ORIGINAL: BadSplice
the KV is the RPM(x1000) per Volt applied. The higher the number, the faster the motor will spin, and more apms will be drawn. A 3s lipo is 12.6v fully charged, 12.6v x 4500kv would =56,700rpm. so yes, it will affect the flight time. Higher kv= more power, less time
...... hope that was helpful
Actually, there is no factor of a thousand for those ratings... if it says 4500kv, that's 4500 rpms/Volt... not 4,500,000 rpms/Volt. The K is not indicating "kilo", but I believe the K in "Kv" is supposed to denote voltage gain of the motor... K is a common variable name for used for gain, and v is the subscript used to indicate voltage gain... for motor, the units would be rpms/Volt for such a gain...