Download all mathcad files shown in this submission to experiment your self with various assumptions:

To read (and run) these programs, if you do not have Mathcad version 7 or higher, you need to download Mathcad explorer - it might be available through the web, although the producer no longer supports it! Note that you may have to press F9 to start the calculation of the worksheet, and note that some of the calculations may take a couple of minutes!