Steam Power For Tanks Ideas And Inspiration

[dy031101]

Continuing from a thread of on same topic from you-know-where......

I've been thinking of the idea of re-engining the early M48 tank with steam engine.  rickshaw's suggestion is that a large exhaust be added.

Then I found out that early M48s actually have their engine exhaust mounted ahead of the gun travel lock, the grilles mistaken by me to be engine exhaust actually being engine and transmission access......

Is that exhaust large enough for use by a steam engine?

(Well, one a second thought, that exhaust seems just large enough to get in the way of my other upgrade idea for the tank......)

Other suggestions on this topic will be welcomed as well.

[Rickshaw]

As this is a whiff and not a real life vehicle, you can basically put the exhaust where you like.   Remember, you're not using the petrol engine in the vehicle, so it would be unlikely to have the exhausts emerge from the hull in the same position.

[tankmodeler]

Granting that this is a WHIF and also stipulating that I am a mechical engineer by trade, I tend to have my WHIFs be eminently plausible and I start to disbelieve things that are simply not possible in the environment in which they are imagined.

Along those lines, a steam powered M48 is simply too implausible to work visually. If you look at the mass of the tank involved (about 50 tons) and power ratio needed to achieve the mobility of the M48, about 15 hp/ton, and factor in the known fact that steam engines have a significantly lower power density than internal combustion engines, the concept simply doesn't work.

Any supposed engine you put in there will look ridiculously too small and any appropriately sized engine will be bigger than the entire tank. You would need an engine the size of an old time locomotive to produce the 750 HP needed to move an M48 properly and such an engine would weight a lot more than 50 tons on its own. Like 2-3 times more.

And where would you put the coal bunker and how would the stoker stoke the boiler? :)

For me, a WHIF has to hang together as being plausible for the viewer to suspend disbelief. If it violates a sense of "rightness", then the idea and the model starts to fall apart.

Just my two Canuck pennies, of course.

Paul

[perttime]

What about... Steam turbine.
You don't necessarily need solid fuels to generate steam.

Apparently ... a steam-powered version of the Messerschmitt Me 264 was hypothesized but never constructed - in 1944. It was meant to be powered by a steam turbine developing over 6,000 horsepower (4,500 kW), fueled with a mixture of powdered coal and petroleum.

[dy031101]

I've been under the impression that steam engine for tanks will have rather much to do with the development of steam cars.

Actually, rickshaw, would you mind reposting the article here?  Thanks in advance.  Always wanting to hear more people voicing their opinions of it.

[elmayerle]

Just throwing a concept out for thought.  A liquid-fueled high-pressure boiler feeding a steam turbine/generator set and the tank run by electricity.  This has the advantage of reducing the mechanical complexity of the system and could allow for multiple drive-motors per track, adding redundancy to improve damage tolerance.

[tankmodeler]

What about... Steam turbine.
You don't necessarily need solid fuels to generate steam.

Apparently ... a steam-powered version of the Messerschmitt Me 264 was hypothesized but never constructed - in 1944. It was meant to be powered by a steam turbine developing over 6,000 horsepower (4,500 kW), fueled with a mixture of powdered coal and petroleum.

It's a scientific fact that any and all external combustion cycles are significantly less power dense than the equivalent power internal combustion cycle. In addition, you need large amounts of water to generate the steam and then large heat exchangers to dump the heat into the air to get your water back. If you use some of the waste heat to warm up the water & increase efficiency, oyu increase weight again to account for the regenerators. Now, the 264 was a large bomber and the ability to use other fuels than scarce petrolium may have suggested a steam turbine to someone, but the hit it would have taken on payload/performance would have been truly brutal.

I've been under the impression that steam engine for tanks will have rather much to do with the development of steam cars.

And the use of steam engines for cars is primarily to permit the use of alternate fuels. Performance will suffer dramatically.

A liquid-fueled high-pressure boiler feeding a steam turbine/generator set and the tank run by electricity.

Still massively inefficient and low powered. There is a fundamental problem with and, repeat, any application of external combustion. They are inefficient and low power. There is no way to get more out of a steam system thatn an equivalent mass internal combustion system. There is a reason that even the largest ships are now using diesels rather than any sort of steam. They are better. On the most fundament level, just simply better. If a diesel exists no-one would ever replace it with a steam engine of any type. If diesels are not available then any vehicle powered by steam will have significantly lower performance on all levels.

