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Jacobs Ladder Spark Plug

moves down the cylinder liner
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a creepy inventors lab woulden't be complete without a Jacobs ladder. its the thing that looks like TV "rabbit ears" with the ark of electricity that travels up it.

why not flip that thing upside down and put it in a piston/cylinder assembly? the ark would obviously have to travel MUCH faster than the ones you are used to seeing. if this could be done, it may be possible to control the vertical location of the ark to a certain degree. this would allow the spark to be just where it needed to be with respect to the flame propegation. i dont know a lot about Jacobs ladders (if that is in fact what they are commonly known as) maybe the voltage would not be enough? does anyone know what governs the movement of the ark up the "ladder"?

auricom_mech, Aug 04 2006

Jacob's Ladder http://www.biblegat...8:10-22;&version=9;
It does not mention that Jacob's wrestling name was The HeBrute. [bungston, Aug 04 2006]

Jacob's Ladder, Cheddar Gorge http://en.wikipedia...dar_Gorge_and_Caves
Oh, and Cheddar Gorge isn't an illness caused by eating too much cheese. [Frankx, Aug 07 2006]

Saab SCC system http://autospeed.dr...A_0766/article.html
[jhomrighaus, Aug 07 2006]

Electrical version - how to make one. http://www.emanator...bigclive/jacobs.htm
[Ling, Aug 08 2006]

[link]






       Do you get to wrestle an angel at the end, or am I missing something here?
DrCurry, Aug 04 2006
  

       either 1) i am calling it a jacobs ladder incorrectly, or 2) there are 2 things refered to as a Jacobs ladder.   

       DrCurry: i think i know the thing you are thinking of, the toy made of wood and strips of cloth right?   

       maybe i am refering to this contraption incorrectly. does anyone know what it is called based on my description of it in my original post?
auricom_mech, Aug 04 2006
  

       Wouldn't work. The arc of Jacob's ladders can only move up. The arc initially starts where the contacts are the closest, heating and ionizing the surrounding air. This air is more conductive than normal air, but also moves upward due to lesser density.   

       Aside from never moving downward, any spark hot enough to ionize gases will ignite a cylinder immediately.
Aq_Bi, Aug 04 2006
  

       Aq_Bi:   

       ok, point recieved. but i had one question:   

       //any spark hot enough to ionize gases will ignite a cylinder immediately//   

       do you mean ignite the metal of the cylinder? or the cylinder of air in the charge?
auricom_mech, Aug 04 2006
  

       ANY spark will ignite the fuel air mixture.(heck anything that is hot enough, like a lump of carbon)   

       Igniting the cylinder would be a pretty radical event to say the very least, but you would need something like a Thermonuclear spark plug or something to do it.   

       The jacobs ladder would ignite the mixture the second it sparked and you would then have no need of a continued spark. Also spark plugs need to fire at a very precise instant in time, after that they have no purpose.   

       by the way it is called a Jacobs ladder because of the way there is always a spark on the wires and they always move upwards.   

       Doc C is just messing with you cause he doesnt like the idea.
jhomrighaus, Aug 04 2006
  

       yeah, it looks like the prinicpals of this idea have already been shot down (justly) by Aq_Bi.   

       but jhom, i wouldent say that the spark plug is useless after its initial fire.   

       dont some MSD systems continue to fire several times after the initial one (this may be wrong)   

       but also, i was trying to consider where the flame front would be at any given point through the power stroke. i think if you could move the spark down the cylinder liner (now we are getting into theory, since my method is impossible) it would help controll the flame propigation. the benifits likely wouldent be much more power, but it might be a way to mimize NOX and CO by more evenly "cooking" the charge.   

       any thoughts?
auricom_mech, Aug 04 2006
  

       I dont think you could move the spark fast enough to keep up with the flame front. Once ignition takes place there is really not much to do but dsit back and watch.   

       Many modern DIS ignition systems utilize a waste spark system where both of the plugs connected to a Coil spark at the same time, the one that has a fresh fuel air charge sparks easily and very hot, the other has a much higher resisitance and so forces the bulk of the charge into the firing cylinder.   

       MSD does have a Multispark system and I really cant say if it does much or not, I suspect that under certian conditions a secondary spark could find new material to ignite. but I suspect that those conditions are very limited, I suspect that it has more to do with extending the overall time that a spark is present.(which even with MSDs system all the sparks Occur in a miniscule sliver of a second)
jhomrighaus, Aug 04 2006
  

       [auricom_mech] There are three things referred to as Jacob's ladders. One is your electrical toy, one is an ancient wooden toy, and another is an ascending rope ladder that is by nature nearly impossible to climb.
jellydoughnut, Aug 04 2006
  

       <cough> There is a huge hill in the next town over from me that the locals call *Jacob's Ladder*...so 4.
xandram, Aug 04 2006
  

       Yes, I should have specified the fuel-air mixture of the combustion chamber instead of "cylinder".   

       Extrapolating this idea, one could design a sparking system between the piston and the top of the chamber. A vertical spark would form along the height of the combustion chamber, and could be drawn out as the piston moves downward. This still relies on ionized gases creating a conductive path, and such a large spark will ensure complete and cleaner combustion.   

