Question: A high speed wind tunnel is supplied with air from a collection of interconnected compressed air tanks situated outside of the laboratory. The air is delivered from the tanks to the tunnel through a long 100-cm-diameter pipe. The pressure at the inlet to this supply pipe is 10 MPa and the air is to be delivered to the tunnel at a pressure of 1 MPa. How long can this supply pipe be if choking is not to occur? Assume adiabatic subsonic one-dimensional flow and a mean friction factor of 0.005.