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.
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
Step 1: Cutting the Notch
Two cuts must be made into the PVC pipe to make a notch, as shown. The first cut is perpendicular to the axis of the pipe. The second is at a 45 degree angle. Make the first cut about 1" to 1.5" from the end of the pipe, as shown.