So to make it easier to read:
$$ F = m \cdot \frac{d \vec{v}(t)}{dt} = m \cdot \frac{v_2-v_1}{\Delta t}= \dot m v_2 - \dot m v_1=((m_{air}+m_{gas})\cdot v_{exhaust})-m_{air}v_{plane}$$
and you're looking for realistic figures for the various variables? Have you tried to find some information directly on the manufacturers' websites, i.e. RR and GE?