Wiring this airplane will involve a lot of learning. I'm hoping that acknowledging ignorance will protect me in this part of the project. And maybe I'll come away with a better understanding - the FAA says I'm allowed to do build an airplane for research and education. Here's hoping some education happens. Reliability is darn important. The A3B6D has two mags mounted on one shaft - it has only a little more reliability than a single mag system. I used this engine (on a BD-4) with that mag + a first generation electronic ignition system made by Light Speed Engineering (Klaus Savier). For the Cozy I plan dual EI and the more modern SDS system - weight savings, more powerful spark, said to be more durable, etc.. Dual EI means that if I lose electricity I lose spark, and I'm guessing the Cozy is a poor glider. Therefore, this all-electric airplane needs a fault tolerant electrical design. Like most builders, I stand on the shoulders of Bob Nuckolls - 50+ years of designing electrical systems for aircraft and probably 30 years of sharing the information through the AeroElectric Connection (first a book and then a forum). Bob recently refreshed his schematic for all electric aircraft - the "Z101" using dual alternators and a single battery. See the drawing below. It is his most recommended design and my starting point. Continuing the homage to Bob K., a snippet from his "getting Started" (in full at http://www.aeroelectric.com/articles/Getting_Started.pdf): __________________________ RULE 9A: A single point ground system shall be established behind the instrument panel with sufficient attach points for all accessories in the cockpit area. In deference to RULE 2, a forest-of-fast-on-tabs ground block similar to . . . http://www.aeroelectric.com/Pictures/Grounding/gnd_bus.jpg The threaded stud on the ground block assembly would penetrate the firewall and be used to terminate battery (-) leads on either side of firewall and the crankcase ground strap on the engine side of the firewall. In the case of canard pushers with the battery up front, the ground bus would be mounted forward of the instrument panel. If the airplane's firewall is metallic, then a brass bolt and appropriate washers and nuts would be used to provide an engine compartment ground stud and connection of the ground lead to the firewall. A ground strap like . . .http://aeroelectric.com/Pictures/Wiring_Technique/bbs.jpg or http://www.aeroelectric.com/Pictures/Wiring_Technique/sbl.jpg . . . will be used to connect the crankcase to the firewall ground stud. The welding cable illustrated in the photo would also be used to make the short, VERY flexible jumpers from battery (+) and (-) terminals. Any ground straps provided around the rubber biscuits of an engine mount will be removed. Engine mounts are for holding engines on airplanes and not use for any part of the electrical system. ------------------------------------------------------- RULE 9B: Avionics and other electrowhizzies on the panel would benefit from an “avionics/panel ground bus” as described in the latest revision of the ‘Connection. See: http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf and . . . http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf and illustrated in . . . http://aeroelectric.com/Pictures/Grounding/AGB_V.jpg http://aeroelectric.com/Pictures/Grounding/AVG_RA.jpg http://aeroelectric.com/Pictures/Grounding/Avionics_Bus_3.jpg http://aeroelectric.com/Pictures/Wiring_Technique/Avionics_Ground_3.jpg -------------------------------------------------- RULE 10: Tefzel wire used throughout with the exception of cranking circuit fat wires where 4AWG or 2AWG welding cable would be used. An alternative FAT wire could be one of the new copper-clad aluminum wires. These new materials are as solderable and crimpable as pure copper conductors. _______________________________________________________ In the next entry I will repeat the electric system build log created by Chad Robinson - he's a skilled engineer and his work deserves consideration. Also, it may help me identify circuits in the tangle of wires I see in the cockpit!