This has the advantage of reducing the mechanical complexity of the system

Without trying to be mean, where would you get this idea? The Steam engine alone is significantly more complex than the diesel as it sits. Adding the electrical generating system and the motors just adds to it. It would be a mechanical nightmare. Even with an internal combustion engine, Dr. Ferdinand Porche couldn't make it work properly on the Ferdinand.

No steam engine buildable using the laws of this universe can be made that will propel a vehicle even 1/2 the weight of an M48 any distance at all and still fit within even twice the volume of the Patton's engine bay.

There's a reason we don't use 'em anymore, y'know!  :)  :)

Paul

[elmayerle]

The thought was that a steam turbine driving a generator set with output going direct to drive motors for the treads would be less complex that the transmission and driveshaft.  I agree that a regular steam engine would not fit as well.  If I wanted true multi-fuel capacity, I'd pobably either use a gas turbine or a SCORE (Stratified Charge  Omnivorous Rotary Engine) for power.

[Rickshaw]

Have a look at the original article which inspired the thread.  According to it, you can get higher power densities from steam than many realise.   External combustion engines don't need massive boilers and long pistons to work.

[jcf]

Steam is still number one in electrical power generation. 

Paul, we get yer point, and speaking as the son of a steam engineer and as someone
who grew up around industrial steam, I agree with most of your points regarding steam
as a motive force*. However, this forum is here to encourage the re-imagining
of what is vs. what could be, so if folks want to envision a new Steam Age, beating
them over the head with the technical reasons why it won't work is counter-productive
as it probably won't change anybody's mind.
 
Jon

p.s. contemporary steam cars are about alt. fuels, which is not true of historical steam cars.

* Don't get me started on Steampunk "machinery", seriously, don't. 

[GTX_Admin]

* Don't get me started on Steampunk "machinery", seriously, don't. 

Damn that is tempting...

[Rickshaw]

Who's seen "Steam Boy"? 

[GTX_Admin]

Who's seen "Steam Boy"? 

 ...but I did enjoy it too.

[dy031101]

I suppose I am not really walking along the full-on "New Steam Age" route...... just some steam powered vehicles here and there, pending availability of internal combustion engine vehicles. 

Anyway, let's go for one that's steam-powered from the ground up then......

Later, it was learned that Henschel in Germany actually had been making layouts for a steam power installation in a Tiger tank at almost the same time. They found that existing boilers and condensers occupied too much space, and since the OKH was disinterested, the project was dropped.

Does anyone know how big the "steam-powered Tiger" would have been if they were going to pull it off?  If not, would anyone be willing to venture a guess on possible size relative to the actual Tiger I based on the boiler and condenser technology of the early 1940s?

[jcf]

Going way out on a limb and saying the same size as a regular Tiger? The quoted text states
"steam power installation in a Tiger tank...".

[Rickshaw]

Going way out on a limb and saying the same size as a regular Tiger? The quoted text states
"steam power installation in a Tiger tank...".

Yes, I think the point being made was that they couldn't fit it inside a standard Tiger I hull...

[dy031101]

Going way out on a limb and saying the same size as a regular Tiger? The quoted text states
"steam power installation in a Tiger tank...".

Yes, I think the point being made was that they couldn't fit it inside a standard Tiger I hull...

Yeah, and so I was wondering how much larger the tank would have been if going steam powered......

[Rickshaw]

Going way out on a limb and saying the same size as a regular Tiger? The quoted text states
"steam power installation in a Tiger tank...".

Yes, I think the point being made was that they couldn't fit it inside a standard Tiger I hull...

Yeah, and so I was wondering how much larger the tank would have been if going steam powered......

How long is a piece of string?  We don't have any data beyond that brief mention.  I'd suggest maybe 10-20% longer?

[dy031101]

I'd suggest maybe 10-20% longer?

Precisely what I need to start contemplating on what I'll do to that Tiger I line drawing  :)

[Weaver]

Articulated two-body tanks and AFVs have been experimented with: how about using that principle to accomodate the greater volume of a steam engine? The boiler/turbine/generator could be in the aft body sending power to four motors on the track sprockets. Keeps the crew safer from boiler explosions too....

[GTX_Admin]

Articulated two-body tanks and AFVs have been experimented with: how about using that principle to accomodate the greater volume of a steam engine? The boiler/turbine/generator could be in the aft body sending power to four motors on the track sprockets. Keeps the crew safer from boiler explosions too....

