And now for a particularly silly notion... TANKS!!!

The earliest fuel, of course, was readily available wood, but its heat content was often unpredictable, and under a forced draft it produced a dangerous exhaust of hot embers that could set fires wherever they landed, in lineside grass or on the passengers' clothing. Although wood-burners with oversized cinder-screen smokestacks survived until the 1900s, by the Civil War coal had been recognized as a far superior fuel. The most visual characteristic of US locomotives, necessitated by the widespread use of wood rather than coal as fuel, was the bulbous chimney, the sparkcatcher to go with the cowcatcher, that was designed to reduce the number of sparks flying from the chimney, which, in the early days, set off numerous fires beside the tracks.

The first steam locomotives burned wood, and cordwood was simply loaded by hand into the tender from piles located along the route. Wood, though cheap and easy for railroads to acquire, was thermally inefficient, and by the 1870s most railroads had switched to coal. Most steam locomotives burned a reasonably good grade of bituminous coal, while some Eastern roads used a bituminous-anthracite mix. A few Western roads burned locally mined low-grade lignite that was little more than messy dirt. The fireboxes and smokeboxes had to be adjusted for each railroad's preferred type of coal. In areas where coal was scarce, particularly in the West, many railroads in the late 1800s began to burn heavy Bunker C fuel oil instead of coal. The heat content was about the same, and sometimes engines were swapped back and forth between oil and coal fuel by replacing the grates and burners and bunkers in the tender.

Before the Civil War, despite some preliminary experimentation that began to yield tangible progress by the 1850's, American locomotives were fired almost exclusively by wood. Within a score of years thereafter, a transformation so rapid had occurred that twenty times more coal than wood was being consumed annually, and more than a fourth of bituminous coal output was regularly absorbed by the railway sector. The underlying mechanism is almost a text book illustration of substitution in response to changing relative prices. To begin with, eastern railroads with large coal deposits along their lines,.and hence both low coal prices and elastic supply, invested in research necessary to eliminate the troublesome technical problems that had limited the development of coal-burning locomotives. Once successful the eastern railroads penalized by high wood prices and the western railroads favored by low coal prices led the parade to mineral fuel.

Captain Igloo wrote:The earliest fuel, of course, was readily available wood, but its heat content was often unpredictable, and under a forced draft it produced a dangerous exhaust of hot embers that could set fires wherever they landed, in lineside grass or on the passengers' clothing. Although wood-burners with oversized cinder-screen smokestacks survived until the 1900s, by the Civil War coal had been recognized as a far superior fuel. The most visual characteristic of US locomotives, necessitated by the widespread use of wood rather than coal as fuel, was the bulbous chimney, the sparkcatcher to go with the cowcatcher, that was designed to reduce the number of sparks flying from the chimney, which, in the early days, set off numerous fires beside the tracks.

The first steam locomotives burned wood, and cordwood was simply loaded by hand into the tender from piles located along the route. Wood, though cheap and easy for railroads to acquire, was thermally inefficient, and by the 1870s most railroads had switched to coal. Most steam locomotives burned a reasonably good grade of bituminous coal, while some Eastern roads used a bituminous-anthracite mix. A few Western roads burned locally mined low-grade lignite that was little more than messy dirt. The fireboxes and smokeboxes had to be adjusted for each railroad's preferred type of coal. In areas where coal was scarce, particularly in the West, many railroads in the late 1800s began to burn heavy Bunker C fuel oil instead of coal. The heat content was about the same, and sometimes engines were swapped back and forth between oil and coal fuel by replacing the grates and burners and bunkers in the tender.

Before the Civil War, despite some preliminary experimentation that began to yield tangible progress by the 1850's, American locomotives were fired almost exclusively by wood. Within a score of years thereafter, a transformation so rapid had occurred that twenty times more coal than wood was being consumed annually, and more than a fourth of bituminous coal output was regularly absorbed by the railway sector. The underlying mechanism is almost a text book illustration of substitution in response to changing relative prices. To begin with, eastern railroads with large coal deposits along their lines,.and hence both low coal prices and elastic supply, invested in research necessary to eliminate the troublesome technical problems that had limited the development of coal-burning locomotives. Once successful the eastern railroads penalized by high wood prices and the western railroads favored by low coal prices led the parade to mineral fuel.

The earliest fuel was, of course, coal because that's what the earliest locomotives were pulling. The first locomotives were used to pull coal out of collieries in England, and then on Sept. 27, 1825, George Stephenson opened the Stockton and Darlington railway line, which was the first public railway mostly for transporting coal from collieries near Darlington (disclosure, my grandfathers and my father worked in collieries in this area) to Stockton. That first steam locomotive, the Locomotion, also pulled the first passenger car containing dignitaries there for the opening and a load of 80 tons of coal and flour. Locomotion 1 covered 15 miles in 2 hours, reaching, at one point, a speed of 24 miles per hour. It was wrecked in 1827 but rebuilt and can still be seen at the Head of Steam museum in Darlington, Co. Durham, England.
Locomotion: https://en.wikipedia.org/wiki/Locomotion_No._1
George Stephenson: https://en.wikipedia.org/wiki/George_Stephenson
Additional disclosure: My mother worked at the Robert Stevenson locomotive works in Darlington during and after WWII.https://en.wikipedia.org/wiki/Robert_Stephenson_and_Hawthorns

AirTech wrote:As opposed to the WWI idea of petrol powered engines and fuel tanks? The British MkV had a crew of 8. One hit from serious artillery nearby and the crew is roasted in spilled petrol from ruptured fuel tanks.

