If you want the simplest and probably the most reliable ignition
  system
  get a two cycle two cylinder small outboard ignition system.
  Fires the same number of times and 180 degrees apart just like a
  2 rotor.
  As close as you will come to a A/C magneto.

  http://www.iboats.com/

  http://www.iboats.com/Johnson-Stators/dm/view_id.271367

  http://www.cdielectronics.com/
  Down load the complete catalog.

  Some of these stators are as low as $20 used.

  The high voltage coils supply 300 volts for a simple CD system
  and the other coils may supply enough 12 volt current for an EFI
  system.  No belts.  If the main electrical system or alternator
  fails the engine still runs.

  This stuff is mass produced in the millions and extremely reliable.

  Paul Lamar

  Some interesting stuff in that catalog. Some of us wouldn't know
  exactly
  what would comprise a complete system, as it looks like they are
  all parts
  of an upgrade for certain motors.
  Did you notice the EFI and ECU units in the catalog? They also
  note that
  these can be reprogrammed for "racing purposes".
  Would this be suitable for our purposes? Of course I don't think
  it would
  be
  a good idea to mention aircraft. One could say I'm making a
  marine rotary
  conversion.
  C. Smith


  Good idea Craig. A racing rotary boat motor :)

  All you need is a source of 300 volts, provided by the rotating
  magnet
  and stationary coil,  a 1 ufd 300 volt cap and a switch of
  some sort. An FET works fine and they are easy to use. Way back
  about 30
  years ago we discovered that a 50 cent CMOS CD4050 or a CD4049
  chip makes
  a great FET driver if most of the six gates in the chip are
  connected in
  parallel.

  Since that times 1000's of FET gate drivers have been  designed
  and built selling for as much as $6 each and so far I have not
  found one that works better than a CD4050.  Many of them require
  a regulated supply which lowers efficiency and cost more money
  and parts.


  I set up this simple CD circuit on the bench in half an hour with
  a 300
  volt DC power supply and it works great.  The FET is a IRF740.

  I am rapidly discovering it is all about the 300 volt power
  supply. You
  need a robust power supply that does not crap out when it is
  shorted to ground
  and that is where the charging coil in the outboard motor comes
  into play.

  Nothing could be simpler than a large magnet passing a coil to
  rapidly
  charge the 1 mfd cap.

  Paul Lamar
  --
  So now I have more questions. Does one of these 2 cyl systems
  have enough
  juice to fire both plugs at the same time?
  Can it be used for multi-spark, or would one need to stack 2 or
  more with
  abit of angular offset, then utilize your FET controller to
  switch the
  spark?
  Last, maybe a failsafe contactor to switch out multispark in the
  event of
  a malfunction of computer to revert to stone axe mode? Or am I
  making it
  overly complicated?
  C. Smith


  I think stacking two would be needed. The charging coils are
  available
  stand alone and very cheap. All we need do is find the curved
  magnets stand
  alone. Jeff can make the rotating magnet holder. The electronics
  are trivial
  as I just demonstrated.  Here is a picture of what the spark looks
  like. The picture is a bit out of focus but you can see the spark.


  Paul Lamar

  K&J Magnetics makes custom magnets, $150 minimum order. I
  wouldn't have
  a clue as to the dimensions or polarization, but
  I'll bet you do. Looks like a quote is free.
  http://www.kjmagnetics.com/custom.asp

  C. Smith


  One of my hangar neighbors fixes Mercury's. I can get the dims
  of one of those flywheels. Probably not for a week as I have
  to go to PA on biz next week.

  Paul Lamar

  Check out the last five magnets at the bottom of this page.
  http://www.kjmagnetics.com/products.asp?cat=168
  A the very least, it demonstrates it is doable.
  C. Smith

  Looks too small. We need something 3 inch radius
  or larger. Some of these big ones are high bucks.

  Paul Lamar

  Every Day Practical Electronics mag just published
  another article by my favorite world wide ignition
  engineer. Namely Australian John Clarke.
  www.epemag.com The subject was "Replacement Module for
  small petrol motors". Page 12

  Here are a couple of pictures of a used outboard motor flywheel
  I bought for $10 in an outboard engine repair shop. I wanted
  the magnets out of it.

  Also some more or less self explanatory Figures from the mag
  article.

  Paul Lamar



  Could something like this be incorporated into the flex plate?
  Tracy's PSRU
  seems to have a lot of open area to route wiring out to the
  electronics.

  Joe Berki
  Limo EZ

  Certainly could fit in that area. Ideal for use with a carb.

