A gas turbine comprising: a fan including a plurality of blades each blade having a leading edge , the fan having a design point fan tip leading edge relative flow angle β ADP , and further having an off-design point fan tip leading edge relative flow angle β at an off-design fan operating point, the off-design fan operating point being an acoustic certification point defined by Part 36 of the Federal Airworthiness Regulations, the acoustic certification point selected from the group consisting of approach, flyover and lateral; a variable area fan nozzle and controller configured to manipulate the amount of air flowing through the fan so that the absolute value of a difference between the design point fan tip leading edge relative flow angle β ADP and the off-design point fan tip leading edge relative flow angle β is in the range of about zero degrees to about six degrees, wherein the design point fan tip leading edge relative flow angle β ADP is defined by the solution to the following set of simultaneous equations W c , ADP A = 417 M ADP 1 + 0.2 M ADP 2 − 3 and tan β ADP = 340 M ADP U c , ADP 1 + 0.2 M ADP 2 − 0.5 wherein further, the off-design point tip relative flow angle β is defined by the solution to the following set of simultaneous equations W c A = 417 M 1 + 0.2 M 2 − 3 and tan β = 340 M U c 1 + 0.2 M 2 − 0.5 wherein (W C,ADP /A) is design point corrected mass flow rate per unit area in kilograms per second per square meter, (U C,ADP ) is design point corrected tip speed in meters per second, M ADP is design point airflow Mach number, and β ADP is in degrees, (W C /A) is off-design corrected mass flow rate per unit area in kilograms per second per square meter, Uc is off-design corrected tip speed in meters per second, M is off-design airflow Mach number, and β is in degrees. a fan including a plurality of blades each blade having a leading edge , the fan having a design point fan tip leading edge relative flow angle β ADP , and further having an off-design point fan tip leading edge relative flow angle β at an off-design fan operating point, the off-design fan operating point being an acoustic certification point defined by Part 36 of the Federal Airworthiness Regulations, the acoustic certification point selected from the group consisting of approach, flyover and lateral; a variable area fan nozzle and controller configured to manipulate the amount of air flowing through the fan so that the absolute value of a difference between the design point fan tip leading edge relative flow angle β ADP and the off-design point fan tip leading edge relative flow angle β is in the range of about zero degrees to about six degrees, wherein the design point fan tip leading edge relative flow angle β ADP is defined by the solution to the following set of simultaneous equations W c , ADP A = 417 M ADP 1 + 0.2 M ADP 2 − 3 and tan β ADP = 340 M ADP U c , ADP 1 + 0.2 M ADP 2 − 0.5 wherein further, the off-design point tip relative flow angle β is defined by the solution to the following set of simultaneous equations W c A = 417 M 1 + 0.2 M 2 − 3 and tan β = 340 M U c 1 + 0.2 M 2 − 0.5 wherein (W C,ADP /A) is design point corrected mass flow rate per unit area in kilograms per second per square meter, (U C,ADP ) is design point corrected tip speed in meters per second, M ADP is design point airflow Mach number, and β ADP is in degrees, (W C /A) is off-design corrected mass flow rate per unit area in kilograms per second per square meter, Uc is off-design corrected tip speed in meters per second, M is off-design airflow Mach number, and β is in degrees. <EOS>