Motor mounting comparison to other eGoats

I've decided not to mount the motor in this traditional location behind the seat.  That location is closer to the CG, so it makes sense for very heavy engines to have a smaller impact on balance.  That location is also large enough to eat a reasonably sized propeller (~49in).  But, it is almost entirely shielded by the pilot's body, meaning there is a lot of turbulence that the propeller has to eat.

Here's the Lima Goat (Pelican) with the typical motor mount location.  From what I can find, this setup is ~20kg according to Alex Ferrer in a YouTube comment (6.4kg motor Freer 202/80 27, 1.9kg KBL ESC 72V-144V/400A, 6.68kg six CNHL 6S 8.0Ah =1kWh, ~2kg wood prop 49x30in == ~30kg thrust, ~6min WOT or 10min sustain for 170kg TOW)

Instead, I'm going out front on a post ahead of the forward nose tube.  This is a traditional location for human powered aircraft (e.g. MIT's Daedalus), and the Romanian Goat was the first Goat that I've seen to do it.  It puts the prop in the cleanest air possible, allowing getting the most out of the propeller efficiency (prop selection matters too, but so is getting the most from that installation by putting it in clean air).  A typical downside is the forward location doesn't match well with heavy internal combustion engines without a long driveshaft.  Even human-powered aircraft usually have a long driveshaft arrangement to make it work.  For me, I went for a minimally sized motor, so the balance works out just fine, and I really need to maximize the propeller efficiency.

Here's the Romanian Goat with the forward motor mount.  From what I can find, this setup is 28kg (4.44kWh battery, 20kW motor (2350rpm, 78kg thrust), 1.3m Helix 3-bladed prop, 45min runtime).

Here's the first mock-up of my selected mount location.  The motor is mounted on its tube (yes, the prop is on backwards) and clamped very roughly in the right place.  I'm planning to pin the mount to the nose tube and support it up from the nose tube roughly parallel to the prop.  If it does not feel sturdy enough, I can add guy wires from near the motor to the leading edge of the wing, which should be more than sturdy enough.

Key weights so far come to 9.3kg (2.5kg motor, 0.4kg ESC, 3.2kg for four 6S 5Ah = 0.4kWh).

What about a motor?

I visited the two local (hour and forty-five minute) grass strips to the West that almost certainly will not allow a car to drive on the runway.  So, what's plan B?

I found two local paved runways (about an hour and a half away) to the East that are in Class G airspace and look to be very low traffic.  Assuming I can't get a car on those either, what's about some power, cap'n?

Came across the E-Help Student system on YouTube, built for ground launches of a hang glider.  With the similar wing loading of the Goat to an old hang-glider, this seems like it'll be just about right to be a sustainer.

Cue some pictures...

Mounting the Rotomax 150cc motor to a 2in tube took some sheet metal brackets.  Not much sheet metal work on a typical Goat, so went out to buy a small sheet metal bender from Harbor Freight to bend these two.

The wiring harness was not the most glamorous task, and I'm still going back to look at the XT90 connectors once I take some measurements of the current during ground runs.

First test runs were literally on the bench in pusher mode.  The ESC needs some settings tweaks for softer start, and the brake needs to be on, but she does spin.

Next is figuring exactly how to mount the motor.  The two main options are behind the seat, like most powered Goats, or on a post ahead of the seat forward of the wing leading edge.  That'll be tomorrow's game before the big game and snow.

Other to-do's:

• Gap seals for the control surfaces
• Trailer tags (paperwork in the mail for the fourth time)
• Carrier cradles for on the trailer (started)
• Line and release system for auto-launch