I posted this today in the forum:
http://en.smath.info/forum/yaf_postst2474_Add-a-Force-Density--or-Unit-Weight--Dimension.aspx#post12905
Later I saw the announcement of the BTS and request to post feature requests here.
Quote from that post follows:
I am attempting to add my own custom unit of pound force per cubic foot (pcf) to the Units.xml file; however, there does not appear to be a dimension available for Force Density (sometimes referred to as "Unit Weight" ) .
Please add this to the available Dimensions so force density units can be added to Units.xml. Some examples of units I'd like to be able to add are below:
-
pounds per cubic foot (pcf)
-
kips per cubic foot (kcf)