PPRuNe Forums - View Single Post - SAT TAT FREE AIR TEMP can someone explain
Old 18th October 2001 | 07:28
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quid
still learning....
 
Joined: Jul 1999
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From: USA
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The speed questions have been answered. Now on to the temperatures.

For all practical purposes (for pilots, not engineers) SAT (static air temp), OAT (outside air temp) and Free Air Temp are all the same. TAT (total air temp) and RAT (ram air temp) are the same.

The difference is the "ram" effect. Let's say you are flying on an ISA standard day at FL 330. OAT will be -51C. If you're indicating M.80, the ram rise will be about 30C, so your RAT / TAT will be indicating around -21. Your TAS will be +/- 467. For each M.01 difference, your TAS will vary 5 kts. For each degree of RAT, your TAS will vary 1 kt.
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