why is it that in modern compressors in gas turbine engines like the J79 the rotor blades are set up at a higher angle of incidence (more aligned to the axial axis) compared to older engines. I also know that modern engines also need bleed air valves or stator actuators or some sort of anti-stall mechanism
is it because the greater the angle of incidence the more room for a higher inlet velocity? or slower higher velocity?...or rpm? something related to one of those.