klehman(at)albedo.net Guest
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Posted: Sun Sep 23, 2007 5:40 am Post subject: AeroElectric-List:Dual ignition |
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Most OBAM aviation installs are somewhat custom with unique wiring or a
unique environment for the electronics. Therefore the reliablility
demonstrated by similar installations (or in an automobile) is probably
not applicable. And my observation is that when stressed electronic
components quit, they are more likely to do so without warning whereas a
mag might degrade slowly. So even though I don't normally run my dual
ignitions (single spark plug) simultaneously anymore, I take comfort in
having it available every time I learn of another related auto
conversion deadstick landing by someone. I have had cranksensor and
coil failures on my road vehicles.
One spark plug does not bother me at all, but if two were available it
would simplify a dual ignition setup that otherwise uses high voltage
coil joiner diodes. Dual ignition is rather pointless to me if a
single component failure (shorted ignition coil) can take out both
systems. Coil joiners may not totally eliminate that risk but the
racing circles have proven that they can dramatically reduce it.
My memory is also trying to tell me that a few road vehicles resorted to
dual plugs for emissions purposes. Can't really remember but it might
have been for low power situations to reduce the risk of misfire and get
quicker flame propagation. My current car engines misfire surprisingly
often at idle power but the CAT converter keeps the emissions police
happy nowadays.
Dual plugs for large bore engines might reduce the need for igniton
advance but I'll leave that discussion for others...
Ken
Peter Pengilly wrote:
[quote]
Probably because the average mag is horribly unreliable - so two
completely independent ignition systems are fitted to make sure you keep
cool. Now ignition systems are potentially much more reliable, however
dual ignition is still seen as "aviation standard".
Peter
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