I graduated with a degree in mechanical engineering and a minor in aeronautical engineering and had never heard of the term "tip stall" until I got involved in R/C airplanes. In reality, a stall is just a stall, whether it occurs at the wingtip, the root, or anywhere in between will determine how it impacts the flight characteristics of the airfoil; however, it is still just a stall. I am sure that with your degree, you can design a wing that will give any stall characteristics that the customer desires (assuming they want any). Sometimes I think that in the world of R/C, the term "tip stall" is over used in cases where poor piloting techniques are more appropriate.