While we are waiting for the steam reply, let me give you the diesel version. At one place I worked, we had a sectioned 567D3A engine "front end" mounted on a turntable that was operated by a small electric motor. We also had a really nice 35mm color slide that showed a very similar cross section of the same type of engine. Over a number of years, I don't recall any of the visitors ever coming up to the front of the room to get a better look at the color slide. But almost everybody who came in there walked up and took a close look at that cross sectioned engine, which was a really impressive display as well as a valuable training aid.

PC

I am not familiar with the sectioned locomotives at Steamtown. Is there more than one? I would like to know more about the Steamtown sectioning, including the cost. But I am not sure how one could quantify whether or not it is doing its job if that means a comparison of the cost to the amount of revenue they generate.

In comparing sectioning to graphic display, I believe that for dollar for dollar you will get more “gee gosh wow” from the graphic display. It may not be the real thing, but it is right alongside of the real thing as a complementary element. Sectioning a locomotive adds something, but it also takes something away. The graphic adds something without taking anything away from the locomotive. The biggest component of a graphic display is the design task. There must also be a substantial design task with a physical sectioning.

It is true that the public may prefer the real thing to a small graphic diagram or projected slide, but that is comparing apples to oranges. For an apples-to-apples comparison, the graphic needs to be full size and electrifyingly well done. Then the public will walk through the view of the graphic, drinking in the details, the same way they walk around the actual locomotive.

I agree with the point about the cost of animation. While it has the highest graphic demonstrational potential, the cost of production as well as the display equipment would be very high. For that reason, I prefer a static illustration. As I mentioned before, whether it is the actual sectioned locomotive, or a graphic display, the perception is only visual. There is no reason why one method should have any more potential than the other.

Actually, it's funny this has come up, as for the last six months or so, I've been working on building a computer model of an old steamer with every part in there that I can (each boiler course is a separate part, mounting brackets are separate parts, etc.), so that people could do precisely what you're mentioning. I can tell you from experience that it takes an incredible amount of time to do that sort of thing, especially if you're really strict about the details and not just guesstimating everything.

I'll have to post some pics sometime so y'all can see it.

tyrok1,
What you are doing is exactly what I was describing as one method to illustrate how a locomotive works. What kind of cad are you using? I undertook the same kind of project to model a Quincy & Torch Lake (ex-Mineral Range RR) ore car with every single detail. As you say, it is a lot of work. What inspired me was contemplating just how many wood and iron parts were assembled together just to make a vehicle that could transport ten tons of rock down the track. It is a lot of work to do the modeling, but it is also a lot of work to just do the measuring. I made five trips to Michigan and spent many hours measuring and sketching.

I'm actually doing it in an animation program, and I'm planning on making it available for reuse when it's done.

By doing it in an animation program, you don't get the polygon bloat that you do with CAD programs. I've already done a few engines now, fairly exact on the outside, but this is the first where I've been able to get detailed and perfectly exact measurements on every part of the inside as well as the outside (where I wouldn't just be guesstimating on the thickness of the metal on the front of the firebox, for example).

You see, part of my job at work is as a computer animator. We've done character animation, TV commercials, logos, etc., and I've always loved trains (especially steam), so I've been building them on the computer for fun for a while now.

I'll have to post some pics here sometime. Most of this engine's already done - a lot of what I have left are things like the piping, gauges, chains, and other details on the outside. But it's built for cross-sectioning, and should be watertight as well (no holes in the surface), so you could do fire, water, and steam simulation and show exactly what happens with incredible realism.

I'll keep you posted, as long as you find it interesting.

That sounds extremely interesting. Can you post something to give an example?

I'll see if I can render up a quick animation for 'ya.

Here's a couple examples of what it looks like. It's an 1870's 4-4-0 with Stephenson valve gear. Almost all of the parts in these renders are perfectly accurate to the original (the smokestack's about an inch too far forward in the external shot, and the cab's missing the forward windows, but that's about it). My goal for this was to build it accurate enough that it could be built in real life off of my model and work exactly as the original did.

When I'm done with this one, I've got access to be able to do the same with (among others) a New York Central Mohawk, which will really be good for demonstrating a few of the later developments like air brakes, injectors, and Baker valve gear.

