I snapped awake at 5:30AM this morning, and couldn’t get back to sleep, so I started a loaf of bread to bake later tonight, and then settled in to thinking about airfoils some more. I had seen references to the “Clark Y” airfoil, but didn’t know how it was defined, so I set out to figure it out. A few minutes of googling revealed a fascinating resource, the UIUC Airfoil Data Site. It has data definitions for literally hundreds of airfoil profiles, including coordinates for the Clark Y. I then dusted off my dim knowledge of gnuplot to draw this (properly scaled) version of the airfoil.

There is a trick to getting gnuplot to work. Here’s the set of commands I used:

set terminal png size 1024,256
set size ratio -1
set ytic .1
set xlabel "Clark Y Airfoil"
plot "clarky.dat" with lines

(You could probably make it look prettier with a bit more work.) The important bit is to set the size ratio: without it gnuplot will change vertical and horizontal scales to fit the data in the window.

Okay, off to make breakfast.