A streamlined train is 105 m long, 2.8 m wide and with sides 2.8 m high. The train travels at a speedof 200 km h1 through air of temperature 15°C, pressure 1 bar and dynamic viscosity 1.76 x 105 PaS. Assuming friction drag occurs on the sides and top only: (i) Calculate the power required to overcome skin friction, assuming a drag coefficient, Cp =0.455/(log10Re2.58 [5 marks] (ii) Show that the assumption of turbulent drag is acceptable. [2.5 marks] (iii) Engineers estimate that streamlining adds 20 m to the train length. If streamlining was removed from the train design, and pressure drag effects introduced, how much would the power requirements change? Assume a pressure drag coefficient, CD = 0.22. [5 marks]

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A streamlined train is 105 m long, 2.8 m wide and with sides 2.8 m high. The train travels at a speedof 200 km h1 through air of temperature 15°C, pressure 1 bar and dynamic viscosity 1.76 x 105 PaS. Assuming friction drag occurs on the sides and top only: (i) Calculate the power required to overcome skin friction, as