In the Pooley's CRP-5, to calculate density altitude, use the AIR SPEED window. Match the pressure altitude (say 300 ft) with air temperature at the airfield, say 30 deg C. Read out the density altitude in the DENSITY ALTITUDE window, ie about 2000 feet. If you matched the temp with the pressure altitude in the ALTITUDE window, you would get a read out of over 3500 feet for density altitude. It could be this is the source of the discrepency in this thread. It wasn't obvious to me that you use the AIRSPEED window, until I read the manual! Just a thought.
