NAVWEPS 00-801-80  HIGH SPEED AERODYNAMICS  Chapter  3  HIGH SPEED  AERODYNAMICS  GENERAL  CONCEPTS  AND  SUPERSONIC  FLOW  PATTERNS  NATURE OF COMPRESSIBILITY  Developments in aircraft and powerplants  have produced high  performance airplanes  with capabilities for very high speed flight.  The study of aerodynamics at these very high  flight speeds has many significant differences  from the study of classical low speed aero-  dynamics. Therefore, it is quite necessary  that the Naval Aviator be familiar with the  nature of high speed airflow and the charac-  teristics  of  high  performance airplane  configurations.  At low flight speeds the study of aero-  dynamics is greatly simplified by the fact  that  air may experience relatively small  changes in pressure with  only negligible  changes in density. This airflow is termed  incompressible  since the air may undergo changes  201 