Author Topic: Calibrating relative (corrected sea level) pressure  (Read 1743 times)

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Offline elisatems

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Re: Calibrating relative (corrected sea level) pressure
« Reply #75 on: December 23, 2021, 08:40:08 AM »
I knew it, I knew it, I knew it.  #-o  Seeing your user name, or whatever it's called, I wondered, but said man anyway. A thousand apologies!

FYI, Mooney drivers are nuts. Just sayin'...

I'm very glad you have the wherewithal to avoid potential icing conditions, as many, especially here in AZ, think that can't happen to them. Wrong. Every winter during colder storms I'd have to bail out "dinks" that had no de-icing, well, other than carb heat. Doesn't do much for weight and drag. PIC lesson learned.
No worries!

"Bail out..."? Sounds like you must work in ATC... if so, thank you for all that you do for us pilots! But yes, I can imagine how pilots who live somewhere it's usually warm like AZ might get complacent and think that ice can never happen to them, but... ice is where you find it, and during the winter months you can find it just about anywhere. Here in the northeast it's a constant presence, I don't think anyone gets complacent about ice (at least, I hope not). Even so, most people have a story to tell.

Once, soon after moving out here, I was flying down to Nashua, NH (KASH) in December. I filed IFR on a day when it was clear up in VT, but there was a stratocu deck just below the MEA right around where I'd enter NH. There was an Airmet Zulu out, and a few PIREPs for icing. As I came up to the layer a little voice told me to cancel and duck under it, but it didn't look very thick, I was above it (though barely), and I decided to just tell ATC I didn't want to linger inside it and please just give me a clean let-down when it was time to bring me down. I couldn't have taken more than 30 seconds to get through it, and I didn't notice any buildup on any surfaces, no degradation of performance, landed without incident... but as soon as I got out of the plane I could clearly see about a quarter inch of ice on the wings in the process of melting off - VERY slowly because it was just above freezing on the ground. Lesson learned!!

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BTW, just because you don't have a glass cockpit, doesn't mean it's obsolete. Kinda like when everyone complains about Davis's consoles being archaic looking, which they are, but still does the job flawlessly.
Oh I know! I have no complaints about my panel, in fact it has some instruments that used to be considered "aftermarket glass"... a Sandel 3308, and a GMX-200. My GPS is a CNX-80 a.k.a. GNS480, so WAAS-capable, a must-have today. It's just not state of the art but that's okay, like you say it does the job flawlessly.

Offline CW2274

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Re: Calibrating relative (corrected sea level) pressure
« Reply #76 on: December 23, 2021, 03:35:04 PM »
I knew it, I knew it, I knew it.  #-o  Seeing your user name, or whatever it's called, I wondered, but said man anyway. A thousand apologies!

FYI, Mooney drivers are nuts. Just sayin'...

I'm very glad you have the wherewithal to avoid potential icing conditions, as many, especially here in AZ, think that can't happen to them. Wrong. Every winter during colder storms I'd have to bail out "dinks" that had no de-icing, well, other than carb heat. Doesn't do much for weight and drag. PIC lesson learned.

a little voice told me to cancel and duck under it, but it didn't look very thick, I was above it (though barely), and I decided to just tell ATC I didn't want to linger inside it and please just give me a clean let-down when it was time to bring me down. I couldn't have taken more than 30 seconds to get through it, and I didn't notice any buildup on any surfaces, no degradation of performance, landed without incident... but as soon as I got out of the plane I could clearly see about a quarter inch of ice on the wings in the process of melting off - VERY slowly because it was just above freezing on the ground. Lesson learned!!
Ah yes, hindsight being 20/20, canceling IFR to get below the deck would had definitely been the way to go. You can always pick up a "pop up" IFR later if need as well. No idea what the MVA's are like where you fly, but never hesitate to ask for lower and/or a vector out of the weather if available. Many times we'll issue an altitude above what is actually available just for the sake of ease of radio transmission, like saying six thousand when actually five thousand seven hundred is available. Can make all the difference in the world in flight conditions. Glad your descent was on your terms and not the ice's!

Offline Randall Kayfes

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Re: Calibrating relative (corrected sea level) pressure
« Reply #77 on: February 09, 2022, 09:57:59 AM »
"Current" airport data is not necessarily needed, recent data should do you just fine - let me explain. All you need is a recent data point logged at the the same time as one of your data log times. Even if it is only logged once an hour at the airport. Go back an hour in your logs and you can still calculate the differential between the two readings. As long as the log times matchup you can see the difference. Looking at it that way you can compare several readings for differential and obtain a higher level of accuracy. That could be helpful in widening your choices of calibration data.

BTW here in Southern Arizona with summers averaging 100F and Winters in the 60's our barometers are nothing but a pain to keep accurate.



Offline CW2274

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Re: Calibrating relative (corrected sea level) pressure
« Reply #78 on: February 09, 2022, 03:26:18 PM »
BTW here in Southern Arizona with summers averaging 100F and Winters in the 60's our barometers are nothing but a pain to keep accurate.
I never adjust my pressure. No need to do so.

