AHC: earliest possible tanks, planes

What is the earliest date that the tank and the airplane could be developed?

While we'really at it, what about a submarine capable of targeting enemy shipping? Or backpack radios?

If you have any other military technology from around the 1850-1930 timeframe that could have come into play earlier, please post.

Thanks!
 
Both seem to depend on the development of a reliable internal combustion engine, so unless you can get to that earlier, you're stuck with the 1890s as the very first opportunity. Steam might work for a tank, but not for an aircraft. Too heavy.
 
Both seem to depend on the development of a reliable internal combustion engine, so unless you can get to that earlier, you're stuck with the 1890s as the very first opportunity. Steam might work for a tank, but not for an aircraft. Too heavy.

Most World War I tanks could travel only at about a walking pace at best. Their steel armour could stop small arms fire and fragments from high-explosive artillery shells. However they were vulnerable to a direct hit from artillery and mortar shells. The environment inside was extremely unpleasant; as ventilation was inadequate the atmosphere was heavy with poisonous carbon monoxide from the engine and firing the weapons, fuel and oil vapours from the engine and cordite fumes from the weapons. Temperatures inside could reach 50°C (122°F). Entire crews lost consciousness inside the tanks, or collapsed when again exposed to fresh air.[5]

Making them steam powered would be hell on earth for the crew.
 
A balloon-plane hybrid thing might be possible in the later 19th century, as long as you have some mechanism to steer the thing. A wood fire or hydrogen would be sufficient for the ballon part. Does this really count as a plane though?

As for the tank, derail a train, remove all of the tow-carts and stick a gun on the front, and you have something that could at least work on level ground. So 1830, if we are willing to go with slightly crazy ideas.

- BNC
 
There was limited interest in the use of steam powered 'traction engines' using the railed 'dreadnaught wheel' during the Crimean War and in 1858 Fowler patented his continuous track system. With a smallish PoD I could see such devices being deployed in the Crimea, as artillery tractors, and possibly being armed. However it's too early for machine guns or cased artillery. Certainly 'clanks' could have been deployed in South Africa during the Boer War, if someone had put the elements together and there was a perceived need.

As for aircraft, well Solomon Andrews flew his dirigible airship in 1863 and offered it for use in the ACW, and that's a decade after Giffard mated a steam engine to a hydrogen balloon. Something like this could have dropped a few crude bombs. Perhaps it would have played a part in the establishment of the Australian Republic in the 1880s after Kelly's Revolution?

One of my favourite aviation what-ifs is this: What if Wilhelm Kress got a suitable engine and flew his seaplane successfully in 1901 in Austria?
 
A balloon-plane hybrid thing might be possible in the later 19th century, as long as you have some mechanism to steer the thing. A wood fire or hydrogen would be sufficient for the ballon part. Does this really count as a plane though?

As for the tank, derail a train, remove all of the tow-carts and stick a gun on the front, and you have something that could at least work on level ground. So 1830, if we are willing to go with slightly crazy ideas.

- BNC
How efficient is steam power compared to internal combustion? Can you get a steam engine that provideo the same power per pound as an internal combustion?

What about a practical sterling engine?
 
How efficient is steam power compared to internal combustion? Can you get a steam engine that provideo the same power per pound as an internal combustion?
No, but you could probably make one powerful enough in the late 19th century to power some sort of tracked armoured vehicle.

What about a practical sterling engine?
Not really useful in this case.
 
How efficient is steam power compared to internal combustion? Can you get a steam engine that provideo the same power per pound as an internal combustion?

What about a practical sterling engine?
I'm not an expert on engines. From my understanding of chemistry:

Burning black coal (~90% carbon), the equation of combustion is C + O2 -> CO2; /\H = -30kJ/mol
In the case of octane, the main component of normal car petrol: C8H18 + (12.5)O2 -> 8CO2 + 9H2O; /\H = -5054kJ/mol

So what does all this mean?

For every mole of black coal burned, approximately 30 kJ of energy is released.
For every mole of petrol burned, 5054 kJ of energy is released.

One mole of carbon is defined as being 12 grams. Extending this, 1 mole of octane is 114 g.

:. 30k/12 = 2500 J of energy per gram of coal (actually about 1.1g of coal due to impurities).
5054k/114 = 44333 J of energy per gram of petrol (actually about 1.05g of petrol due to impurities).

So, to have an engine that provides same power per unit mass, you would need to condense the coal into a space of about 1/18 of its normal size. Which is a bit ridiculous. A much more practical way of doing this is to upsize the engine to be 18 times bigger. A normal car engine, after a quick internet search, is approximately 1000 cm3, or a cube of 10cm side length. For a steam engine of the same power, one would need a cube of side length 26.2cm.

