Hi, all. Continuing my initially Raymer-heavy self education, I want to make better estimates of the zero-lift drag for less than conventional planes. Raymer just uses the total wetted area times some skin friction value, but not all flight surfaces are created equal. Wings are probably cleanest, but tail feathers are in disturbed air so their area will count for more. The research backing his equations is also probably dominated by tractor fuselages, where the boundary layer gets tripped almost immediately. So I need to get a rough idea of the ratios of drag contributed by wings vs tails vs fuses (tractor and pusher) with respect to their wetted area. I was able to find the ratio between the friction of laminar vs turbulent boundary layers for plates, but not much beyond that.
Anybody out there know any rules of thumb or have some educated guesses? If not, how might I go about figuring this out on my own?
Anybody out there know any rules of thumb or have some educated guesses? If not, how might I go about figuring this out on my own?