I like that idea! :)

[tankmodeler]

Does anyone know how big the "steam-powered Tiger" would have been if they were going to pull it off?  If not, would anyone be willing to venture a guess on possible size relative to the actual Tiger I based on the boiler and condenser technology of the early 1940s?

It is very hard to establish exactly how many HP a steam locomotive makes as, like a jet engine, the HP generated increases as the speed increases. However, I found a piece that stated that a set of locomotives designed at the turn of the 1900's were the first to make 1 hp per 100 lbs of weight. If we assume that the engines of 1944 would be better and also assume that these could make, say 1 hp per 66 lb, then to produce eeh 690 hp of the Tiger I's Maybach engine would require a steam engine of 690 x 66 = 45,540 lb just for the engine. This includes the traction set up for the locomotive wheels, which we wouldn't need, but does not include the weight of the fuel and water needed to run the engine itself or a transmission to get that power to the tank's tracks. If we lose, say 10,000 lb for the locomotive wheels and call the addition of the fuel and water and transmission a wash for losing the Maybach and the regular Tiger I transmission, we are left with an additional 35,000 lb or 17.5 tons of additional mass on top of the 56 ton mass of the Tiger I. Of course, such an engine is almost the same size as the Tiger 1 hull in its entirety, the extra enclosed volume now needing to be armoured similarly to the rest of the tank, so the mass increases again. Now the power/weight ratio has dropped rather a lot so either the performance will drop a lot or the engine has to get bigger again to maintain the power ratio.

Does that help?  :)

Paul

[tankmodeler]

Steam is still number one in electrical power generation. 

True, but the power for the steam comes from fissioning nuclei, so I don't think we can compare them, can we?  :)

However, this forum is here to encourage the re-imagining of what is vs. what could be, so if folks want to envision a new Steam Age, beating them over the head with the technical reasons why it won't work is counter-productive as it probably won't change anybody's mind.

I realise that completely, however, dy031101 asked questions relating to the reality of the steam engine that might power a Patton and whether the tank exhausts and location might be accurate for a steam engine.

If one wants to imagine a steam power Patton, just put the exhaust anywhere you want and make it any size you want. If one starts asking "how big should it be to power a Patton" you get a more factually based engineering-esque reply.  :)

Paul

[Rickshaw]

I think point here is that we need to differentiate between the motor and it's support systems.   The original article provides plenty of proof that you can make a small, compact but powerful steam motor.  What isn't discussed is how much water and fuel needs to be carried.  Nor does it mention, except in passing the need or not of a condenser.  If to this one chooses to add a generator to utilise electrical motors, which can also be bulky, then the package starts to become much bigger.

In particular the question of the condenser comes up as a big one.  Without it, you end up needing more water and frequent replenishment stops.  Condensers tend to be bulky and any saving in water gained may well be eaten up by the volume required of the condenser.  The quality of the water also becomes an issue.  "Hard" water with loads of dissolved minerals causes problems with scaling and other deposits.   Fuel is also an important consideration.  Solid fuels I'd suggest are basically not going to work (although powdered forms may).   How much is required would depend on how it's being used and the size of the boiler.  The original article mentions "boilerless" designs which are intriguing.

The original article as a general rule suggests, "that a steam engine of 500-horsepower is the equivalent of a 1000-horsepower internal combustion engine." so you're getting twice the power for half the size?

[GTX_Admin]

Steam is still number one in electrical power generation. 

True, but the power for the steam comes from fissioning nuclei, so I don't think we can compare them, can we?  :)

Err...I think you will find that there are far more power generation units utilising steam turbines that are fuelled by coal, oil, natural gas etc.  Nuclear powered units are only one option!

[tankmodeler]

Err...I think you will find that there are far more power generation units utilising steam turbines that are fuelled by coal, oil, natural gas etc.  Nuclear powered units are only one option!

Oh, I know that. I'm just being contrary to be a pain in the arse!  :)

The original article as a general rule suggests, "that a steam engine of 500-horsepower is the equivalent of a 1000-horsepower internal combustion engine." so you're getting twice the power for half the size?

Is that how we should interpret that statement? I would read it as for the size of a 1000 hp unit you only get 500 hp. Or for the same HP you need an engine twice the size.

And, of course, your comment on the ancillery equipment is very true and is also where the bulk of the mass of the system is.

