OvermodSpeaking strictly for myself (and specifically NOT claiming that my definition has to be accepted) I reserve the 'steam engine' label to engines that actually use steam for power, not non-motive (or, indeed, anti-motive) displacement of air.
My own experience is that whenever the history of steam engines is discussed Savery and Newcomen engines are part of it. However, there is usually mention that those engines are really atmospheric engines rather than true steam engines.
OvermodIf I am not mistaken (I don't have a detailed diagram at hand) there is a starting or purge valve in the head of the cylinder. This is opened to blow out the air before the engine starts working steam.
I was wondering about a purge valve. But I have never read of one in any description of a Newcomen engine and I've never seen one in a diagram.
If I am not mistaken (I don't have a detailed diagram at hand) there is a starting or purge valve in the head of the cylinder. This is opened to blow out the air before the engine starts working steam.
Oddly enough, there is some modern steam machinery that does not work right when trapped air is present -- some flavors of condenser and feedwater heater, and the Holcroft-Anderson recompression setup, come to mind -- and these have to have purge valves or 'air pumps' of some sort, too.
The steam and air mix, and not really 'segregate', as you indicate. But it only takes a few moments for kinetics to mix air and steam, and eject an increasing net amount of the air from the system. I think you are correct in thinking it would take a MUCH longer time to start the engine if the relief valve were not present...
Overmod I think I can ASSURE you that the movement would be self-starting with little manipulation under those conditions. If you happen to have too much water in the pump down the shaft... spill out a little water. At some point it will certainly self-start.
I think I can ASSURE you that the movement would be self-starting with little manipulation under those conditions. If you happen to have too much water in the pump down the shaft... spill out a little water. At some point it will certainly self-start.
Your explanation hangs together, Bob, but I have to say it sounds counter intuitive to me.
Back in my school days I learned that air is a fluid. If you are going to have a container of air and you want to replace the air with another fluid such as steam you must give the air a way to get out. If the piston has a tight seal and is at the top of the cylinder and the steam injector is turned on it seems to me that a little steam would be admitted but not much. So when water is sprtized in there won't be much steam to condense and there won't be much of a vacuum.
It also occurred to me that maybe the seal was not real tight. As the steam is admitted the air can escape around the edge of the piston. As the steam reaches the top the seal is both heated and moistened and that might lead it to swell and give the tight seal the machine need to operate.
What I do know is that Newcomen engines were used for a great many years and they worked well enough to do their job.
John
Firelock76From what I remember reading a long time ago, both Saverys and Newcomens engines were a bit of a flop, inefficient and with a bad habit of stalling. It was James Watt who made the steam engine truly practical.
What Watt initially did was do the condensation of the steam to water+vacuum in a SEPARATE vessel (condenser) rather than sprinkling water directly into the cylinder to accomplish the condensation as Savery and Newcomen had done. Since the whole cylinder and piston didn't have to be thermally cycled, the engine required much less mass flow of steam to 'break the vacuum (and incidentally displace any atmosphere that has leaked in) on each stroke, therefore less fuel had to be burned.
(One little point: on an atmospheric engine, the condensate helps seal the piston. Which is why the normal location of the cylinder is 'on top' and the stroke is up, not down...)
John WRYour comment about the Newcomen engine set off questions in my mind. Why would it stall?
Any time the generated 'vacuum' was insufficient to give enough pressure differential to move the load completely up to 'spill'. This might happen if the steam were not hot or dense enough to displace the atmosphere completely before a given stroke. It might happen if there were too poor a seal between piston and cylinder, resulting in the atmospheric equivalent of blow-by. It might happen if there were too much water, or a hydraulic lock of some kind, on one of the cascaded pump cylinders down in the mine, or too much cumulative load in the pump stages -- the flow of water might be variable, in a way the operator up at the head of the shaft could not see or predict.
Remember that, as with British vacuum brakes, the absolute highest pressure that could be exerted on the piston is around 14 and a half psi, and practically it would be some fraction of that. Not difficult to lose a significant amount of that pressure for little causes... and when the force of the atmosphere up no longer exceeds the gravitational attraction of water, pump rods, and the rest of the stuff... you will get a stall.
