Creamy, are you sure you chose the right profession?
The Bosch Automotive Handbook (Robert Bosch invented the magneto / spark plug system) says you need about 12,000 volts for a spark, but most ignition systems deliver about 30,000 volts.
It goes into some detail about the energy of the spark (0,2MJ is required) and the voltage profile. It seems modern systems need a sharp defined initial spark for what they call "flashover" followed by a continued lower voltage spark which "helps stabilise combustion".
It reminds us that the spark intensity required varies with A/F mixture, BMEP (ie turbocharging) and spark timing.
The debate on plug gaps also reminds me that a spark initiates more easily from a sharp edge. In the olden days (when we re-gapped automotive plugs rather than throwing them out and replacing them) part of the procedure was to file the centre and outside electrodes to get square edges again. This is impracticable with massive electrode aircraft plugs.