Just curious if you've made any further progress. I'm really interested in seeing this suceed.

I didn't get to the starter today but now have the transmission, idler and brake under servo control https://plus.google.com/+RobShearerCA/posts/jGTyWEZDVjZ. Will be waiting a few more weeks for the high torque steering servo.

hope to get the starter wired up tomorrow. Im testing things with a cheap ebay apm as i dont yet have a receiver compatible with the navio board. On the apm i think theres a dedicated relay pin (A9) plus you can assign other pins as relays in the full parameter list. So ill use A9 to trigger a 12v relay that will in turn trigger the solenoid to engage the starter.

This looks really cool!

Any plans to control the starter and the ignition through relays and through APM? With the engine I'm using for #Goliath - A Gas Powered Quadcopter I've got a relay board that's hardwired to a remote. I haven't done the work yet to integrate the control of those two items into the Pixhawk or the Firmware, so I'm really curious how you're going to handle it.

It's probably a good choice to use a single servo for throttle and choke. I looked at your picture of the throttle plate with the servo attached. I had removed the throttle plate on Goliath because it was heavy and I wanted to disconnect the governor. However it required adding a separate servo for the choke since the linkages were gone.

Good luck on the rest of the project, I'm looking forward to seeing how it comes together!