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Pat Mussotte

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  1. Pat Mussotte's post in Lear 35 A Temperature Gauge wrong? was marked as the answer   
    Don't be confused! There are to "kinds" of temperature measured: the first one is the SAT or static air temperature which is the atmosphere temperature at a given point or altitude. The "other one" is the RAT (sometimes name TAT, very close to RAT, for total air temperature)or Ram air temperature which is the temperature"felt" by the probe located on the plane. This one is higher than the SAT due to the friction of the air at high speed. There is a formula binding the 2 temperature which is
    TAT= SAT(1+0.2(M Square))
    Suppose your at 35000 ft at M.8, the SAT is -56°C or 217°K(273+(-56)the TAT will be
    217K(1+.2(.8square))=244.8K  or 244.8-273=-28.2°C
    So there is a rise in temperature of 28°C due to the speed
     
    PS: 273K=0°C
    I hope I'm clear enough
     
    Cheers
     
    Pat
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