For example, the engine for the M1 tank is the Lycoming (now Honeywell) AGT1500C gas turbine that produces about 1500 hp and weighs about 2500 lbs. The actual gas turbine part of the engine, i.e. where the air is compressed, fuel burned and power extracted, is pretty small and only weighs about 400 lb. The regenerators. intercoolers and preheaters that allow the powerpack to be efficient enough (barely) to be practical in a tank weigh the other 1100 lb. Plus the 500 gal of fuel. And no water. And all of this is with modern materials and processes.

The Maybach engine in the Tiger 1 also weighed about 2600 lb for 690 hp. If we use the ratio from the article per my interpretation above (could be wrong, but am going with it for now) then the basic steam turbine engine to produce 690 hp would mass about 5200 lb using equivalent WW II materials and science. Using the ratio from the AGT1500 of ancillery equipment to basic engine weight of almost 4:1 (1100:400) then the steam system mass in a Tiger-sized steam turbine engine might be 20,000 lb.

Plus fuel and water.

These are just spitballin' type numbers of course, but a steam turbine engine that is efficent enough to run a tank any tactically useful distance is bound to be many times the size of a similar internal combustion engine. Once the volume starts to go up you can either reduce the protection around the entire vehicle to keep the mass down, or increase the mass greatly and suffer a significant reduction in performance.

Or, of course, you can cover the hull and turret in rivets, plant a big smokestack on the engine deck, put a smoothbore breechloader in the turret and call it a steampunk tank and built it.  :)   

Paul

[GTX_Admin]

Or, of course, you can cover the hull and turret in rivets, plant a big smokestack on the engine deck, put a smoothbore breechloader in the turret and call it a steampunk tank and built it.  :)   

 :)

[Weaver]

The original article as a general rule suggests, "that a steam engine of 500-horsepower is the equivalent of a 1000-horsepower internal combustion engine." so you're getting twice the power for half the size?

Is that how we should interpret that statement? I would read it as for the size of a 1000 hp unit you only get 500 hp. Or for the same HP you need an engine twice the size.

The full quote is this:

Doubling steam power does require about eight times the heat exchanger volume, but nevertheless, some of the engines themselves, as just noted, are very small. And, delivery of power at the drive sprockets of a tank is the proper method of comparison because it eliminates conventional power train losses. A steam engine needs no power train and, unlike the internal combustion engine, the external combustion engine torque output is maximum even when starting from a stop. Thus, it is estimated that a steam engine of 500-horsepower is the equivalent of a 1000-horsepower internal combustion engine.

The way I read that statement is that he's saying the torque characteristics of a steam engine make it the practical equivalent of an IC engine of twice the horsepower.

[Queeg]

The way I read that statement is that he's saying the torque characteristics of a steam engine make it the practical equivalent of an IC engine of twice the horsepower.

Hence the reason why Heavy trucks use diesel engines, low rpm torque is king. They want traction not high speed incremental gains. Electric motors have similar bonuses, esp now control systems can manage and feather the hard start.

I like Steampunk stuff, some of it looks reall great (like the steam powered the flying "aerospacecraft" from Mutant Chronicles movie). But you have to sacrifice some practicality and just accept it for what it is - a bit of rollicking fun.  A tank using steam power will be big and slower. Because it's big you need a larger gun to make it worthwhile, then a bit more armour etc etc etc

[dy031101]

Guess I'm looking at more of a steam-powered Löwe...... 

[Queeg]

Guess I'm looking at more of a steam-powered Löwe...... 

Lol ...... probably more of a Maus, which looks like a train incidentally. The Germans didn't waste any money on the asthetics part of that project ......

[dy031101]

The scaled model of a steam-powered tank proposal in 1964 mentioned in article posted by Rickshaw.

It uses a pair of steam turbines though (whereas the article actually places more emphasis on steam engines that do not employ turbines), each turbine delivering 250hp at 24000rpm.  It is claimed that, including a three-to-one reduction gear, the turbines in full size were expected to be no more than 9in by 18in in size.

EDIT: Re-phrased as pointed out by jcf.

[elmayerle]

So we perhaps go the other way, a steam-powered, steam-punk Bolo?  Controlled by a steam-driven babbage engine?

[jcf]

It uses a pair of steam turbines though (whereas the article actually places more emphasis on just steam engines), each turbine delivering 250hp at 24000rpm.  It is claimed that, including a three-to-one reduction gear, the turbines in full size were expected to be no more than 9in by 18in in size.

A steam turbine is a steam engine, the difference is that instead of the steam moving piston(s)
in cylinders the steam spins a series of discs.

[Rickshaw]

Just let me throw another example of what can be achieved with steam - the British Steam Car Challenge which raised the land speed record for steam powered vehicles to 148mph over a kilometre course.

