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TrevorS

Incorrect TAS

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While flying at 35 000 feet at M0.80 (with no weather), the IAS was 271 knots which is correct.

However, the TAS indicated on the MFD was 451 knots and should be 461 knots.

Can others confirm this?

 

Trevor

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True Airspeed for a given Mach number is not a constant - it varies with temperature. It would be 461 knots if your OAT was -54C. If the OAT was -45C, it would be 471 knots. For 451 knots, the OAT would have to be -64C, which is quite cold for FL350 but not impossible. I don't know what FSX/P3D injects for temperature if no weather is being used.

 

Jim Barrett

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OAT was -54C and TAT was -27C.

This should plz be looked at. Everything standard - no weather.

 

Trevor

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TAT -27 /SAT -54 gives TAS 463 for Mach .80 per the FlyBy E6B iPad app, and my old Jeppesen CR-5 computer, so Trevor's expectation of seeing 461 is pretty accurate.

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Hi Mathijs

 

According to J.K. Hochwarth's calculation and conversions program.

According to the real CRJ inflight performance manual with ISA + 0.

 

Trevor

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Thank you.

May I say that this is a fantastic airplane. The wait has been worth it.

My sincere appreciation to all those involved.

I feel like a little boy on Christmas morning who has just unwrapped this present!!!!

 

Trevor

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TAS is a value directly from FSX/P3D. It's not calculated by the CRJ. As only the simulator knows the complete set of environment data, we can only assume that this calculation is correct.

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Yet doing the same flight in the level-d 767 at Mach0.8 shows a TAS of 461 knots!!!

 

Trevor

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