I do know one thing James Watt did was to fit the size of the boiler to the size of the cylinder. If the boiler was too small then it might not generate enough steam or be slow to generate the steam the piston needed. That could slow or even stall the engine for a while. Do you know if that is the reason?
That would certainly be a good reason. On the other hand, inadequate steam generation would (in my opinion) reduce the cyclic rate of the engine, rather than predisposing to stall, unless whoever or whatever was working the valves was cutting off too soon -- leaving an incomplete vacuum inside the cylinder, or not purging enough to overcome leaks and losses.
Another question occurs to me. How did they start a Newcomen engine? When the engine was stopped the pump was at the bottom of its stroke and the steam cylinder was at the top of its stroke so the stean cyliner would be filled with air.
I must be missing something, because this is exactly the situation that has to prevail to start a Newcomen engine.
You turn the steam into the air-filled steam cylinder. This heats the air (which is a gas) so that it displaces quickly and is replaced with a (smaller, actually) mass of hot steam in vapor phase. At this point there is pressure equalization between whatever mix of steam and air -- increasingly steam, as the admission continues -- and the air under the piston, until you close the admission valve.
Now you have a cylinderful of glorified water, that wants very badly to be water again (and shrink that 1200x in volume when it does), and under it you have... well, atmosphere, which would be leaking in even if you didn't give it really good access to the bottom of the piston. Spray in the water, and the steam condenses (to about 1/1200th of the displaced volume... leaving some small amount of vapor corresponding to equilbrium for the effective degree of vacuum in the remaining space.
To get the beam back down, you have to admit fresh steam to the cylinder, and any residual atmosphere that has sneaked past the seal into the cylinder will rapidly be heated and displaced. Again, self-starting, with a little more 'oomph' since the purge doesn't need to absorb heat from the steam this time.
I have never seen any reference to exhausting this air to start the engine.
What did you think made the vacuum to start the engine? Some sort of Bernoulli ejector? The steam dilutes and purges the air during initial admission, and the seal keeps atmosphere from rushing in through the piston-cylinder gap after that first stroke... if all goes as designed.
If the steam piston was a little loose the air might escape around it...
Exercise for the reader: What would MAKE the air 'escape around it'. Gravity is all pulling down on the piston. Steam used for compression would be pushing down on the piston. But ONLY when the piston moves UP will you get 'air to escape around it' ...
... when the steam was admitted only a little steam would enter the cylinder and when it was condensed the cylinder would still be full of air.
Gas laws are different. The steam is hot, but when it gives up its heat to make the air hot, that percentage of it condenses and its volume gets very small with the phase change. Gas kinetics (if you don't trust me on this, look the subject up) very rapidly get the hot gas to purge, relative to the continued admission of steam -- it is not long before things have 'equalized' with mainly steam instead of air in the cylinder. And a little water down at the bottom helping to seal the piston, etc.
I've never seen any reference to this issue so I don't know how it was dealt with.
I can't remember having seen an engineering reference to atmospheric engines that did NOT describe how it was dealt with. Once you understand that steam admission is used to purge the atmospheric mass, the rest should be easy to see.
Firelock76Newcomen's engine was a stationary engine primarily used to pump water from mines, coal or otherwise. The piston was attached to, in effect, a "walking beam" which operated the pump mechanism. It had a habit of stalling in mid-stroke, so the engineer would have to give the beam a good shove up or down to get it running again. A good shove on the beam is what got it started to begin with.
Wayne,
Especially during the early years Newcomen's boilers were too small for his engine. Steam would enter they cylinder, the piston would rise and a spritz of water would condense the steam and cause the cylinder to fall back. Since the walking beam was heavier on the pump side it began to draw the piston up again actually drawing steam into the cylinder. However, if the too small boiler had not recovered the piston would rise to the top of the cylinder which was not full of steam. The steam valve was shut off and water spritzed in again. But with the cylinder only partly full of steam the piston would stall in mid stroke. Of course the operator could grab the beam and pull it the rest of the way down to help the engine. When the piston got to the bottom hopefully the boiler would recover.