Anyway, it being an older engine, it's a very simple machine - no brakes, no injector, none of that newfangled stuff - so it would make it an ideal teaching tool due to its simplicity. So, like I said, I plan on making it available for museums and such to use to show how it works.

I've got an animation showing more of the engine, and one of it in motion with pistons pumping. If I can get it up online to show you, I'll be sure to put a link here so you can see. But, I think 'ya get the general idea of it from these.

Your computer renderings are in many ways impressive. However, I believe that these images, coupled with your own comments, only underscore the superior educational value of an actual sectioned locomotive (subject to all of the candidate criteria previously discussed - lack of rarity, lack of any special intrinsic historic worth, low operational potential, etc.)

You say of your virtual locomotive as follows :
[quote="tyrok1"] It's an 1870's 4-4-0 with Stephenson valve gear. Almost all of the parts in these renders are perfectly accurate to the original (the smokestack's about an inch too far forward in the external shot, and the cab's missing the forward windows, but that's about it). My goal for this was to build it accurate enough that it could be built in real life off of my model and work exactly as the original did. *** I think 'ya get the general idea of it from these.[/quote]

Presuming that the original of your design sufferered an immediate and catastrophic boiler explosion on its maiden run, you have succeeded in your goal of accuracy. I refer to the complete absence of radial crown stays, which would likely have caused a rupture of the crown sheet, the wagon-top roof sheet, or both. If this occurred at significant pressure, the boiler might have violently catapulted off the frames and landed disasterously some distance away. I say "likely" and "might," because you've also depicted some sort of weird combustion chamber (the angled slope sheets) with what appears to be a second firehole. It's not clear if the fire goes above (and the coal is to be shoveled upward and through) the angled sheets (in which case the lack of combustion air would probably prevent a crownsheet failure by ensuring that no water is ever boiled). If indeed the fire goes below this device, the choking of the draft by that second aperture would similarly result in practically no steam being produced.

Also, the "combustion chamber" plates are not stayed to each other, meaning that they would probably pretty quickly bulge and fail if indeed their design is meant to indicate a water space. If the gap between them is not a water space, then after a period of glowing red hot, these portions would simply melt and drop. My uncertainty as to whether these parallel sloped sheets contain water is due to the fact that they are attached blindly to a single plate that curiously serves as a combined doorsheet and backhead (I believe George Stephenson tried that on the "Rocket" in 1829 and quickly learned that a proper stayed firebox was essential; your locomotive's firebox would have glowed red-hot inside the cab, an effect that would be both extremely unnerving and highly uncomfortable for your virtual engine crew. Also, with the whole boiler being unlagged, any steam produced would have suffered from serious heat-loss inefficiency and your nice glossy "Russia Iron"-colored external finish would not have lasted many hours (no barbeque spray paint in the 1870s).

Perhaps you've misinterpreted a drawing? For example, maybe you mean to depict some kind of arch tubes or circulators in the firebox - a bit anachronistic, to be sure - and you misunderstood a cross-section of a tubular shape as two parallel plates? Or maybe this information come from some other source... maybe the old 1970s plastic-kit model of "The General"?

Please do not misunderstand my point. I'm not simply having a go at you; animation design problems can presumably be resolved. But you appear to sincerely believe your locomotive would work - you say that it would "work exactly as the original did." However, these are quite fundamental design flaws that I daresay anyone with steam experience (actual or theoretical) would recognize immediately. Presentation of this design to museum visitors, no doubt with utmost best intentions, as an explanation of how a steam locomotive works is rather like a physics professor teaching that the earth is flat (maybe that happens in some of our "faith-based" educational institutions, but I digress... ).

What all of this really points to a high potential for significant deviation between the way a computer animator might understand a locomotive design when creating a virtual sectioned version, and a proper engineering understanding, which - in condensed, essential form - is the message sought to be conveyed. The "real thing" suffers zero depiction inaccuracies when sectioned - it is what it is.

-G.J.C.

