Plausibility Check: Steam engines on WW2 tanks

In OTL, some cars were designed with steam engines into the 1920s, and in Britain the Sentinel company marketed its last steam-powered lorry as late as 1931, but the invention of the electric starter and the availability of cheap petrol gave a decisive advantage to the internal combustion engine. However, could a country such as Germany, which in case of war would face serious oil shortages, develop tanks with steam engines in the 1930s and 1940s?

why not they considered a steam aircraft? https://www.alternatehistory.com/discussion/showthread.php?t=346689

did wonder why the wood gas was not used for longer distances by the German military (might have been and the photos not widely circulated?) if by trucks at least. http://en.wikipedia.org/wiki/Wood_gas

The reason why Internal Combustion engines made the Tank possible was the very nature of efficient storage of the fuel and the power to weight ratio . A tank that carries it's fuel as coal is going to be the size of a small Destroyer and a mobile as a snail . It will also need a water top up every 20 miles and more coal every day . it is possible yet not practical . As far as power goes a powerful coal powered train shows what is possible but then again it also shows the size of the vehicle needed .

alspug said:

A tank that carries it's fuel as coal is going to be the size of a small Destroyer and a mobile as a snail .

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If I showed you this lorry and didn't tell you it ran on steam power, would you have guessed?

alspug said:

The reason why Internal Combustion engines made the Tank possible was the very nature of efficient storage of the fuel and the power to weight ratio . A tank that carries it's fuel as coal is going to be the size of a small Destroyer and a mobile as a snail . It will also need a water top up every 20 miles and more coal every day . it is possible yet not practical . As far as power goes a powerful coal powered train shows what is possible but then again it also shows the size of the vehicle needed .

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Oil is quite suitable as a fuel for steam engines, I should think.

alspug said:

A tank that carries it's fuel as coal is going to be the size of a small Destroyer and a mobile as a snail .

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Er, they used steam tanks in WW1...this is not a pure hypothetical.

Thande said:

Er, they used steam tanks in WW1...this is not a pure hypothetical.

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Not during but America experimented after WW1

http://en.wikipedia.org/wiki/Steam_tank



Not a tank but it's steam driven and it has tracks!

Sior said:

Not during but America experimented after WW1

http://en.wikipedia.org/wiki/Steam_tank

Not a tank but it's steam driven and it has tracks!

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I wonder what American tanks would have looked like in WWII if the US had adopted designs like this for the standard tractor in the inter-war period. It certainly would have given American designers a lot more experience to apply.

I am well aware of the use of oil to run a steam engine however the original post makes it clear the use of the steam engine is a way of avoiding using oil therefore I have discounted that from my argument .

Wood gas is possible and if you want to tow a trailer with a stack of firewood on it and a converter that's fine go ahead mind you one hit to the fuel pipe and you come to a sudden stop .

I could envisage a large steam locomotive engine being used and in a 200 ton plus AFV being successful , ie would be heavily armoured yet inferior to a diesel or petrol engined AFV . On a smaller scale it is not impossible yet I do not know how to convert tractive effort into HP to equate the power of each . I will say however that it is far easier to pump petrol or diesel into a firebox or piston then shovelling coal or loading wood into a wood gas generator .

Is it possible ? my answer is yes
Is it practical at all ? My answer is no not in our universe .

P.S. found a rough system of converting tractive effort . it appears the LNER Class A4 steam locomotives had a roughly 2000 hp engine . this could be out by %20 to %50 easily as I had to make an assumed speed to work out HP . This locomotive weighed 102 tons , I have no doubt whatsoever that this engine could be used to drive a 200 ton class AFV and be acceptable if you want a fleet of Maus like AFV . I have no doubt you could go smaller but you need to allow working space to keep the boiler and firebox well away from the ammunition . this indicates a separate engine room and the extra length that entails . armouring this extra space drives weight up . Diesel fuel is a higher calorific fuel and takes up a smaller volume for weight as well . Diesel is between 2 and 3 times as effective on a purely calorific measurement not taking into account internal versus external combustion engines . I have no idea of the true measure of the efficiency of a steam engine but the Internal combustion engine has a fuel to power conversion rate of approximately %25 to %30 . the remainder being lost in waste heat etc . In an External combustion engine far more of the Fuel to Power is wasted and although perfect for big power generators and other large constant speed systems it is not efficient as a vehicle engine .

The Doble Steam car with its flash boiler had ridiculous amounts of torque, over 1500 ft.lbs

Thats what the Sherman tank had with the Ford GAA

At 0 RPM.

You could spin the rubber right off the rims if you floored it.

Not bad for 150HP

alspug said:

Wood gas is possible and if you want to tow a trailer with a stack of firewood on it and a converter that's fine go ahead mind you one hit to the fuel pipe and you come to a sudden stop .

I could envisage a large steam locomotive engine being used and in a 200 ton plus AFV being successful , ie would be heavily armoured yet inferior to a diesel or petrol engined AFV . On a smaller scale it is not impossible yet I do not know how to convert tractive effort into HP to equate the power of each . I will say however that it is far easier to pump petrol or diesel into a firebox or piston then shovelling coal or loading wood into a wood gas generator .


P.S. found a rough system of converting tractive effort . it appears the LNER Class A4 steam locomotives had a roughly 2000 hp engine . this could be out by %20 to %50 easily as I had to make an assumed speed to work out HP . This locomotive weighed 102 tons , I have no doubt whatsoever that this engine could be used to drive a 200 ton class AFV and be acceptable if you want a fleet of Maus like AFV .

