Forces on the flier in the frame of aircaraft (non inertial reference frame) is:

(i) Normal reaction (N)

(ii)Pseudo force $\left(\frac{m{v}^2}{R}\right)$

(iii) Gravitational force d(mg)

According to problem,

                        v_T = v_b = v_m = v

The net force on flier at every point should be zero in the frame of aircraft. For top point T,

                             $N_T+\text{mg}=\frac{{\mathrm{mv}}_{\text{T}}^2}{R}\therefore N_T=\frac{{\mathrm{mv}}^2}{R}-\text{mg}$

                             = 0.7 kN

For bottom point,$N_B=\text{mg}+\frac{{\mathrm{mv}}_b^2}{R}=\text{mg}+\frac{{\mathrm{mv}}^2}{R}$

                             = 2.1 kN.



For middle point,$N_m=\sqrt{{\left(\frac{{\text{mv}}_{}^2}{R}\right)}^2+{\left(\text{mg}\right)}^2}=1\text{.}5kN$