MIMF

I am working on a quena and flute for a regional contest. They are both made out of pvc. I cannot however make either sound like anything more than hollow. To fix this I have tried widening the holes and shortening the length do no avail. Can anyone help me?

Trevor Robinson authored a book on making wood wind instruments - "the amateur wind instrument maker". It explains a little bit on how to tune them.
You might also post your question in the woodwind section of this forum, you might get more responses.

Flutes are supposed to sound kinda hollow. What are the length and bore diameter of these instruments, and what pitch are you aiming for? And how wide is the embouchure hole on the flute? What kind of lip on quena? A very general rule on flutes is to keep them about 30 times as long as their inner diameter for best tone, but that can vary significantly in practice.

undercutting the tone hole(s) will smooth the transition between wall and hole, mellowing the effects of turbulence. It will also affect the pitch, so be explorative as you do this.

Some discussion of the effects of undercutting, hole location, hole size, and bore perturbations are found in the literature. See Bob Marvins article in GSJ, also the several GSJ articles on renaissance flutes. Pipe Organ flue pipes are basically single-note flutes...

Dana, please spell out GSJ for the benefit here of anyone who does not know this acronym.

Galpin Society Journal.

The bore diameter/Bore length ratio of a flute can be variable from about 1/25 to 1/36. the shorter wider bore will give a more hollow flutey tone and the longer narrow bore will give a more reedy tone. here is a long known flute calculator program by Pete Kosel (I thing the link in the MIMForum needs an update). You can change individual frequencies, diameters and bore thicknesses on this calculator. I hope this helps.

http://11wall-west.com/~ph_kosel/flutomat.html