16885J/ESD35J-ct1,2002 Basic sweep concept Consider Mach Number normal to leading edge sinμ=1/M M=M.cosA u=Mach angle the direction disturbances travel in supersonic flow For subsonic freestream M.<M.- Lower effective"freestream Mach number delays onset of transonic drag rise For supersonic freestream M<l,A>H- Subsonic leading edge M>1,A<H- Supersonic leading edge Extensive analysis available but this is gist of the concept16.885J/ESD.35J - Oct 1, 2002 Basic Sweep Concept • Consider Mach Number normal to leading edge • For subsonic freestreams, Mn < Mf - Lower effective “freestream” Mach number delays onset of transonic drag rise. • For supersonic freestreams – Mn < 1, / > P - Subsonic leading edge – Mn > 1, / < P - Supersonic leading edge • Extensive analysis available, but this is gist of the concept sin P=1/ Mf P = Mach angle, the direction disturbances travel in supersonic flow Mf Mn=Mfcos/ P /