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mark.bitterlich(at)navy.m
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 Posted: Fri Mar 27, 2009 11:42 am Post subject: Shower of Sparks; What is it? |
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Walt,
Here is how I look at it, and of course everyone is welcome to have
their own opinion on the matter.
Most aircraft engines use mags. Magnetos do not work real well at low
RPM, so starting an engine with them becomes a problem because starters
do not usually spin them fast enough to provide enough spark energy.
Because of that, two systems have been devised to provide for enough
energy to start a mag equipped engine.
1. Impulse couplers.
2. Shower of spark systems.
It appears you want to break down the "shower of sparks" term into two
sub-categories depending on where the secondary portion of the
transformer is located. If the primary and secondary of the transformer
are in the same box, you call it a "boost coil" system. If the
secondary is in the mags, it is called a "shower of sparks" system. If
I am correct in that this is your view, that's fine.... But I don't see
it that way. Just happens to be my personal opinion on the matter. But
for the sake of discussion, I would appreciate a reference to the use of
the term "boost coil".
To explain: I personally consider any ignition system that uses the
basic design of a doorbell buzzer to create a square wave that then
feeds a transformer can be properly referred to as a "shower of sparks"
system.
Regardless of where the primary or secondary of the transformer (in
proper terms: The Ignition Coil) is located, the overall design concept
remains identical. A "doorbell buzzer" (per se) is used to rapidly and
continuously open and close a set of points, that creates a "buzzing"
noise. These points are fed by DC battery voltage, and as they open and
close they create a square wave. A square wave is a form of Alternating
Current. Alternating current is needed to operate a transformer. A
transformer always has a primary (voltage input) and a secondary
(voltage output). In the typical M-14 engine design, the primary and
the secondary and the "buzzer" are all located in the same box. This is
identical to the system that was first used in the Model T Ford engine.
This constant energy source is then fed to the magneto cap where it is
then fed through the normal mag rotor to the normal mag cap, then to the
spark plugs of the engine. A second "point" on the rotor is used to
create a retarded timing situation.
The end result is that instead of just one big single energy surge going
to each spark plug in sequence, initiated by the mag point set, there is
a solid stream of spark energy going continuously to each spark plug as
the rotor turns creating more than one spark to each plug, thus the
term: "A SHOWER OF SPARKS". If this is a Trade Word term, so be it.
Some systems actually connect the buzzer points to the P lead of the mag
itself. In the end, you get the exact same effect.... "A shower of
sparks".
Yes, the Yak's use a box that contains the buzzer, the primary and the
secondary of the ignition transformer in one box. I call that a shower
of sparks transformer. You call it a "boost coil". No problem.
Mark
P.s. Good reference:
http://www.aeroelectric.com/articles/Shower-of-Sparks/ShowerOfSparks.pdf
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mark.bitterlich(at)navy.m
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| Posted: Fri Mar 27, 2009 12:33 pm Post subject: Shower of Sparks; What is it? |
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I am going to add to and simplify this whole posting to a few less
words.
In my opinion any system that uses a door bell buzzer device to open and
close an external point set, that in turn causes a square wave to be fed
to an ignition coil is a "Shower of Sparks" system. It is called that
because, it creates a literal "shower of sparks".
Some shower of spark systems use a transformer outside of the mag
itself. Some others use the internal mag coil to accomplish the same
end. Either way, both methods use a buzzer coil arrangement to create
the square wave that takes battery voltage, converts it to a square
wave, feeds it to a transformer, steps up the voltage and creates a
continuous stream of high voltage that is distributed to the spark plugs
and allows them to fire continuously as the rotor spins and makes
contact with the cap contacts.
The Yak and CJ's use a system where the buzzer, and the transformer are
external to the mag. I guess I just can't see why the name of the
system concept should be changed depending on whether the "coil" is
inside, or outside the mag. But I never agreed to changing cycles per
second to Hertz either! 
Mark Bitterlich
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jan.mevis(at)informavia.b
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| Posted: Fri Mar 27, 2009 1:02 pm Post subject: Shower of Sparks; What is it? |
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I agree with your analysis.
But cycles per second IS Hertz, as you know. What's in a name ...
