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   Post on VGs/ uncambered airfoils and drag in Avidfoxflyers General Hangar

   By zadwit, posted 9 Jun 2018

   Here is an interesting video circa 1938 about flat , uncambered and streamlined air foils. IF you look at the flat or undercambered airfoil, at high angle of attack the airflow seperated pretty far forward on the wing. This is why it is important to get the VGs up front, if too far back they are in "dead" air and cant do any good. I think Trent said 4% of the airfoil which I think is only 2" aft of the wing leading edge...
   Also the undercambered airfoil has more drag than most airfoil even at 0 angle of attack. I guess they work on really slow very low powered airplanes but as kitfoxs amd avids got bigger and bigger engines, it reared its ugly head as a drag producer... one last thing and I am not sure it is talked about here but thin undercamberd airfoils can exhibit nasty stall characteristics without any aerodynamic warning......in fact I have read lots of accident reports , "I was in a 45 degree bank at 50 mph with 2 on board and it stalled"
   ANyway I thought the video was of interest to all here. IT also shows how slats work...