Aircraft Tug

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For small aircraft, a towbar is sufficient, but for larger aircraft a power assisted tug is necessary for moving the aircraft. Commercially available aircraft tugs are considerably expensive, so many people use small tractors or golf carts to pull their aircraft.For this project I wanted to see if I could build a remote controlled aircraft tug for a reasonable price.

The goal was to design a remotely controlled tug capable of pulling a Cessna 310 with an estimated weight of 5,200 lbs while keep the cost under $1,000.

Code for the project can be found on my github.
Arduino Code: https://github.com/AnthonyDipilato/AircraftTugArduino
iOS Code: https://github.com/AnthonyDipilato/AircraftTugIOS

Warning: This project involves heavy machinery with moving parts. I will not be held responsible for damages and/or injuries resulting from reproducing this project.

For the initial design I decided on two 2 13″ wheels directly driven by a pair of powered wheelchair motors. To hitch up to the plane it would use a platform with a ramp that lifts to lock the it into place.

I drew a mock up in Fusion 360 to give me guide for the dimensions of the frame.

The frame was welded using 1″ square tubing.

   
Electronics:

 

I 3D printed a panel to mount the electronics and included cooling fans for the motor drivers.

The panel was mounted using 3D printed L-brackets. I originally printed brackets to hold the batteries in place but replaced them welded steel angle to keep them more secure.

    

Testing the connection from an iPhone to the tug.

 

The first test was a failure. It did not have enough torque with the 13″ wheels to move the plane.

I decided to switch to a track design so I could increase the torque by using a small sprocket to drive the tracks. I drew a mockup in Fusion 360.

For the tracks, I used Rexnord 814036219 4-1/2″ tabletop chain.

   

To adjust tension on the track, I used a treaded rod attached to the idle pulley bracket.

    

Tracks test.

Test #2 also failed. The single row of rollers allowed the chain to twist and come off the sprockets.

I added a second row of rollers to keep the track in line. For better traction, I glued 1/4″ 60A neoprene to the track using contact cement.

                   

For the wheel hitch, the plane’s wheel pushes down the horizontal bar which lifts the ramp. The ramp is then locked in place by a pair of electromagnets.

 

Example of the ramp lifting on the wheel hitch.

Example the wheel hitch working using a wheel.

Example of the wheel hitch locking into place with the magnets.

Test #3 was a partial success. It was able to pull the plane but the Axles for the idle sprockets ended up bending.

I reinforced the idle sprocket axles and replaced the 15 tooth drive sprockets with 11 tooth to increase the torque.

Test #4 was a partial success. The additional strain on the rollers during the turn caused the roller axles to bend.

I replaced the roller axles and welded a length of tubing along the outside to reinforce them.

Test #5 was a success.