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PMDG MD -11 FLEX data finished.
Posted 03 April 2009 - 05:00 AM
Michael A. R. Clavier
Posted 03 April 2009 - 12:22 PM
Posted 03 April 2009 - 01:03 PM
Pa = Alt + 145442.2*(1-(P/29.92126)^0.190261) Pa= Pressure Altitude, a=Altitude, P=pressureDa = ((Pa + 288.5-0.0019812*Pa)/0.0019812)*(1-((288.15-0.0019812*Pa)/(T + 273.15))^0.234969) Da=Density Altitude, Pa=Pressure Altitude, T=Temperature
Thank you both! I feel like I
The altitude you read on the guage when it's set to the current altimeter setting is INDICATED altitude. PRESSURE altitude is what the instrument reads when it is set to standard pressure (29.92/1013.2). To make the conversion if the pressure is not standard, you have to do a little math. Remember that 1" of pressure is 1000 feet. If the indicated altitude is 300 and the baro is 30.02, simply subtract 29.92, getting .1. So, .1" is equal to 100 feet. Subtract that from your indicated altitude to get a pressure altitude of 200 ft.Converting PRESSURE altitude to DENSITY altitude requires a bit more math, and honestly, I've only ever done it with a flight computer (E6B or CR3). Basically, you're correcting pressure altitude for non-standard temperature, so if the temp is higher than standard, your density altitude goes up and performance goes down. If the temp is less than ISA, density altitude decreases and performance increases.Important to remember is that density and density altitude are different. In other words, higher density is a lower density altitude. It's all in the terms...Most performance charts I've seen are in Pressure altitude, not density...thats the only reason why I asked the question, as it makes a significant difference...
Posted 03 April 2009 - 08:53 PM
Posted 04 April 2009 - 03:17 AM