Author Topic: To go True or Magnetic  (Read 4290 times)

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Offline CW2274

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To go True or Magnetic
« on: November 02, 2015, 06:49:26 PM »
At suggestions, I've started this for those who wish to discuss whether you calibrate your PWS anemometer vane to true north or magnetic, such as myself, pros and cons.
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Offline CW2274

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Re: To go True or Magnetic
« Reply #1 on: November 02, 2015, 07:22:30 PM »
At suggestions, I've started this for those who wish to discuss whether you calibrate your PWS anemometer vane to true north or magnetic, such as myself, pros and cons.
That being said, I'm taking bets that I'm the only "magnetic" guy on this board..... ;)
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Offline Old Tele man

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Re: To go True or Magnetic
« Reply #2 on: November 02, 2015, 07:36:32 PM »
C.D.M.V.T.?

I used the "true" heading from this FFA picture for TIA:

« Last Edit: November 02, 2015, 07:40:16 PM by Old Tele man »
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Offline ValentineWeather

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Re: To go True or Magnetic
« Reply #3 on: November 02, 2015, 08:33:38 PM »
CWOP wants true north in siting guide. http://www.wxforum.net/index.php?topic=21081.0;nowap

Offline CW2274

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Re: To go True or Magnetic
« Reply #4 on: November 02, 2015, 08:39:04 PM »
C.D.M.V.T.?

I used the "true" heading from this FFA picture for TIA:


Earles, I have no idea what you're talking about, so I'll dumb it down for myself. All runway headings shown are magnetic. The declination compass even shows 11.1 degrees east with an annual rate of 0.1 degrees west. Respectfully, what's your point? :-?
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Offline CW2274

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Re: To go True or Magnetic
« Reply #5 on: November 02, 2015, 08:44:47 PM »
CWOP wants true north in siting guide. http://www.wxforum.net/index.php?topic=21081.0;nowap
For overall comparison sake, I'm sure they do, kinda hafta. Like I said, I'm probably alone, but I prefer the straight up comparison to the NWS/FAA sites in my area.
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Offline Dr Obbins

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Re: To go True or Magnetic
« Reply #6 on: November 02, 2015, 09:27:48 PM »
While we all strive for perfection, in reality how much does it really matter? If you are off by 5 what are the consequences?

Offline Old Tele man

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Re: To go True or Magnetic
« Reply #7 on: November 02, 2015, 09:32:32 PM »
Quoting the lyrics "...whichever way the wind blows..."

11.1E in 2005 -- at 0.1W per year -- means in 2015 "true" north has drifted to 10.1E magnetic.
« Last Edit: November 02, 2015, 09:39:33 PM by Old Tele man »
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Offline ValentineWeather

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Re: To go True or Magnetic
« Reply #8 on: November 02, 2015, 09:53:48 PM »
I would say even getting within 40 degrees with eyeballs is a win. Much harder than you would think. I tweak afterward with software.

Offline CW2274

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Re: To go True or Magnetic
« Reply #9 on: November 02, 2015, 09:55:09 PM »
While we all strive for perfection, in reality how much does it really matter? If you are off by 5 what are the consequences?
It doesn't. None. Merely a topic of conversation. Akin to having a brand new SHT11 to use or going with a 15. I have a 15.
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Offline CW2274

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Re: To go True or Magnetic
« Reply #10 on: November 02, 2015, 09:58:50 PM »
Quoting the lyrics "...whichever way the wind blows..."

11.1E in 2005 -- at 0.1W per year -- means in 2015 "true" north has drifted to 10.1E magnetic.
Ten now, thank you. Even I won't re-calibrate for that. ;)
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Offline CW2274

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Re: To go True or Magnetic
« Reply #11 on: November 02, 2015, 10:01:54 PM »
I would say even getting within 40 degrees with eyeballs is a win. Much harder than you would think. I tweak afterward with software.
40!!! Remind me to NEVER let you operate on me! :lol:
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Offline Old Tele man

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Re: To go True or Magnetic
« Reply #12 on: November 02, 2015, 10:53:46 PM »
Never substitute a Proctologist-MD for a Neurologist-MD.  \:D/
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Offline ValentineWeather

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Re: To go True or Magnetic
« Reply #13 on: November 02, 2015, 10:56:30 PM »
I would say even getting within 40 degrees with eyeballs is a win. Much harder than you would think. I tweak afterward with software.
40!!! Remind me to NEVER let you operate on me! :lol:
That's for sure. Reason I said 40 degrees we moved a station and it looks 40 degrees off tonight. I won't know for sure until I visit tomorrow. Could be some local direction issue however. Thought it was dead nuts on.

Offline ValentineWeather

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Re: To go True or Magnetic
« Reply #14 on: November 02, 2015, 10:59:47 PM »
Never substitute a Proctologist-MD for a Neurologist-MD.  \:D/

But I did stay at a Holiday Inn Express.

