Universal Electric Airplane Tug

Inceptus wants an easy to use electric airplane tug that works with a wide variety of tire sizes as well as aircraft with wheel pants.

=Problem Definition=

Background Currently, there are no airplane tugs on the market that can tow multiple aircraft with little input from the user or without significant modification with changes in wheel type. As the average age of the general aviation pilot increases, the need for an easy to use powered airplane tug increases. Also, most flight schools have multiple airplane tugs to pull specific airplanes. The goal is to create a solution for this problem by designing an airplane tug that can be used with a wide variety of tire sizes and types including those with wheel pants. Our solution will be easy to use and require very little input from the user.

Specifications
 Tire Sizes 
 * The tug must be able to move aircraft with the following tire sizes:
 * 4.00x4
 * 5.00x6
 * 6.00x6
 * 7.00x6
 * 8.00x6

 Strength Requirements
 * The design shall be able to carry a rolling load of 4000 lbs, up a 2% grade and must be able to handle a static load of 500 lbs.

Mounting/ Interface Requirements
 * The tug shall be able to mount and interact with all different types of wheels, including wheels with pants.

=Project Learning=

Pallet Jack
The client wants a system that can be used as a prosthetic on the pallet jack shown below. The pallet jack is electric and can supply power to any electrical systems that might be used on the final design.

Linear Actuator
All of the ideas above use a linear actuator to capture an aircraft wheel. The linear actuator must have a stroke length of at least 10 inches. This could run off the power supply of the pallet jack. The pros of using a linear actuator are it is light weight, small in size, and has a long stroke length. The cons of using a linear actuator are they are expensive, needs power, and requires a control system.

Using 8020
The client suggested the use of 8020 to build the final design. Also, 8020 is modular and would allow rapid prototyping at a low cost, and there is large amount of scrap 8020 in the University of Idaho machine shop that can be used for free.

=Final Design= We combined the best parts of all three design ideas to make our final design. The design is meant to be a prosthetic attachment for an electric pallet jack that our client has given to us. The biggest problem we encountered was how to close and open the gate with little to no user input. The images below shows how the mechanism captures wheels, how the gate works, and how the clamp works.

Manufacturing
The majority of the parts were laser cut, and we used a slot and key design to simplify the manufacturing process. This design eliminates guess work and allows everything to be aligned properly. Also, we designed it so we only had to machine one part. To save money, we made custom linear sliders out of steel square tube. We purchased UHMW sliders and mounted them to the square tubing. We also made mounts for the latch and hinge out of steel square tube.

Validation
In testing we found that it picks up aircraft with tail wheels with ease. We tested it with an aircraft with wheel pants and found that it works with no problems. Also, we found that the UHMW rollers work as predicted. When the wheel starts to get pinched the wheel starts to roll onto the rollers. One other thing we found out in testing was, if the aircraft as flat tire our product will not work very well, because it pinches the tire instead of lifting it. =Team Members=

=Additional Documentation=

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