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+clc
+// Example 1.7.py
+// A flat plate with a chord length of 3 ft and an infinite span(perpendicular to
+// the page in fig 1.5) is immersed in a Mach 2 flow at standard sea level
+// conditions at an angle of attack of 10 degrees. The pressure distribution
+// over the plate is as follows: upper surface, p2=constant=1132 lb/ft^2 lower
+// surface, p3=constant=3568 lb/ft^2. The local shear stress is given by tau_w =
+// 13/xeta^0.2, where tau_w is in pounds per square feet and xeta is the distance
+// in feet along the plate from the leading edge. Assume the distribution of 
+// tau_w over the top and bottom surfaces is the same. Both the pressure and
+// shear disributions are sketched qualitatively in fig. 1.5. Calculate the lift
+// and drag per unit span on the plate.
+
+//
+
+// Variable declaration
+M1 = 2.0        // mach number freestream
+p1 = 2116.0     // pressure at sea level (in lb/ft^2)
+l = 3.0         // chord of plate (in ft)
+alpha = 10.0    // angle of attack in degrees
+
+p2 = 1132.0     // pressure on the upper surface (in lb/ft^2)
+p3 = 3568.0     // pressure on the lower surface (in lb/ft^2)
+
+// Calculations
+
+// assuming unit span
+
+pds = -p2*l + p3*l   // integral p.ds from leading edge to trailing edge (in lb/ft)
+
+L = pds*cos(alpha*%pi/180.0) // lift per unit span (in lb/ft), alpha is converted to radians
+
+Dw = pds*sin(alpha*%pi/180.0) // pressure drag per unit span (in lb/ft), alpha is converted to radians
+
+Df = 16.25 * (l** 4.0/5.0) // skin friction drag per unit span (in lb/ft) 
+                             // from integral tau.d(xeta)
+
+Df = 2 * Df * cos(alpha*%pi/180.0) // since skin friction acts on both the side
+
+D = Df + Dw                  // total drag per unit span (in lb/ft)
+// Result 
+printf("\n Total Lift per unit span = %.0f lb", L)
+
+printf("\n Total Drag per unit span = %.0f lb", D)
+