 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Tim Olson
Joined: 25 Jan 2007
Posts: 2881
|
 Posted: Fri Dec 28, 2007 7:51 am Post subject: Compass Requirements in Experimental Aircraft (updated) |
 |
|
Another builder asked me to forward this because he's on
vacation, but wanted to join in the thread:
"But another very important issue regarding magnetism is that the steel
parts in the plane can pick up residual magnetism from permanent magnets
and it can be a real problem to sniff out and get rid of with a
magnaflux (I think he means degaussing -Tim) tool. I believe a I made
a complete posting regarding this in the RV10-list archive. But even
the helical steel coil in scat tubing is capable of causing totally
eronous compass readings. I had this occur when we re-did the
instrument panel in our glastar. I even avoid using magnetic tip tools
now that I've seen how difficult it can be to solve the residual
magnetism problem.
-bob newman
Tim Olson wrote:
| Quote: |
So one of the morals to the story is that magnetic base antennas
have no place in an airplane. They won't just screw with your
nearby compass but can screw with your much more sensitive EFIS
magnetometer as well. Any antenna with a magnet should be cut
apart and have it's magnet yanked...if you're going to use it
in the plane.
Tim Olson - RV-10 N104CD - Flying
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
 |
bicyclop(at)pacbell.net
Guest
|
| Posted: Wed Jan 02, 2008 11:03 pm Post subject: Compass Requirements in Experimental Aircraft (updated) |
|
|
Hmmm, it never occurred to me to setup the GPS for true instead of magnetic. I can see how it would be confusing. Every moving map GPS I've ever played with has some sort of setup page where you can decide between true and magnetic as well as North up or track up. My preference is magnetic and track up.
It has been quite a while since I last drew a line on a chart, used a plotter to find the true course and then converted it to magnetic using the local variation. I tend to use a flight planning program which gives my course bearing in magnetic, figures the time enroute and fuel burn and even takes into account winds aloft at my planned altitude. Even then, I just enter the destination in the GPS and go direct most of the time. If the track and the direct to numbers are the same, my heading is correct no matter what the DG or compass may say. As long as the ETE + 45 minutes and the time remaining on the fuel totalizer jibe, it's all going to be OK.
When ATC issues a vector, I turn to it on the EIFS (DG to those who have 'em). It usually isn't that different from the GPS track, but I can see how it might be off a ways if there are strong crosswinds (or lots of precession). ATC really doesn't care a whole bunch about what your actual heading is. They can't tell anyway. When they tell you to fly a heading, they are looking for a resultant radar track. If that track is not what they want from you, they'll ask for another 10 or 15 degrees of heading change from you. The whole concept of flying headings came from a time when you had no realtime way of knowing what your track was, but track is what we are always trying to accomplish. Knowing the difference between actual track and heading tells use what the winds are doing, but staying on course is all about track. Heading is still the language that ATC is required to use, but they'd probably be happier dealing with track since that is what they display. I have often heard ATC ask folks what their "heading" would be to such and such destination, and you can bet that the pilots look at the direct to bearing on the GPS for the answer. Armed with that, the controller knows, with some degree of confidence, what the radar track will be and whether it will conflict with other traffic.
Pax,
Ed Holyoke
MauleDriver wrote: [quote] Robert Feldtman wrote:
| Quote: | Secondly - most of us use our GPS to set our DG anyway - not the compass.
|
Is that true? I am under the impression that it continues to be necessary to set the DG relative to magnetic north in order to correctly respond to vectors.
I believe that ATC gives only magnetic heading vectors (though it seems that it's time to go to true headings). It's an important issue in IFR ops but still relevant in VFR. Usually it doesn't make much of a difference but I just did 400 miles in 45knot winds at 8,000 and below it really did make a difference. (BTW, it was a glorious tailwind!)
Do many of you use the GPS to set your DG? I navigate with by GPS, follow vectors using my DG, use my compass to set my DG, and constantly try to discern the meaning of the difference between the two.
Perhaps I can simplify things a bit. Thinking it through, I could easily keep my DG set to my desired GPS course. But I would then have to remember to reset it or at least check it when getting vectors. I usually only get vectors at the beginning and end of flights. But I guess I've just learned to use my GPS as primary during point to point navigation and use my DG as primary during vectors and put up with the difference between the two.
Bill "can't wait to get that 45 knots all the time when I move to an RV10" Watson
[b]
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
MauleDriver(at)nc.rr.com
Guest
|
| Posted: Thu Jan 03, 2008 5:54 am Post subject: Compass Requirements in Experimental Aircraft (updated) |
|
|
Jim Baker wrote: | Quote: | | Quote: | | Quote: | I believe that ATC gives only magnetic heading vectors (though it seems that it's time to go to
true headings). |
|
| Quote: | | Quote: |
I'll second that. My current job is a contract procedures
development specialist for the FAA and the things we see with
facility Mag Var issues would make most folks cry.
A lot of the facility Mag Vars go back to the 60s, 70s and 80s.
Consider what happens when you have an NDB with a 60s Mag
Var, a nearby VORTAC with a 70s Mag Var, and an ILS with an
80s Mag Var.
ZZV ZANESVILLE VOR/DME Variation: 06W (1990)
TVT TIVERTON VOR/DME Variation: 03W (1965)
Only 32 miles from each other. If you saw how much havoc
changing just one Mag Var causes, which you really can't do
efficiently because of the ripple effect....change one, you'd better
be prepared to change a lot of them. That's why Mag Vars don't
get changed often.
Personally, I'm hoping for the pole reversal........
|
|
|
Accommodating the legacy of past technologies is like having a 2 ton stone around one's neck! Arrrrghhhh! I can't even imagine. On one hand we all want to move ahead as fast as possible, on the other, none of us want any piece of equipment we use to become obsolete. The whole VOR infrastructure is down there but I haven't tuned one in since my last training exercise. And in 7 or 8 years of instrument flight, I've never been asked to intercept a radial (even a hold). They are handy waypoints though.
When is the next pole reversal predicted? I guess I'm dead then huh?
[quote][b]
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
