Fan Tip Speed and Shock Waves
Having a few idle moments and calculated that the tip speed for the fan on a GE90-115B at 100% N1 is Mach 1.18 at sea level and 1.35 at 35,000 feet. (Just been reading "Not Much of an Engineer" by Sir Stanley Hooker). To me that means shock waves a plenty and hence inefficiency (if I read across from propeller theory correctly). Put me out of my misery, whats going on?