Lets discuss the effects of steam driven tanks if they're invented in the late 1800's

[Shurik]

Still leaves water.

I just don't think there's room within the tank to have sufficient stores of fuel to operate for very long - that's not a problem for tank locomotives because they can stop and refuel every so often, but for armored war vehicles that's disastrous.

Also, I suspect the interior of any steam tank is going to heat up to unbearable levels quickly.

There's also the simple fact that anything running on iron/steel rails is VASTLY more efficient than anything running on land. Trains ran, and still run because a steel wheel running on steel track is VERY efficient. That's why modern diesel-electrics are able to get in the neighborhood of 400mpg per ton. Translate that sort of energy efficiency backwards to steam rail vs road, and you've got a rediculously inefficent vehicle.

*Sigh* I know. I've been wondering if a machine like the Lombard can haul 125 tons if it can handle having the weight of armour as well as weapons on top of it. I need to do some more research to finda way to make this plausible. If not I'll go for a deisel powered machine with a steampunk aesthetic.

There is a great difference between towing something and carrying something.

This.

Plus, while your screw-drive thing looks awesome (I'll give it that), the force required to drive two massive steel screws, bearing all the weight that it is, against the ground in a manner designed to provide forward momentum is just about the most inefficient use of force possible. Think about it, you're trying to divide all the available mechanical force between the task of moving the thing forward, as well as overcoming the friction between the rotating screw and the ground. It's FAR less efficient than just using wheels, which is a major technical hurdle in of itself.
OTL the only time it was even contemplated (never really getting beyond prototype stages both in the US and Russia) it was for very specific types of terrain: ice and snow (very low screw-rotation friction) or extremely muddy areas where floatation was vital (also vastly reduced friction).

That's not even touching how quickly those screw blades would wear out running over anything other than soft mud or snow. Grinding those things on even slightly gravely ground? They'd be worn out in no time flat.

Another item for thought:resource allocation. How many high-grade field guns could be manufactured using the same human and material resources that would be required for even one of those things? I have no idea, but I'd venture at least 10. And giving up 10 guns for one of those things... I wouldn't buy it.

Finally, I'm curious about it's use. It's been mentioned using it as a "mobile pill-box". I'm guessing about the only armament the thing could be really equipped with would be infantry-type weapons: rifles/muskets. Artillery of any sort would add immense weight, not to mention crew requirements.
That means, the effective range of its armament would be no greater than a standard rank-and-file group of infantry-men. Likely much worse given the accuracy of light-arms of the time.
Meanwhile, I don't know the effective range of field-guns at the time but I'd conservatively estimate that they could easily begin taking pot-shots at it, at twice the range of your steam-tank's weaponry. Massed artillery fire (such as was employed at the time) an the thing would be turned into swiss cheese before it was ever close enough to take a single shot.

Just a couple thoughts I had.

 

[Shtudmuffin]

Snip

Shurik, do you have to ruin me outside of Viva la Revolucion too?

Anyway, these responses to your points will be brief, and some might be missing, as I am on my phone.

First off, screw drives have a lot of torque. Worm gears, basically a gear version of the screw propulsion, have one purpose only-to convert speed into torque. And that's exactly what's being done in this kind of drive.

As for the screws wearing out, if they are designed well I would imagine they could dig into the ground. They likely wouldn't travel on gravel/stone/roads, but instead be used in the field and around city perimeters. I don't think the drive wearing down would be a big problem, and it seems likely that the flanges of the screw could be easily reproduced.

 

[amphibulous]

Plus, while your screw-drive thing looks awesome (I'll give it that), the force required to drive two massive steel screws, bearing all the weight that it is, against the ground in a manner designed to provide forward momentum is just about the most inefficient use of force possible.

As anything but an excuse to sell wargamers models it is idiotic. It's going to turn soft ground to mush and will then have function as a propellor - and the power to weight ratio needed to will be incredible. There are good reasons why no one has ever done this in real life!

 

[RamscoopRaider]

Honestly I think steam powered war vehicles would be very very niche machines

The only role I can think of is short range devices (too unreliable and hard to fuel for anything else) to support an infantry assault against an entrenched foe without heavy (bigger than swivel guns) direct fire artillery

This is a pretty niche role, you won't find many situations where you have an enemy that poorly equipped where a steam powered vehicle could reasonably be used and deployed (I could only find one in my ASB TL and that was a very specific set of circumstances)

 

[amphibulous]

Another item for thought:resource allocation. How many high-grade field guns could be manufactured using the same human and material resources that would be required for even one of those things? I have no idea, but I'd venture at least 10. And giving up 10 guns for one of those things... I wouldn't buy it.

