Costas loop parameters

Hi,

I would like to design a Costas Loop

I have a loop filter : F(s) = (tau2.s+1) / (tau1.s)

so i have the resonant frequency at : wn = sqrt (Kd.Ko / tau1)
Kd : is the phase comparator gain (V/rd)
Ko : is the VCO gain : (rad/s/V)
and the damping factor : z = 0.5 * tau2 * wn

Is the settling time is like a second order PLL to be : wn * Ts(5%) = 3
for a z = 0.707 ?

Because when I compute all the elements, I don't have the correct Ts or
the correct z...

Thanks