While not necessarily a practicable design for an Armoured Fighting Vehicle (AFV) it does indicate that steam has been under-rated as a power source for vehicles for a long time IMO.

[jcf]

Just let me throw another example of what can be achieved with steam - the British Steam Car Challenge which raised the land speed record for steam powered vehicles to 148mph over a kilometre course.

While not necessarily a practicable design for an Armoured Fighting Vehicle (AFV) it does indicate that steam has been under-rated as a power source for vehicles for a long time IMO.

True, but the old record of 127.659 mph stood for 103 years. 

[Rickshaw]

Yes but it could be claimed that was because of the VICC (Vast Internal Combustion Conspiracy)(tm)!! 

[AndyJ]

Something I've been playing around with since 2010 is a steam powered Landcrawler designed to fight Martian war-machines in WWoW II.

http://beyondthesprues.com/Forum/index.php?topic=2579.0

Power was definitely something that was a design constraint and although I tried to keep it as feasible as possible there just had to be design fudges. also it's supposed to be a fun build, not an engineering proposal 

[dy031101]

Something I've been playing around with since 2010 is a steam powered Landcrawler designed to fight Martian war-machines in WWoW II.

http://beyondthesprues.com/Forum/index.php?topic=2579.0

Power was definitely something that was a design constraint and although I tried to keep it as feasible as possible there just had to be design fudges. also it's supposed to be a fun build, not an engineering proposal 

Did not notice this one until now...... wow......

Hey hey hey, is anyone willing to venture a guess on, if I want to shrink it to using regular tank armaments (a 105mm gun, for example), how much smaller the engine deck would be?

[Old Wombat]

I'll give it a guess.

Assuming a single QF 4" (or 4.7") Mk. I/II in the turret;

The turret would have approximate (LxWxH) dimensions of 4.5m x 3m x 1.5m (in a more compact WW1/2 era configuration)

The engine deck is approximately 1.2x the length of the turret & about 1.05x the width.

So;

(1.2 x 4.5m) x (1.05 x 3m) = 5.4m x 3.06m (or approx. 5.4m x 3.1m) = 16.524m² (or 16.74m²)

Using the more approximate size;

In 1/35th: 15.43cm x 8.86cm = 136.70cm² (which seems to be about the size of AndyJ's build)

In 1/48th: 11.25cm x 6.46cm = 72.68cm² (which I think should be AndyJ's scale)

AndyJ didn't mention his scale in the original Steam Landcrawler MkI thread, so I'm guessing it's 1/35th scale-o-rama'd to 1/48th (although the StuIG 33B he said was in the same scale looks to be 1/35th, in which case, Andy, your current turret is probably slightly undersized for the twin 8" guns).

:)

Guy

[AndyJ]

I'll give it a guess.

Assuming a single QF 4" (or 4.7") Mk. I/II in the turret;

The turret would have approximate (LxWxH) dimensions of 4.5m x 3m x 1.5m (in a more compact WW1/2 era configuration)

The engine deck is approximately 1.2x the length of the turret & about 1.05x the width.

So;

(1.2 x 4.5m) x (1.05 x 3m) = 5.4m x 3.06m (or approx. 5.4m x 3.1m) = 16.524m² (or 16.74m²)

Using the more approximate size;

In 1/35th: 15.43cm x 8.86cm = 136.70cm² (which seems to be about the size of AndyJ's build)

In 1/48th: 11.25cm x 6.46cm = 72.68cm² (which I think should be AndyJ's scale)

AndyJ didn't mention his scale in the original Steam Landcrawler MkI thread, so I'm guessing it's 1/35th scale-o-rama'd to 1/48th (although the StuIG 33B he said was in the same scale looks to be 1/35th, in which case, Andy, your current turret is probably slightly undersized for the twin 8" guns).

:)

Guy

Oh yeah, it's 1/35 scale, which is of course The One True Scale for anything on tracks 

There are a lot of scale issues with this build what with the underpowered propulsion*, the somewhat cramped turret and the woefully inadequate condenser array  However, these are all the typical sorts of self-imposed problems that plagued British armour design up until the Centurion, so I'm sort of following a fine tradition there...

I did toy with the idea of working this to 1/43 scale as there are a lot of steampunk type figures in that scale but I just couldn't face working outside of my 1/35 scale comfort zone. Although it may not be too late to reconsider that decision...