Newcomen designed a special valve activated by a "bouy" in a tube which floated on top of the water. As steam pressure built in the boiler it pushed the bouy up which then opened a valve to the steam injector when the boiler was ready. This solved the problem but slowed down the boiler.
Ultimately larger boilers were installed. That was the real solution.
Of course there was room for improvement. If there were not we would still be using Newcomen eingines today. Yet Thomas Newcomen figured out how to combine steam and the force of gravity on the atmosphere to raise water to a much greater height than had ever been possible. I think that is pretty impressive.
Hi John!
Oh boy, it's going to take a bit of remembering on Mr. Newcomen, it's been years since I've read about it. Without resort to "Da Wikepedia" I think it went something like this"
Newcomen's engine was a stationary engine primarily used to pump water from mines, coal or otherwise. The piston was attached to, in effect, a "walking beam" which operated the pump mechanism. It had a habit of stalling in mid-stroke, so the engineer would have to give the beam a good shove up or down to get it running again. A good shove on the beam is what got it started to begin with. It got the job done but there was definately room for improvement.
If I'm wrong, wrong, wrong on this don't anyone of you hesitate to correct me.
Wayne
Your comment about the Newcomen engine set off questions in my mind. Why would it stall?
Another question occurs to me. How did they start a Newcomen engine? When the engine was stopped the pump was at the bottom of its stroke and the steam cylinder was at the top of its stroke so the stean cyliner would be filled with air. I have never seen any reference to exhausting this air to start the engine. If the steam piston was a little loose the air might escape around it but if it fit well air could not escape. Then when the steam was admited only a little steam would enter the cylinder and when it was condensed the cylinder would still be full of air. I've never seen any refernce to this issue so I don't know how it was dealt with. I can think of ways to deal with it but I wonder what they did back when the engines were used.
John WR ... when James Watt put a cap on the top of the cylinder of a Newcomen engine and began putting steam on both sides of the piston did he invent something new or was that an evolutionary step in the development of the steam engine?
... when James Watt put a cap on the top of the cylinder of a Newcomen engine and began putting steam on both sides of the piston did he invent something new or was that an evolutionary step in the development of the steam engine?
Yes, he did, and yes, it was. The earlier point about Watt's 'retarding' the progress of high-pressure steam is quite valid, but we also need to remember that Watt, after inventing the condenser to improve operation of atmospheric engines, also developed the true steam engine using pressure to push the pistons. Most of what I (pedantically) was trying to establish was that pressure on a piston to produce engine was not a 'new' thing with Watt et al., and that steam as a means of producing that pressure had been considered (and rejected) before Pepin's time.
The real honest truth is that I understand and agree with your distinction between an atmospheric engine and a steam engine. But Savery's engine would not have worked without steam even though he condensed the steam to create a vacuum. So in my own head I wonder if Savery really did have a steam engine but a different kind of steam engine.
Yes, but under that definition the Space Shuttle also uses a different kind of steam engine. With more in common with Isaac Newton's application (over a hundred years before Watt). Speaking strictly for myself (and specifically NOT claiming that my definition has to be accepted) I reserve the 'steam engine' label to engines that actually use steam for power, not non-motive (or, indeed, anti-motive) displacement of air.
In fact, in a sense, the Savery/Newcomen principle is still with us as a primary 'evil' in steam-locomotive design; nucleate condensation is a primary drag on the efficiency of any long-stroke long-expansion engine -- and I also argue that reducing this, not overcoming 'wall losses' per se, is the most important advantage of superheat on modern locomotives.
(BTW, comments I make on here are not intended as criticism or one-upsmanship of your ideas, or as "I know more than you, nyah nyah nyah' show-offery. If they come across that way, I apologize in advance, repeatedly as necessary)
Firelock76 From what I remember reading a long time ago, both Saverys and Newcomens engines were a bit of a flop, inefficient and with a bad habit of stalling. It was James Watt who made the steam engine truly practical
From what I remember reading a long time ago, both Saverys and Newcomens engines were a bit of a flop, inefficient and with a bad habit of stalling. It was James Watt who made the steam engine truly practical
They certainly were inefficient. However, an experienced operator could get them working smoothly. Savery's was a vacuum pump which limited it severely. Newcome's however, was not. Newcomen engines were used for a great many years despite their inefficiency and there are some that still are operated on special occasions.
