I understand the basic physics of a Swanee whistle: shorter tube -> higher pitch.
But when I take the head joint off my flute, play a note and poke my finger up the tube, this behaves in exactly the opposite way. The further in my finger is, the lower the note. At first glance, it seems to be shorter tube -> lower pitch. I want to know why this is.
For the record, I'm not changing my embouchure and the note pitch changes way more than I can bend a note with my lips or by turning the mouthpiece - I'm definitely not using any trickery to do this.
I've only just discovered the physics of musical instruments page from this question, and I think it might be something to do with closed- vs open- pipes. I know a flute (and its head joint, presumably) behaves like an open pipe. So maybe my question should really be "Is a Swanee whistle a closed pipe?". I think the swanee whistles that I've seen have a mouthpiece similar to a recorder or penny whistle - you blow in the top and the air is split slightly lower down - I'm not sure of the technical term for that part of the instrument.