Pressure applied to Medusa nuke engine canopy

$\frac{
    4
}{
    3
}\cdot \frac {
    15 \cdot m
}{
    8 \cdot \pi \cdot {

    \sqrt{
        \frac{
            4 * \gamma
        }{
            \gamma - 1
        } \cdot \frac{
            E
        }{
            m
        }
    }

    }^3 \cdot t^3
} \cdot 1 - \frac{
    r^2
}{
    \sqrt{
        \frac{
            4 * \gamma
        }{
            \gamma - 1
        } \cdot \frac{
            E
        }{
            m
        }
    }^2 \cdot t^2
} \cdot (\frac {
    r
}{
t
})^2$