James Watt certainly made a big contribution to the development of the steam engine. However, Watt was afraid of high pressure steam. His stationary engines did power factories and even steam boats they they never ever would have powered a locomotive; they just did not have high enough pressure to do so.
Mostly, I see Savery, Newcomen and Watt as developing engines that had to be developed before we could get to steam locomotives.
From what I remember reading a long time ago, both Saverys and Newcomens engines were a bit of a flop, inefficient and with a bad habit of stalling. It was James Watt who made the steam engine truly practical.
And Overmod me old son, if the N&W Mighty 611 is awakened from her 18 year sleep, then we'll KNOW God is a railfan!
OvermodBut let's be honest: those aren't steam engines, they're atmospheric engines.
Yes, Bob. Thomas Savery's engine is powered by atmospheric pressure, not steam. And Thomas Newcomen's engine was also powered by the atmosphere. But when James Watt put a cap on the top of the cylinder of a Newcomen engine and began putting steam on both sides of the piston did he invent something new or was that an evolutionary step in the development of the steam engine?
There is no such switch on the nose gear of an airplane. I use my radar on the ground all the time to observe the weather in my departure path. There is a switch on some aircraft to put the transponder in standby on the ground to avoid interference. You are correct in that we don't take the radar out of standby until well clear of ground personnel
.
Firelock76 Look at it this way: you boil water and you get steam, but how many centuries did it take before someone figured out how to use that steam? Hot air/ smoke rises, but how long did it take before someone figured out how to trap hot air in a balloon and fly with it? And aviation? The Romans could have built gliders if they knew the simple principles involved in flight. See where I'm going here?
Look at it this way: you boil water and you get steam, but how many centuries did it take before someone figured out how to use that steam? Hot air/ smoke rises, but how long did it take before someone figured out how to trap hot air in a balloon and fly with it? And aviation? The Romans could have built gliders if they knew the simple principles involved in flight. See where I'm going here?
But ... let us not also forget that it's highly likely that innovation 'stops' just at a level where steam locomotives -- or, in fact, railroad locomotives as we now use them, or even rail vehicles as Kneiling would have used them -- are the technology to utilize it.
High-efficiency fuel combustion ( as in fuel cells or MHD) won't apply to external combustion as cost-effectively as to other types of power (road vehicles and powerplants respectively). Better chemical sources are applied to batteries ... and we are already at the point where the pitfalls of energy storage in combustion fuel are beginning to be evident in battery chemistry ... laptop fires and Dreamliner surprise syndrome, anyone?
Reminds me a bit of a science fiction story -- I believe it was by 'Doc' Smith -- where some fellow invented an invisible field that he could use to hold the buck and the die of a riveting arrangement perfectly steady, so that one man could drive and set his own rivets. If I had access to THAT kind of field technology... I don't think I would be driving rivets with it. George O. Smith had some very similar themes, but he usually understood how they would be 'transformatory' in unanticipated ways ... and told stories about them.
As a case in point: Most of the available alternate-fuel technology I've seen has one of two problems: either it's best applied to make synthetic fuel that is better optimized as an 'energy carrier', or it becomes massively unstable under 'anomalous condtions' (curse you, TATP!!!) If you concentrate too hard on Procrustean rail use of these things, you will get into the aluminum-beryllium lightweight buggy whip/titanium hypersonic yaw-string situation faster than you may realize.
Small-scale economies: better personal vehicles
Large-scale power release: better electricity, including electricity as a process 'fuel' for synthesis equipment.
Large-scale fast power release: better aircraft or SSTO launch systems.
The immediate use of thousands or millions of nanostructured lithium-ion batteries for rail transportation has been with us for almost a decade. GE has a documented report on construction of an 'optimized' hybrid road-locomotive battery (it's in a free DVD you can obtain from one of the CFD software companies, Comsol). It isn't *that* likely that a new principle... say, zero-point or vacuum energy ... will be JUST at the scale that optimizes its use for propelling long, loading-gage-restricted consists with low rolling resistance.
