a=.072;b=30/74;c=30;
a1= 2.32;b1=.238;


d=100;
d1=d/100;
psi=9*10^(-8);psi1=9*10^(-10)
f=a:b:c;
f1=f.^2;
f2=f.^.5;
e3=(.1*d1).*(a1.*f2+b1.*f);
hc=10 .^(-e3);
kf=psi*d/.3048;kf1=psi1*d/0.3048;
xf1=kf1.*f1.*hc;
semilogy(f,xf1)
hold on

xf=kf.*f1.*hc;
semilogy(f,xf)