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Post by houstonceng on Apr 2, 2018 16:41:40 GMT
Hi Kerrin, Bob Bramson referring to the disc/lanquid depth of slot being the thickness of the tube is surely a nonsense! So you make 3 otherwise identical whistles for the same boiler pressure. One is made out of thin brass treblet tube, one is made out of commercial central heating boiler type copper tube, and one is machined out of solid as per 'Norm' with thick walls. According to Bob, they will all have a considerable difference in the depth of disc/lanquid slot! But in each case the whistle is the same length, diameter, and boiler pressure. What I presume Bob meant was to make the disc/languid depth of slot the same as thin brass treblet tube - which makes more sense - but is still too wide a depth of slot to prevent overblowing and jumping an octave and shrieking in 3.5 and 5"gauge locos. In respect of the above, a small diameter long whistle tube is far more prone to overblowing and jumping an octave and shrieking, so it is quite a complex subject. Incidentally, organ pipes work at something like 2 to 4 psi. They are made of lead or wood in most applications. The complex analysis of same has no application to miniature steam whistles. Cheers, Julian I made a number of very successful whistles using 15mm Cu pipe using Bob Bramson's design ("Wheezeles Whistles" articles in ME Vol 206, Issue 4389) and have no problems with overblowing and "jumping an octave". The slot is automatically made the same width as the Cu tube wall thickness. The sort of whistles we use are basically a fipple flute (same as the Acme Thunderer, school recorder or tin-whistle) and it seemed correct, to me, to have the slot directly in line with the fipple, which is what Bob's design does. AFAICT, the total whistle system - boiler pressure, valve, tubing and whistle design - is the source of a good "fundamental note" or a "shrieker" and needs to be better analysed. All I can say is that Bob's design worked for me with the previously mentioned change to the "Maid of Kent" pipework. One thing I have heard people say is that a whistle that works on air will not work on steam. Absolute rubbish. Yes, the velocity of sound in steam is different from that in air, so the note will be a different frequency, but I know from practical experience that I can test a whistle on air and it will work on steam. I think that the myth was perpetrated back when LBSC was writing - possibly by him or "Pepper Harris" - but one of LBSCs whistles was modified from the Scout/Guide/Police type whistle and it worked on steam and it was originally designed to be blown by a Scout, Guide or "Constibule".
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 717
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Post by oldnorton on Apr 2, 2018 18:30:37 GMT
I'm curious to know how you define thick & thin wall tube. Treblet tube may have been available in LBSC's day but I cannot any reference to it being available to buy today. I want to make a 1/2" diameter whistle, but a quick check of suppliers show that only 18g or 20g tube is available in that size. Hi, 18g or 20g I describe as thick, 0.048" - 0.035" walls, and is what I have used. The thin tube in commercial whistles is 26g or around 0.017". Treblet refers to a hard brass that was/is specified for musical instruments. You could use that, if you find it, or a soft metal since others have successfully used copper. Norm
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Post by Jim on Apr 2, 2018 19:50:08 GMT
For what it's worth I used .5"OD x .015" wall brass tube from K&S metals and sold in hobby shops for the 3 chime whistle on the Britannia. I'm more than happy with the result. The photo shows the various components. Jim.
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Post by joanlluch on Apr 2, 2018 22:19:44 GMT
Hi Jim. What are the lengths of your three chimes?. As per your photo above it looks that at least one of them will produce a relatively deep tone. That should sound great!
As a side question for anybody, I found that many full size polyphonic whistles produced musical chords that were rather discordant (from a musical point of view). I always wondered whether the choice of that particular combination of tones was thought of and done for a purpose, or the resulting chord was just a consequence of an arbitrary choice of individual chime lengths alone with no detailed study on the combined effects. Anyone knows which was actually the case?
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Post by Jim on Apr 3, 2018 3:49:06 GMT
Hi Joan, This is the drawing I was sent by another member of this forum (sadly I can't for the life of me remember who, I think it was Frank but I can't sure) and is the basis for the whistle on Boadicea. I also have an article by D A Gulliver Brown who uses a straight bar manifold rather than the round one shown here with the air/steam supply entering directly below the centre pipe. I decided on the this form of straight bar manifold as it was more compact but discovered when air was applied it went to the central pipe rather than equally to all three to give me a single chime whistle. As a result I went back to the round manifold and have had no problems since. Turning the insert The components laid out. The black rod was used as a template to cut and file to to ensure had the same depth of cut out the 2 shorter pipes had an identical opening as specified in the drawing. The 6 11/16ths pipe had a longer cut out as shown in the drawing with an *. The assembled whistle. And finally mounted on the original bar manifold but with the unwanted holes plugged, I don't like wasting things that can be reused. I hope you find this helpful. Jim.
