Pete,
Thank you for the informational links. I can appreciate the inherent differences between the two mediums. I have read that steam creates a volume or mass something like 1600 times as great as the water it was created from, which is no doubt why it was such a successful power source for locomotives. When I began pursuing this aspect of the railroad hobby, I was very curious about powering a whistle in the absence of steam. The manufacturer of my whistles, Mike at MD Whistles, was instrumental in my decision to purchase and successfully use his products, after he explained how compressed air can be used effectively as a substitute for steam. A minimum pressure of 135psi was specified (I use 150), along with a minimum 60 gallon compressor tank, and a 1" air line (I use steel pipe and a 1/4 turn ball valve). As you mentioned, a whistle uses a significant amount of air to operate. I purchased my first whistle from Mike last July (the Nathan 5 chime), and I can testify to it's thirst for air to operate. Mike told me to expect it to drain the compressor tank in 8 seconds or less. It does that very efficiently, and there's no way I would ever expect the 3hp 2 cylinder 220v 60 gallon compressor to keep up with the demand. My installation is a "one demonstration session per tankful" system. But you can trust me it works very well indeed - just ask my neighbor's cows. They get on their feet and line the fence, and stare right at me with their ears sticking straight out. It is a hoot. As Stix mentioned, the 5 chime sound is a little bit mournful, and blown on air apparently is extremely attractive to bovines. Last August I wrote a post here in the forums about my 5 chime whistle installation in use, cs.trains.com/thread/209461.aspx. I don't know if this link will work as shown. I'm still trying to master some of these techniques. The name of the post is "Nathan 5 chime steam locomotive whistle on the farm in Oregon". Mike told me a whistle operated on air will sound an octave lower than on steam, which seems logical considering the differences in the properties of both mediums. I used my 5 chime to remove the snow from the roof of my greenhouse last winter - from about 30' away the sound waves did the job very well. If you are interested, check out Mike's products @ mdwhistles.com.
Respectfully,
Wilton.
Steam whistles are not designed to sound off of air pressure alone. I'm afraid you will be terribly disappointed if it even sounds at all. Plus the shear volume of air needed will tax the largest of compressors.
Here are a couple of links for you.
http://www.absoluteastronomy.com/topics/Steam_whistle
http://www.steamlocomotive.com/appliances/whistles.php
http://www.smokstak.com/forum/showthread.php?t=63618
Steam when entering a chamber will expand where air will not. Air when entering a chamber will dissipate and swirl. You need that thermal expansion to resonate the bell.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
oregon shay This was a five-note whistle, with a much shorter bell, and therefore, much higher in pitch. This whistle produced a bright G-major 6th chord (GBDEG) Wilton.
This was a five-note whistle, with a much shorter bell, and therefore, much higher in pitch. This whistle produced a bright G-major 6th chord (GBDEG)
I agree that there are many variables that will affect the quality and nature of the sounds a whistle can create. I am influenced by the unconventional dynamics of my own installation - using compressed air in place of steam. I would dearly love to have access to a boiler. But I suspect that might not endear me to some of my more tolerant neighbors who do enjoy hearing a steam locomotive whistle, and the memories it brings back for them.
Stix,
As far as the notes played by a Nathan 5 chime are concerned, my understanding of them are based on (1) the knowledge of the manufacturer of my whistles, who has the blueprints, technical data, and dimensions for the bell chambers, and (2) some research from Wikipedia's Train Whistle page - "Another very popular American train whistle was, again, a Nathan product. This was a five-note whistle, with a much shorter bell, and therefore, much higher in pitch. This whistle produced a bright G-major 6th chord (GBDEG) and, again, was heavily imitated, copies being made by many different railroads. China copied American five-chime whistles for their own locomotives."
Actually G-B-D-E-G isn't a G-major chord. G major is G-B-D-G. I think it would be a G-6th chord? It incorpates the G chord and Em, the relative minor (E-G-B-E).
I am not a musician and never claim to be. I know from stories that back in the day when locomotives were assigned to a certain engineer (before pool service) that they would attempt to tune their whistles to their taste. I have also read in trade and historical society books that steam whistles did not have a particular note due to the fact that there are way too many variables. Steam pressure, steam volume through the valve, saturation of the steam (dry or wet), crust and deposits accumulated on the bungs and valves, foam in the top of the boiler, and the hand of the engineer or fireman all play into how a steam whistle sounds. Just the saturation level of the steam could play a major part in how it sounds.
An air horn will sound the same no matter how hard or how long you hold the button or pull cord. The sound will be the same until all air is exhausted. The volume of air pressing on the diaphram at the back of the trumpts will always be the same.
In the week since I posted this question, numerous internet searches have made me rather certain that this type of information can be hard to come by. While searching for "note" facts for the 3 chime I came upon the same data (and more) for my Nathan 5 chime whistle. The Nathan 5 chime sounds a G major chord (GBDEG). I have also been seeking information regarding which railroads used the Nathan whistle. A call to the Union Pacific Historical Society this AM, researching which whistle was used on the UP 3985 Challenger locomotive, revealed that the UP uses the Nathan 5 chime (which they removed from the Big Boy 4-8-8-4 that is on display there in Cheyenne), along with whistles from their FEF 4-8-4 locos, as well as an Illinois Central whistle. I recently received my Athearn Genesis Challenger 3985 loco - now I know which whistles are prototypically correct for it. Looks like my next search should be for contact information for an historical society for the Virginian Railway.
I recently purchased a Virginian 3 chime whistle from MD Whistles (my second whistle from MD), and am trying to find a source of valid information on what notes or chord steam locomotive whistles "play". Any insight would be appreciated.