Are airfoil profiles patented? If not, why? For something that takes so much research and can effect performance drastically, there seems to be no patents on airfoils.
Too simple in appearance to patent? They appear simple at first but the performance characteristics behind them are quite complex.
I have found patents describing 3D objects such as turbofan blades using a combination of airfoils, twist and sweep combined. There seems to be nothing showing or describing a 2D profile of a wing unless it's flaps.
There certainly are airfoils that are patented. Here is an example. Here is another airfoil by the famous aerodynamicist Richard Whitcomb. I think it is tricky in practice to obtain a patent in that you need to define the airfoil in a way that isn't so narrow as to be useless for protection. Just claiming a series of coordinates would provide very little protection as someone could make minor changes to avoid infringement.