I live in Las Vegas and I am working on a project to create electricity using the forces of moving air curents, as in convection heat. I will be using typical 4, 3, and 2 Inch PVCX (ABS) plastic pipe as my housing, so the device will be easily flashed on the roof as it draws air from the attic and outward, creating electricity. I need help calculating draw. I need to know how long to make the different sections in order to draw the air out. I am trying to find a set of calculations for designing a fireplace as these would be more likely to suit my needs. Can anyone help me? I'm going broke just trying to get the first prototype in manufacturable format. The costs of computers and 3D software is astronomical for a Disabled Veteran living on the benifits of a Grateful Nation. Please email me at: email@example.com or write: Joseph R. Keezer 805 Griffith Avenue, Las Vegas, Nevada. 89104. Thank You.