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

 --

 Paul,

 I appreciate the circuit diagram. Thanks for posting it.
 Instead of another triggering coil weren't you considering using
 a hall sensor circuit?

 I personally wouldn't mess with trying to make an alternator and
 just concentrate on two [ignition-charging] coils. Alternators
 are cheap and well tested with high regulated amps in a small
 package.


 Doug in Japan

 I tend to agree with you Doug on that. In fact one might
 spend less money just using an alternator.

 I just weighed Tracy's damper plate and was shocked to find it
 weighs 5 pounds. Here are some places to machine to save a pound.

 I also placed 4 round 1.5 inch magnets but I don't think it is
 practical to install the charging coils here without a major
 redesign of Tracy damper plate. Just not enough space
 between the damper plate and the PSRU adapter plate for both
 magnet and charging coil. Perhaps with large 2 inch dia. holes in
 Tracy's PSRU adapter plate that the coils could poke through.

 Paul Lamar

                        
Paul The part of Tracy uses is from Ford and i have one  which you can keep the front drum to secure your magnet and cut the rear part by using the outer surface of the drum to secure with rivets the same way Tracy did it.
The drum thickness is very low beside the facing rib .
I am sending you a photo it might help you on your project

Jean Prudhomme

Hey Jean thanks a bunch. I was wondering where that part came
from.

BTW I am thinking of setting up a high speed DC electric motor in the lab to test these ideas.


Paul Lamar