On 05/18/2011 06:24 PM, Ed Anderson wrote:

One thing my precepitions  is that your are starting to get close to violating  the old Keep it Simple Stupid principle.  The more components, the more redundancy, the more things that could go wrong with the systems and there perhaps unintended interaction.  Not saying there should not be any redundancy - that is why I fly with the EC  after my HALTECH system went belly up (fortunately on the ground).  But, you gotta know where to draw the line.

 

  Another factor is that unless these systems are automatic, you will find your time (and attention span) somewhat limited when things start to go wrong (don't ask me how I know).

 

Component count is important, but system interaction is where the complexity really comes from.  Compartmentalized pieces with simple interfaces is my approach to driving out the complexity demons.  I have two ignition controllers that both run under the guidance of the ECU.  Sounds complex, but there are only two signals to worry about.  One is the EDIS talking to the MS.  The other is the MS talking to the EDIS.  If the communication breaks down, the EDIS automatically run independently.  One has it's own power source to make it more redundant, much like a magneto.  Just a dedicated, bone simple, 70W PM generator.  Because of the way the VRs are mounted, I can depend on the battle hardened electronics to drive a pulse that may not occur at the most optimum advance, but at least close enough to keep the engine going.

The fuel backup is just a line with a control valve.  Doesn't get much more primitive than that.