Matronics Email Lists :: View topic - Shower of Sparks lesson (LONG)

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Shower of Sparks lesson (LONG)

Matronics Email Lists Forum Index -> Yak-List

View previous topic :: View next topic

Author Message

mark.bitterlich(at)navy.m
Guest

Posted: Thu Mar 26, 2009 2:11 pm Post subject: Shower of Sparks lesson (LONG)

I just had an interesting maintenance experience that I thought I would pass on since "starting problems" seem to be a subject of discussion lately.  



Here is what happened: 



Hit starter button, engine cranked OK, but did not start.  Engine was getting plenty of fuel, so it seemed to be an ignition related problem.   Closed main air valve (YAK-50) and pushed starter button until starting system was out of air.  Then hit starter button again and noticed that something did not sound exactly right.  There was a small amount of "buzzing" coming from the shower of sparks vibrator power supply in the nose compartment, but listening to the left mag... there was no noise at all coming from it.  Repositioning the prop did not change this.  



Long story short, the "needle screw" that penetrates the starting ignition wire coming from the shower of sparks unit to the left mag (in the mag itself) was no longer making contact, thus there was no energy making it to the spark plugs.  



Well.. this high voltage shielded wire for the starting shower of sparks system is pretty special.  It is wrapped in Teflon material and is very hard to penetrate with the screw in the mag cap.  I ended up trying a lot of things, including sharpening the "screw in thingy" so that it hopefully would penetrate.  Then tried a piece of metal clamped around the wire, folding it back..... that worked, but it also ended up causing a short circuit to the metal cap of the mag.  Oops.  So much for a brand new mag distributor cap.  By the way, when this thing starts burning up electrically, it smells just like rotten eggs.  Something to be aware of.  



A lot of methods to get this amazingly simple, yet very difficult to get working just right, simple wiring connection were tried and very honestly... failed.  The engine would hit on one or two cylinders, try to start, but just would not.   Once again took the mag apart, and then found the wire itself burned in half.  WTF .... OVER!  



Ended up taking this stupid mag apart about four times.  I know the Russians manage to do this easily.. but it sure was a pain in the tail for me and with the two A&P's there helping.  



In the end, I took a special wire crimp used for splicing two 12 gage wires together, then crimped THAT to the end of the ignition wire strand itself, cutting it down to exactly the right length (little less than ¼ inch) and then sticking THAT whole mess in the hole and tightening the pointy screw thingy into THAT whole design...which finally fixed it.. for how long is still to be determined.  



But.... In the process I came up with some interesting tests which I thought I would share with the maddening crowd.   I'll pass them on just FYI.  Some may find fault with doing something like this... If anyone does, I'm sure they will let me know.   



That said, many of us start our M-14's  the same way.  As soon as the darn thing fires, we immediately flip on the mags and away we go.  Works good.  However... it can mask the kind of problem that happened to me.  There needs to be a method to really check whether your shower of sparks system is working perfectly, or just half ass.  By that I mean, not sending energy to every cylinder in the firing order.  Hmm.  



I  came up with this test, and it works.   



1.	I start the engine and let it warm up normally.  

2.	Then I shut off the main air supply with the main air valve. (If you have a YAK-52, you can run your flaps up and down to get all the air out of the system at this point. )

3.	Then with the engine at idle, or very close to it... and I repeat... at idle, or very close to it.... I take my left hand and put it on the mag switch, and with my right hand, I get ready to hit the start switch. 

4.	Then, I shut off the mags... and of course,  the engine immediately dies.  

5.	Before it can slow down much at all, I push in and HOLD the starter button.  The engine should RUN.  It will sound a little weird because it is running with very retarded timing.  But it should RUN and it should run smoothly.  Only hold the start button in for maybe a few seconds... no more than say 2 seconds at most. Even less will get the job done.   

6.	Then I release the starter button, and as the engine dies, I flip the mags back on, or.. you can just release the starter button and just let the engine die and then restart it later if you like. 



If it all works as described, the electrical part of your starter system is working just fine.  GREAT!  Another thing not to worry about.  On the other hand, if you do this and your engine misses and fires erratically... you have an issue that you need to fix.  SOON!  Make sure you do this when the engine is hot... such as after a flight.  It is possible that a cold engine will work perfectly, but a HOT engine will not.  If this happens... the odds are extremely high that your problem is in the mag itself.  In the high tensile ignition wire connection to the "distributor cap" itself.  The little "sharp screw" thingy is highly suspect.  



This is not a test I would advise doing on every flight of course.  Once every few months, or even once a year ought to be enough.   Personally, I am going to do it right before every long cross country flight, but I tend to be a little paranoid.  