  Paul Lamar


  Hi Paul,
  I took your advice and purchased an old 13b for tear down and
  familiarization purposes.  I also purchased Tracy's book and
  read it cover to cover 4 times (I learn a little more each time
  I read it).

  I want to start off sort of in Tracy's footsteps by using carbs.
  I have two Johnson / Evinrude 2 barrel carbs that I will
  fabricate onto an intake manifold, but I keep getting hung up on
  the ignition side.  I think the idea of using an outboard
  ignition system is the way to go for me.  I have electrical
  schematics for my 1973 Johnson that I can scan and send if it
  would help with this thread.  The main components would be
  stator, spark advance mechanism, power pack, flywheel with
  embedded magnets and coils.

  My only question is that on the Johnson, spark advance is
  controlled by the spark advance mechanism via a direct
  connection to the throttle.  Would we need to incorporate this
  into the design for a/c use or is there a different way of
  overcoming the spark advance problem?


  Franklin

  How much HP did the Johnson carbs develop?
  To work it should be around 200 to 250 HP.

  In other words what is the carb throat inside diameter?
  You will need about 3 square inches per carb.
  Do you plan to p-port?
  http://www.rotaryeng.net/fund-of-intake.html
  P-ports are worth it as the intake manifold becomes
  trivial to fabricate.

  Do you have access to a lathe?
  You will need it to make a rotating magnet holder for the
  front of the e-shaft. I have a fellow that can make
  that part for you if necessary.

  Yes by all means scan the Johnson electrical schematics.
  That will help when buying parts for the ignition.

  Don't worry about ignition advance. Just run the engine
  at 22 BTDC fixed. Aircraft engines like boat engines
  cruise at one RPM.

  Paul Lamar

  Paul,

  How about a dual ignition systems?  Assume coil-on-plugs design
  and that we would use a two stroke marine engine magneto and
  coils incorporated into the starter gear or torsion plate area
  of the housing.  Also assume we would have  capacitor driven
  ignition modules like the new solid state digital programmable
  MSD, 6AL-2.  Check them out.  Small and compact.  One for each
  rotor.

  First some givens about our rotary engines with the single
  leading plug:  The engine doesn't run very well on trailing
  plugs alone, as quite a lot of the fuel goes out the exhaust and
  is burned in the exhaust system.  Said another way, with a two
  rotor engine and a leading plug fouled, the exhaust system may
  well overheat, or the engine would run rough enough that we
  would want to shut it down after a short time.  That means the
  Achilles heel of the Mazda rotary is the leading plug.   As
  quite a few members have pointed out though, a spark plug is
  pretty basic technology.  Yes I agree  but I also can't count
  the number of times I have had them crap out on a  2 stroke oil
  burning engines.  Prudence would dictate changing them quite
  regularly since it is a critical point of failure or beg Mazda
  to cast us up some two bung leading plug housings.

  Conversely if the trailing plugs fail the engine power only
  reduces about 3% if that.  So with a good leading plug and a
  magneto system,  the engine would continue to operate just fine.
  BSFC will be a little off but we won't get our feet wet and the
  plane can continue on for many many hours.

  OK we can all agree that  a magneto is basic technology and
  very fail-safe.  The magneto fires when a magnet passes by
  coils set 180 degree  (20Bs would need three spaced at 120
  degrees) apart.   These coils could be wound to produce 300
  volts.  Timing can be fixed  for a cruise rpm.

  Now for the plus alpha.  The MSD ignition devices can be
  programed to fire the leading (and trailing) plugs many times
  and at moments when the magneto isn't doing that.   Each MSD
  power pack could  get its signal to prepare for  a firing
  sequence from the magneto or modified coil voltage pulse. Since
  the MSD devices have intelligence they can vary the timing with
  rpms. and other inputs received from sensors or even a
  MEGASQUIRT engine control board.

  The question is,  How do we isolate the MSD power from the
  magneto power because they are both hooked up to the same coil?
  Diodes are the easy answer but I wonder if that is a robust
  solution?  In the scenario above  power unit could be charging
  the leading plug coil.

  A FET switch  might be an answer but the fail safe would have
  to allow the magneto to continue firing the leading plug coil

  FETs on the two MSD outputs to the leading and trailing plugs
  would allow split timing if necessary at the higher rpms.  For
  instance the magneto fires the first burst on the leading plug,
  followed immediately by two stronger pulses from the MSD
  Capacitor while perhaps a third pulse from the MSD is directed
  only to the trailing plug.

  Your thoughts?