That was not the normal event.

AirTech wrote:Compared to this spilled coal is a non-event.

Ehm? Burning coal on the floor of a tank? That most definitely is NOT a "non-event"!

AirTech wrote:Steam leaks are another problem and for these, containment is required and the firing doors are a significant hole in this.

You can pretty much guarantee that any steamtank WILL have steamleakage after having been on a battlefield for a while. It´s very difficult to design it to be impervious unless the tank is never going to go anywhere but flatlands without much obstacles.

AirTech wrote:The heat issues are significant, and was a real problem in the British type K steam submarines.

And a submarine is literally surrounded by the perfect cooling medium, water.

And while the steam engines were only directly involved in one of the catastrophic losses of that sub-class(out of 6 in just 14 years of service for 17 subs), they were contributing factors for dozens of incidents that could or did sink them.

One of the worst submarine classes EVER. And much of that due to the use of steam engines.

AirTech wrote:Ventilation helps a lot, and a steam engine actually makes this easier as the boiler draft helps with ventilation. (Ventilating a submerged submarine causes interesting problems

A submarine can be built to vent heat into the ocean, and does so to some extent automatically.

AirTech wrote:Automatic firing of solid fuels is relatively easy with a walking bed grate, wood chips or lump coal are usually used with this but hay and bagasse (sugar cane waste) also works. Blown fuel feeds requires coal dust or saw dust which are hard to obtain in the field (fuel slurries are even worse but the US Army have coal dust slurry as an accepted alternative fuel for its ground gas turbine engines, including tanks).

And you do realise that such automatic systems involve bigger SIZE and greater WEIGHT don´t you?

And both of those translates into a BIGGER tank, which means much more total weight.

AirTech wrote:You have to bear in mind that most peoples mental images of steam engines are state of the art circa 1880. (The rail industry kept building these into the 1930's). Serious state of the art systems for fired steam generation have more in common with nuclear systems than most people realize

Having a brother who was for years involved with steam trains and to some extent boats, and with my involvement with the railroads here, which built a rare few steam locomotives as late as the 1950s, kept some few in active service until the 1970s(they were superior for use after extreme snowfalls and in heavy snow in general), with the war contingency reserve not being abolished until the 1990s(which of course included having people that could work them, like my brother), i´m pretty damn sure i´m not stuck in the 1880s in regards to steam.

Tenshinai wrote:
Having a brother who was for years involved with steam trains and to some extent boats, and with my involvement with the railroads here, which built a rare few steam locomotives as late as the 1950s, kept some few in active service until the 1970s(they were superior for use after extreme snowfalls and in heavy snow in general), with the war contingency reserve not being abolished until the 1990s(which of course included having people that could work them, like my brother), i´m pretty damn sure i´m not stuck in the 1880s in regards to steam.

The design of steam locomotives was essentially frozen in the 1880's. The fact that they were still running in the 1950's is hardly surprising (as steam loco's (or any loco's) are very robust machines). The steam turbine designs were overrun by the quicker to start diesels with closed circuit lubrication systems (reciprocating steam engines are almost without exception total loss lubrication systems)(Closed circuits results in less wear).
One of the keys with a steam engine is minimizing heat losses from the boiler and maximizing losses from the condenser so the boiler tends to be well insulated. Unfortunately boilers need air in bulk and with solid fuels you cant remove the fuel from the boiler to shut it off so when submerged you have a fire still burning in the boiler, fouling the air if not isolated and leaving an explosive gas mixture waiting for you if you do... (Steam submarines were even more uncomfortable than the diesels because of heat from the boiler room soaking through the bulkheads). Submarines need insulation in the occupied areas from the cold sea around so a heat source that is intermittent is a pain to manage.

AirTech wrote:The design of steam locomotives was essentially frozen in the 1880's.

No they were not. End of story.

AirTech wrote:The fact that they were still running in the 1950's is hardly surprising (as steam loco's (or any loco's) are very robust machines).
The steam turbine designs were overrun by the quicker to start diesels with closed circuit lubrication systems (reciprocating steam engines are almost without exception total loss lubrication systems)(Closed circuits results in less wear).

Please DO reread what you quoted eh? The last steam locos were BUILT here in the 50s (aftereffect of WWII).
And those were new designs.

However, the last design built in more than 10 copies, the E10, was based on the shortrun E9 from the mid 1920s(only 4 built), as they had been found to have superior design.

Though still generally reciprocating engines because steam turbines didn´t like the climate here(they were widely used for generating electricity in the engines, but not as main propulsion system). Not to mention how they were far more expensive to run, had terribly poor lowspeed efficiency and was unable to change rotational direction. They also needed a far more expensive condensor to be fully effective.

The last actively running steam locomotive on a "normal" basis were in the 1970s(Sept 20th 1977). Like i already wrote.

Tenshinai wrote:The last actively running steam locomotive on a "normal" basis were in the 1970s(Sept 20th 1977). Like i already wrote.

FWIW, I think China built the last new steam locomotive in the 1990s (or at least the last export steam loco, as at least two were imported to the US for an excursion RR.) There are(were?) a couple of documentaries on YouTube about Chinese Steam Railroads and Locomotives.