You'll notice I mentioned "...all of the parts in these renders..." - it's because not all of them are done/there. I guess I should have made that more obvious. None of the parts are riveted together yet, and there are no stay bolts of any kind. That firebox was a pain in the neck to build, not being able to use welds. All of the pieces are separate pieces of sheet metal, cut to overlap enough that they could be riveted together. If you look close, the lower section of the firebox is just hanging there - it would drop onto the tracks. It's also missing the throttle, pressure relief valve, water pump, grates, sight glass, and all other instrumentation in the cab, among other pieces. As I said earlier, this is a work in progress, and I'm not releasing it until it's done.

But, yes, I certainly wouldn't _want_ anyone to build it _exactly_ the way it is either - it's a lap-seam boiler and has link-and-pin couplers. But, as a preservationist, I'm trying to exactly duplicate the original.

I'll post more when I'm a bit further along.

**EDIT**
Actually, come to think of it, it didn't even have radial staybolts. It had straight (and a bit odd) ones attached to bars which were then bolted to the outside of the boiler. These were rough times. :)

Just re-read your post, and I see your point. The space between the sections of the firebox is indeed water space, and this engine ran long enough that it was later equipped with air brakes. The drawings were from an 1870's edition of the Railroad Gazette, so they're certainly not a recent invention. I know it's a bit odd, but that's exactly how it's depicted.

Also, the metal can't get much hotter than the surrounding water due to convection in the boiler, so it still would have worked without melting the firebox, I would imagine. Maybe it was a primitive form of a pre-flue spark arrestor (the diamond smokestack has relatively little) or brickarch? I don't know. But it was most certainly a two-part firebox.

It is certainly true that cutting an engine open will reveal the facts of what’s inside. However, a drawing that leaves out or misrepresents the facts (for whatever reason) is not evidence to me that drawings are fundamentally incapable of depicting the facts, and therefore not a valid alternative to cutting an engine open.

I contend that illustration is not only a valid solution to depiction, but also, a solution that is capable of greater clarity and aesthetic attraction, at a lower cost than actual physical sectioning. Also, unlike physical sectioning, illustration is not limited to locomotives that are deemed unfit for operation or whole display. And also, unlike physical sectioning, illustration can accompany the display of the subject locomotive, which has been left intact, so a viewer can study the whole subject and its dissection as separate entities. Whereas physical sectioning, while revealing the inside, becomes a distraction to the accurate perception of the original, whole state of the locomotive.

I'm very much enjoying answering your comments on this - I find them quite interesting, and it really shows how carefully you're looking at this. It really makes me feel good to know that all that time to build it is going to good use.

Those sheets have exactly 3" of water between them. You can't assume so much from one view.

Now, to address the point about the lagging. You'll notice, if you look at the cross-section view, that the bands that hold the boiler jacket on are curiously far from the boiler, while in the external view, they're touching the jacket. What you're seeing as Russian iron got lost in the cross-sectioning and is not visible in that view. The lagging is not finished - it's waiting for me to finish one remaining missing part on the outside of the boiler.

For the fire burning in the top section of the firebox, I must be missing something, because I don't see the logic in it. That section would quickly fill up with ashes (along with the flues) due to the fact that it's not resting on the grates. On top of that, it would get relatively little air due to the size of the opening between the two parts of the firebox and the fact that it gets no air underneath. Plus, by plugging up the flues, exhaust would also be restricted. That is, if you could get the fuel up there and get it lit through that opening. If you could explain this further, that would be great!

I appreciate your careful observations on this - I'll be sure to run it past you all when it's finished to make sure I didn't miss anything. And if you have anything else you notice about it, feel free to PM me, and I'll do my best to answer it to the best of my ability. Thanks!

Not completely sure - but I think what we are looking at is a failed expepriment in using a water filled arch in place of a brick arch in the very early days of experimenting with arches in fireboxes. I recall reading about such things a long time ago in some old book somewhere - can't lay hands on it now. Might be useful to remove it completely since it doesn't represent the "average" technological adaptation, which would have been a simple firebox at the time. Brick arches supported by arch tubes would have been more common later on.

dave

Tyrok - don't let the comments discourage you - and be sure to PM me if you get to a point that you would like to share the final renderings for others to use and teaching. I have a few websites that I would be interested in using them. I used to do a lot of AutoCAD and 3DStudioMax stuff so I know the time it takes and I appreciate what you've got there! I think that what you have there is one an excellent answer for this problem.

Sully