Postby Tony Collins 1073 » August 23rd, 2010, 7:58 pm
It is a coincidence that you suggest motorbike coils Chris. That is exactly what I use on the Weslakes with my ignition system. I prepared and sold two Weslakes for Ludwic Faber and his friend Geunter For their two 1/2 scale Sopwiths [ camels? ] That was in 1999 and they are still flying the same two aircraft at shows. Same engines, same ignition systems. No failures. Why? because they like most Germans, they followed my instructions to the letter and didn't think that they knew better like a couple of fellows I could name.
My well known "Grosse Stik" uses an identical module, just a smaller ignition coil. That has now been flying for nearly thirteen years. Same system. And like the Weslakes, no screened leads. Thats inductive discahrge ignition for you.
A lot of failures are with the hall sensor which sends the signal to the module. This can occur especially with a freshly charged battery which hasn't had time to settle to its normal voltage.
The small high voltage coils in the more commonly used CD ignition systems Do have physical size against them, and if the spark is initiated without a spark plug in the lead, or if there is an open circuit HT lead this can cause an internal arc across the the windings cause carbonising and failure in some cases.