Recent Progress in the Calculation of Potential Flows 



3.0S > UJ > 35 a = 10° 



- - T- 1 I .■■»«■« « « " ff "*"*"- ■ 



Fig. 6 - Shape of the vortex wake (at three separate times) generated by a sym- 

 metric 8.4-percent-thick von Mises airfoil, that has been given a sudden in- 

 crease (10°) in angle of attack at time 0.55 U/c and a sudden decrease (10°) at 

 time 3.05 U/c - .■ ■... . :-.'■■, ■., ,■■.- . 



'^.^.^^^^^ 



Vy = 07869 COS{4.3t) 



Vx = IO 



♦ • KZa^^^^^E ^ACA 0015 



Fig. 7 - Shape of the vortex wake generated by anNACAOOlS airfoil 

 vibrating in a simple harmonic manner with an amplitude of 0.018c 

 (a) frequency = 4.3 U/c. 



333 