Steam? OK, I know about Hero of Alexandria in the Classical Times, but his steam engine was a gimmick that no one knew what to do with.
Let us not forget that this is from a culture that discovered the idea of cybernetic machinery, described accurately what the technology could do... and then dismissed it as stupid, because they already had speaking tools that could do any then-conceivable job of 'thinking' more cost-effectively.
When I was about 12, I had the bright idea that if the Greeks or Romans had discovered steam power, it would have revolutionized sea warfare. Boy, did I have a lot to learn!
Anyway, there's no telling what the mind of man will come up with, or what God in His wisdom will reveal to man in His own good time,
This is very true. I can only hope that God is a railfan.
John WR Firelock76Look at it this way: you boil water and you get steam, but how many centuries did it take before someone figured out how to use that steam? Thomas Savery invented his pumping engine about 1698. As far as I know that was the first practical use of a steam engine.
Firelock76Look at it this way: you boil water and you get steam, but how many centuries did it take before someone figured out how to use that steam?
Thomas Savery invented his pumping engine about 1698. As far as I know that was the first practical use of a steam engine.
But let's be honest: those aren't steam engines, they're atmospheric engines. Steam only does the displacing of the atmosphere and then intentionally is made to condense, so the atmosphere does the actual work. Pressure steam needed to wait a while, for materials and fabrication technology to come up to snuff.
In any case, interestingly enough, part of the retardation of acceptance of steam as a prime mover is that the internal-combustion principle was recognized much earlier, and explicitly as not involving a messy Rankine cycle to generate pressure on pistons to do work. That principle, of course, is the use of gunpowder. And yes, it's perfectly practical to build a slow-speed engine using gunpowder or something like it as the fuel. No problem with exhaust, for example, or boiler technology, or supplying a separate working fluid other than combustion gas...
... piston seal and 'rod angularity' were addressed, interestingly enough, precisely as if the piston was a cannonball, with its 'mating surface' to the cylinder spherical like a cannonball, and the sealing accomplished with wadding (of appropriately fireproof construction!) that is just wrapped around the spherical piston. I think I recall the thing being set up inline, like an organ, with the cylinders working on a recognizable crankshaft, like one of the Arabic ganged water pumps in reverse, so there is time to 'reload' each cylinder after it fires.
Steam was a backward step from this, and I find it notable that as soon as a few comparatively slight details about fuel, materials, cylinder cooling, and ignition were addressed -- noe of which couldn't be done with 16th-Century materials! -- the IC motor became a thoroughly practical device with advantages over most steam power even of advanced form.
(I never thought an HPS degree would prove so useful, and a source of so much fun!)
carnej1What is a "recycled PT tender"?
He means a great big long centipede tender, like the ones behind the NYC Niagaras. PT is the NYC acronym for 'pedestal tender' (meaning the construction where multiple tender axles work in a rigid frame, similar in principle to a reciprocating-locomotive frame, with controlled lateral for better curving).
Think of the tenders currently on 844 and 3985 (or 4014 et al.)
Firelock76 OK, I was joking when I mentioned a "super-sized" solar cell, I'm sure everyone knows that. But I'm going to be just a tad serious here. I don't know what the future may hold, but there just may be another power source just waiting to be discovered that's unthought of now, and possibly right under everyone's noses. Look at it this way: you boil water and you get steam, but how many centuries did it take before someone figured out how to use that steam? Hot air/ smoke rises, but how long did it take before someone figured out how to trap hot air in a balloon and fly with it? And aviation? The Romans could have built gliders if they knew the simple principles involved in flight. See where I'm going here? Steam? OK, I know about Hero of Alexandria in the Classical Times, but his steam engine was a gimmick that no one knew what to do with. Anyway, there's no telling what the mind of man will come up with, or what God in His wisdom will reveal to man in His own good time, How about this: A locomotive with solar cells and a recycled PT tender behind as a battery! Don't that get your juices flowing?
OK, I was joking when I mentioned a "super-sized" solar cell, I'm sure everyone knows that.
But I'm going to be just a tad serious here. I don't know what the future may hold, but there just may be another power source just waiting to be discovered that's unthought of now, and possibly right under everyone's noses.
