Saturday, February 6, 2021

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

1 comment:

Kevin Kat said...

Hello. It’s been awhile since I’ve commented. Glad to see you are moving to completion with your goat project:). You’ve really done a fantastic job. I’ve also thought about powering my goat. I’m in the later stages of my build as well. Yesterday and today, I worked on gap seals for the elevator and the rudder. I pre-shrunk some Dacron sail cloth for that. For the Ailerons and flaps, I thought of using Blenderm. It’s a surgical tape. I heard about it while on a build forum for the EMG-6 motor glider. Apparently it works really well. I thought I’d give it a try. Finding a place to do some flight testing may pose a challenge for myself also. I’ve got plenty of work to do before I get to that point though.

I really like your check list style approach to building. You inspired me to create check lists for my own build as well. I really enjoy your build blog, and love your powered solution for the goat. I noticed you called it a sustainer motor. Have you done any math to see if you could take off with the power generated from the motor? Or is it only possible to sustain flight to avoid a land out? Honestly, I have so many questions about the motor option. If the motor truly is just a sustainer, will the prop be locked in position while the motor is not being used? Or will it windmill, and if so what effect will that have in drag on the goat? I’m sure you will answer some or all of these questions in future posts, and I really look forward to reading about your experiences with it! Again I want to congratulate you on a job well done, I know your not quite finished, but the finish line for building is very near:). One last question, what are your thoughts about radios? Personally, I have a Vertex VXA-710 someone donated to me to listen to the aviation band, and possibly even make traffic calls if and when necessary, but making any calls to your ground crew on an air band frequency is illegal. I think HG pilots that need to communicate to a ground use ham radio frequencies. I’ve thought of taking the ham radio test to get legal, and buying 2 or three affordable hand helds that allow for a head set to be worn while flying. What are your thoughts and ideas?

Kevin Kat

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