Three identical eagles of wing span $s$ are flying side by side in a straight line with no gap between their wing tips. Assume a single horse shoe vortex model (of equal strength $\Gamma$ ) for each bird. The net downwash experienced by the middle bird is
(A) $\frac{\Gamma}{\pi s}$
(B) $\frac{\Gamma}{2 \pi s}$
(C) $\frac{\Gamma}{3 \pi s}$
(D) $\frac{4 \Gamma}{3 \pi s}$
Three identical eagles of wing span $s$ are flying side by side in a straight line with no gap between their wing tips. Assume a single horse shoe vortex model (of equal strength $\Gamma$ ) for each bird. The net downwash experienced by the middle bird is
(A) $\frac{\Gamma}{\pi s}$
(B) $\frac{\Gamma}{2 \pi s}$
(C) $\frac{\Gamma}{3 \pi s}$
(D) $\frac{4 \Gamma}{3 \pi s}$