Prandtl-Glauert Scaling of Induced Drag Three aerodynamics students, Wilbur, Orville, and Amelia, are discussing compressible subsonic flight. They agree that a wing of aspect ratio AR with elliptic lift distribution in incompressible flight has an induced drag coefficient given by = 2 () However, they have three different thoughts on the Prandtl-Glauert scaling of this three- dimensional flow. That is, given the incompressible result as above, what does Prandtl-Glauert scaling give for at a compressible flight Mach number of ? Their opinions are stated below. They flipped a coin and this time Wilbur won and goes first: Wilbur states, "Induced drag acts on the wing through pressure on the wing. Induced drag coefficient can be computed by integrating these pressures in their coefficient form. The pressure coefficient scales as1 1 2 . Therefore an integral of pressure coefficient will also scale as 1 1 2 ." In equation form, Wilbur is stating that: = 1 2 . Orville counters, "Look, the left-hand side is clearly just a non-dimensionalized force. Therefore, the right hand side is also just a non-dimensional force. Both forces are pressure forces and therefore scale as 1 1 2