Where does the switch go? As long as magnets are spinning past those coils, they'll make electricity. To disable one spark circuit the switch can either open the circuit on the secondary side or it can ground it out. I'm not sure of the ramifications of each option, but if it must be grounded out, and if we are using just one plug, then we still need diodes because otherwise grounding one of the plug wires will ground them both.It may be simpler to just have an either/or ignition system(s). A simple switch and you are either on one or the other. So you are happily flying along and "bummer" the engine quits, so you flip the switch and you are happy again.
If it is okay to ground a high tension lead (i.e, it won't cause any damage), then I was thinking that we could have two diodes in parallel on the main system and two in series on the backup system. In operation, we would fly on the primary system. Two diodes in parallel there assures the juice keeps flowing even if one fails open. The backup system gets checked during runup and then grounded out. The two diodes in series assure the primary circuit doesn't leak to the backup coil or the grounding wire even if one diode on that circuit fails closed.And, using double the diodes only prevents one failure mode, and doubles the chance of the other falure mode.diodes can failed open OR closed.
Agreed. The current GA ignition system is there to mitigate issues not related to reliability, but performance. The huge cylinder volume and presence of lead fuel/fowling is why you need dual ignition. Fixed timing also doesn't help. Ignition reliability was solved decades ago. But the magneto is still here and that's the problem.leave the stock ignition single spark plug system and single fuel system alone ilk.
Maybe there's some sort of shielded relay that would work. Otherwise, running high voltage spark plug wires (3 total for each cylinder) to the cockpit might come with issues. Switch or relay, the contacts will get a pounding as they open and close. It'll need to be up to that.
While I haven't read every post in this thread I've been watching it a bit lately and wondering when someone would point that out. My ignition isn't computer controlled but my Corvair engine does have dual ignition with timing advance and uses a single iridium spark plug per cylinder. Ignition coils are wired into a single coil selector:I think you are getting to the point where the cure is worse than the disease
Aha! Thanks. So, the complexity is there, just hidden under the plastic.This is your diode set-up