Instructables
This instructable shows how to create a simple whistle out of 1" diameter PVC pipe. 

The general design used here is not my own, as I have relied on many sources from the internet and elsewhere.  This is just my particular implementation of this simple whistle design.  I have included more detail on the construction and performance from my own experience in building it.  I have also included some optional features of my design, such as an attachement for use with an air compressor, and a moveable slide that allows the pitch can be changed.

By adjusting the length from the opening to end of the pipe, the pitch can be increased or decreased.  The pitch produced depends on the speed of sound and the length of the whistle from the notch to the capped end.

The pitch, in Hertz (Hz), can be calculated as:

Pitch =  [Speed of sound (in ft/second)]  /  [ 4 X Length of wistle (in inches) / 12 ]

The length of the whistle corresponds to 1/4" the wavelength of the sound produced.
The speed of sound is approximately 1100 feet per second.           
      
Parts List

Qty (1)  1" PVC end cap
Qty (1)  Length of PVC pipe.  The exact length is determined by the desired pitch.  About 10"   is a good length to start with.
Qty (1)  1" PVC coupler
Qty (1)  1" to 1/2" PVC adapter
Qty (1)  2" length of 1/2" PVC pipe
Qty (1)  Length of 1" diameter wooden dowel or other round stock that will fit tightly into 1" PVC pipe
 
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labdude3 months ago

SirJames, you can cap or not cap, as you see fit, however, not capping will result in a sound one octave higher, eg. Bb 4 would be approximately 14" capped (or stopped). Making the same length pipe unstopped, would produce a Bb5, one octave (2 x freq.) higher.
This is routinely done on organ pipes to extend the lower register without additional length. eg. A low C organ pipe, unstopped is ~17 ft long. One octave lower, would require a pipe 34 ft long, so rather than make a 34 ft pipe, they use a 17 ft pipe with a stop.

This is a bit of an oversimplification, and other factors come into play. But try it and see.

But as you mentioned, the sound does actually emerge from the slanted opening.

SIRJAMES093 months ago

So the one end does not get capped?....I thought that any whistle only allowed the air to exit through the hole by the mouth piece....

I would love to make this! :)

TY for Sharing Sir.

Phil B4 years ago
Thank you for an interesting and useful Instructable. I hope to clear my "to do" list enough to try this before long.