       Technical problems include electrically insulating the piston, and the need for a more powerful high voltage generator may offset any benefits, but it could work.
Aq_Bi, Aug 04 2006
  

       The original Jacob's ladder is a biblical reference (link), which is what the good Doctor referenced. I was not aware that any rassling went on, but reading between the lines I am sure that it did.
bungston, Aug 04 2006
  

       [Aq_Bi] I think Saab already did this. The piston had a little tower in the center that acted as the ground electrode.
jhomrighaus, Aug 04 2006
  

       For you pups who were in grade school when it came out, Jacobs Ladder is also the title of one of the all time freaky spooky movies - really an excellent film. I recommend that those of you in the mood for such viewing rent it tonight. Do not look it up on IMDB first. The less you know the better it will be. Trust me.
bungston, Aug 04 2006
  

       Ok, fine. Electrical thingy, wooden thingy, rope laddder, a hill near [xandram]'s house, suspense movie, biblical thingy, a string figure from the cat's cradle hobby, a perinnial plant, a book about the genome, a collection of articles on psychotherapy, and a fiction book; that's eleven...anything else?
jellydoughnut, Aug 04 2006
  

       The MSD system does help to ignite more unburnt fuel than a single spark system, but it is much more effective on older cars with weaker ignition systems to begin with. If you put one on an already (relatively) efficient car like a new Honda or something, you wont see much gain, unless it has been altered in some way (turbocharged, reprogramed to run slightly richer for more power, etc.), but on an older gas-guzzler, it could help tremendously. 10-20% gain in gas mileage and 15 or so HP on something like a big block V-8 luxury car from 50 years ago.   

       And it doesnt require a larger/better alternator to get a higher spark voltage. Eery car already has a coil to step up the voltage greatly, and spark plugs require very little current to spark. It takes more current to tell the plugs when to fire than it does to fire them.
Hunter79764, Aug 04 2006
  

       [jellydoughnut]- yeah, I've got this mate, right, he's a Jewish roof-tiler...
m_Al_com, Aug 05 2006
  

       NNNNnnnnNNNNNOOOooooo OOOOOooooOOOOOooo o!!!!!!
jellydoughnut, Aug 06 2006
  

       [jellydonut] - a steep climb up the side of Cheddar Gorge? (link)
Frankx, Aug 07 2006
  

       Wow. Learn something new everyday.
jellydoughnut, Aug 07 2006
  

       regarding the idea that Aq-bi had about the big spark that travels down the column of charge to the top of the piston:   

       someone proposed that idea in this section of the halfbakery. "Thunderheads" i believe its called. i already voiced my opinion there about why i dont think this would work as a sustained spark. i would imagine it would be fine as a single spark (like Saab apparently has already baked).
auricom_mech, Aug 07 2006
  

       Jacob's Ladder is also the common name for a plant-Polemonium Retans.
xandram, Aug 07 2006
  

       Listed.
jellydoughnut, Aug 07 2006
  

       Aq_Bi, I have never played with a Jacob's ladder (electrical type), but if asked, I would have replied that they ought to work at any angle because they look a little like a rail gun, if you squint your eyes just so.   

       Edit: see link for how to make one. Hmm, they seem to work as Aq_Bi mentioned. Maybe the current is too small. What we need is a plasma rail gun.
Ling, Aug 08 2006
  

       it has to do with the heated air that makes it move. if you changed the layout of the electrodes it would work the other way.
jhomrighaus, Aug 08 2006
  

       so it is possible to get any direction you need from one? now its just a matter of the velocity? does anyone have any thoughts on how this could reduce polutants since the change would theoretically burn more completely?
auricom_mech, Aug 08 2006
  

       You can only Get up or Down, And you have to orient the entire apparatus upside down to gow towards the transformer.   

       A ladder works by establishing an arch at the nearest points of the electrodes. This arc then ionizes and heats the air around the arc. This ionized heated air begins to rise. This air mass also exibits a lower resistance to current than the surrounding air and so the arc can be longer for the same voltage output. As it follows the path of least resistance 2 things happen the path of least resisistance is slightly higher as the warm ionized air rises and the length of the arc can effectively increase as the resistance decreases. The narrower the gap, the hotter the arc so the faster the arc will move.(so little narrow ladder are very fast, wide ones much slower) They will not work sideways and must be reconfigured to be flipped, but in all cases the arc will only move upwards. In a Vacuum such a device would form an arc and then nothing else would happen, they will also not work in a windy area or around a fan(though they may work a little bit but the arc will appear to blow out away from the electrodes and will not reach is full length). This type of system will not work in an engine because the moving air does not allow it to travel, it will simply behave like a normal spark plug. Also the length of a typical spark plug firing cycle is measured in thousanths of a second, so all you get is a little "snap" and your finished. At high engine RPMS if one could observe the spark it would appear to be a nearly continious spark as it is cycling so fast.   

       This Idea was doomed from the start.
jhomrighaus, Aug 08 2006
  
      
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