In this paper we introduce the boundary layer stability equation solver PSE-Chem. This software employs a physical model approach to studying supersonic and hypersonic boundary layers and it incorporates the relevant physics including thermal and chemical nonequilibrium eddects. Reentry F, a Mach 20 5° cone with very small nose bluntness, is used as a test case to determine the N factor at transition. Our results are compared with published results from other researchers. Results are also presented which show, using the eN method, the stabilizing effect of increasing nose radius under these conditions. The sensitivity of the methods is illustrated in the ability to calculate how small nose radius changes affect the transition location at stations hundreds of nose radii downstream.