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PC680-powered RV-6 dragger/tug

JordanGrant

Well Known Member
Hello RVers. For years, I've wanted to build an electric RV-6 tug to drag our airplane up the gentle slope into the hangar. I've thought that maybe a retired Odyssey PC680 battery could have enough juice to do the job for an airplane the size of an RV-6, but I wasn't sure. Well, I'm happy to report that it can be done! See below for my version of the battery powered RV tug.

oqI.jpg


I used this project as my excuse to finally go buy a MIG welder. It's built from welded mild steel: 1" square tubing, 1x1" angle, 1/4" plate, and 16ga sheet for the battery tray. The motors are electric power chair motors sourced from Ebay. The other key bits are a reversible motor controller (basically 2 relays), an ammeter/power display, on/off switch, and DPDT momentary rocker switch for forward/back control.

To make a secure connection between the tug and the airplane, I put a longer axle bolt through the tailwheel with a couple of 1/2" OD bushings on the outside of the tailwheeel mount. You can see in the picture how the slots in the tug connect up to the tailwheel on the bushings. It has been quite secure with this method so far.

oqM.jpg


For anyone building something like this in the future, one key thing I had to do was robust up the electrics to handle the amperage required to pull the airplane this way. The installed ammeter reads a bit over 70A being pulled by the motors (at the worst point), and my wiring/fuse is designed to carry up to 80A. So plan on designing for at least that level of current.

Just like the airplane, this project is a work in progress. I consider this about Version 4 of the prototype, but the first one that really works well enough that I can share it! I have a few more improvements in mind if I get some time to work on it further.

On this version, so far the limiting factor is mostly just the traction on the wheels. My 7-yr-old son can pull the airplane up the grade into the hangar with it, although he has barely enough weight to push the handle down and make sure the wheels don't slip. I have a great video that I'll try to post later.

Cheers!
 
Very nice...I've been agonizing over whether to get a MIG welder too...these kind of projects make me want to order one now. Did you teach yourself how to weld or take a class. The welds look nice from the photos
 
Hey, That looks superb!
I have been looking into this as well. Can you share what type / Model Motors you are using? how do you control motor speed?
 
The welds are NOT nice, but low res pics, a grinder and paint cover all manner of sins. They are functional, though. I'm self and YouTube-taught, only. I wish I had a chance to do a class!
 
I used "Jazzy Power Chair" geared electric motors. This is the link to the Ebay ad for them: https://www.ebay.com/itm/223399560043

They are available all over Ebay and prices vary, but I got these (with wheels) for $100. They are nominally 24V motors, but obviously I'm driving them at 12V. That results in a moderate speed without any regulation. For simplicity and cost savings sake, I elected not to do any speed control, and it works out since I'm using 12V. They move at a brisk walk with no load, and then they go pretty slowly when they are under load pulling the plane. Still, it would be nice to have speed control, so that's one of the things I'd like to improve on.
 
Very nice...I've been agonizing over whether to get a MIG welder too...these kind of projects make me want to order one now. Did you teach yourself how to weld or take a class. The welds look nice from the photos

Don't agonize, just get one. And spend a little more to get a decent one. The cheap flux core models are will stick something together, but if you really want to weld something you'll want one with a CO2 bottle and some moderate amperage.

I have a Mig and a Tig, and unless I'm welding an actual airplane part I use the Mig. Great for making fixtures and tools, projects like this tug, or general household repairs. At first I only had a Tig and while theoretically it will do everything a Mig will it's a little slow and cumbersome. I was amazed how much I used the Mig once I bought it.

It's pretty easy to learn. Spend the money for a good helmet as seeing what you are doing is imperative.

DEM
 
This really hits me at the right time. I am recovering from a leg injury and have been wondering how to move the rocket around. I have quite a few ?old? Odessey batteries around the farm still doing useful jobs and this looks like a great project!
Thank you for posting this idea
 
Sure wish I had a set of plans for this.

Hey.....we build airplanes.....we should be able to figure this out from a couple of photos....give creativity a chance to run free. :D

Nice tug, and yes, a MIG (with gas bottle) is a great tool for the shop. :)
 
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Very nicely done. I am curious if the wheelchair gearboxes and motors could provide enough torque for a much heavier airplane. I have been contemplating building something similar to move the Comanche 260B I just bought.
 
