It can certainly be tricky getting consistent tone in the second octave. Beginner's conventional wisdom says blow harder to make the octave jump. But when I was new at the flute a great flute player and Uilleann piper by the name of Tim Britton told me that the trick in the second octave is that you need less -- but more focused -- air than in the bottom octave. So my suggestion would be to practice upper octave notes by thinking about better focus but less air than you play for the bottom notes.
It can certainly be tricky
It can certainly be tricky getting consistent tone in the second octave. Beginner's conventional wisdom says blow harder to make the octave jump. But when I was new at the flute a great flute player and Uilleann piper by the name of Tim Britton told me that the trick in the second octave is that you need less -- but more focused -- air than in the bottom octave. So my suggestion would be to practice upper octave notes by thinking about better focus but less air than you play for the bottom notes.
Hopefully that will help!