More work toward a motor-Goat

A test assembly outdoors was necessary to get the thrust angle to match with what I picked for the starting visual.  I suspect that some thrust-line changes will be needed based on cruise attitude and the pitch coupling (noting the Romanian Goat said it took a lot of up elevator in this mount location), but for now I simply set it parallel with the bottom of the wing and match-drilled.

Mounting the battery is the next major task.  With 25ft of 8AWG wire tripled over for an ~8ft extension, I was able to reach from the motor, down the nose tube, back along the nose side rail, to beside the seat.  Like most others, I'll mount the battery beside the seat.  Instead of mounting to the struts, I decided to extend the seat tubes to make a little shelf of sorts. It did take removing the seat and destroying a couple torque seal marks to get it all, but that was a fun afternoon.

Seat off!  You can also see the final structural mounting for the motor and see the wiring runs.

New little shelf.  In retrospect, I should have put it on the left side so my right hand can stay on the stick, but maybe next version.

And here's the first mock-up of the battery tray.  The ESC is going here also.

Let's talk a bit about the battery tray.  I watched several videos about the e-help and related DIY systems (this one was particularly useful) to decide a rough plan was to make a u-shaped tray with Velcro loops to secure the batteries.  The other major decision was to place the ESC directly on the battery tray.  The battery to ESC leads apparently need to be short due to inductance issues, and let the three phase AC lines be the long runs (EMI and start-up routine are potential issues).  

I ended up making a small aluminum bracket to hold the ESC.  This was the first time I bent up a complicated sheet metal bracket, and it went pretty well.

 

Here's how the ESC is held in its bracket.  It will be riveted (or bolted) to the bottom of the battery tray.  There is lots of metal surface area to help with heat transfer.

The battery tray itself was fabricated in a similar manner, bent from sheet metal.  The cylindrical bosses are handles.

And here are the batteries and a watt-meter (this model) mounted in the tray.  I still need to put slots for the Velcro straps to hold the batteries in place.  There will also be a couple switches in the panel for ESC arming and the throttle power.

The last major component to solve is/was the throttle actuator.  For this ESC, I need a PWM signal going from 1.0 to 2.0ms and bringing its own power (the ESC is opto-isolated).  The awkward part to me was that no small servo driver had a convenient remote-mount potentiometer.  I ended up buying a $7 servo driver, de-soldering the rotary potentiometer, and remote-mounting it in a custom 3D printed mount that will fit in the end of the control stick.  I stuffed the servo driver inside the same 3D printed mount, so I only need to run it power and get back the PWM signal.

Here's the final servo driver and remote potentiometer arrangement.

The bracket fits inside the control stick tube (ignore the holes --- same size tube from the scrap bin!).

That's all for now.  I'm still working on tidying up the wiring for the panel and then will need another beautiful spring day for a test re-assembly and run in the back yard.  Stand by for more...