How about this: A locomotive with solar cells and a recycled PT tender behind as a battery! Don't that get your juices flowing?
What is a "recycled PT tender"?
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
But how about lineside solar collectors set at optimum angles to the prevailing sunlight with the power being collected and routed directly to the overhead catenary wires, keeping the system in readiness for a train at all times. Excess generation could be resold to local power companies and industries along the right of way. This would be a simple extension of railroad investments in pipelines and fiber optic cable using their existing routes. Just drive through Calfornia's central valley and Arizona and Nevada's deserts. Lots of sunshine and almost no opposition to its use.
When all said and done, wouldn't it be much simpler and cheaper to put up the catenary?
A far as radio frequency power transmission goes, anything with enough power to run a locomotive is likely to bust the E and B field limits of IEEE C95.1 standards for exposure to electromagnetic fields regardless of frequency. I can tell from personal experience about feeling the heating effects of the 63 MHz magnetic fields used in MRI.
As for Tesla coils, those are short electric dipole antennas, getting reasonable power transfer (with path loss less than say 20 dB) would require operating in the near field zone, which is typically given as the geometric mean of the wavelength and the size of the antenna. A 100m tall Tesla coil operating at 30 kHz (10,000 m wavelength) would have a near field zone of 1,000m. A larger near field zone can be had by going to lower frequencies, but the receiving antenna will need to be large to remain efficient.
"Scalar energy" sounds suspiciously like the stored energy around a resonator.
- Erik
erikemUmmm, no. Thomson-Houston and Westinghouse were doing AC lighting systems before Tesla's corroboration with Westinghouse.
But Erik, Tesla's and Westinghouse's battles with Thomas Edison are well known. And when it comes to understanding electricity Edison just didn't.
MikeF90 Tesla setups look pretty omni-directional to me.
Tesla setups look pretty omni-directional to me.
The big 'dome' setups, like the one for Wardenclyffe, were highly directional. The dome is not the antenna -- there were (going to be) many small directional 'emitters' like the seeds in a dandelion 'puff'. A given emitter would not be brought 'live' until it had confirmed (via radio) that it was pointed at something actively receiving.
Of course, this was well in advance of Yagis, or digital signalling of the required precision, so how it would have worked in practice -- who can say.
I notice that the EEs are ignoring the 'scalar wave' part of the Tesla solution, which is supposed to be different from the old E x B electromagnetic radiation we former Class 1s knew and loved. There is also the 'telluric current' return path -- how that was supposed to produce high amperage RF current instead of just proportional RF slosh in and out of ground capacitance, I don't know, and how it was supposed to power aircraft and rubber-tired vehicles for any length of time could have been interesting in its own right.
The short answer to the 'failure' of broadcast power was wireless -- the use of which as a practical medium of communication would be short (pun intended!) And while we're at it, telegraph and telephone wiring will neatly collapse the e-field and produce... well, you know. Same for electrical power wiring. Or fence wiring. Etc. (Not difficult, is it, to figure out why Mr. Morgan chose not to finance this approach -- even before you take up the issue of metering the current draw rather than just the channel and direction...
Also, way too much 'power' in for an (as yet) unquantifiable output at some remote location. Where the does the rest of the energy go? Hopefully not as a surge somewhere in nearby power transmission lines.
"Surge" might be too gentle a word. Remember Tesla's was a world without delicate low-voltage semiconductors that give up the ship faster than the French on exposure to high stat voltage. Fortunately at the requisite frequencies it's unlikely you'll have high sustained current... but unfortunately, yes, there will be 1^2R losses, and yes, there are resonances in the same sorts of material that do poorly on exposure to high-wattage RF -- you know some of them from microwave oven mistakes...
As a side note, (except indirectly by geothermal means) we've haven't been able to harvest useful power from the worlds largest power source - the molten iron core of the planet.
Or, much more accessibly, the cold Rankine-cycle sink of deep ocean water, easily circulated a la GSHP for much less cost than cooling... Remember that pulling a vacuum is worth much greater proportional HP to an expander than higher initial pressure -- see the Titanic's engines if you need a graphic demonstration.