Offline Scalphunter

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Re: To go True or Magnetic
« Reply #15 on: November 02, 2015, 11:07:06 PM »
http://flighttraining.aopa.org/magazine/1998/August/199808_METAR_Winds_True_or_Magnetic.html


this list airports that do not give wind in magnetic heading.

 Also marine weather reports use true  headings instead of  magnetic.

John



Offline Old Tele man

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Re: To go True or Magnetic
« Reply #16 on: November 02, 2015, 11:22:30 PM »
Everything is EXACT...except for the EXCEPTIONS (ha,ha)!
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Offline CW2274

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Re: To go True or Magnetic
« Reply #17 on: November 02, 2015, 11:38:58 PM »
Never substitute a Proctologist-MD for a Neurologist-MD.  \:D/

But I did stay at a Holiday Inn Express.
   :lol:
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Offline CW2274

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Re: To go True or Magnetic
« Reply #18 on: November 02, 2015, 11:45:23 PM »
http://flighttraining.aopa.org/magazine/1998/August/199808_METAR_Winds_True_or_Magnetic.html


this list airports that do not give wind in magnetic heading.

 Also marine weather reports use true  headings instead of  magnetic.

John
Wow, not saying it can't still be the same, but that article's 17 years old.
I was in the Navy for 5 years, but certainly never a mariner.
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Offline Harryca

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Re: To go True or Magnetic
« Reply #19 on: November 03, 2015, 12:03:29 AM »
Everything is EXACT...except for the EXCEPTIONS (ha,ha)!

Way back in the day when I used to attend classes at IBM, the instructors would invariably say things like, "This is the way it always works or this is always true EXCEPT..." which always got a few chuckles from everybody.

Offline yahtah

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Re: To go True or Magnetic
« Reply #20 on: November 03, 2015, 12:04:44 AM »
I think the real question here is how do we set a standard for aiming the anemometer. I'm grappling with that same question as I consider siting my flagpole for this. I have a short pole for the system now and aimed it at Polaris as best I could. For a deeper discussion about "North" consider reading the WiKi about True, Celestial, and Magnetic Norths.

https://en.wikipedia.org/wiki/True_north

Magnetic North is changed periodically, so maybe Celestial is the more stable reference. "North" only refers to some arbitrary place until it is defined and fixed with a bench mark.
« Last Edit: November 03, 2015, 12:07:37 AM by yahtah »
-Lee

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working on an RPi webcam and a 30 ft. flagpole...

Offline CW2274

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Re: To go True or Magnetic
« Reply #21 on: November 03, 2015, 12:24:12 AM »
I think the real question here is how do we set a standard for aiming the anemometer. I'm grappling with that same question as I consider siting my flagpole for this. I have a short pole for the system now and aimed it at Polaris as best I could. For a deeper discussion about "North" consider reading the WiKi about True, Celestial, and Magnetic Norths.

https://en.wikipedia.org/wiki/True_north

Magnetic North is changed periodically, so maybe Celestial is the more stable reference. "North" only refers to some arbitrary place until it is defined and fixed with a bench mark.
I never even heard of "celestial north", and people thought I was making it too complicated!
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Offline CW2274

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Re: To go True or Magnetic
« Reply #22 on: November 03, 2015, 12:28:17 AM »
I think the real question here is how do we set a standard for aiming the anemometer. I'm grappling with that same question as I consider siting my flagpole for this. I have a short pole for the system now and aimed it at Polaris as best I could. For a deeper discussion about "North" consider reading the WiKi about True, Celestial, and Magnetic Norths.

https://en.wikipedia.org/wiki/True_north

Magnetic North is changed periodically, so maybe Celestial is the more stable reference. "North" only refers to some arbitrary place until it is defined and fixed with a bench mark.
The standard is your preference. 99% use true. Even thought it's only 10 degrees difference for me, I use magnetic.
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Offline yahtah

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Re: To go True or Magnetic
« Reply #23 on: November 03, 2015, 12:37:32 AM »
Just asking what level of accuracy do you want? How far will you go to calibrate your instrument? GPS? Is it accurate?

HAhaha!  :lol: I aimed mine at Polaris when I had a clear night. Celestial.

JMHO.  :grin:
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Offline CW2274

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Re: To go True or Magnetic
« Reply #24 on: November 03, 2015, 01:00:14 AM »
Just asking what level of accuracy do you want? How far will you go to calibrate your instrument? GPS? Is it accurate?

HAhaha!  :lol: I aimed mine at Polaris when I had a clear night. Celestial.

JMHO.  :grin:
Oh, that celestial! I thought that was true north because that's also what I used. I then dialed in my declination on the console.
As far as my level of accuracy, I have it dialed in to a presumable plus or minus of two degrees of magnetic. 
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