A study has been made of techniques that could be used to extend axial singularity methods for incompressible flow, to deal with compressibility effects. In particular the accuracy of common linearisation methods has been investigated, together with methods for the iterative solution of the full potential equation using distributions of sources in the flow field. These field sources account for the non-linear terms in the equations, and a computer programme has been written to implement the method. For a range of body shapes, and subsonic Mach numbers, simple distributions of sources in the field lead to accurate results after only four iterations. Starting in 1946 as the College of Aeronautics, the Cranfield Institute of Technology was granted university status in 1969. In 1993 it changed its name to Cranfield University.