Core taps -- even mantle taps -- are much higher priced for the watt-equivalent than the idea may first appear. If you thought geothermal corrosion and scaling were fun ... imagine the fun putting a whole heat exchange setup (for molten salt or NaK or whatever as the circulating working fluid or transfer agent...) at the bottom of a hole that deep. And then keep that hole from shifting or closing up on you...
... not to mention what happens if you try to fix it.
But then there's always my favorite movie as an 8-year-old: "Thank God it's only a motion picture!"
AFAIK a Testa coil produces a lot of electromagnetic interference across the spectrum. Not very nice to impact existing electronic devices and communication services.
That's only if you let the secondary spark across an air gap. Or out into free space like this.
I'd think that while there might be some harmonic interference from radiated power RF, proper antenna design would solve most of the emitting side, although I'm not sure about the antenna...
... or, as Bugs said to the audience -- "WHAT AM I DOOOOOOING?'
A theoretical alternative (maglev aside) might be to transmit energy along the RR ROW only (riiiight)...
Not as silly as it seems. Look at the 'grasshopper telegraph' (or the old PRR inductive phone setup) and imagine a different method -- directional focusing shields, perhaps? -- to optimize the 'sidelobe' coming off the wire so that the effective field is maximized in the space between emitter and receiver. Then have 'a plurality' of wire segments that are progressively energized as the locomotive advances...
Hmmm. Think microwave to light wavelengths.
Power light is do-able... but the cost is in the implementation. You would need a lateral array of something like VCSELs along the entire length of the 'wired' section, in parallel to get effective 'beam' spot density. Give the receiver an anamorphic lens and allow it to 'talk' to the laser array controller so only the lasers actually being received at the source are at full power. The modern generation of lasers can be upward of 40% efficient from AC supply to beam strength, so...
... but go back and look at the size of the required spot, and then start thinking about how you're going to use light, or IR, or whatever, to actually produce tractive power. Putting it gently, some of the physics does not scale...
Besides the power conversion and moving target tracking challenges, the crew would have to be protected from that level of energy density (in kind of a reverse microwave oven - Faraday cage).
The beam tracking was do-able even with 1917 relay-logic technology (if a little involved and very, very, very jitter- and vibration-intolerant!). Nowadays we should be able to keep the CEP acceptable even before doing adaptive beam shaping or the like to keep the effective spill minimized and power transfer... such as it is... maximized.
I am tempted to note that this is a really, really good way to be sure railroaders wear their properly-designed safety vests and other PPE. But I do not want enraged railroaders lining up down my driveway with deer rifles... 7-cartridge mag limit or not. (30-'06 is a puny caliber for sporting, but it works just fine through car doors... ;-] )
BTW the U.S. military has been trying to do much the same thing with various high energy laser systems since the 1970s without much success.
Oh, they have PLENTY of success -- just not particularly cost-effectively. And getting meaningful burnthrough on a convex mirrored surface that rotates as it is rising is really the major difficulty.
(One of my favorite April Fool's pranks involved a report that lasing at gamma-ray frequency was possible via hyperfine transition in Hf158 (I think it was) and grazing-incidence optics could then be used to focus the incident beam nicely on anything made of metal. (OK, folks... what's the principal joker in that deck?)
If they could propel a small missile with microwaves they might be interested, but when the missile disappears from the line of sight ...... thud.
You don't actually propel the missile with microwaves (or light, which is a bit better); you shine the beam to overcome transition temperature for a solid fuel (of some kind) whose combustion products are relatively transparent to the beam, or are emitted for thrust at some angle outward from the incident beam. Then you do that fancy two-way optical correction with MEMS etc. so that the beam stays collimated properly with altitude. (And use a spiral-scanned co-beam to keep 'water-vapor' blockage... or atmospheric density, for that matter... minimized around the path of the power beam. (If you are fancy enough, you can use lasers for vernier control, too, which makes the entire vehicle passive, difficult to detect, etc. etc. etc.)
