Introducing my new contrabass overtone flutes

I demonstrate the overtone flutes I made out of 2 inch PVC. They all share the same head and base, and I add various length tubes to get different fundamental notes of D2, C#2, C2, and B1. If I go much lower then the true fundamental is choked and doesn't play well. I definitely can go a bit higher, but too much and the length to bore ratio is too small to function as an overtone flute.. The flute head is a bit of a hybrid in design. It has a slow air chamber like a Native American flute, but the fipple is shaped more like a recorder. I've got the materials to make a 3 inch bore PVC head - If I succeed then I will try to make an overtone flute with a fundamental of C1 or lower.