296 Lecture 15 
possible [16] to maintain extensive laminar flow over aerofoils if they are de- 
signed to have a favorable velocity gradient over the region involved. Dr. A.A. 
Griffith put forward a suggestion, that if a wing were designed (Fig. 15.19) to 
have a favorable gradient at all points except one, where a discontinuity in 
velocity occurred, and if suction were applied to remove the boundary layer just 
forward of this point, then laminar flow would occur everywhere. 
E ae 
Seay al... 
Suction Crees Cravze 
pia aly ha Ae 
Fig. 15.19. Thirty-per-cent-suction wing and theoretical 
velocity distribution: (a) wing with suction chamber, (b) 
theoretical velocity distribution. 
05 
(b) 
