A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Piloting
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Compass Questions ?



 
 
Thread Tools Display Modes
  #1  
Old July 13th 15, 11:36 PM posted to rec.aviation.piloting
Bob
external usenet poster
 
Posts: 10
Default Compass Questions ?

Hello,

Not a Pilot, but always interested in the engineering aspects.

This question came up, and I realize that I am not sure of a correct answer.

Regarding the compass heading that shows in the glass displays:

How is it derived ?
GPS ?

If not GPS, what ?

Is it then Magnetic or True ?

Does the Pilot have to correct for variation/declination changes during
a flight ?

Does aviation use True or Magnetic when discussing or flying ?

etc. ?

Thanks,
Bob
  #2  
Old July 14th 15, 12:20 AM posted to rec.aviation.piloting
Larry Dighera
external usenet poster
 
Posts: 3,953
Default Compass Questions ?


Hello Bob,

I'm unable to provide the answer as to the technology employed by
computer-generated displays to display magnetic information, but I would expect
something like a Hall device might be employed. As you implied, it could as
easily be derived from GPS data corrected for magnetic variation at the
particular location.

Magnetic/compass headings are not true, but magnetic. Navigation Sectional
charts http://skyvector.com/ are depicted in True coordinates, and the
pilot/navigator must correct for magnetic variation in drafting his flight
plan. ATC expects all course/heading numbers to be magnetic.

You'll find more information he
http://www.faa.gov/regulations_policies/handbooks_manuals/, and he
http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2015.pdf.

Hope that helps.

Best regards,
Larry Dighera



On Mon, 13 Jul 2015 18:36:54 -0400, Bob wrote:

Hello,

Not a Pilot, but always interested in the engineering aspects.

This question came up, and I realize that I am not sure of a correct answer.

Regarding the compass heading that shows in the glass displays:

How is it derived ?
GPS ?

If not GPS, what ?

Is it then Magnetic or True ?

Does the Pilot have to correct for variation/declination changes during
a flight ?

Does aviation use True or Magnetic when discussing or flying ?

etc. ?

Thanks,
Bob

  #4  
Old July 14th 15, 11:47 AM posted to rec.aviation.piloting
Bob
external usenet poster
 
Posts: 10
Default Compass Questions ?

Hi,

Thanks for replies and help.

What I was referring to are the new, modern, "glass" displays where most
everything shown is derived
from transducers located elsewhere.

e.g. when a display shows a Heading of, e.g., 075, it is of course
getting this info. from some kind of transducer, located elsewhere.

Is it derived directly from GPS ?
A Hall effect compass ?
or,... ?

Thanks again; interesting subject.

Bob
-------------------------------------------------------------------------------------------------------------

On 7/13/2015 6:36 PM, Bob wrote:
Hello,

Not a Pilot, but always interested in the engineering aspects.

This question came up, and I realize that I am not sure of a correct
answer.

Regarding the compass heading that shows in the glass displays:

How is it derived ?
GPS ?

If not GPS, what ?

Is it then Magnetic or True ?

Does the Pilot have to correct for variation/declination changes during
a flight ?

Does aviation use True or Magnetic when discussing or flying ?

etc. ?

Thanks,
Bob


  #7  
Old July 14th 15, 06:01 PM posted to rec.aviation.piloting
Don Poitras
external usenet poster
 
Posts: 70
Default Compass Questions ?

Dave Doe wrote:
In article ,
, Dave Doe says...

In article ,
lid, Bob
says...

Hi,

Thanks for replies and help.

What I was referring to are the new, modern, "glass" displays where most
everything shown is derived
from transducers located elsewhere.

e.g. when a display shows a Heading of, e.g., 075, it is of course
getting this info. from some kind of transducer, located elsewhere.

Is it derived directly from GPS ?
A Hall effect compass ?
or,... ?

Thanks again; interesting subject.


Well I'm not sure on that - perhaps others will reply. However,
cellphones usually use one or more magnetometers (hope I spelt that
right ). A GPS can't get a magnetic heading, only True.

I play with Arduino's a bit - and Googling 'arduino magentometer' gives
a few results, eg...
http://bildr.org/2011/01/hmc6352/
http://bildr.org/2012/02/hmc5883l_arduino/
http://eclecti.cc/hardware/hmc5843-m...ry-for-arduino

I *assume* that the compass in a glass display uses the same sort of
technology.


Apologies to the apostrophe police - that's terrible!


--
Duncan.


The display in a glass panel is GPS course. You need a magnetic compass to know
your heading. The difference between the two is wind correction, magnetic
variation and compass deviation.

While I don't doubt that someone could create a device that would send
magnetic heading info to a glass panel, it would have to be some obvious
secondary display. You want to be looking at your true course if you want
to get from A to B.

--
Don Poitras
  #8  
Old July 15th 15, 11:36 AM posted to rec.aviation.piloting
Dave Doe
external usenet poster
 
Posts: 378
Default Compass Questions ?

In article , , Don
Poitras says...

Dave Doe wrote:
In article ,
, Dave Doe says...

In article ,
lid, Bob
says...

Hi,

Thanks for replies and help.