Note: Warning: Whatever:  I would not advise doing this with any air left going to the starter system as this will allow the air valves in the cylinder to go active with the engine already running.  Not a good thing.  The already ignited fuel/air mixture on the power stroke SHOULD keep them from opening, but I just do not want to go there.  



Another much more simple way to test this system would be to just start the engine normally, and then very simply ....just do not turn on the mags.  Instead hold in the starter button to see if it actually will run on the starter button alone.  The downside of doing THAT is that you are still trying to feed air into cylinders that are also being fired by burning fuel which just can NOT be a "good thing" so I would advise avoiding that method even though in theory it might not cause any harm.  



Just passing along another lesson learned.  



Mark Bitterlich

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

wlannon(at)persona.ca
Guest

Posted: Thu Mar 26, 2009 7:49 pm Post subject: Shower of Sparks lesson (LONG)

Mark;



You , and many others on the list, refer to the start system as "shower of 

sparks".



The CJ is the only aircraft of this genre that I am fully familiar with and 

that start system utilizes a boost coil.  Is the Yak 50, 52 different?



Shower of Sparks was, many years ago, a Bendix registered trade name for a 

start system that utilized a low voltage ( 12 or 24) vibrator that bypassed 

the magneto primary circuit and energized the MAGNETO secondary to provide 

the high tension current for starting, through the normal distribution 

system, that a slow turning mag. could not.



The boost coil by comparison is a self contained primary/secondary unit that 

provides the high tension directly to a retarded electrode in the mag. 

distributor.



The early T6/ Harvard 2 use a boost coil.  The T6G/ Harvard 4 utilize a 

vibrator, i.e.;  Bendix "Shower of Sparks".



I understand there is another shower of sparks system ( by Lamar? or?) but I 

have no idea how that works.



What system do the Yaks use?



Walt



---

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

wlannon(at)persona.ca
Guest

Posted: Thu Mar 26, 2009 8:56 pm Post subject: Shower of Sparks lesson (LONG)

Correction to last.

"----bypassed magneto primary circuit--- -"  should read "points" not 

primary circuit.

Walt

---

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

mark.bitterlich(at)navy.m
Guest

Posted: Fri Mar 27, 2009 8:55 am Post subject: Shower of Sparks lesson (LONG)

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 





--

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

dsavarese0812(at)bellsout
Guest

Posted: Fri Mar 27, 2009 9:14 am Post subject: Shower of Sparks lesson (LONG)

FWIW, the unit on the CJ is identical in every way and thus  interchangeable with the unit on the Yak 52.

 Dennis

  

 [quote]   ---

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

JOE HOWSE

Joined: 10 Jan 2006
Posts: 140
Location: DUNCAN BC CANADA

Posted: Fri Mar 27, 2009 5:43 pm Post subject: Shower of Sparks lesson (LONG)

Walt



The 18T uses a boost coil



Joe> 



 	  Quote:

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

_________________
J.C. HOWSE

yakplt(at)yahoo.com
Guest

Posted: Sat Mar 28, 2009 10:09 am Post subject: Shower of Sparks lesson (LONG)

Which creates a bath tub worth of sparks.    

  

 Sorry, just could not resist.  

  

 Mark

 

 

 

   From: Joe Howse <joeh(at)shaw.ca>

To: yak-list(at)matronics.com

Sent: Friday, March 27, 2009 9:42:18 PM

Subject: Re: Shower of Sparks lesson (LONG)



--> Yak-List message posted by: "Joe Howse" <joeh(at)shaw.ca (joeh(at)shaw.ca)>



Walt



The 18T us Photoshare, and much much nbsp;                    =======================

 [quote][b]

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

yakplt(at)yahoo.com
Guest

Posted: Sat Mar 28, 2009 2:20 pm Post subject: Shower of Sparks lesson (LONG)

Joe, please give me a reference for a "boost coil".   Any reference at all would be ok... internet, technical manual, anything.  I am not picking on Walt here.  I've been around electronics all my life, since age 8 anyway, and I have never heard that term before Walt used it.  I am sure he or you either read it somewhere, or heard it somewhere, and I have been all over trying to find it written down in any technical manual and have yet to find it.   If I am wrong in NOT using the term, then I want to be educated on it. 

  

 Mark Bitterlich

  

  

 

   From: Joe Howse <joeh(at)shaw.ca>

To: yak-list(at)matronics.com

Sent: Friday, March 27, 2009 9:42:18 PM

Subject: Re: Shower of Sparks lesson (LONG)



--> Yak-List message posted by: "Joe Howse" <joeh(at)shaw.ca (joeh(at)shaw.ca)>



Walt



The 18T uses a boost coil



 [quote][b]

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Yak-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum