressed full upon the mountains, brings to a boil the hypnotic spectrum of this beautiful range lying stalwart in the serene, hellishly scalding æther; uncaring as am I of what is to come. Unaffected as am I by what has passed before. Uninvested as am I, also, in what considerations our cities have for them to-day. Deep blue streaks of covellite gravel like an otherworldly blood glitter as they cascade down the tanned piles of scree. It is as if angels—fallen or not, I could not say—slashed open the maroon veins of cuprite fingering their way from out of the shadows of the angled basal peaks, leaving wounds gushing with the precious ore. The azure metal is in fact the blood of our electrical society. Wires of covelite can coolly pass enormous currents to our devices, and it is so common that I had never before stopped to consider its natural beauty. More so is the beauty to-day as this region has not been mined. Surely it will be, in time. An army of machines like the one I bring here now will bear down on them. Will siphon from them the hill-blood ‘till man’s ravenous appetite abates. Wildcatters will plunge their enormous drills into these hills and steal away with their very essence.

“Don’t worry. I’m not here for your blood.” Well! Did I just talk to a mountain? “To-day, and now, my fellow. We are one man and one mountain, beyond the reach of the city’s ore contracts, its land claims, and its prospectors. We are far and away all alone. To-day, I talk to mountains. And –God. It is good.

Answer 1

Transport airship

From what I gleaned from the story they are at a fortress of some kind, unbeknownst to anyone else. They have mining activities, bit seemingly little else. To maintain population and goods to justify that existence they need to have trade. As the only travel is by airship or steamtrain, and the fortress is unlikely to be unknown to the world if connected by train, it leaves only airships as a means of transportation.

The mining might be done underground without special airships and the like, but we can know for sure they need to transport stuff by airship. People, but mostly goods. The mining is unlikely to be solely for the fortress, but will be used for trade. This trade can be ysed to sustain the slave population as well as luxuries of the higher ups.

There are probably several kinds of airship available, but anyone breaking out is most likely clise to a transport airship for the mined goods. Otherwise it is a ship purely to move people from the fortress to the mining location. Either one will serve, but personally I like the idea of a cargo airship better. It is large and has a certain appeal, and can be surprisingly nimble and fast if unloaded if the story demands it. They can also be build more sturdy to haul the cargo, making them better suited against attacks and damage.

I would have the escapee break out, commandeer a cargo airship and speed away as my most likely scenario.

Answer 2

The Prison is a Chop Shop

Chop shops are a prefect job for pirate slave labor. It is labor intensive, a bit hazardous, and is necessary for pirates to be able to turn the scrap from uncompliant victims into profits. And most importantly, it gives you a good reason to give your prisoners direct access to vehicle equipment without it being an obvious security oversight because all the stuff the prisoners are handling would be seen as non-functional in the eyes of the pirates.

It’s a tool or equipment that pirates logically would have stolen/acquired for their own use (rather than for hawk - items with trade value trade are more protected and harder to explain how he accessed it)

This part you have backwards. It is security risks, not value, that the pirates need to be mindful of. In a prison system, all vehicles are considered high security risks; so, the guards would take every precaution to keep prisoners away from any fully functioning vehicle. However, pirates will often have access to parts that need serial numbers scrapped off or some minor bullet holes patched up before they can hawk them. So instead of having access to a vehicle, he instead has access to valuable parts that are individually seen as low security risks.

The the air tight cabin could be the cockpit of vehicle the pirates shot down that the prisoners have not fully cut down into spare parts yet. The balloon section could be from an airship they shot down that the prisoners have been tasked with sewing back together. The Helium could be from the welding equipment (because you need a noble gas to prevent welds from oxidizing). And the propulsion could be anything from that stack of spare motors in the corner that still need thier serial numbers removed before they are ready for sale.

This idea of vehicle made from spare parts would fit especially well with:

He will almost certainly make the escape by improvised flight, which means he will be hanging from some spare ballonnets and using something for directional motion. Probably won’t have time to rig control surfaces and none need to be in the donor vehicle. Just brute force propulsion.

Answer 3

What is a mining scout?

The basic idea is that you need something that can travel around to look for minerals to mine. Since there isn't a breathable atmosphere you don't really want to have to suit up and walk around while lugging equipment all the time. So instead you have a small 1 or 2 passenger vehicle designed to easily maneuver in the terrain that would be able to go look for places to mine. To do it's job it would need to have a way to gather samples, possibly from deep underground with a core drill, but that might not be important for the story. What is important is that it is small, maneuverable, suited for the environment with air and fuel, and designed to travel long distances without outside support.

My favorite brainstorming ideas so far:

Power Armor Something like vault tech power armor but with cargo loading arms that the pirates use to haul around the vast piles of loot that they capture. It seals up so it can be air tight to load ships out in the vacuum of the planet surface and carries a fuel, water, and air supply.

Captured buggy The pirates captured some rich kid joy riding out in his buggy for ransom, and the buggy got left behind in the pirates storage area.

Mining scout It's a small relatively fast buggy that has a core drill to take mining samples, again captured in a raid by the pirates but not really considered useful or valuable, so it just got stashed and almost forgotten. Hero can maybe find a way to overcharge the engine to make it go a bit faster than it normally would at the expense of faster fuel and water use, which could lead to some dramatic tension.

Gyrosphere Something like the rolling ball in Jurassic World, where the person is sealed inside and it just rolls around. Maybe it's part of a larger craft where the cockpit will stay upright even if the vehicle takes a tumble, and Hero seals it up and turns the gyro motors into a way to move it around.

Scope
By limiting scope what I mean is to explain some of the transportation ideas that you already have. Nothing flies, and there are no rockets, so do they all have wheels? Treads? Legs?

Old stuff:
So this question is probably a bit out of scope if only because there are so many possibilities that it would be hard for any person to know the "best answer".

For instance, the planet has mining, so a mining vehicle would be an obvious choice.
The surface is rough and scared by meteoroids, so wheels don't work well, so they have multi legged mining transports like AT-AT's. Or maybe smaller, faster scouts similar to AT-ST's. Depending on how much time he has maybe he can put together something new from parts found in an engineering shop.

Honestly, it doesn't really matter so long as you set them up in the story first.
The hero is being transported to the stronghold by his enemies, he looks out the window and sees the vehicle traveling across the land, and there is some kind of comment, either internal or external, that explains what it is and what it's used for.