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uuu
Elder Statesman
your message here...
Posts: 2,849
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Post by uuu on Apr 3, 2018 7:32:27 GMT
.... As a side question for anybody, I found that many full size polyphonic whistles produced musical chords that were rather discordant (from a musical point of view). I always wondered whether the choice of that particular combination of tones was thought of and done for a purpose, or the resulting chord was just a consequence of an arbitrary choice of individual chime lengths alone with no detailed study on the combined effects. Anyone knows which was actually the case? Expanded question.. Are the notes chosen to generate an additional frequency by interference, similar to barber-shop singing? Wilf
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Post by joanlluch on Apr 3, 2018 8:33:08 GMT
Hi Jim, Thanks for that. This is definitelly helpful. I have already stored it on my records for future reference.
Joan
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Post by joanlluch on Apr 3, 2018 9:09:12 GMT
.... As a side question for anybody, I found that many full size polyphonic whistles produced musical chords that were rather discordant (from a musical point of view). I always wondered whether the choice of that particular combination of tones was thought of and done for a purpose, or the resulting chord was just a consequence of an arbitrary choice of individual chime lengths alone with no detailed study on the combined effects. Anyone knows which was actually the case? Expanded question.. Are the notes chosen to generate an additional frequency by interference, similar to barber-shop singing? Wilf Hi Wilf, Yes, that's what I wonder too. Particularly if the specific resonant frequencies involved were chosen deliberately. On the standard musical scale only special notes are used to prevent that any two random notes would sound dissonant, including any combination of their harmonics. But that does not seem to exactly apply for multi-tone steam whistles. That's a complex subject, and not one that I am an expert in any way, but I just always wondered if some of the loco whistle harshness was created on purpose to make them sound more dramatic. Some of the American whistles sound quite frightening dissonant to me, the sound effect seems something very deliberate but I never read a document explaining it in detail. Joan
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Post by doubletop on Apr 3, 2018 9:40:07 GMT
I'm also now realising that although the area of the mouth is to be equal to the cross sectional area of the pipe the key is the height of the mouth (cutup) and not my basic mouth width = 75% of pipe diameter. (I think LBSC could have crept in here as he may have proposed a mouth width of .375" on a 1/2" pipe). Somewhere along the line the documentation proposes that the cutup should be 1/12 pipe length (L/12). I'm trying to establish how Weisenberger got to L/12 and have unlocked the spreadsheets to see where that came from, but it is just used "as is". I'm getting to grips with the spreadsheets from the Steam Whistle site and can now answer where the cutup = L/12 came from when the intent is to make the cross-sectional area of the mouth equal to the cross-section area of the pipe. What was throwing me was how the area and circumference of the pipe bore a relationship to the length of the pipe, and what’s more the same ratio regardless of the length of the pipe. Using a bell type whistle where the full circumference of the pipe is used as the lip of the mouth the area of the mouth is given by Pi x D x cut up (length of the mouth). The cross sectional area of the tube is Pi x R^2 or Pi x (D/2)^2 So Mouth Area = Cross Sectional area Pi x D x Cutup = Pi x (D/2)^2 Cutup = Pi x ((D/2)^2)/ Pi x D Cutup = ((D/2)^2)/D Cutup = D/4 The general recommendation by the Steam Whistle group that the scale (ratio of length to diameter) should be 3:1 e.g. D=L/3 then cutup would be equivalent to L/12. However, we would probably never use a scale of 3:1 as we are using tubes of the order of 0.5” to 1” diameter and 4” to (say) 7” in length which gives scales between 4:1 and 14:1 so we would always calculate cutup on the basis of tube diameter, that is cutup = D/4. The next consideration is the fact that we are only using a portion of the circumference of the lip of the tube and not the full 360deg say 60, 90deg or 180deg. As the width of the mouth will be narrower the length of the cutup needs to be adjusted accordingly to keep the area of the mouth equal to the cross-sectional area of the tube. So the dimensions of the mouth of a simple single tube whistle are given by Length of Mouth (Cutup) = D/4 x 360/angular width of mouth.All this is all theory based on the info from the Yahoo Steam Whistle Group and the paper “Basic Hooter Whistle”. It all appears to be well established work and we just need to be able to confirm that it works for us. Pete
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Post by doubletop on Apr 3, 2018 9:47:18 GMT
I thought I'd posted this earlier
From Jims drawing and the spreadsheets from the Yahoo Steam Whistle Group
Tube End Cap Insert Overall Air Steam
4.375 0.0625 0.4375 3.875 875hz 1125hz 5.25 0.0625 0.4375 4.75 714hz 918hz 6.875 0.0625 0.4375 6.375 532hz 684hz
Does that refelect the actual?
