To John Nolte, in regard to nodal holes -- Thank you for the information.
I was thinking of a toy flute type of instrument.  The length of the tube
on a toy flute remains the same but, when you uncover certain holes the
toy will play different notes.  The location of these holes I was
thinking could be applied to pipe making.

I was not trying to make the pipe sound two notes at a time.  I understand
over-blown pipes like the ones used in violins with the frein or roller
bridge.

Regards
Ed Hattrup