We wanted the trailer to be fast so I used road bike wheels because they are thin and narrow with minimal rolling and wind resistance. We dropped the frame down to lower the center of gravity so it would not easily tip. The frame is four inches below the center line of the wheels. The battery is dropped another 4 inches in a plastic bin so that the heaviest part of the trailer is only about six inches above the ground. The trailer worked well throughout the whole trip. We originally suspended the battery with bungees in the bin of the trailer to give it cushioning, but after further research we decided it was better to mount the battery rigidly so we secured it to a makeshift aluminum frame. The solar panels were each four pounds (20 pounds total). I wanted to be able to tilt the frames East, West, and South toward the sun so that we would get the maximum energy possible. To do this, I built interchangeable bars to raise the front, back, or sides up or down.

 

 

 

 

 

 

 

 

 

 

 

 

 

We used aluminum for the frame because it is lightweight and relatively strong.  For the center of the frame holding the most weight I used square aluminum tubes with 1 inch diameter, wooden dowels inserted through them to add strength and prevent the bars from flexing. The aluminum bars are from Home Depot and direct from an aluminum manufacturer.  I used aluminum L bars to provide strength in both directions for the rest of the frame because these are lighter and easier to work with than square tubes.  . The L bars are stiffer  than flat bars. The frame is made with rectangles and crossbars. The trailer is overall lightweight and tows straight. We considered welding parts together which would have been lighter and stronger but instead used nuts, bolts, and lock washers because of time constraints. There are over 250 bolts holding the trailer together.