Report

Temperature, Pressure, and Density Danielle Hettmann and Chris Saleh SYST460 – Fall 2011 Ambient temperature: measure of the temperature of the air in the region surrounding the aircraft Ambient temperature varies with altitude: Below 36,089 feet: ambient temperature (˚R) = -3.566˚ * (altitude/1000) Above 36,089 feet: ambient temperature (˚R) = 389.988˚ θ = (Tamb rule of thumb: ambient temperature drops 1˚ C for every 1000 feet increase in altitude Delta ISA + ∆ISA) / (TSeaLevel + ∆ISA) Temperature Ratio Below 36,089 feet, Tamb/TSeaLevel = θ = 1 – (6.8753 X 10^-6) * pressure altitude Above 36, 089 feet, Tamb/TSeaLevel = θ = 0.7519 Ambient Pressure: Measure of the pressure of the air in the region surrounding the aircraft Pressure Ratio : =Pamb / PSeaLevel Below 36,089 feet, the Ambient Pressure (lb/ft2) = (1 - ˚ * 6.88 X 10-6 * Pressure Altitude)5.26 Above 36,089 feet, the Ambient Pressure (lb/ft2) = 0.223360 e ( (36.089 – Pressure Altitude)/20.8057) Ambient Density: Measure of the density of the air in the region surrounding the aircraft Density Ratio: = (Slugs/ft3) = amb / SeaLevel Boyles Law: Density (), pressure (), temperature (θ) = / θ