Pretending it could work, I'd say far more. Just consider trying to fabricate the worm drive screws and a robust bearing system. Call it +20 - and then remember the phenomenal maintenance cost. Then remember you have to apply Lanchester's law...

Meanwhile, I don't know the effective range of field-guns at the time but I'd conservatively estimate that they could easily begin taking pot-shots at it, at twice the range of your steam-tank's weaponry. Massed artillery fire (such as was employed at the time) an the thing would be turned into swiss cheese before it was ever close enough to take a single shot.

Swiss cheese would have lots of little holes, so no. This would take one explosive shell, then the lucky part of the crew would be dead of fragments and blast and the less lucky boiled by steam leaks.

 

[amphibulous]

Honestly I think steam powered war vehicles would be very very niche machines

The only role I can think of is short range devices (too unreliable and hard to fuel for anything else) to support an infantry assault against an entrenched foe without heavy (bigger than swivel guns) direct fire artillery

This is a pretty niche role, you won't find many situations where you have an enemy that poorly equipped where a steam powered vehicle could reasonably be used and deployed (I could only find one in my ASB TL and that was a very specific set of circumstances)

Not even this. Steam vehicles have appalling off-road mobility and an incredibly poor cost benefit ratio - you're always better off putting your money into something else. (I would suggest mortars and better supplies, field kitchens, and field hospitals.)

The only sane uses are protecting roads or rail against insurgents - about how the British used them in the Boer war. In these applications the poor power to weight ratio won't matter too much.

 

[RamscoopRaider]

Not even this. Steam vehicles have appalling off-road mobility and an incredibly poor cost benefit ratio - you're always better off putting your money into something else. (I would suggest mortars and better supplies, field kitchens, and field hospitals.)

The only sane uses are protecting roads or rail against insurgents - about how the British used them in the Boer war. In these applications the poor power to weight ratio won't matter too much.

A steam caterpillar tractor was tested that could pull a 5.4 ton artillery piece plus ammo across rough ground in 1910 without too many problems and under some conditions proved better than the horses previously used, so mobility could become good enough for off road use (sadly my only source is wiki)

Of course by this point you are getting past the point mentioned in the OP and of course the device did better when a gasoline engine was installed

Still if you have a specific enough set of circumstances you could see a role, but they have to be very damn specific circumstances (field modification of commercial steam vehicles in area with no appropriate gasoline engines, where army higher ups send few heavy weapons that has good enough terrain for steam powered tracked vehicles and no enemy heavy weapons and an enemy that digs in deep in such a way that mortars prove ineffective), of course the money could be spent on something better, but governments don't always spend defense money rationally

 

[Shurik]

A steam caterpillar tractor was tested that could pull a 5.4 ton artillery piece plus ammo across rough ground in 1910 without too many problems and under some conditions proved better than the horses previously used, so mobility could become good enough for off road use (sadly my only source is wiki)

Of course by this point you are getting past the point mentioned in the OP and of course the device did better when a gasoline engine was installed

Still if you have a specific enough set of circumstances you could see a role, but they have to be damn specific circumstances

As was noted earlier though: there is a difference in force exhertion between simply pulling weight, as opposed to actaully carrying weight (as would be required for armor, armament, etc).

 

[RamscoopRaider]

As was noted earlier though: there is a difference in force exhertion between simply pulling weight, as opposed to actaully carrying weight (as would be required for armor, armament, etc).

Oh certainly

I'm just wondering if something that can tow 16400 pounds (5.4 tons plus 5600lbs standard ammo load) can handle mounting 3000-6000 lbs of weapons and armor and still move over okay terrain

And I'm thinking that if it can someone somewhere might do it [if not, well I write ASB]

 

[amphibulous]

A steam caterpillar tractor was tested that could pull a 5.4 ton artillery piece plus ammo across rough ground in 1910 without too many problems and under some conditions proved better than the horses previously used, so mobility could become good enough for off road use (sadly my only source is wiki)

Yes, but now we're up to the date when tracks are possible and steam engines have another 30 years of development over the 1880s - and 50 years over the USCW.

 

[amphibulous]

I'm just wondering if something that can tow 16400 pounds (5.4 tons plus 5600lbs standard ammo load) can handle mounting 3000-6000 lbs of weapons and armor and still move over okay terrain

It may need - probably will - wider and/or longer tracks to handle extra weight without extra wheels.

