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My world is far away exoplanet with water and some oxygene, but without life or plants, which means without coal and organic materials inside.

High tech people from Earth come there and made some quick (and succesfull) terraforming but after that, and after building the cities, vast majority of them cannot survive the planet conditions and people starts to die slowly due to health complications. Planet is classified as dangerous and deleted from future missions from Earth. Those few people who survives starts wars for goods and tech era is finished in three or four generations after all machines will run out of energy and get destroyed.

After hundreds of medieval years they just adapt for the planet, and start to rise again. They start new industrial revolution (with some historic books written by wise people from first era, so they have handwritten historic step-by-step guide to some crutial inventions, which speeds things up). They will use hydropower, got lots of mining, got steam engines, railways, boats, cars, ethanol engines instead of classic fuel. People gets to 1850 - 1900.

But what about planes in such era?

1) Materials: can be such a strong conventional engine built without steel? Can it be just an iron engine, or lithium / aluminium or whatever unorganic metal? Does any material have such good behavior like steel, but not based on organic materials?

2) Fuel: can it runs on etanol, whale oil or some bio fuel instead of classic fuel? Or it should only be sort of eletric / solar engine and thus produced quite later?

*note: this is max reality world. The only made-up thing should be the apocalypse. Everything other should be real, like we were really there and tryin to survive with everything we have.

Really thanks for answers.

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    $\begingroup$ If you are seeking maximum reality, it should be noted that a planet is exceedingly unlikely to have oxygen in the atmosphere without some form of photosynthesis going on. $\endgroup$ – Arkenstein XII Mar 24 at 21:43
  • $\begingroup$ @Arkenstein XII To be fair he never mentioned atmospheric oxygen. Yet there is actually a planet in ths solar system with no life, water and some oxygen; Ganymede. Additionally as soon as there is water [H2O] there is automatically oxygen [O]. $\endgroup$ – TheDyingOfLight Mar 24 at 22:48
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    $\begingroup$ /Does any material have such good behavior like steel, but not based on organic materials/. I am perplexed by this. How is steel based on organic materials? $\endgroup$ – Willk Mar 24 at 23:38
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    $\begingroup$ @Arkenstein XII As for natural O2 atmospheres without biological processes check out this paper. [1] There is a mineral named titania capable of catalysing oxygen production under UV light from water. [1] nature.com/articles/srep13977 $\endgroup$ – TheDyingOfLight Mar 25 at 8:36
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    $\begingroup$ The fact that they don't have carbon (the mineral) does not mean they don't have carbon (the element), otherwise they couldn't terraform the planet, since all terran life is carbon-based. Once you have trees, you can make charcoal from them, which is by the way the preferred fuel for steel smelting furnaces. $\endgroup$ – Rekesoft Mar 25 at 10:32
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The fact that they have ethanol means that as part of their terraforming efforts, they have a thriving plant life, probably terran based, established on the planet after colonisation. This is the only way this planet makes scientific sense anyway, because without photosynthesis going on there would be no way that the oxygen would be replenished after animals breathe it. Mind you, the amount of free oxygen in a non-plant based planet would also indicate very low levels of iron near the surface of the planet, otherwise it would oxidise and take the oxygen out of the atmosphere, but for the sake of argument let's say;

1) biofuel is a thing because there are now plants there, and
2) all metallurgy has become possible only through deep mining

So the question is whether or not planes are possible. The answer is of course yes, but your biome does put some constraints on them.

WW1 planes (for instance) were largely built with wood frames, and many of the early ones had canvas coverings. The wright brothers engine also contained a lot of aluminium to keep it light. It's entirely possible with the technology base you're talking about though that a lot of it could have been built using ceramics. This is assuming you have an internal combustion engine in the first place.

Iron, steel and other metals and alloys are a challenge because of weight, and I'd argue that building planes out of wood frames and a heavy material covering would get planes with a suitable engine up and running. Given that there are even parasail ultralights (essentially engine frames with a seat in front and a parachute above it for lift) means that you could get people flying on this world.

But, these technologies and building materials don't scale well. At our current level of technology we can't run a jet engine on biofuel, although it's coming I believe. Internal combustion engines could do it certainly, and many ultralights run on standard car fuel which in many cases now contains 10% ethanol anyway. So, it's arguable that you'd be able to get small planes up and running in your world, but you're not going to be able to scale up to something like an Airbus A380 with that building design.

