A plane’s efficiently is directly related to the aspect ratio of the wing. This is because a long thin wing has very little induced drag, or the drag produced from the creation of lift.

MK2 was initially designed around the 2 cell wide wing, to maximize wing surface area for solar cells at a reasonable aspect ratio. However this calls into question whether a 1 cell wide wing, a wing with a higher aspect ratio, would be significantly more efficient. In order to keep the same number of cells on a 1 cell wing, the wingspan needs to increase to 13 feet. For the sake of time, I am using the same fuselage and 2 cell center wing section, and are building new 1 cell wing tips that fit into the existing spar.

Immediately upon launching the plane, it required full throttle to stay in the air and was not gaining altitude well. The wings were also bending significantly under the additional leverage. This was anticipated, but I still was surprised at how floppy the whole aircraft flew.

	MK2	MK2 High Aspect Ratio
Mean Cruise Wattage	74.02 W	104.03 W
Wing Aspect Ratio	8.7	19.7

Overall the longer wing was much less efficient and flew substantially worse. This indicates that there are many more important factors in the efficiency of an airplane than its aspect ratio. Therefore I decided to stick with the 2 cell wing, which had been flying with pretty much no issue. The only situation why I would switch to this longer wing would be if it was substantially more efficient. It may be beneficial to explore a combination of the two, with a shorter 1 cell section at the end of the wings, or possibly just extending the 2 cell wing to be longer. Regardless any extension of the wing will require a second carbon spar to prevent wing flex.

My best guess on why this wing was less efficient was the design of the leading edge. I initially designed the leading edge the same way is with the 2 cell wing, but shortened it to save weight and to make the chord slightly smaller.

It is possible that the relatively blunt leading edge was creating a vortex on the top of the wing, increasing the stall speed dramatically and kind of artificially increasing the wing thickness. However, this is just a guess based on my very rudimentary knowledge of wings.