The other option used is a used garden tractor/riding lawn mower, work very well and watching garage sales/ local adds can usually be $100-150
 
Bob - if you do a search through posts here by Troy Branch you'll see he posted a link to his homemade tug, built to move his RV10. It's a similar concept but of course intended for a nose dragger airplane. His design works well, including offering variable speed control.

Personally, I opted to go very heavy duty and purchased an AeroTow tug very similar to the current GetJet model. It's old as the hills but built like an absolute tank. It was intended to move airplanes up to about 8000lbs and looks overbuilt even for that purpose. I love the idea that it gets the nose wheel off the ground, using the weight on the nose wheel to help provide additional traction.
 
Sure wish I had a set of plans for this.

I've considered trying to write a submission for Kitplanes. Even if I don't do that, I'll try to write down some of the key things once I reach a final configuration, to make it easy to replicate (i.e. dimensions, angles, part sources). As was mentioned, the MIG welder (with gas) makes the structural stuff pretty easy to make.
 
Do you lift the tailwheel off the ground while moving, or does it just pull the tail along with the wheel running on the ground?
 
Do you lift the tailwheel off the ground while moving, or does it just pull the tail along with the wheel running on the ground?

It works either way, actually. It's easier to turn/steer the tug with the tailwheel up, and lifting the tail puts all the weight on the tug wheels, which helps with traction (on a smooth hangar floor, the tug wheel can spin unless you load them up).
 
Tug attachment

Loved the tug pushing the Citabria
How does it attach to the tailwheel?
Would it work on rv-a model?
Any more pictures?
 
Wiring in the relays for forward and reverse

I am planning on building one of these while I?m on lockdown and wasn?t sure how to wire in the relays. This is a good wiring instructional video in case anyone else is interested. I got two 80 amp relays from amazon.

https://youtu.be/xpFzAtG3OzE
 
Loved the tug pushing the Citabria
How does it attach to the tailwheel?
Would it work on rv-a model?
Any more pictures?

Attaching the tug to the airplane was a challenge. At first, I tried some methods that slid under the tailwheel and had it just kind of scoop it up. That didn't work well - the wheel wanted to slip out and fall down. If you look close at the pictures, you can see I cut a couple of notches in the "fork" of the tug. Those marry up to the 1/2" Outer Diameter bushings I put on the tailwheel axle bolt (I used an extra long axle bolt). With some slightly oversized washers outboard of those bushings, the fork can easily hook into the tailwheel axle and securely lift it up.

Unfortunately, I doubt that method works with a nose wheel. You would have to find some creative way to make a similar method work with the A-models. This is the advantage and disadvantage of rolling your own tug. The commercial tugs have generic designs that work with lots of different types, but that means they are over-designed (and over-expensive) for a smaller airplane like the RV-6. But, conversely, my design really only works with my airplane, because I had to do a small modification to the aircraft.

Good luck!
 
Best Tug A2 starts at $2995. Just buy one of those. Mike Patey needs the money to build a new Draco II. :D

I had a light (heavy twin) I use to pull slightly up hill into my hanger. I put an electric wench on the back wall and pulled it in while I steered with the tow bar. Once straight it did not need steering.

I still can push an RV4/6/7/8 in most hangers. If I can't do that anymore I am going to get a fit 23 yr old girlfriend to help me ... :D (although a tug would be cheaper).
 
Electric Wench??

Sounds like Elon Musk was inspired while watching Blade Runner.
 
Very nicely done. I am curious if the wheelchair gearboxes and motors could provide enough torque for a much heavier airplane. I have been contemplating building something similar to move the Comanche 260B I just bought.

Have you seen some of the people the scooters are lugging around town?? A well built RV pales in comparison...
 
This post inspired me to build my own PC680 powered tug. I have an incline in front of my hangar that makes it a bit difficult to push my RV-7A up and into the hangar.

This is my second and final rendition of my tug. I ended up using the after market fork assembly from MiniMax tugs. This gave a nice solid hook up to my nose wheel

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I used a Sabertooth dual 60A motor driver (https://www.dimensionengineering.com/products/sabertooth2x60) This is an impressive speed controller that provides a lot of configuration option. Here is a picture of my tug control center.

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A shot from the front, with LED headlamp on. At some point I will get around to building a cover for the electronics

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