Definitely not kidding you. Many years with the flight test department of a major full scale manufacturer, and the many suprises I encountered merely illustrate the fact that even with the resources available there , airplane design is not nearly the exact science some think. Just a couple of instances come to mind, significant errors in engineers range calculations for one of the early jumbos due to attempts to extrapolate wind tunnel data to reynolds numbers where empirical data did not yet exist, and flying around for several months with 1400 pounds of lead pigs in the forward area of the cargo compartment until the envelope could be expanded as the airplane was quite tail heavy. ( a subsequent stretched model was made with a much longer nose to correct). To a greater extent than the layman suspects (or the engineer will admit) there is a bit of TLAR in much full scale design. The two aircraft I mentioned in my earlier post further illustrate my approach and are excellent fliers. If you are trying to set new world records (i.e.Burt Rutan) get as deep into the science as you like, but if you are planning a sport fun machine, it's a lot of effort for little gain.