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thanks for that research!

my comment about wood gas was specifically for longer treks, have no idea the speed and ease which a vehicle could be converted back so the idea may be moot(?)

IF a trailer could be towed and then an AFV converted back quickly that might be a significant enough savings (for WWII Germany) to employ.

your mention of steam locomotive, might work to move a rail gun short distances? the Krupp K5 (Anzio Annie, etc) http://en.wikipedia.org/wiki/Krupp_K5 was projected to get two tank chassis to free it from rail lines.

Besides the issues previously raised with solid fuels, there is also the need for large quantities of distilled water. After the steam is done pushing cylinders or spinning turbines, it has to eject its heat somehow. In automobiles and most locomotives this is done by ejecting the steam itself along with the exhaust gases. However this means you need a constant supply of distilled water for your tanks, which is as much a logistical burden as fuel transport.

You can also install condensers to reduce water consumption, but now any lucky bastard with a Mosin Nagant can perform a mobility kill on your tanks.

Where do you get a regular supply of fresh water on a battlefield. Steam engines even with condensers, economisers and big water tanks have to stop a lot to top up with water.

fastmongrel said:

Where do you get a regular supply of fresh water on a battlefield. Steam engines even with condensers, economisers and big water tanks have to stop a lot to top up with water.

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You need Gasoline constantly, as Tanks got Gallons per Mile, its not that much of a change.

The Doble Steamer, had a 24 gallon water tank. With the condenser, it had a 1500 mile range, and 11-15 miles per gallon on the kerosene burner, that tank was 25 gallons.

The Doble needed Kerosene stops four times as often as Water

Of course this brings in the risk of another method of destroying a tank - when the guy tending the boiler gets distracted because, y'know, he's getting shot at, forgets to tend the injectors, the water level goes too low and the whole works goes sky high.



For those not steam-wise, basically when the water level gets too low in a conventional locomotive-type boiler the piece of metal atop the firebox separating it from the boiler (what we call the crown sheet) becomes uncovered by water. It gets hotter and hotter until eventually it fails, causing all the water in the boiler to vaporize. Pretty much instantly. In a locomotive this usually has the pleasant effect of lifting the boiler right off the frame (in a particularly violent accident in San Antonio around the turn of the century, pieces of the engine were found over a mile away - this ended 26 crewmen) and mashing the crew into little pieces if they haven't already been scalded to death by steam shooting out the firebox door. Not a very pleasant way to go.

joeferrito said:

Of course this brings in the risk of another method of destroying a tank - when the guy tending the boiler gets distracted because, y'know, he's getting shot at, forgets to tend the injectors, the water level goes too low and the whole works goes sky high.


For those not steam-wise, basically when the water level gets too low in a conventional locomotive-type boiler the piece of metal atop the firebox separating it from the boiler (what we call the crown sheet) becomes uncovered by water. It gets hotter and hotter until eventually it fails, causing all the water in the boiler to vaporize. Pretty much instantly. In a locomotive this usually has the pleasant effect of lifting the boiler right off the frame (in a particularly violent accident in San Antonio around the turn of the century, pieces of the engine were found over a mile away - this ended 26 crewmen) and mashing the crew into little pieces if they haven't already been scalded to death by steam shooting out the firebox door. Not a very pleasant way to go.

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Thats why the move to flash boilers from firetube boilers.

No large amounts of superheated steam to do that, and if run dry, no explosion

marathag said:

You need Gasoline constantly, as Tanks got Gallons per Mile, its not that much of a change.

The Doble Steamer, had a 24 gallon water tank. With the condenser, it had a 1500 mile range, and 11-15 miles per gallon on the kerosene burner, that tank was 25 gallons.

The Doble needed Kerosene stops four times as often as Water

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The Doble ran on kerosene though, so you might as well use a diesel engine if you have kerosene available. Using firetube instead of watertube boilers further degrades fuel efficiency, another argument for diesel engines.

Starting an internal combustion engine. Check fuel, oil, water if needed, turn a switch press a button Brmmm Brmmm off you go.

Starting a Steamer. Check fuel, oil, water, crank a handle to get the fuel up to pressure so it gets to the burners or injectors press a button or light a blow torch Wummff the burner lights then crank a handle to get water into boiler and wait whilst pressure builds up frantically tapping the pressure guage willing it to go past working pressure. When its finally up to pressure (10 to 15 minutes for a flash boiler anything up to an hour for a Firetube boiler) off you go but you will need a boilerman to keep an eye on the water, Flash boilers were prone to running dry very quickly and when that happens its back to the boilersmiths.

Despite what many people think Tanks spend a lot of time with the engine off waiting for orders to do something. Internal combustion engine no problem (lots of tanks have a small aux engine to keep the battery topped up) steam boilers dont like the hot and cold cycle once its hot you need to keep it hot till the end of the working day.

You will need a condenser which is a big thing much bigger than a radiator especially if its an air condenser.

Its doable but its going to be BIG tank.

All right, points taken, but how about field maintenance? Wouldn't the greater mechanical simplicity and much lower number of moving parts in a steam engine be an advantage over an internal combustion one?

MrP said:

All right, points taken, but how about field maintenance? Wouldn't the greater mechanical simplicity and much lower number of moving parts in a steam engine be an advantage over an internal combustion one?

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Steam engines still have quite a few moving parts... You might simplify basic maintenance but I think overall you need more labor to keep the things rolling.