The physics team began the preliminary wing design by researching and selecting an airfoil profile. We chose the Clark-Y because of its popularity in ultralight aircraft and desirable properties such as a tame and “mushy” stall. To get a conceptual starting point for the required reference area, we examined similar ultralight airplanes and their wing designs and noticed the reference area typically ranges from around 120sqft to about 180sqft. One specification of ultralight aircraft is that they must have a stall speed at or below 24 knots. Based on an estimate of the maximum lift coefficient of the Clark-Y profile and the 24 knot stall speed limitation, we were able to write the following equation to solve for the minimum reference area:
This resulted in a reference area of approximately 166sqft which fits right within the anticipated range. We then looked through a few textbooks to approximate an aspect ratio, or the ratio between the wingspan and the chord and decided upon a range of 4-7. Here’s a quick conceptual comparison:
