1. Make any changes to results of previous assignments that have been suggested, then select a base point maximum takeoff weight, wing loading (wing area), and aspect ratio, based on similar aircraft or your ideas on what your airplane should look like. Determine the initial cruise CL of the airplane assuming that the initial cruise weight is about 97% of the take-off weight for subsonic aircraft and about 90% of takeoff weight for SSTs. If you are designing a subsonic airplane, and your CL is less than 0.3 or greater than 0.6 you may want to revise your initial altitude or area estimates. Supersonic airplane CL's range from .08 to .15 (This is just a rough estimate so we can start airfoil and wing design.)
2. a. For a typical section operating at the airplane CL, find the maximum thickness consistent with flight at your selected cruise condition for a range of wing sweep angles, based on the simple critical Mach number method described in the notes. At this point you will only need to select a general airfoil type (e.g. peaky or supercritical). For supersonic wings use the same procedure, but if the normal Mach number is greater than 1.0 use linear supersonic theory and limit the thickness to that resulting in a section Cd of .0020 / cos3L. The results should be presented in a plot of allowable t/c vs. sweep. (Click here for additional hints for supersonic wings.)
b. Select a reasonable thickness ratio and sweep angle at this wing station.