Pete
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barlowworks
Statesman
Now finished my other projects, Britannia here I come
Posts: 877
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Post by barlowworks on Apr 3, 2018 9:49:31 GMT
Hi Joan
Could it be that the whistles were chosen to be deliberately discordant. That way the tone would tend to be slightly "wrong" to our ears and so more noticeable than one that had a perfect pitch. You tend to be more aware of things you don't like.
Mike
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Post by joanlluch on Apr 3, 2018 10:33:53 GMT
Hi Joan Could it be that the whistles were chosen to be deliberately discordant. That way the tone would tend to be slightly "wrong" to our ears and so more noticeable than one that had a perfect pitch. You tend to be more aware of things you don't like. Mike Yes, exactly that's my point.
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Post by doubletop on Apr 3, 2018 10:47:00 GMT
...............And finally mounted on the original bar manifold but with the unwanted holes plugged, I don't like wasting things that can be reused. I hope you find this helpful. Jim. Jim It looks very good but have you tried it on steam yet? I ask because this thread was started as a result of my failed efforts, one problem being the condensation in the system having to gurgle its way through the languid before any meaningful sound was emitted. That circular manifold of yours looks to be an ideal water trap.... ........Just seen the note at the bottom of the drawing that seems to address the possible problem, but can fully make it out.. Pete
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Post by steamer5 on Apr 3, 2018 10:49:04 GMT
Hi Jim, Thanks for the drawing!! I'll send it to the construction shop......aka my Dad!!..... he's been wanting a chime whistle for some time. I got a pile of condenser tube many years ago, with a bit of luck it might be useful!
Cheers Kerrin
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Post by steamer5 on Apr 3, 2018 10:53:16 GMT
Hi Pete, DAM heres me thinking Jim had posted a winner! BUT as a thought given Jim has a 3 hole square manifold up stream of that I wonder if an auto steam / water drain could be fitted, aka a cylinder drain, what do you think??? Even to the circular manifold???
Cheers Kerrin
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Post by Jim on Apr 3, 2018 12:02:22 GMT
Hi Pete, DAM heres me thinking Jim had posted a winner! BUT as a thought given Jim has a 3 hole square manifold up stream of that I wonder if an auto steam / water drain could be fitted, aka a cylinder drain, what do you think??? Even to the circular manifold??? Cheers Kerrin Hi Kerrin condensate in the whistle could be a problem though I've tried to minimize it by angling the pipes up as much as possible withing the confines of the frames. I also made sure the 'mouths' of the pipes faced down to aid draining. The steam pipe to the whistle could also trap condensate and if that occurs and presents a problem I will fit a snifter type valve similar to the ones fitted to the steam brake line to drain water but seal under pressure. I'll find out tomorrow when I do a second steam up to check things before making the journey over to Orange. Jim
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Post by steamcoal on Apr 3, 2018 19:47:33 GMT
Hi Pete.
Talk to Reece Cobb in Nelson. He made me a very nice whistle , mid to deep tone.
I have his e-mail if you like.
Hayden
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Post by Jim on Apr 4, 2018 12:01:24 GMT
I'm not sure how this will turn out but this is an unedited clip of the 70036's second steam up that I did today. The 3 chime whistle that sounds is the one show in an earlier post in this thread. youtu.be/vtjJaiNmff0I hope the link works Jim
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Post by steamer5 on Apr 4, 2018 12:23:12 GMT
Hi Jim, Hows the grin?? 19 seconds just isn't enough, sounds like shes running sweet. The whistle sounds pretty good too, were those the first "blows", just wondering if it had been warmed thru I rang dad to say I had plans for him, hes pretty happy......just has to figure out were to put it. His loco is an NZR WW in 5" & given that he has twin axel pumps, twin oil pumps, plus balance lines between side tanks, it should keep him out of mischief for a day or two! He asked me to pass on his thanks for the drawings
Cheers Kerrin
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Post by joanlluch on Apr 4, 2018 12:30:18 GMT
Hi Jim, sounds great !
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