While working on the EDIS logic diagram, it occurred to me that the duty
   cycle on the coils might be too high for use with the rotary engine. My
   reasoning is as follows. A 4 cyl, 4 stroke engine has one ignition event
   per rev. Auto engines seldom stay at max torque or HP for very long. I
   don't know what RPM that would be in one of the engines the Ford EDIS
   coils were intended for, but I suppose it would be in the 3,000 to 4,000
   range. This would equate to 3,000 to 4,000 spark events per minute. I
   expect most of these engines would operate at 2,500 RPM or so most of
   the time, except in city driving. I think this results in a relatively
   low duty cycle. Doc


Doc, you dont seem very well informed on this issue.
a 4 cyl 4 stroke would have 2 sparks per rotation (2 cyls on power
cycle), usually both from the same coil.  Typical engine duty being 3000
RPM, peak being 6000 giving a typical duty of 6000-12000 SPM (sparks per
minute per coil) in a typical 4-cyl.

The rotary has 2 sparks per rotor per rotation of the e-shaft, but each
spark plug has its own coil so it is one spark per rotation of the
e-shaft for each coil.  Making our aircraft duty 5000-7000 SPM.  Well
withing range.

I am not sure, but I think the vette uses 2 coils for its 8 cyl.
Usually the rev.limiter tops out at 6500 (I think) but a lot of guys
have the computer re-programmed and regularly red-line at significantly
higher (like 7500 for a stock engine often higher than that).

That would be 8 cyl divided by 2 coils, divided by 2 for being a
4-stroke piston is again 2 sparks per coil per rev.  That yields duty
cycles of 2000-15,000 SPM.

Perhaps the vette uses 4 coils (meaning coil duty of 1000-7500 SPM), but
that would still put our duty cycle just under peak duty for the vette,
which seems to work out OK.  No major probs with coils in flying aircraft.