Since the thread is "Subsonic Aerodynamic Vortex", I'll start with that. One of the more interesting things I've discovered in studying aerodynamics of powered models is how small the vortex/induced drag component is compared to parasitic drag. Because we have so much power on tap, level flight requires very little angle of attack to generate sufficient lift to offset the weight of the plane.

Reynolds number is a dimensionless quantity derived from fluid velocity as well as the chord of an airfoil. Our planes fly much slower and have much, much smaller chords than big boy planes so our Reynolds numbers are much lower. The unfortunate result is that most published lift/drag data is at Re's 10 times what we need.

If you want a good book on the subject my favorite is Martin Simons "Model Aircraft Aerodynamics"[link=http://www.amazon.com/Model-Aircraft-Aerodynamics-Martin-Simons/dp/1854861905/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1238456643&sr= 8-1]here.[/link]

I think many of the classic pattern ships could be made even better with more advanced airfoils and planforms, but thats a BIG discussion.