Why do I like designing model airplanes with thin wings so much?
The thickness of a wing refers to the thickness of its cross section or airfoil. It is the height of the thickest part of the airfoil divided by its front to back length.
On full-size airplanes, thicknesses of 12% are common. But to our model airplanes the air molecules are proportionately larger. All of my model airplane designs have used airfoils that are 10% thick or less. Unless you have a good reason to do otherwise, I recommend that you do the same.
Thin wings have lower maximum lift (which is not so good) and less drag (which is good).
Having less lift means that the model will stall at a faster speed than it would otherwise. Keeping the wing loading low is a common way to compensate for the higher stall speed.
Thin wings have stalls that start at the leading edge, which means that the flow separation abruptly spreads and destroys the wing’s ability to produce lift. In other words, thin wings have sharp stalls.
Less drag is generally a good thing to have. The model will have better penetration into the wind, for example. But it also means that it will speed up quickly when the nose is pointed down. A thin wing would be a poor choice on an aerobatic airplane that wants to maintain a constant airspeed.
My recent Pickerel design has a very thin wing and a very streamlined profile. Despite the low wing loading, it handles wind gusts very well. I also learned to be vigilant during turns because if I let the nose drop it would gain a lot of speed. Applying correcting up elevator in the turns became second nature very quickly.
I like thin wings. They make a model more versatile, able to fly in a wider variety of wind conditions. Of course, a thin wing is harder to build strong, but that is part of the challenge of airplane design!