You have the thing in line-of-sight to CONSIDERABLE altitude, the problem being not that it goes 'out of line of sight' but that for orbital insertion you have to get up to high speed 'sideways' (or it just falls back with a thud from an inverse forced orbit' situation). Some very tricky engineering is involved in doing that. But nothing particularly 'difficult' from a theoretical point of view.
Much more difficult is masking the beam trajectory, and emission point, from countermeasures. Same problem as with laser designators, just much much more obvious, and as you point out without much option to interrupt the power beam if under 'observation' or attack.
The big problem with beams coaxial with ROW is grade crossings. You would need multiple emitters for 'blocks', probably integrated with the signal-system logic. And some other stuff. Expect the very first roasted trespasser to ruin the economics for ever.
BTW: there are plenty of power frequencies that do not interfere dramatically with human tissue uptake or relative opacity/reflectance. We routinely tested the 11kW (17kW ERP @ 103.3MHz) output of our antenna by holding up an old fluorescent tube and watching its end light up. You only get the dramatic disappearing-Navy-tech result with very high powers at frequencies that interact with, say, H-O bonds...
RME
erikem Ummm, no. ... Solar power and wind power both need some sort of economical energy storage system before they can realistically provide a significant portion of the electric power production.
Ummm, no.
...
Solar power and wind power both need some sort of economical energy storage system before they can realistically provide a significant portion of the electric power production.
Can't always believe what a science-channel show on a specific individual tells you, I guess, which is understandable. Still, he had a piece of the action vs Edison's DC.
One method I recall seeing in the past for storage was a kinetic system - water was pumped up into a reservoir (lake sized) during excess power production, then released through turbines during high demand periods. Might be kinda hard to find suitable reservoir locations, though, among other issues...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68 Murphy Siding If we're allowing ourselves to dream that trains could be powered using 100 year-old, wishful thinking technolgy from a near-mad genius... Tesla did give us AC - if Edison had his way, we'd be using DC in our houses...
Murphy Siding If we're allowing ourselves to dream that trains could be powered using 100 year-old, wishful thinking technolgy from a near-mad genius...
If we're allowing ourselves to dream that trains could be powered using 100 year-old, wishful thinking technolgy from a near-mad genius...
Tesla did give us AC - if Edison had his way, we'd be using DC in our houses...
Ummm, no. Thomson-Houston and Westinghouse were doing AC lighting systems before Tesla's corroboration with Westinghouse. What Tesla did give us was polyphase AC and induction motors (though it took WEMCO's B.G. Lamme to get the design right.
The only way solar could power trains would be as a component of the supply for a catenary system.
Or charging battery powered locomotives. Solar power and wind power both need some sort of economical energy storage system before they can realistically provide a significant portion of the electric power production.
Murphy Siding If we're allowing ourselves to dream that trains could be powered using 100 year-old, wishful thinking technolgy from a near-mad genious, why don't we just get some app for our I-phone that does the same thing?
If we're allowing ourselves to dream that trains could be powered using 100 year-old, wishful thinking technolgy from a near-mad genious, why don't we just get some app for our I-phone that does the same thing?
I'm absolutely positive that somebody is thinking of such an app right now!
Thanks to Chris / CopCarSS for my avatar.
Well... lets see... the sun delivers about 1340 Watts of energy per square meter at the top of the atmosphere.
About 9 % is reflected and about 22% is absorbed by the atmosphere so only about 69% reaches the surface of the earth so you have available about 925 Watts per square meter to capture and turn into electricity.
Assume a 100% efficient conversion by some new fangled solar cell, (and unlike athletes that often claim to give 110%, solar cells cannot give more than 100%!).
So if your engine is covered in solar cells and the engine is, say... 20 meters long and 3 meters wide, then you have 60 Square Meters of solar cell available to make electricity.
That gives you 55,500 Watts of power to run your train when the sun is shining BRIGHTLY.
Uh... that is only about 75 Horsepower at NOON on a CLOUDLESS day.
I suppose that if you limit train travel to daylight hours, you might be able to haul a few people, SLOWLY to their destination. Assuming no tunnels, trees or clouds.
Presently solar cells are theoretically 33.7% efficient, so today you would only have about 26 Horsepower... at noon...
Semper Vaporo
Pkgs.
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