*The steam generation and turbo-generators might not be too far outside of what would be required as this was designed with assistance from my sister who designs these things as her day job, although usually nuclear powered. Estimated power output from a single oil-fired Babcock water tube boiler supplying two 500 kW Parsons HP turbo-generators and two 250 kW Parsons LP turbo-generators would give a max output of 1.5 MW supplied to two traction motors. Or in old-money, 1200 hp to power something with a design weight of 150 - 200 tonnes, it would likely be quicker than the Maus, although TBH my 85 year old Mum would be quicker than the Maus 

[Old Wombat]

 

Of course 1/35th is the One True Armour Scale! (D'you hear that Airfix! Helicopters, too, dammit! )

So, all dy031101 needs to do is fit a QF 4"/4.7" Mk. I/II (maybe 2) in a similar sized turret & he's cooking with gas!

:)

Guy

(Note: I chose the QF 4" Mk. I/II & the QF 4.7" Mk. I/II because they were all available in the 1900-1910 time line. )

[dy031101]

So, all dy031101 needs to do is fit a QF 4"/4.7" Mk. I/II (maybe 2) in a similar sized turret & he's cooking with gas!

(Note: I chose the QF 4" Mk. I/II & the QF 4.7" Mk. I/II because they were all available in the 1900-1910 time line. )

Well actually what I'm looking for is more of a "Panzer Löwe with steam engine" rather than a 1900s land corvette...... so yup, single-gun tank turret and other regular tank stuff.

But Parsons steam turbo-generators and adopted marine boilers?  F**k yeah! 

[Old Wombat]

The other reason I chose those guns is that they fit into the 105mm-ish bore range which you mentioned.

You could always use later Marks of the QF 4" or 4.7" for a WW2 version.

The crunch is that the engine deck would actually remain about the same size, maybe a few cm/in difference due to design differences.

:)

Guy

[AndyJ]

So, all dy031101 needs to do is fit a QF 4"/4.7" Mk. I/II (maybe 2) in a similar sized turret & he's cooking with gas!

(Note: I chose the QF 4" Mk. I/II & the QF 4.7" Mk. I/II because they were all available in the 1900-1910 time line. )

Well actually what I'm looking for is more of a "Panzer Löwe with steam engine" rather than a 1900s land corvette...... so yup, single-gun tank turret and other regular tank stuff.

But Parsons steam turbo-generators and adopted marine boilers?  F**k yeah! 

If you can get hold of a copy HMS Dreadnought (Anatomy of the ship), it has some excellent diagrams of the steam systems and turbines. Gave me good inspiration for the one I used on the landcrawler. Be prepared for an inordinate amount of space to be used up on your steam Löwe though, so perhaps a longer hull with extra set or two of wheels? I used a Mörser Karl hull and I think even that limited the amount of stuff I could cram in.

[Rickshaw]

I think and E-75 or even an E-100 hull would be more suitable.  Perhaps make a bit wider by splicing some plasticard down the middle.  With the E-100, I'd perhaps use a Smallturm from a Panther turret to give even more room (with an 88mm L/71).  This assumed advanced boiler technology and engine designs with advanced fuels are used.

[dy031101]

Assuming we are not limited to German-made weapon...... what's the minimum tank gun available to Western Europe that can be effective against a T-54?

[Rickshaw]

105mm Vickers L7.  It was developed for that purpose afterall.  I supposed if you could up the MV on the US 90mm T54 (and derivatives) or the 20 Pdr, it would work.  However, chamber volume becomes a limiting factor.

When the Soviet T54 took the wrong turning into the British Embassy in Budapest in 1956, they realised they needed a much higher velocity to penetrate it's glacis.  It was one of those God Sends which determined the course of NATO's armament procurements.

[tankmodeler]

The key things that really limit the usefullness of steam to power vehicles is the power supply and the steam pressure prior to entering the first turbine.

If you can posit something like an Edgar R. Burroughs "9th Ray" to generate the steam without having to carry coal and fireboxes, you then can concentrate your available volume on things like the wall thickness of the boiler & piping to get the pressure waaaaay up. If you have the "9th ray" sort of limitless power, you can also dispense with things like regenerators, intercoolers and condensors that also take up large amounts of volume and mass.

If you are looking at an Edwardian era Burroughs-esque sort of Science Fantasy, then this can all still hold together. Ya just have to wisely pick what parts of the real universe you choose to ignore.  :)

Paul

[dy031101]

Another source of aesthetic inspiration......

[GTX_Admin]

 :)