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Friday, June 28, 2013

Pokey LaFarge - another very cool musical sound

Years ago, I was in Atlanta for a training class. An old navy buddy recommended that I try "Fat Matt's Rib Shack", for some good southern cooking. I enjoyed the meal, but I enjoyed the band even more. The band was Pokey LaFarge and the South City Three.

I don't know how you would classify the music; It seems to vary between early Amerian Blues and Dixieland. It's a distinctly early 20th century American sound, and I really like it. There can't be many bands playing this kind of music anymore.  I have a couple of their albums on order from Amazon right now. As far as I know, their music is original, not covers.  Every one of these guys is a kickass musician.  Check em out!

Monday, June 24, 2013

New musical discovery - Jonathon Wilson

Taking a quick break from power plants...

I was reading Boing Boing today.  One of the articles was a rave review about musician Jonathon Wilson, and how under-appreciated he is.

The review was *SO* over the top in praise that I decided to have a listen to some of his tunes on SoundCloud.  The dude is damn good.  You have to like the late 60's acid rock style like Pink Floyd & The Moody Blues to appreciate the cool retro sound he's creating.  He sounds a lot like Floyd when they were at the top of their game. 

It took some adjustment on my part to give these songs enough time to get flowing.  Most of the music I listen to these days starts thrashing immediately :)  I really like this first song. 

Saturday, June 22, 2013

Nearby Corliss Steam Engine

After putting together a series of blog posts about the history of steam engines, I ran across one in my own backyard!  Being new to the area, we were playing tourist, and poking around in the nearby town of Newport, Washington.  Imagine my surprise when we rolled up on this monster!  Yep, that's a standard bus stop bench in front of it. 

According to the sign, it put out 478 horsepower and the big wheel turned 100 RPM. 

This got me thinking about what it must have been at the turn of the 20th century to see one of these beasts in operation... So I checked Youtube, and guess what?  They have a few videos of Corliss steam engines running.  Check them out!

Below is a 500 Horsepower Corliss engine that was once used to power looms in a textile factory.  It's a little freaky watching that massive connecting rod move back and forth so quickly.  Most impressive in fullscreen mode!

Unfortunately the above video doesn't clearly show the steam valve train.   But happily, I found another video that does.  You can easily see how the eccentric wheel operates the wrist-plate, which in turn drives the entire valve train.  I spent a little time trying to understand the purpose of the vertical rods dangling from the upper steam inlet valves and learned something. 

The inlet valves do not shut when the wrist-plate rocks back.  Instead they are closed by the governor tripping them each cycle.  The vertical rods, which are attached to dashpots, allow the steam valves to close more slowly than if they were shut by the wrist-plate, admitting more steam to the cylinder.  An early (and succesful!) type of variable valve timing.

Once again I will turn the valve train explanation over to Wiki, who does a far better explanation than I ever could:

"The inlet valves are pulled open with an eccentric-driven pawl; when the pawl trips, the rapid closure is damped using a dashpot. In many engines, the same dashpot acts as a vacuum spring to pull the valves closed, but Corliss's early engines were slow enough that it was the weight of the dashpot piston and rod that closed the valve.

The speed of a Corliss engine is controlled by varying the cutoff of steam during each power stroke, while leaving the throttle wide open at all times. To accomplish this, the centriugal governor is linked to a pair of cams, one for each admission valve. These cams determine the point during the piston stroke that the pawl will release, allowing that valve to close.

As with all steam engines where the cutoff can be regulated, the virtue of doing so lies in the fact that most of the power stroke is powered by the expansion of steam in the cylinder after the admission valve has closed. This comes far closer to the ideal Carnot cycle than is possible with an engine where the admission valve is open for the length of the power stroke and speed is regulated by a throttle valve."

And lastly, a drawing of this complex arrangement, showing the pawls that open the inlets, and the vertical rods with attached weights.

AC vs. DC Power

At the end of the 19th century, an epic battle was shaping up.  On one side were Thomas Edison and Lord Kelvin, who advocated using Direct Current (DC) power distribution systems.  On the Alternating Current side of the battle were George Westinghouse and Nikolai Tesla (and nature). 

The battle was known as the "War of the Currents".  DC power systems had already been developed and in use in the United States for several years, and were the standard in use in the 1880s.  From Wiki:

"During the initial years of electricity distribution, Edison's direct current was the standard for the United States, and Edison did not want to lose all his patent royalties.  Direct current worked well with incandescent lamps, which were the principal load of the day, and with motors. Direct-current systems could be directly used with storage batteries, providing valuable load-leveling and backup power during interruptions of generator operation. Direct-current generators could be easily paralleled, allowing economical operation by using smaller machines during periods of light load and improving reliability. At the introduction of Edison's system, no practical AC motor was available. Edison had invented a meter to allow customers to be billed for energy proportional to consumption, but this meter worked only with direct current. The transformation efficiency of the early open-core bipolar transformers was very low. Early AC systems used series-connected power distribution systems, with the inherent flaw that turning off a single lamp (or the disconnection of other electric device) affected the voltage supplied to all others on the same circuit.  The direct current system did not have these drawbacks as of 1882, giving it significant advantages."

