Finding static pressure of rotor

[helinewbie]

I've been reading a helicopter aerodynamics book and found that you can only find the induced velocity by using the Momentum theory and Bernoulli's Principle. If I don't know the thrust the rotor is generating, then I have to find the induced velocity of the rotor, where
Atmospheric pressure = static pressure + 1/2*(air density)*(induced velocity^2). How can I find the static pressure? Say if I only am building a small model, instead of a full-scale helicopter, I wouldn't have the static pressure measurement tool in the full-scale helicopter.

 

[Navin A S]

The static pressure can be calculated from the atmospheric pressure and air density by using the equation for Bernoulli's Principle. Since you know the atmospheric pressure and the velocity of the rotor, you can calculate the static pressure. You can also use the equation for momentum theory to calculate the thrust that the rotor is generating, which can be used to calculate the induced velocity.