Steam Engines

Castenea wrote:

n7axw wrote:Hi JMS,
Pokermind seems to be to be the most knowlegeable poster on this thread on this subject. Go back and look at this post of 3/12. What he describes there is a low pressure steam engine that if it avoided the problem with machining was probably using leather gaskets. The thing is huge, sometimes filling buildings. The output? Between 5-15 hp. Now visualize a lawn mower. That is less than the average rider.

Now imagine getting this monstrosity aboard one of Thirst's screw galleys along with the coal and water needed to make the thing go. I don't think that it works. Presuming it to be possible at all. the galley has become so heavy and ungainly as to have lost all of the advantages that it was originally designed to exploit to start with. Btter to stick with hand cranks!

Don

Be careful comparing steam engines to internal combustion engines. Steam engines with pistons are very torque biased and get their maximum torque are very low RPMs, as in less than one. The average car engine idles at ~700 RPM and gets max HP at between 3K and 4K RPM.

I am no expert on this stuff. Mostly my views are in response to the guys who posted earlier in this thread who described earlier steam engines as being inefficient, huge, producing between 5-15 hp. I am merely submitting that those early inefficient steam engines as described by Pokermind and others do not fit on one of Zhwaigair's screw galleys. It's both too bulky and too heavy and doesn't produce enough power for the mass needed if it could be put on at all. By way of contrast, my riding lawn mower engine, an internal combustion engine-- produces 17.5 hp and would comfortably move that galley. Or, beyond poor Zhwaigair's dreams, why not a 427 cu in hemi. Cranking that thing up would scare Thirsk and his bunch or at least surprise them. They would have to figure out how to control the results before it crashed into something. But they don't have access to the tech needed for internal combustion engines, so...

So I have to stand by my thesis which is simply this: The steam engine they could produce without the capacity to do precision machine work, using leather sleeves in the cylinders, cannot be reasonably be expected to be useful in the small galleys that the Dohlarians are wanting to use in Shoal waters for coastal defense. In fact, I doubt that it would really be practical for larger galleys. That is all I am saying.

Don

My experience is that you want a high torque, low horsepower engine in small displacement hull applications. Until you develop hulls which skim the surface, your speed will be limited by ratios involving the Froude number (roughly the wavespeed of the surface gravity wave for which you boat length is 1/2 wavelength). If the steam engines have high enough torque, you can probably reach you maximum speed.

n7axw wrote:(SNIP)

So I have to stand by my thesis which is simply this: The steam engine they could produce without the capacity to do precision machine work, using leather sleeves in the cylinders, cannot be reasonably be expected to be useful in the small galleys that the Dohlarians are wanting to use in Shoal waters for coastal defense. In fact, I doubt that it would really be practical for larger galleys. That is all I am saying.

Don

I agree.

In fact, I'm finding the entire obsession with fitting the crank galley with a steam engine somewhat surprising - as it simply isn't going to happen.....

Thirsk is the one developing the crank galley. Clyntahn is the one with the designs for the steam engine. Clyntahn dislikes Thirsk for a variety of reasons - the largest being that Thirsk is developing new ideas.

So to expect Clyntahn to give the design to Thirsk, and help him develop even more new ideas, is somewhat out of character.


Also consider this - that the Charisian use of steam engines in shipping is only a recent development. Their first use was in factories - enabling the factories to be sited in different locations (i.e. close to the source of coal, rather then close to the source of water-supplied power), and it is only with the development of more reliable and powerful engines that they have started being used in the barges.


So, for different reasons, I'm in agreement with Don - I don't believe steam engines will be used on the crank galleys.

Steam engines work even if they are poorly maintained, parts are out of line, poorly designed, and poorly constructed. I know from working on a 12" to the foot rebuild of a very worn out steam engine. So worn out that sometimes I wonder how it did work towards the end of its first life.

The big issues are the safety appliances and proper construction of critical items like pressure gauges, boiler, safety valves, valve gear, etc.

Just to give an example of what knowledge has been forgotten here and now. It has been recently discovered that modern steels for boilers corrode worst than the older less uniform steels that were used 100 years ago. Why? Because the older steels had impurities that inhibited corrosion - by accident because now we can control the composition of steel alloys to a much greater degree.

