11. At the "'upper critical Mach number "', airflow around the entire aircraft is supersonic. 12. North American conducted this test, their High Mach Number Investigation , on November 13. 13. At the "'lower critical Mach number "', airflow around the entire aircraft is subsonic. 14. The actual critical Mach number varies from wing to wing. 15. At low Mach numbers gliders have such long, narrow wings. 16. These waves are studied to obtain a relation between deflection angle and Mach number . 17. The upstream Mach number , M _ 1, begins at 1 and ends at 5. 18. For low Mach number \ scriptstyle Ma, the drag coefficient is independent of Mach number . 19. There are also gravity currents with large density variations-the so-called low Mach number compressible flows. 20. Increasing the nozzle pressure ratio further will not increase the throat Mach number above one.