Jan
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yakplt(at)yahoo.com
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| Posted: Sat Mar 28, 2009 10:08 am Post subject: Shower of Sparks; What is it? |
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Exactly Jan.... in my early days Cycles per Second was abbreviated as "CPS". Made sense to me. Somewhere along the way the powers that be decided that in order to honor the person who invented AC, they would call CPS "Hertz" instead. I guess that is also use the termt "Morse" code, but I hate it when I learn one thing and then suddenly the rules change and it has a whole new name! Of course I also think tubes worked a hell of a lot better than transistors .
Mark
From: Jan Mevis <jan.mevis(at)informavia.be>
To: yak-list(at)matronics.com
Sent: Friday, March 27, 2009 5:01:25 PM
Subject: RE: Shower of Sparks; What is it?
--> Yak-List message posted by: "Jan Mevis" <jan.mevis(at)informavia.be (jan.mevis(at)informavia.be)>
I agree with your analysis.
But cycles per second IS Hertz, as you know. What's in a name ...
Jan
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wlannon(at)persona.ca
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| Posted: Sat Mar 28, 2009 8:14 pm Post subject: Shower of Sparks; What is it? |
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Mark;
Booster Coil references;
There are many.
We could start with Brimm & Boggess Aircraft Engine Maintenance, 1939
edition but of course you have never heard of that.
Also could quote T6 & Harvard TO.'s & EO's but you do not have those.
The above only give a basic description in any case so I will give you one
that describes all of the auxiliary starting systems and which you should be
able to download.
It is FAA Advisory Circular AC65-12.
Page 192 to 196 in my 1971 copy . I believe there is now revision A which
may or may not have the same page numbers.
As well as reading the text you will be interested in the illustrations
particularly 4-21 - Booster Coil and 4-22 - Induction Vibrator.
There are also schematics for both the high tension and low tension retard
breaker types. The second refers to the low tension magnetos for high
altitude operation of radial engines where each spark plug has it's own
secondary coil.
You will also note that Fig. 4-21 is an exact picture of the Chinese (and
I'm sure the Russian) booster coil. It was copied from the AN unit.
As for me wanting to break it down into sub-categories the fact is that was
down probably before you were born and by people probably a lot smarter than
me.
However you can call it shower of sparks or whatever the hell you like, its
a free country..
Walt
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yakplt(at)yahoo.com
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| Posted: Sun Mar 29, 2009 11:19 am Post subject: Shower of Sparks; What is it? |
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Walt, <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Appreciate the references. Thanks for your patience and understanding.
Mark
p.s. You're darn toot'in it's a free country, and my thanks for every man and women that is helping to keep it that way today.
From: Walter Lannon <wlannon(at)persona.ca>
To: yak-list(at)matronics.com
Sent: Sunday, March 29, 2009 12:12:18 AM
Subject: Re: Shower of Sparks; What is it?
--> Yak-List message posted by: Walter Lannon <wlannon(at)persona.ca (wlannon(at)persona.ca)>
Mark;
Booster Coil references;
There are many.
We could start with Brimm & Boggess Aircraft Engine Maintenance, 1939
edition but of course you have never heard of that.
Also could quote T6 & Harvard TO.'s & EO's but you do not have those.
The above only give a basic description in any case so I will give you one
that describes all of the auxiliary starting systems and which you should be
able to download.
It is FAA Advisory Circular AC65-12.
Page 192 to 196 in my 1971 copy . I believe there is now revision A which
may or may not have the same page numbers.
As well as reading the text you will be interested in the illustrations
particularly 4-21 - Booster Coil and 4-22 - Induction Vibrator.
There are also schematics for both the high tension and low tension retard
breaker types. The second refers to the low tension magnetos for high
altitude operation of radial engines where each spark plug has it's own
secondary coil.
You will also note that Fig. 4-21 is an exact picture of the Chinese (and
I'm sure the Russian) booster coil. It was copied from the AN unit.
As for me wanting to break it down into sub-categories the fact is that was
down probably before you were born and by people probably a lot smarter than
me.
However you can call it shower of sparks or whatever the hell you like, its
a free country..
Walt
---
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