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TAT and SAT

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Guest LSangiovanni LIML

on my PSS A320 panel should mean...which one should i take into account for engine anti ice system?thanks in advanceLuigi ;-)

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You always use TAT for determining Anti-Ice use as it takes ram air temp rise into consideration and this is the actual aircraft skin temp. For example, you could have a SAT of -15C but a TAT of -5C due to the rise.Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.sstsim.com/images/team/JR.jpgwww.sstsim.com

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Guest Adverse Yawn

To give you some idea of the difference between TATS and SAT: TAT = SAT + (TAS/100)^2

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Guest LSangiovanni LIML

ok, thank you both.what are T.A.T. and S.A.T. for?Luigi ;-)

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Guest Adverse Yawn

Total Air Temprature (includes ram rise effect).Static Air Temrature, equivelent to OAT (Outside Air Temp).

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Guest LSangiovanni LIML

thanks again for the adviceLuigi ;-)

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TAT will only be achieved where the airspeed is effectively zero at the leading edge of flying surfaces and at the nose of the aircraft. As the airfow speeds up again over the aircraft the speed will increase and the TAT will fall. TAT is not the skin temperature over the aircraft. Even where the air reaches TAT, the skin temperature will not, because heat will be conducted away into other cooler parts of the aircraft structure.The high temperatures on Concorde were the result of kinetic heating caused by friction between the outside air and the skin of the rapidly moving aircraft, not the TAT effect.I would like to know what the manuals for aircraft with both temperature gauges say about their use in relation to icing.

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>TAT will only be achieved where the airspeed is effectively>zero at the leading edge of flying surfaces and at the nose of>the aircraft. As the airfow speeds up again over the aircraft>the speed will increase and the TAT will fall. TAT is not the>skin temperature over the aircraft. Even where the air reaches>TAT, the skin temperature will not, because heat will be>conducted away into other cooler parts of the aircraft>structure.>>The high temperatures on Concorde were the result of kinetic>heating caused by friction between the outside air and the>skin of the rapidly moving aircraft, not the TAT effect.>>I would like to know what the manuals for aircraft with both>temperature gauges say about their use in relation to icing.You have it backwards. As soon as an aircraft is moving, TAT rises and is always going to be higher than SAT. Manuals for aircraft with both temperature gauges will tell you to reference TAT when airborne and SAT when on the ground for decisions pertaining to the operation of anti-icing systems.

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The TAT as defined does increase with speed. However, it is not the actual air temperature, except in the conditions I mentioned in my earlier post. It is certainly not the skin temperature.It is analogous to the dynamic pressure measured by a pitot static tube which it also not the general air pressure around an aircraft.

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