 

[Awilla the Hun]

Finally, I'm curious about it's use. It's been mentioned using it as a "mobile pill-box". I'm guessing about the only armament the thing could be really equipped with would be infantry-type weapons: rifles/muskets. Artillery of any sort would add immense weight, not to mention crew requirements.
That means, the effective range of its armament would be no greater than a standard rank-and-file group of infantry-men. Likely much worse given the accuracy of light-arms of the time.

The HG Wells Land Ironclad had semi automatic rifles, as I recall.

It could also possibly mount a Gatling, if it could ever start moving at all.

 

[Texian]

What happens when your steam powered, screw driven tank tries to "charge" hill?
Answer: It won't. If it's larger than 20 feet in length, the single screws on either side won't be able to flex enough to stay in contact with the ground and the screws will lose traction. That being said, even if you manage to mount the hill, even geared steam locomotives, specifically designed for extreme incline can only manage to chug up a 10% grade, maybe. 4% grade with any steam engine that isn't geared. That's if the whole thing doesn't explode from the boiler pressure first. Because Steel and Iron from the mid 1800's was absolutely top notch stuff...

Let's just out a Monitor Turret/Mortar Pad on a flat train car and call it good.

 

[Elfwine]

What happens when your steam powered, screw driven tank tries to "charge" hill?
Answer: It won't. If it's larger than 20 feet in length, the single screws on either side won't be able to flex enough to stay in contact with the ground and the screws will lose traction. That being said, even if you manage to mount the hill, even geared steam locomotives, specifically designed for extreme incline can only manage to chug up a 10% grade, maybe. 4% grade with any steam engine that isn't geared. That's if the whole thing doesn't explode from the boiler pressure first. Because Steel and Iron from the mid 1800's was absolutely top notch stuff...

That underlined part is not really something that's different regardless of motive power, though. And I'm not sure how it compares to IRL tanks.

Boiler explosions weren't that common in the mid-1th century - hardly unheard of, but not a regular thing either.

And the problem wasn't the quality of the iron (steel is not in use until later) of the mid-19th century.

 

[SPJ]

It may need - probably will - wider and/or longer tracks to handle extra weight without extra wheels.

Yes. For my concept of a steam powered armored half-track I've been thinking about taking the design for the Lombard or Phoenix and changing the placement of the tracks and wheels. First instead of having the tracks mounted beneath the cabin I'd mount them on the opposite side of the smoke stack so that the stack is between the tracks and drivers cabin. This way I can have the engine placed in the back of the vehicle and perhaps away from most enemy fire. Then I would have a pair of large steel wheels placed at the front of the vehicle and another pair near its center to hold more weight. Also I'd have the tracks and wheels spread further apart than what’s on the Lombard. This I hope would help to increase the machines load baring strength. Also I think I might change the shape if the bowler to make it thinner and longer than what the Lombard has to displace weight along its length.

Also in regards to armor I think that by mounting either a saddle water tank or side tanks around/over the engine would increase the protection provided to it. Also instead of providing the vehicle with armor made of thick layers of iron of steel a design similar to the first ACW ironclads could be used that reinforced thinner metal armor with wood on the inside. I think in most cases this would help protect it from rifle fire and light artillery fire using black powder charges. If anyone could provide further details on what sort of armor is necessary to protects something from at least light field artillery please let me know.

The HG Wells Land Ironclad had semi automatic rifles, as I recall.

It could also possibly mount a Gatling, if it could ever start moving at all.

The best/earliest weapons I could imagine mounting on such a vehicle would be breach loading cannons like a 12 or 20-pounder Armstrong gun (how much these cannons weigh themselves idk). And/or cartridge receiving Gatling guns and I believe the model 1874 was the first of these.

 

[Shtudmuffin]

What happens when your steam powered, screw driven tank tries to "charge" hill?
Answer: It won't. If it's larger than 20 feet in length, the single screws on either side won't be able to flex enough to stay in contact with the ground and the screws will lose traction.

Who's to say it can't go up sideways or diagonally? The machine can move from side to side, it isn't just relegated to forward and back movement. And I don't think too many steep hills like that could be found in a typical battle (but I don't know a thing about hill grades, so...)

 

[modelcitizen]

Industrial advantage means leverage viz steam-engine tanks.

Folks like the Confederates would get squashed like grapes.

 

[wolf_brother]

Doesn't Thande have these in LTTW?

 

[davroslives]

Steam and Steel

This looks rather interesting...http://www.boardgamegeek.com/boardgame/82211/steam-and-steel

 

[RamscoopRaider]

Yes, but now we're up to the date when tracks are possible and steam engines have another 30 years of development over the 1880s - and 50 years over the USCW.

Yeah that's true, so it wouldn't meet the OP's requirements which seem to be impossible with OTL laws of physics