What I was referring to are the new, modern, "glass" displays where most
everything shown is derived
from transducers located elsewhere.

e.g. when a display shows a Heading of, e.g., 075, it is of course
getting this info. from some kind of transducer, located elsewhere.

Is it derived directly from GPS ?
A Hall effect compass ?
or,... ?

Thanks again; interesting subject.

Well I'm not sure on that - perhaps others will reply. However,
cellphones usually use one or more magnetometers (hope I spelt that
right ). A GPS can't get a magnetic heading, only True.

I play with Arduino's a bit - and Googling 'arduino magentometer' gives
a few results, eg...
http://bildr.org/2011/01/hmc6352/
http://bildr.org/2012/02/hmc5883l_arduino/
http://eclecti.cc/hardware/hmc5843-m...ry-for-arduino

I *assume* that the compass in a glass display uses the same sort of
technology.


Apologies to the apostrophe police - that's terrible!


--
Duncan.


The display in a glass panel is GPS course. You need a magnetic compass to know
your heading. The difference between the two is wind correction, magnetic
variation and compass deviation.

While I don't doubt that someone could create a device that would send
magnetic heading info to a glass panel, it would have to be some obvious
secondary display. You want to be looking at your true course if you want
to get from A to B.


The OP is asking about just about such a device. And it's clear they do
exist in a glass display (a compass that is).

Take for example, the Cessna website. If you navigate to say the Cessna
TTx - and check out the glass Avionics section, and look at Equipment
Details (rather than Standard Features), it specifies a Magnetometer ...
"GMU-44 Magnetometer (dual)"

Albiet a compass is almost obsolete and uncessary with todays navigation
equipment, but let's not forget runways - still lined up and named
magnetic. Makes me wonder when that will change.

--
Duncan.
  #9  
Old July 15th 15, 11:56 AM posted to rec.aviation.piloting
Don Poitras
external usenet poster
 
Posts: 70
Default Compass Questions ?

Dave Doe wrote:
In article , , Don
Poitras says...

Dave Doe wrote:
In article ,
, Dave Doe says...

In article ,
lid, Bob
says...

Hi,

Thanks for replies and help.

What I was referring to are the new, modern, "glass" displays where most
everything shown is derived
from transducers located elsewhere.

e.g. when a display shows a Heading of, e.g., 075, it is of course
getting this info. from some kind of transducer, located elsewhere.

Is it derived directly from GPS ?
A Hall effect compass ?
or,... ?

Thanks again; interesting subject.

Well I'm not sure on that - perhaps others will reply. However,
cellphones usually use one or more magnetometers (hope I spelt that
right ). A GPS can't get a magnetic heading, only True.

I play with Arduino's a bit - and Googling 'arduino magentometer' gives
a few results, eg...
http://bildr.org/2011/01/hmc6352/
http://bildr.org/2012/02/hmc5883l_arduino/
http://eclecti.cc/hardware/hmc5843-m...ry-for-arduino

I *assume* that the compass in a glass display uses the same sort of
technology.


Apologies to the apostrophe police - that's terrible!


--
Duncan.


The display in a glass panel is GPS course. You need a magnetic compass to know
your heading. The difference between the two is wind correction, magnetic
variation and compass deviation.

While I don't doubt that someone could create a device that would send
magnetic heading info to a glass panel, it would have to be some obvious
secondary display. You want to be looking at your true course if you want
to get from A to B.


The OP is asking about just about such a device. And it's clear they do
exist in a glass display (a compass that is).


Take for example, the Cessna website. If you navigate to say the Cessna
TTx - and check out the glass Avionics section, and look at Equipment
Details (rather than Standard Features), it specifies a Magnetometer ...
"GMU-44 Magnetometer (dual)"


Albiet a compass is almost obsolete and uncessary with todays navigation
equipment, but let's not forget runways - still lined up and named
magnetic. Makes me wonder when that will change.


--
Duncan.


You're right. I was wrong. It makes sense that the glass HSI would need
to work like the mechanical one and that gets set manually to the
current compass setting.

--
Don Poitras
  #10  
Old July 15th 15, 03:39 PM posted to rec.aviation.piloting
Dallas
external usenet poster
 
Posts: 541
Default Compass Questions ?

Bob wrote:

Regarding the compass heading that shows in the glass displays:



The heading information from the PFD comes from a directional gyro. The
directional gyro's drift is constantly corrected (slaved) by a magnetic
compass located in the tailcone on the airplane. The output of this compass
is electrically "enhanced" and amplified through a "flux gate".

Bottom line: A very accurate, stable, compass reading that never needs
adjustment.

--
Dallas
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB: PZL KI-13 Compass Romeo Delta Soaring 1 October 30th 17 08:47 AM
Still have a compass? [email protected] Soaring 19 November 22nd 13 11:33 PM
compass turns with high mounted compass (Cessna 152) Ray Instrument Flight Rules 22 April 7th 05 07:39 AM
Looking for a PZL compass Kirk Stant Soaring 8 February 12th 04 10:27 PM
Mig-29 questions & general aviation questions 2003 Steven Military Aviation 1 October 20th 03 06:06 AM


All times are GMT +1. The time now is 11:14 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.