Mailing List lml@lancaironline.net Message #17165
From: Lorn H. Olsen <lorn@dynacomm.ws>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: [LML] LNC2 - OAT error
Date: Thu, 16 Jan 2003 00:26:20 -0500
To: <lml>
I calibrated the OAT on my Rock Mountain Micro Encoder on the ground.  However, I still noticed significant in flight errors, especially in the wintertime.  On a recent flight at 19,000, with a reported OAT of -25c, I was indicating -12c.

Clark Baker, N250JF, LNC2 360 - 550 hrs tt (and still debugging!)

Clark,

What was your indicated speed? Are you turbo charged or not?

Don't forget to consider compressibility. Even without turbos, when you are flying at 19,000 ft and indicating 130 kts at standard temperature of -22 C with a TAS of 174 kts, there is a temperature rise of 4 degrees centigrade. Of course if you are turbocharged the temperature rise would be much higher. As a matter of fact, at 19,000 ft and indicating 170 kts at standard temperature of -22 C with a TAS of 228 kts, there is a temperature rise of 7 degrees centigrade.

Why do you think that the reported temperature is the real temperature. I use what is reported as an indication of what is going on, not as actual fact.

Thanks for the info though. I am going to take a look at the inside end of my probe also.

Lorn
--
Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.
248-478-4301, mailto:lorn@dynacomm.ws
LNC2, O-320-D1F, N31161, Y47, SE Michigan
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