Clandestino -
"its not time to shoot down DP Davies yet," - it's just that he said "This has no significant effect on the aeroplane", you said "Yes, rain will affect aerodynamic performance of any airfoil" - which is it?
Are you saying that Nasa also "has pretty bad reputation in scientific circles."?
The NASA paper tested "a cambered airfoil representative of typical com-
mercial transport wing sections" - NB not laminar flow.
The NASA summary
"The results obtained for various rain intensity levels and tunnel speeds
showed signifi cant losses in maximum lift capability and increases in drag for a given lift as the liquid water content was increased. The results obtained on the landing con guration also indicate a progressive decrease in the angle of attack at which maximum lift occurred and an increase in the slope of the pitching-moment curve as the liquid water content was increased."
I think on balance NASA wins over Mr C.