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Thread Tools | Display Modes |
#11
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"Peter" wrote in message news "Mike Rapoport" wrote: Either way, the Shadin should be reading the same or lower than the OEM OAT guage. I am sorry but I still don't get that. Total Air Temp should be SAT, adjusted UPwards for the airflow heating. But different parts of the aircraft will have different mach numbers. Which bit is TAT supposed to represent? Exactly, TAT represents SAT adjusted upwards for Mach. The problem with your senario (160ktas, 10K', ISA and Shadin reads 3C higher) ) is that the difference in readings is the same as the *total* calculated difference between SAT and TAT. The OAT guage would need to have a local flow of *zero* and the Shadin would need to have a local flow equal to the freestream Mach number. Think about it this way: Possibility #1 Both OEM OAT and Shadin displaying TAT and Shadin reads 3C higher (stated condition) Since total difference between SAT and TAT is 3C (calculated by Julian earlier in thread) and the Shadin reads 3C higher, for the OEM guage to be reading correctly the mach number at its location would have to be 0. To be exact, the difference in Mach number has to be exactly the same as the speed of the airplane, pretty unlikely. Possibility #2 The OEM OAT is displaying TAT and the Shadin is displaying SAT. SAT is always lower than TAT so the Shadin should show a lower temp. You could be right, which would presumably mean the stock OAT probe has a higher mach number than anything else. Two possibilities, either the airflow over the OEM OAT probe is zero or one (or both) temperature readings are inaccurate, a much more likely senario. Mike MU-2 |
#12
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"Peter" wrote in message ... I need to wait for a reply from Shadin as to what their "True Air Temp" is supposed to mean. Lets us know what they say. Mike MU-2 |
#13
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Thanks. This is consistant with what I observe in my airplane. It is
unfortunate that they chose to name things differently from everyone else, and particularly inappropriate to use TAT to mean SAT when there is a "TAT" in common use. Mike MU-2 "Peter" wrote in message ... "Mike Rapoport" wrote I need to wait for a reply from Shadin as to what their "True Air Temp" is supposed to mean. Lets us know what they say. Shadin's reply: Shadin's OAT = = Other's TAT (Total Air Temp) Shadin's TAT (True Air Temp) = = Other's SAT (Static Air Temp) They also sent me the installation manuals for models 200 and 2000. Peter. -- Return address is invalid to help stop junk mail. E-mail replies to but remove the X and the Y. Please do NOT copy usenet posts to email - it is NOT necessary. |
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