RE: Airfoil Numbers
They are just like shoe sizes - really and mean about as much in many cases -
For model planes you could select a full page of these identifications and EXACTLY reproduce them for say--a 1000 square inch 10 lb aerobatic model ---then do a blind test and likely never find a farthings worth of difference in performance .
However for a specific setup at a specific FIXED speed (specific task) ONE of these (if you can really find and fly it) will show up as best .
I am often accused of making light of all these "numbers"
Not so --it is just that for the most part they apply to situations most model sport flyers will never see.