Subject: Re: Formulas and Formulae (are few a far between) From: <TheGluePot@aol.com <mailto:TheGluePot@aol.com>> Date: Tue, 3 Apr 2001 06:53:33 EDT There is nothing more fun than answering simple questions; too bad the = ones below are anything but simple, nevertheless, here goes: > As I plan the layout for my organ, it will be necessary to change = certain > things found in its last layout. That layout was also, not original. = What > I seek is the optimum distance that a regulator be offset from its = chest. > Also, if I build new regulators, how do I scale them? Regulators are built to deliver wind according to rank(s) draw. Each rank = has its own draw rating, a large scaled flue will have a high draw as = opposed to a tiny regal reed which uses little wind. Thrown into the mix is the operating pressure desired and possible tremulation requirements. For a single rank like a Vox Humana you could use an 18" x 24" single rise regulator with curtain valve and have no problems. On the opposite = extreme a scale 38 Open Diapason would require a 30" x 40" regulator to handle quick = large chords and the three valve style regulator is hard to beat. For multiple ranks the regulator size increases. Pipe organs have not yet = been engineered closely enough to be very specific on component size. It is = still by-and-large an empirical art when a pipe organ is built. This drives engineers nuts! While I have a doctorate is in Physics, a Masters in Industrial Design, and a BS in Electronics Engineering, I approach organbuilding the way my grandfather and dad did. It is the "that looks about right" school of design then add 50% fudge factor and another 50% safety margin for operating headroom. In essence, you pick up the 8' CC = of the largest flue (usually the Open or a Grossflute). You look at the = windway cross-sectional area and the pipe toe hole then check the cutup and see if = the voicer has written the windpressure on the pipe (hopefully). In your head you are thinking, "a full chord with octave couplers will have x = number of pipes drawing wind." Mentally you add the average toe hole/windway = areas for all the ranks in a largest draw case then make the total valve areas 3 = to 4 times your estimate of the maximum. Then, as a rule-of-thumb, the size = of the regulator top area is greater than 10 times the total valve area. I prefer 12 times myself but this figure varies wildly depending on = tremulation method (if any) and other factors. Figuring what spring ratings you need = is the easy part and the formula I worked out is Total Spring Tension =3D The = Number of Square Inches of Regulator Top times (x) [The Desired Wind = Pressure divided by (/) 27.68]. The 27.68 is one PSI. So, a regulator that is 20" = x 30" for a pressure of 3.5" will require (600"sq. x [3.5/27.68] for a = combined spring equilibrium force of 76 pounds tension. If four springs are used, each will be at 19 pounds tension at pressure equilibrium. > One specific problem that I now have deals with a four rank echo chest. = It > appears that I cannot locate the regulator any closer than six feet = away. > Is that too far? The chest is on 3 1/2 inches of pressure. What are the ranks? Small scaled echo flues and a reed will work just = fine with a windline of six feet and a windline diameter of 4+ inches for your straight echo chest. Unification would require just slightly larger = windline diameter in the 6" region. REMEMBER, a pipe organ is a *low* volume = *high* pressure device when you think in terms of the fluid dynamics normally = used in the design of HVAC units. You would be surprised at how small a = diameter of windline may be used in most instances and I have laughed to myself on seeing some drastically stupid overdone winding, the worst was a one foot section of clear acrylic 4" tubing to connect a simple 12 note treble = offset chest to a main windchest where a 1" windline would have been more than adequate and visually less obtrusive (even a soda straw would have carried = enough wind). On second thought there was an organ in San Mateo that had = 14" windline run everywhere when a 6" line would have been just fine. The concrete drilling through the walls for the 14" line cost almost as much = as the used organ! > In general, how does one figure regulator size? Additionally, how far = can > a regulator be removed from its chest? Of course this discussion should > include the distance a trem is located away from the chest. And last, = what > size windway between chest and regulator should be used, given the = number > of ranks Most good organ builders will try to get the regulators as close to the windchests as possible. Since the air in the wind conductors acts like a spring delay line, keeping the windlines as short as possible makes for = more steady wind and more solid pipe speech. There is another school of organ building where reservoirs are used instead of regulators and long wind conductors are OK because the builders like the unsteady wind sound. I personally tend to think of it as *musical jello* since I am bothered by = any pitch sag caused by neo-baroque style winding. Some builders even go out = of their way to underwind and create unsteady wind saying that it gives the organ a more live character. I cannot sit and listen to these instruments = which many have proudly proclaimed to be in vogue. > Curious is Missouri > Bob Taylor >> I have probably created more questions than I answered and I fear that my explanations are less than clear but I hope my comments have helped a = little. Best wishes to all, Al Sefl Whose winding is achieved with beans

Also, any tips on temporary repairs to regulator leather? The regulators have fairly good leather except for some small (under 2") cracks at the corner folds. I'd like to fix that temporarily to get started setting the pipework up for tests and wait to releather until I'm ready to mount the regulators in the final position. Again,all help is appreciated. Best Wishes to all, Lloyd Collins lcollins@premiermeansbusiness.com <mailto:lcollins@premiermeansbusiness.com>

For temporary patching, do just that -- carefully glue appropriately sized = bits of new leather over the cracked areas. Probably will work best if = you remove the reservior top and prop it up from within, while you apply the patches and allow the glue to dry. Be careful to keep the patches off = wood areas of the ribs, so they will all go away cleanly when you strip and releather the reserviors properly. Good luck! Tim Bovard Little Rock, AR