Model Engine Maker
Supporting => Engine Ancillaries => Topic started by: sshire on September 02, 2013, 08:42:14 PM
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I'm back to the boiler build tomorrow, but, after hearing the PMR whistle on a Youtube video, I was underwhelmed. Wimpy Whistle.
Hey, how hard could it be to make a whistle. A bit of Googling and more Youtube watching and I came up with a prototype. I still need to try some variation of the opening angle and size. The final build will be a 3 chime whistle.
Parts laid out as an exploded view. All will be soldered.
(http://i1126.photobucket.com/albums/l604/sshire/Steam%20Whistle/SteamWhistle-3.jpg) (http://s1126.photobucket.com/user/sshire/media/Steam%20Whistle/SteamWhistle-3.jpg.html)
The 3 inside parts. The stem on the right side piece will be threaded to match the rest of the boiler fittings.
(http://i1126.photobucket.com/albums/l604/sshire/Steam%20Whistle/SteamWhistle-1.jpg) (http://s1126.photobucket.com/user/sshire/media/Steam%20Whistle/SteamWhistle-1.jpg.html)
The shell.
(http://i1126.photobucket.com/albums/l604/sshire/Steam%20Whistle/SteamWhistle-2.jpg) (http://s1126.photobucket.com/user/sshire/media/Steam%20Whistle/SteamWhistle-2.jpg.html)
Proof of concept test.
https://www.youtube.com/watch?v=k6IemLrmx4s
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Not bad on air, it'll sound even better with steam.
Hugh.
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Hugh
Didn't realize there was a difference. Another steam tidbit for the collection.
I do want to try varying the angle and depth of the v-notch. Pitch is just a function of tube length. More fun.
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Nice, and three chimes would be excellent. There's all kinds of fun you can have with whistles and horns:
https://www.youtube.com/watch?v=when3v7NVFk
Simon
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Simon
:lolb:
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Hi Stan,
Your whistle sounds a little "breathy" to me. According to a reference I have here, that could be caused by your windway not being focused enough on the edge at the top of the aperture. This book recommends the stream of air (or steam) be about as wide as the aperture, and probably less than a sixteenth inch thick. The 'thickness' of the stream should hit head-on at the upper edge of the aperture, with the edge cutting the stream roughly in half.
The shape of the aperture also has an effect, with short wide openings producing a clearer focused tone, and long, narrow openings producing a breathier tone and requiring more blowing pressure.
Reference: Musical Instrument Design by Bart Hopkin
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The aperture is 0.04. I think the issue is the shape of the notch. I'm going to start with a smaller one and keep testing and filing until I like the sound. I was thrilled that it made any sound.
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I built a whistle once. It has a bore that just slides over the 3/16" tubing I use for exhaust on a number of my engines. Slip it on and the engine literally whistles while it works. I use it occasionally as an attention getter at shows. Its main advantage is that it can be easily removed to silence it because it does get annoying after a while.
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Loved the video Simon..one could have loads of fun with something like that...at least until the cops caught up with you :)
Bill