That is why the very early steam engines were so heavy and over-sized for safety. They were built as my father would have said "Hell for stout". That is the only type of engine the COG will be able to build in the relevant time period - before the 1000 year return of the Arch Angels.

WES wrote:Steam engines work even if they are poorly maintained, parts are out of line, poorly designed, and poorly constructed. I know from working on a 12" to the foot rebuild of a very worn out steam engine. So worn out that sometimes I wonder how it did work towards the end of its first life.

The big issues are the safety appliances and proper construction of critical items like pressure gauges, boiler, safety valves, valve gear, etc.

Just to give an example of what knowledge has been forgotten here and now. It has been recently discovered that modern steels for boilers corrode worst than the older less uniform steels that were used 100 years ago. Why? Because the older steels had impurities that inhibited corrosion - by accident because now we can control the composition of steel alloys to a much greater degree.

That is why the very early steam engines were so heavy and over-sized for safety. They were built as my father would have said "Hell for stout". That is the only type of engine the COG will be able to build in the relevant time period - before the 1000 year return of the Arch Angels.

Interesting post. Can you comment on the bit about machine work and leather sleeves from your own experience?

Otherwise, I would observe that Temple probably has a limited time left before things go south on them militarily. My guess is about a year extreme outside. Not much time to build something for which you only have a description of principles rather than actual plans.

Don

n7axw wrote:
(SNIP)

Otherwise, I would observe that Temple probably has a limited time left before things go south on them militarily. My guess is about a year extreme outside. Not much time to build something for which you only have a description of principles rather than actual plans.

Don

G'Day Don,

Building the steam engine is the easy bit.

Rebuilding your industry to take advantage of it is another thing entirely!


Personally, I think that the steam engine design is a double edged sword, that is going to turn around and bite the Temple on the but - as they will devote resourses to develop a steam engine and a practical use for it, and then (as Don pointed out) have the war end.....

If you're not very engineering-oriented a very good book on this subject is THE MOST POWERFUL IDEA IN THE WORLD, by William Rosen (Random House, 2010). It traces the development of the steam engine from the earliest day to the 19th-century locomotive, marine, and stationary Corliss engenes, describing every step along the way and every problem overcome.
It will give you a very good idea of the problems the Temple mechanics will have to surmount to develop anything remotely useful.
It's a great read. Enjoy!!
Philip Stanley

The steam engine was the first to use power from fossil fuels. Other non animal sources wind and water were dependent on the weather, the wind does not always blow, millraces and rivers freeze in winter. It was the first 24/7 source of power, and allowed the first direct use of Solar power to make steam to run a steam engine.

The fossil fuels coal and oil were the most commonly used fuels but, anything that will burn can be used in boilers. Cotton gins used cotton seed for fuel, saw mills used slab wood for fuel, and farmers often used straw for fuel.

Machine tools needed to make a steam engine, plumbing, boiler etc. can also make machines that use the power and, thus begin an industrial revolution.

Merlin will no doubt see their introduction by CoG as good in the long term although bad in the short term.

Poker

n7axw wrote:Interesting post. Can you comment on the bit about machine work and leather sleeves from your own experience?

Don

Timothy Hackworth, writing in 1828, about his new prototype locomotive "Sans Pareil" for the 1829 Rainhill trials states that " . . . . Stevenson's have now delivered the new cylinder casting which is a vast improvement as it is only one half-inch out of round . . . ." On a Seven inch bore"

Packings for the cylinders and rod glands were a roving of Leather and Oakum compounded with Tallow.

No one has mentioned Hot Air engines or Stirling engines yet. Since early steam engines had a nasty tendency to suffer boiler explosions, Hot Air engines (of which the Stirling is the most evolved) were developed as substitutes.

These sorts of engines, while heavy and low powered like their steam counterparts of the time, provided much of the same benefits as steam engines without the danger. Indeed, had things gone a bit differently in history, these sorts of engines may have displaced steam engines in many applications, since they dispensed with the weight of the boiler and water, and the Stirling engine is the most efficient type of engine possible (working at close to the "ideal" Carnot cycle for heat engines).

OF course, like all engines, they also benefit from being built to close tolerances, which seems to be beyond the state of the art for the CoGA controlled territories.