whittakrew asked: Any documentation on the tug build? I have been thinking about doing one also
My hand-truck electric tug started out as a rough idea based on a tug someone else made from a shovel. I did a quick preliminary design in CAD and then started shopping for materials. My initial material list had to be modified to accommodate what was available off-the-shelf from Home Depot.
I also made one change to the airplane under a 337 with my mechanic. There is a large washer under the bolt that connects the tailwheel assembly to the leaf spring. That washer was replaced with a small piece of angle iron. The vertical arm of the angle had an extra hole drilled in it to tie the plane down. That avoids getting the tiedown rope or strap smeared with grease from the tailwheel bearing.
The tug uses a ratcheting tiedown strap to pull the tailwheel onto the shelf of the hand-truck. The ratchet of the strap bolts to the tug on a crosspiece near the handle. The strap routes under a round steel tube welded to the lower frame so it pulls the tailwheel straight back. It works pretty darned well. It’s easier if you raise the tailwheel off the ground once it starts onto the shelf. Then the ratcheting strap just pulls the tug under the plane while the tailwheel rotates rather than pulling the whole plane back onto the tug.
The motor, controller, battery pack and throttle all came from the electric scooter world. There is lots of hardware to choose from on sites like:
https://www.monsterscooterparts.com/trsc . My first setup used a 24 volt, 300 Watt motor, but I failed to read the small print. The motor only developed 300 Watts of power at 3,000 rpm. At low rpm, it didn’t have enough torque to move the plane. Well buggers! I figured out the required torque by attaching a pry bar to the tug’s wheels and measuring the torque required to move the plane. 10 foot-pounds was the answer. So, I wound up buying a 48 volt, 1 kW motor to get that amount of torque (it actually provides 13 foot pounds of torque at static rpm). That meant getting a new motor controller and throttle too. All of that came from the recreational electric scooter world.
I posted some pictures of the build process on backcountrypilot.org. Here’s the link if you are interested:
https://backcountrypilot.org/forum/best ... r#p346859
One of these days, I might pull together an “as-built” set of drawings and a material list, but it isn’t a high priority for me.