Calliope #5!!
Well what fun! Kris came by to work on her car and I got her help to get the semi-dismantled calliope #4 out of the RV (a tight squeeze!) and onto the workbench. I got Rich to come over and together the three of us did some kanoodling on what should come next.
First up was what to do with #4. After talking to the pros I decided the best thing I could do is give #4, sans whistles, to Rich who has an idea that it could be used either as some sort of MIDI-controlled flame effect device or as a multiple air-rocket launching carousel. Either way it sounds like a fun challenge and I can’t wait to see what comes next!
Before dragging the old mechanics and electronics to Rich’s ‘shop’ Kris and I did a rough calculation to determine manifold volume. Working the numbers seperately we both came up with a piddly 95 cu in. for the steel torus. Although more than the 48 cu in of calliope #3 it was still a bit less than I would desire for a proper plenum.
The goal in making calliope #5 is umpty fold, but the change in layout will make the design compact enough to be carried by one person, which also means it might actually fit atop the boiler in my fairly narrow steamboat. The plenum will be made from 4″ square 1/8″ wall steel tube. It will have an internal volume of at least 235 cu in, even tho footprint of the whole device will be about half what it was. Routing of wiring will be greatly simplified as well and that increases the likelihood that #5 will be capable of running propane. Now that I understand the importance of maximizing valve orifice area I’m going to search for off-the-shelf valves that operate more like organ valves rather than solenoid valves that depend on a small piston sealing an even smaller hole. The trick will be finding them with 1/4” NPT thread; to get the smallest footprint I can manage.
After remachining the existing valves on #4 I managed to cut plenum pressure from 80psi to 20psi. The valves I have been using look like this:
http://www.ascovalve.com/Common/PDFFiles/Product/8262_8263_HSeries_GP_R1.pdf
What I want to find and/or build is something that’s still solenoid operated but that toggles a plug of some kind to lift (or better fall into plenum), exposing a much larger opening. By having valve fall into plenum area the gas flow would help reseat it to give a crisper cutoff, yes? The valves closest to this concept that I’ve found so far look like this:
http://www.ascovalve.com/Common/PDFFiles/Product/8210R1.pdf
The goal is to get the silly thing to work on as little pressure as possible; say 5psi or less… The kicker, of course, is that 24 solenoid valves won’t be cheap; I figure a thousand bucks at least and although I’m told my economic forecast is a little rosier these days I’m still waiting for the check, so to speak…
After talking with Rich and Kris I gather that the electronics for 24 pipes is not much more complex than those for 12 so the idea is to combine the 1” dia pipes made for calliope #3 with the 1-1/2” dia ones from #4, giving me 2 octaves and the ability to play more MIDI tunes with less tune ‘squeezing’ needed.
Anywayyyy the first step is to start sketching out a top view so that I can get an idea of just how closely I can pack valves, to determine the length of 4” square tube I’ll buy to make the plenum. In #4 I put the solenoid valves far enough apart so that they could be screwed into their corresponding fittings on the plenum; i.e. about 4” apart. But by using unions instead of straight pipe nipples I can reduce this distance to maybe 3”. By staggering the pipes in the Y direction I can decrease the X separation still further. An added benefit of staggering pipes in a double row: if I decide to use propane I can make a much more compact, straight pilot light that will nest between pipes in staggered rows.