Innovation would shortly end most of the advantages held by Direct Current however, and by 1896 the war would be over.  The first innovation was a high-efficiency transformer.  This allowed conversion of AC power to very high voltage for transmission with low losses, and conversion to low voltage near the end user.  DC power was generated at 110 volts, and due to line losses at this voltage, there had to be a power plant within a mile or so of the end-user.  This arrangement would require a power plant to be installed every mile or so!  A great arrangement for Thomas Edison, but not so great for everyone else.

What actually caused DC to lose the Battle of the Currents is an electrical relationship, stated in  Ohm's Law.  Ohm's law says that Power is equal to Voltage times Current, or P = V x C.  A corollary of that law is that Power is equal to the square of current times resistance, or P = I^2 x R.  This corollary is what killed Direct Current as a means of using electrical power.

In any electrical system, transmission lines will have a certain resistance to current flow.  This resistance causes heating, and reduces the ability of the transmission line to carry full load.   This is the P - I^2 x R portion of Ohm's Law.  Doubling current increases resistive heating by 4 times, and this power that is wasted heating up the power line is lost to the end user.

Therefore, with a semi-understanding of Ohm's law, P = V x C, we can see we need to minimize current if for a given Power to transmit power over any kind of distance.  This is done by raising voltage as high as practical.  With a transformer we can adjust AC voltage at will, whereas DC has to be generated at the desired end-user voltage, and the entire system must run at that voltage.

There is another reason AC power won the battle:  It is simpler to work with at the generator.  With a DC machine, the power is produced on the rotor, and must be removed using carbon brushes from the commutator.  There are limits to how much current can pass through these brushes, so a typical power plant would have several small machines, each producing a small amount of power.

With an AC generator, the electromagnetic field rotates, and power is produced in the stationary windings of the machine.  Because there is no need to pull power from a rotating member, the AC generator can make a great deal more power than its DC counterpart.  The largest Dynamo ever built could convert 500 horsepower to DC power.  An equivalent physical-size AC machine would be able to convert 10,000 horsepower, with far less complexity and maintenance.

Looking at the small machine below, we can guess a few things: 
  • The commutator segments would require regular care to ensure they remained insulated from each other. 
  • Maintenance of brushes and tension would be an ongoing affair.
  • Due to low voltage, the output current would be large.  You can see how fat the output leads are. 
  • With such high currents, moving this electricity would require vast amounts of copper.  

 In the end, AC (rightfully) won the battle, and so now we live in an Alternating Current world.  The Wiki version of this fascinating story is here.

 And here is a video describing the battle!

Steam Power and Electricity - Dynamos

Steam engines were invented around 1700 AD.  Using a steam engine to turn a generator in order to make electricity would have to wait for another 130 years.  Electricity was not understood, and the earliest generators used electrostatic principles to push electrons around.  Surviving examples of these static-electricity type generators include the Wimshurst generator and the Van de Graaf generator.

Friday, June 21, 2013

Old Mission State Park - Cataldo Mission

Recently we were asked to chaperone on a field trip for our daugher's class.  The field trip was to the Cataldo Mission, now called "Old Mission State Park".

I've forgotten a lot of the Idaho history that they taught in Boise grade school, and Northern Idaho always seemed such a long way from where I grew up...

Long story short, I learned a lot about the mission and the interesting story behind it. 

In the early 1800's, the Coeur d'Alene Indian Tribe had heard about certain powerful white medicine men who wore black robes and had great magic.  The "medicine men" were actually Catholic Jesuit Priests, a sect devoted to spreading the word of God through evangelism. 

The Indians sent several chiefs all the way to St. Louis to request their own priest.  In 1842 The Jesuits responded to the request and sent three priests to the area. Their first activity was to choose a location for a mission.  The first was along the St. Joe River, but the site was subject to flooding. In 1846 they chose the current location.

In 1850 the church was taken over by Father Antonio Ravalli, who began designing the new mission building.  He was Italian, had traveled Europe, and seen many of the great Cathedrals there.

He made sure that the building was constructed by the Indians themselves, so that they could feel part of the church. The frame of the building was built using only broad-axes and wood augers.  There were no lumber mills (or even roads) in the area at that time, so each board was made flat by hand from a log using only an axe.  The boards are held together by wooden pegs driven through holes.  Amazingly, even with this primitive construction, this is Idaho's oldest standing building! 

After framing, the walls were filled in with "wattle and daub", which is a blend of creek willows and mud.  The ceiling was initially white, but the indians wanted the ceiling color to more accurately represent the sky, so they created a stain from huckleberries and stained the center three ceiling panels blue.

Unfortunately in the 1920s, the indians were forced to move to a reservation, and the unique building of worship that they had created with their own hands was taken from them.  It was abandoned then, and fell into disrepair, until the Idaho Centennial commision decided to restore it in 1976.  Following the restoration, the mission building is still about 90% original.  On a happier note, the building has since been returned to the Coeur d'Alene Tribe.

Below are the two primitive tools used in the construction of this entire building.  Augur and broadaxe.

Beautiful handmade floor planks

Below is a statue carved by Father Antonio Ravalli.  It is not marble, but local pine.  Near the bottom is a photo of Father Ravalli.

 Father Ravalli made this elaborate candle holder from used cans.

A photo of the altar.  Everything is made from pine trees, and finished to look like marble and hardwoods.  The "wallpaper" is made from bits of fabric and old newspapers.

An overview from the back of the mission.  It's an awe-inspiring, hand-made frontier cathedral.