  Doug in Japan

  I think you are making a mountain out of a mole hill here Doug.
  A phenomena call sag happens when the plugs get to be about 50
  hours
  old or so. Minor loss of power.

  The solution is put in new plugs on a regular basis. The plugs
  catch
  hell in a rotary as they spark twice as often as a 4 cycle piston
  engine. The same as a two stroke. Now this has been reported with
  inductive type ignition only but as far as I know nobody is using
  a CD
  system in a flying aircraft. CD systems have a proven track record
  of making plugs last longer in piston engines.

  No telling what the CD spark plug life would be in a rotary
  until we
  get some good data. The MSD ignition apparently only fires more
  than
  once up to some RPM which I know not. I have talked to their
  engineers
  about it and they don't seem to understand the rotary so they
  cannot
  give me a good answer. One MSD system per plug would give a lot of
  redundancy.

  We don't have any data running on trailing plugs
  alone for a period of time so it is hard to say what will happen.
  Ignition failures of any kind are rather rare with the possible
  exception of 2nd gen igniter ballast resistors which can be traced
  to continuous high RPM use. The wattage rating of these resistors
  must be increased.

  Tracy also had problems with early Corvette
  coils over heating but I suspect that was caused by excessive
  dwell and the fact they were being triggered twice as often.

  One unknown is the charging coil in an outboard motor may not be
  able to charge more than one capacitor at a time so the outboard
  type ignition system may require two magnets, two capacitors and
  two charging coils per rotor for firing both leading and trailing
  coils. Some experiments need to be made to check and see if this
  is true.

  You will also need outboard type CD coils as RX8 or Corvette
  coils per plug  will not work with CD systems.

  The thing about 2 cycle outboard coils is they are designed
  to run at high RPM and CD systems are actually easier on coils.
  They become mere pulse transformers and not a device to
  store energy. In that case they should be far more reliable

  Paul Lamar

  Hello Paul,

  Attached please find the wiring diagram for a 1977 V4 2 cycle 85
  HP outboard.  I do believe the stator and circuitry is more
  complex than the application we are looking for due in part that
  it is working 4 cylinders instead of two.  If perhaps someone
  had a wiring diagram of a 2 cylinder 2cycle outboard it would be
  even better.

  With regards to the throat diameter of the carbs I was
  considering, I was going to use Tracy's estimate of 1 square
  inch per 50 horsepower.  Is that in the ball park or should I go
  larger?  I have not thought about a P-Port yet as I'm still
  learning and the thought of taking a grinder to the engine is,
  at this point, beyond my ability.



  Regards,
  FranklinHello Paul,

  Attached please find the wiring diagram for a 1977 V4 2 cycle 85
  HP outboard.  I do believe the stator and circuitry is more
  complex than the application we are looking for due in part that
  it is working 4 cylinders instead of two.  If perhaps someone
  had a wiring diagram of a 2 cylinder 2cycle outboard it would be
  even better.

  With regards to the throat diameter of the carbs I was
  considering, I was going to use Tracy's estimate of 1 square
  inch per 50 horsepower.  Is that in the ball park or should I go
  larger?  I have not thought about a P-Port yet as I'm still
  learning and the thought of taking a grinder to the engine is,
  at this point, beyond my ability.


  Regards,
  Franklin


  Nothing was attached Franklin. Try again.

  1 square inch is on the small side for 50 HP. 1 square inch
  is more like 45 HP

  Jeff can do the p-port thing for you.
  jeff.doddridge@gmail.com

  A lot easier than making a manifold however you must
  be willing to disassemble and reassemble your engine.
  Mazdatrix will also build a P-port engine for you with
  Jeff's modified p-port rotor housings.

  Since you are using carbs you won't need the slide throttle.

  Read this. http://www.rotaryeng.net/intake.html

  If you still want to use a side port a lot depends on how
  much room you have under the cowl when building manifolds.
  What kind of airplane are you building?

  Is your engine a 4 port or six port?
  Are you good at tig welding aluminum? Steel welding?
  Steel tubing is the easiest to use as the welding skills
  required are minimal.

  Here is a trick for the transition of round tubing
  to oval intake ports. Don't try to flatten a round
  tube. The area will be much reduced which will seriously
  affect the HP you get. We have been all over this in years
  past. A lot of people have been disappointed in the results
  when building side port manifolds.

  Paul Lamar

  Let me try the attachment again.


  Regards,
  Franklin


  There seems to be enough parts for a two rotor but they
  must be rearranged. I am not sure as there is no picture of
  the flywheel showing the position of the charging coils
  and firing coils. Do you have  a digital camera or a cellphone
  with camera?