Internal combustion engines are certainly the order of the day if you want to follow an Earth analogue, but it's also possible to design an electric engine that spins a propeller if you're not that interested in speed. In modern times, the batteries for these are getting lighter and lighter, but in your world I'd argue that the lack of chemical energy in the form of oil and coal would have meant that your industrial revolution would never have followed the same technological path as the industrial revolution on Earth was driven by cheap and accessible energy in the form of fossil fuels. On your planet, I'd argue that they would have gone down an electricity / solar or wind generation model, and battery storage, simply because it would have been the most convenient model in the first instance, especially if they needed most of their initial crops for food.

So; simple, lightweight planes that are probably slow but designed with wings that make them much more energy efficient, that don't scale up very well but could be used as personal transport for couriers, scouts, et al is what I suspect would be the order of the day, along with either an electrical or biofuel engine of some kind.

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If metals are scarce I would suggest wood and cloth as main construction materials. This was done historically and successfully [1]. My guess why it never became mainsteam is that wood is a natural material, thus has unpredictable features and is not uniform. Aluminium is just easier to work with and more predictable.

Concerning steel free engines I was only able to find this [2] they only discuss the pistons, but those are the parts taking the most stress. So if the pistons can be made with these other materials, so can the entire engine. Yet there is an issue. Why would your planet lack steel? You mentioned terraforming and I assume you meant establishing an earth like biosphere. To have a functional biosphere you need hydrogen, oxygen, nitrogen, sulfur, phosphorus and carbon. (and a bunch of trace elements) These elements are the basis of organic chemistry, which is somewhat crucial to life. Steel is an alloy of iron and carbon. Do as soon as your planet has any lifeforms on it you will have carbon. (using human remains for steel production sounds like a intriguing story idea) This article [3] disscusses steel production and how to do it without coal very detailed.

Using biofuel for aircrafts seems plausible, although there seem to be a number of issues [4]. Production seems to be difficult uneconomical compared to fosdile fuel, but on your world that would hardly be an issue.

Have you considered alternative aviation methods? Airships might be more popular if planes are hard to construct. Yes they are slower, but imagine a airship covert in thin solar panels or sheets to travel the planet somewhat slowly, yet hyper efficient.

[1] https://www.aircraftsystemstech.com/2018/09/history-of-wooden-aircraft.html?m=1 [2] https://www.google.com/amp/s/www.researchgate.net/post/what_is_the_best_material_that_can_internal_combustion_engine_piston_made_from_to_get_best_result/amp [3] https://coalaction.org.nz/carbon-emissions/can-we-make-steel-without-coal [4] https://en.m.wikipedia.org/wiki/Aviation_biofuel

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As to the engine: Ford has been using aluminum engine blocks for a while now - the aluminum is alloyed with strengthening metals but the key is that it can contain the combustion pressure without blowing out one or all of its spark plugs - losing compression, stalling and crashing. I guess it might be possible to use other metals, Magnesium is common in aircraft because of its high rigidity and low weight but its not very heat tolerant. Tungsten is heat tolerant but brittle and may degrade from the combustion stresses. If you can get a lighter weight material then you improve your thrust : weight ratio which allows bigger or more heavily armed aircraft or longer range aircraft. A big limitation to this kind of engine will be the amount of oxygen in your planet's atmosphere. If it is lower than Earth then the intake section will need to be more powerful to deliver enough pressurized combustion air to the combustion chamber. This could get challenging because if you have an outlandishly large intake that may create parasitic drag.

As to the airframe: it has to be able to withstand the stresses of fixed wing flight. The fuselage, wing spars and stabilizers are all going to be subject to twisting, torsion, compression and many other forces during maneuvers. A lighter weight material like wood probably cannot stand up to a ton of punishment like that. A steel framed fusleage and steel wing spars will allow higher G maneuvers, but also means more weight and so calls for a stronger or more numerous engines.. you're beginning to see how tough it is to engineer fixed-wing combat aircraft.

what you might want to consider instead if this is late 1800s / early 1900s equivalent is airships

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