Does the wikipedia entry also account for the "adjustment factor" needed in, say... pipe organs? I checked out the page, however, I still don't know if it has it in there or not. Coming straight from theory, you should be able to calculate directly what the length should be. However, if you do this then it won't sound quite "right." I know this might be just hearsay, but I spoke to a pipe-organ tuner on the subway once about this kind of stuff while studying for a physics test.