Thanks, Ken...
Just to amplify a little: in 1951, contemporary with the P.1 windtunnel model in the Nahum paper, no practical Mach 2 fighter design existed in the US. The F-104 was as yet not conceived and the F-102 was being built in its pre-Area Rule and unsuccessful initial shape. The second-best supersonic design to have reached that stage by 1951 may have been the Draken!