I don't know how the engine sizes would scale in the case of a tank, but using the simple idea that a tank requires 10 car engines, due to having a mass ten times greater, this engine would now have a side length of close to 60cm (2 ft).

Simply put, the engines can be done. The fuel (coal), is the most difficult aspect for steam engines.

- BNC
 
Until the early 1930's in the UK sentinel type steam lorries were still competitive. A steam plant of this type was IIRC proposed for a tank in WW1. The Americans actually got as far as building a prototype of their steam tank in 1918. So bringing that forward a few years may not be ASB.
 
For earlier development of heavier than air flight see Stephen Baxter's short story Brigantia's Angels (Sideways Award 1995). Frost's prototype would probably have worked it it hadn't been wrecked. A workable proposal for tanks was sent to the War Office in Britain in 1908 and filed away without being seriously considered. All we need there for an ATL is a senior clerk or junior officer who has read H.G. Wells "The Land Ironclads".
 
I'm not an expert on engines. From my understanding of chemistry:

Burning black coal (~90% carbon), the equation of combustion is C + O2 -> CO2; /\H = -30kJ/mol
In the case of octane, the main component of normal car petrol: C8H18 + (12.5)O2 -> 8CO2 + 9H2O; /\H = -5054kJ/mol

So what does all this mean?

For every mole of black coal burned, approximately 30 kJ of energy is released.
For every mole of petrol burned, 5054 kJ of energy is released.

One mole of carbon is defined as being 12 grams. Extending this, 1 mole of octane is 114 g.

:. 30k/12 = 2500 J of energy per gram of coal (actually about 1.1g of coal due to impurities).
5054k/114 = 44333 J of energy per gram of petrol (actually about 1.05g of petrol due to impurities).

So, to have an engine that provides same power per unit mass, you would need to condense the coal into a space of about 1/18 of its normal size. Which is a bit ridiculous. A much more practical way of doing this is to upsize the engine to be 18 times bigger. A normal car engine, after a quick internet search, is approximately 1000 cm3, or a cube of 10cm side length. For a steam engine of the same power, one would need a cube of side length 26.2cm.

I don't know how the engine sizes would scale in the case of a tank, but using the simple idea that a tank requires 10 car engines, due to having a mass ten times greater, this engine would now have a side length of close to 60cm (2 ft).

Simply put, the engines can be done. The fuel (coal), is the most difficult aspect for steam engines.

- BNC

So the problem with steam engines is not the design of the engines themselves, but the fuel?

Are there any alternatives to burning coal in a steam engine, such as gas? Could you even use some liquid other than water in the boiler?
 
Steam engines are not limited to coal. Depending upon the firebox, steam engines can burn: coal, dung, wood, plant waste, alcohol, plant oils, or a dozen different grades of petroleum. Coal was merely the least expensive fuel at the turn of the century.
The limitation on steam engines the weight of the boiler, condensers, etc.
By the turn of the century, a variety of experimenters (Chanute, Lielenthal (sp?), Wright Brothers, etc. had learned the basics of controlling hang-gliders and we're just waiting for light-weight engines to complete their dreams of powered flight.
For engines with high power-to-weight ratios look at petrol-fuelled motorcycle engines being built by motorcycle racers (e.g. Glenn Curtiss) at the turn of the century.

As for hassles with heat and fumes in early tanks, simply install an airtight bulkhead between the engine compartment and the crew compartment. Bonus points if you make the bulkhead double-walled. Double bonus points if you draw cooling air in between the two walls to keep the bulkhead face close to outside air temperatures.
 
So the problem with steam engines is not the design of the engines themselves, but the fuel?

90% of the time, yes. You need a lot more coal than you do petrol, and today's tanks' fuel tanks don't have the range to go much further than 200km. In the 1890s, the same volume of coal might get you 5km.

- BNC
 
No, but you could probably make one powerful enough in the late 19th century to power some sort of tracked armoured vehicle.
Steam has much higher torque than IC engines of the era.

the 20HP Stanley Steamer had enough torque to spin the tires off the rims, and full torque was available at any engine rpm. It was a 20hp continuous, limited by the boiler. The engine was good for over 100hp.
And that twin cylinder had 15 moving parts, and didn't need a gearbox, just a single reduction ratio.

Given good roads, was capable of 70 mph.
 
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POD has to be after January 1st, 1900? Because otherwise, I may just as well write a story where the Roman Empire avoids the upheavals of the 3rd Century Crisis, goes on to successfully resist the period of the Great Migrations, meaning its high level of urbanization and complex social structures enable it to develop proto-capitalist modes of ownership by the 7th century, better metallurgy by the 9th century, the scientific method by the 11th, better farming techniques by the 13th century, large scale and widespread wind- and waterpowered industries by 14th and the beginning of the steam age in the early 15th century, which should get you tanks and planes sometime in late 16th-early 17th centuries.
 
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