Offline Randall Kayfes

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Re: Calibrating relative (corrected sea level) pressure
« Reply #79 on: February 09, 2022, 04:28:29 PM »
Greetings, yes that Cessna with retractable landing gear looks killer. From there though CW (ATC wow what a broad skillset you must hold to do that job), you said on our Davis VP2's you set the elevation to zero on 29.92 day and then let it go sounds great to me as adjusting twice a year is a pain. I just want to make sure that is what you said? I can't afford another console (Vue)



Offline CW2274

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Re: Calibrating relative (corrected sea level) pressure
« Reply #80 on: February 09, 2022, 04:41:40 PM »
Greetings, yes that Cessna with retractable landing gear looks killer. From there though CW (ATC wow what a broad skillset you must hold to do that job), you said on our Davis VP2's you set the elevation to zero on 29.92 day and then let it go sounds great to me as adjusting twice a year is a pain. I just want to make sure that is what you said? I can't afford another console (Vue)
Yeah, with the VP2, that's exactly what I did and lived with it being too high in low pressure and too low in high pressure. Hence the Vue console and the altimeter setting being available. It's a complete pressure headache cure. I'd save up. BTW, it doesn't have to be exactly 29.92, just the in the ballpark with benign WX conditions.

Offline Randall Kayfes

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Re: Calibrating relative (corrected sea level) pressure
« Reply #81 on: February 09, 2022, 04:47:28 PM »
CW, thank you, I will have to give that a go. BTW if I get a Vue console (currently I am using an Envoy) does it pass on the solar and UV data and will it handle my sonic wind sensor.
« Last Edit: February 09, 2022, 04:51:31 PM by Randall Kayfes »



Offline CW2274

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Re: Calibrating relative (corrected sea level) pressure
« Reply #82 on: February 09, 2022, 05:03:35 PM »
BTW if I get a Vue console (currently I am using an Envoy) does it pass on the solar and UV data and will it handle my sonic wind sensor.
Solar/UV, I don't think so...the wind sensor shouldn't matter.

Offline PaulMy

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Re: Calibrating relative (corrected sea level) pressure
« Reply #83 on: February 09, 2022, 05:46:41 PM »

Hi Randall,
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BTW if I get a Vue console (currently I am using an Envoy) does it pass on the solar and UV data and will it handle my sonic wind sensor.

I have the VP2 Plus ISS and Envoy/USB logger, and also a Vue console with WiFiLogger sending to WL.com and to my CumulusMX and Solar and UV is logged and sent to WL.com https://www.weatherlink.com/bulletin/a3a3c5e7-b8bd-4910-ba3a-f6ad6e1f09d1


Sorry, I don't have the sonic wind sensor so can't comment on that.


Enjoy,
Paul
Davis Vantage Pro 2 Plus 24-FARS Wireless - Komoka, ON Canada
Envoy/USB Logger/Cumulus v1.9.4  www.komokaweather.com  
WFL/CMX www.komokaweather.com/komokaweather-ca2/index.php
WLL/CMX www.komokaweather.com/cumulusmxwll/index.htm
WLL/CMX www.komokaweather.com/cumulusmxwll/index.html
WLL/CMX www.komokaweather.com/cumulusmxwll/index.php
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Offline mcrossley

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Re: Calibrating relative (corrected sea level) pressure
« Reply #84 on: February 10, 2022, 08:23:14 AM »

Sorry, I don't have the sonic wind sensor so can't comment on that.


It's just a wind sensor, no different from any other data wise.
Mark

Offline Randall Kayfes

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Re: Calibrating relative (corrected sea level) pressure
« Reply #85 on: February 12, 2022, 01:19:53 PM »
So here is the real question I did not make very clear in the beginning:

The Vue does not include the solar UV suite like my VP2+ does. So, if I use a Vue Console (sans the Vue ISS) and the Vue Console holds/interrogates my data logger and then reports to my WL PC and my WL PC reports to WL Live will the Vue console know enough to push the solar/UV data to my WL PC even though the console will not display it.



Offline PaulMy

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Re: Calibrating relative (corrected sea level) pressure
« Reply #86 on: February 12, 2022, 01:48:43 PM »
Hi Randall,
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and my WL PC reports to WL Live
I presume you mean "reports to WL.com"

Quote
The Vue does not include the solar UV suite like my VP2+ does. So, if I use a Vue Console (sans the Vue ISS) and the Vue Console holds/interrogates my data logger and then reports to my WL PC and my WL PC reports to WL Live will the Vue console know enough to push the solar/UV data to my WL PC even though the console will not display it.
I don't have the same configuraion as you (Vue to WLPC) as mine is Vue console with IP logger to WL.com.  But the View console does receive the solar and UV from the VP2 ISS Plus and sends it to WL.com.  I can view all the Vue console data through the IP and that includes Solar and UV. 
I presume the Vue console will do the same to WLPC.  Hopefully someone with the same configuration as you mention can confirm that.


Enjoy,
Paul


Davis Vantage Pro 2 Plus 24-FARS Wireless - Komoka, ON Canada
Envoy/USB Logger/Cumulus v1.9.4  www.komokaweather.com  
WFL/CMX www.komokaweather.com/komokaweather-ca2/index.php
WLL/CMX www.komokaweather.com/cumulusmxwll/index.htm
WLL/CMX www.komokaweather.com/cumulusmxwll/index.html
WLL/CMX www.komokaweather.com/cumulusmxwll/index.php
Blitzortung Station #1076


Offline Randall Kayfes

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Re: Calibrating relative (corrected sea level) pressure
« Reply #87 on: February 14, 2022, 07:11:39 AM »
That answers my questions. Thank you Paul