For a given airfoil, is drag the only aerodynamic effect of increasing that airfoils thickness.

Thanks,
Ben

No, lift also increases ever so slightly and the rounder leading edge usually leads to a more gradual, mushier stall.

There are a number of airfoil families where the designers of the family basically just increased the thickness ratio. The increase in thickness often gave a greater AOA with an associated increase in max lift before the stall.

Of the few I've looked at, the L/D was pretty much the same. So the induced drag differences won't probably matter. However, parasitic drag is what it is, so if you keep the same chord, you will see that increase. Will it matter? It did in C/L combat airplanes that flew in the 120mph range.

Do you have some airfoil in mind? Symmetrical? Undercambered? How fast will the design be expected to fly?

For our lower Reynolds numbers oddball things start to happen when you go much above 15% though. It all depends on what you're wanting to do.

BTW, there is a well known and understood "trick" in the design of C/L precision aerobatic model design. It's most often employed with tapered wings. Increasing the thickness ratio toward the tip is the trick. And it isn't actually a trick at all. It's simply a sensible use of aerodynamics. As thickness is increased, so does the stall AOA. It's actually nothing more than "aerodynamic twist" being applied.

In fact, the wing may or may not increase in thickness. It all depends. What happens is the taper shortens the chord of the airfoils moving toward the tip. So if you don't decrease the thickness of those airfoils at the same rate you decrease the chords the ratio of thickness to chord increases. Taa daaaaa.......

Lots and lots of C/L stunter designs fly better for it.

The question came up after I built a Dick Sarpolus design called the RIGHT ANGLE. It was a large sport .60 - .90 aerobatic design with a VERY THICK airfoil! (I got the plans from Model Aviation magazine). The length of the constant chord rib (not including aileron) was 11 3/4" and the thickness of the rib was 3". It pulled through maneuvers well, although slowly, and when power was cut, it really slowed up. I needed to make my landing pattern tight if I didn't want to drag it in with power. Aileron control seemed somewhat sluggish (airflow turbulence ???) but very controllable. Stall speed must be really low because my landings were super easy and slow.

Thanks for your replies