  BTW I just found a source for magnets. This is a major
  breakthrough for us.

  http://www.maxrules.com/fixomccdi11.html#MAGNET

  I can now go wild designing a magnet holder which is the key
  to the whole works.

  Paul Lamar

  Attached are pictures of the flywheel from the Johnson.  As you
  can see there are sets of magnets embedded into the flywheel and
  then machined smooth.  There are 6 sets of magnets or 12 magnets
  all together.  I'm not certain but I do believe that the sets
  are opposite in polarity.  I'm fairly certain I read that
  somewhere.

  I'm planning on building an aerocanard and I'm trying to keep it
  as simple as possible.  Don't believe I will be able to do the
  gravity feed fuel system, so I'll have to go redundant on the
  low pressure fuel pumps.

  Franklin Canosa

  Lots of magnets in there. I think I have found a picture of
  what goes with it which I included. Do those look familiar?
  The two light colored coils are the charging coils for the
  CD ignition. The other two are the generator coils.

  The big challenge now is making a light weight holder for all
  those magnets that will fit the e-shaft. Do you have a friend
  with a lathe? You will get an alternator out of the deal.

  Paul Lamar


  Paul,

  Yes those are part of the CD system.  The blue ring device is the
  'spark advance mechanism' that we can probalby do without as you
  suggested we just time the engine to 22 BTDC.  The stator is
  correct and you are correct (I believe) about the different coil
  purposes.

  I don't have direct access to a lathe, but would be willing to
  send down the parts from my old outboard for experimentation
  purposes.  I still have the stator, flywheel, a couple of good
  coils and perhaps even the power pack.  I was going to try and
  sell them on ebay, but I would probably get 10 bucks for the lot,
  and this is a far more fun and useful application of the parts.

  Let me know your thoughts.

  Franklin


  I would like to take a close look at that flywheel.
  Most of the other parts are interchangeably or can be bought
  used or new.

  I would like to put it in a lathe can cut it down
  to drastically cut the weight and then make an aluminum
  hub for it to fit the flange on the e-shaft. The flywheel
  aspects of it are not needed and in fact it is not good
  to add rotational inertia to the front end of the e-shaft.

  This. I think, is the key to making this system practical.

  With the flywheel I have all I need do is drill out
  the rivets to remove the magnets. I can then mount
  them in an aluminum hub.

  Paul Lamar


  Paul it may be simpler than that. Machine the outboard flywheel
  to fit under
  the damper, machine it lite and use as is. a stupid suggestion by
  milo!

  I'll investigate that option shortly. I have one of Tracy's
  dampers sitting right here.

  -------------------------------
  Here is what I have so far. I just had an idea this morning
  on how to make this a bit cheaper and better.

  If I chuck the front hub with
  the bolted on pulley in the lathe I can take an small internal
  cut out out of the steel pulley to insure it is concentric.
  Then press in something that looks like this.
  The groove will be filled with uni carbon to cut
  the rotational inertia and increase the burst strength.
  Important at 7500 RPM.

  Paul Lamar


Paul

"More than one way to skin a cat."  BTW, historically that phrase
was about cat fish not the long felines.

Generators or magnetos coils work in the radial plane like most
alternators and the featured motor boat stators as you have
posted.   Another way to do it is counter sink circular magnets
into an aluminum starter gear or perhaps Tracy's Al. flex plate
and place the coils pointing in the axial axis.   Coils and
magnets can be mounted on either side (or both) the flex plate/
starter gear in a circular pattern.

  However just slapping in a outboard motor stator and coil
components  is no guarantee it will work as the operating design
rpms are quite different and the speed range on the rotary quite
wide.  Output voltage and efficiency varies with rpm so voltages
will be all place.  You may need a DC- DC converter circuit board
to smooth out the voltage.


Doug in Japan


Good idea Doug. Circular or cylindrical magnets are much easier
to buy that is for sure and much easier to implement. Maybe no
cheaper. We are looking at $100 for just four. The cheapest is to
find an old outboard motor and scavenge the magnets out of the
flywheel.

I'll do a dwg using the round magnets.

Voltage variation on the CD ignition system will not be much of a
problem. Outboard motors have to have spark at starting
RPM's too.

You may not get 12 volts at start up but 6000 RPM at cruise
will be no problem.

-------------------------------------------------

To make a magnet carrier out of this will require a new plate
and cutting down the Ford spline flange. The number of
rivets Tracy used is way over kill. My RX8 clutch disk
has only four. The rivet circle diameter will have to be reduced
to make room for the magnets. Round or other wise.

Paul Lamar