Temperatures

[Guest]

Can some one confirm me what OAT,SAT and TAT stand for and maybe something about each one. thanks.http://events8.tripod.com/pilot_tag.JPG

[Guest jase439]

OAT is your outside air temperature (basically if you opened the window on the tarmac and stuck a thermometer out the window).TAT is your Total Air Temperature and is your air temperature measured at the probe (usually about 20C warmer than OAT). As the air passes over the probe, there is an effect called "ram rise" which tends to elevate the actual temperature due to friction and the compression of air. Alot of turbine performance data is measured in terms of TAT, however. You also concern yourself about potential icing when the TAT is between 0 and 10C, etc...SAT is your Static Air Temperature and is a measure of TAT corrected for the compression of air that occurs as the aircraft surface passes through it. It's a calculated measurement. There's a complex formula for this (it's a function of TAT, Mach Speed, and the specific heat of air, pressure). OAT and TAT are probably the most meaningful to you.J

[Guest]

just to add on to TATas rightly pointed out it is a function of ram air rise..the friction generated by airflow past the plane.a good thumb rule to estimate TAT is to add 10% of IAS to SAT . this is the tempraeture of air that your engines are breathing.the ram rise is not a constant figure at a given mach no. for eg u may need to fly about 480 odd knots at sea level to get M0.80 ,while at jet flight levels ,depending of crs on OAT ,which again depends on how high u are..rqeuired IAS may be bet 320 to 260 odd knots ,obviously ,260 knots is not gonna generate the same friction as 480 knots at seal level...bi bi kunal