I start a project in QGIS. I set the CRS to anything (in this case I use EPSG=26918 a NAD83 datum). I also enable on the fly projection. Then I import a vector. In this case a kml, which I believe is a CRS of WGS84. Then I use openlayers and add a google satellite image. Everything looks good and lines up well. I then open a composer window and add a map and a scalebar. When I check to see if the scalebar is accurate I find that it is not.
If I go back to the project and check the measurements with the measurement toolbar I find that the measurement is accurate when the ellipsoid button is checked and inaccurate when the ellipsoid button is not checked. The measurement that I get when the ellipoid button is not checked is the same as I get in the composer window when I use the scalebar to figure out a length.
I guess I have a sense of why this happens. But I want to know how I can get an accurate scalebar in my composer window when I am using a google satellite image?