Why Two Mags?
I was going to put this in Tech Log but feel the answer is to be found in history.
The modern day FARs require two mags for redundancy, but I have vague memories of reading that two mags were originally the answer to extracting more power out of the big bore aero engines. Using a single spark plug the problem lay in the speed of the flame front not achieving full combustion of the charge in the required amount of time. Redundancy was merely a useful byproduct of the arrangement. Of course the two plugs needed to be on opposite sides of the head to achieve the desired effect of speeding up the combustion process.
Any thoughts? Be interested in any documentation that may illuminate.
Interestingly the DB601 had the two plugs on the same side of the head and allied analysis thought a power loss in the region of 10% was the result (don't quote me as I am on the road at the moment and the exact details are home on the library shelf).