Compass swinging?

"Matt Barrow" wrote in message
...

Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html


Less prone to what kind of errors?

"Stan Prevost" wrote in message
...

"Matt Barrow" wrote in message
...

Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html


Less prone to what kind of errors?
Turning, acceleration, deceleration...

"Matt Barrow" wrote in message
...

"Stan Prevost" wrote in message
...

"Matt Barrow" wrote in message
...

Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html


Less prone to what kind of errors?

Turning, acceleration, deceleration...



The ones I have flown with, and installed in my airplane, have those same
errors as the whiskey compass, because they work on the same principle, they
are just geared to indicate direction with a vertical card. They do seem to
be more stable in turbulence. Well, actually I haven't tested acceleration
and deceleration, but turning errors seem to be the same.

The main advantage I find in a vertical card compass is the more natural
presentation they give, it doesn't seem backward like the whiskey compass,
and matches the presenation on other directional instruments.

RST Engineering wrote:
C'mon Roy, you've been around airplanes long enough to know the real
answer -- "Why that compass card has been in the airplane since I bought
it."


Same reaction here. Doesn't everyone here have at least two GPS's
onboard that show a ground track bearing 10 times better than the
compass? No lecture about the difference between heading and ground
track please. We're all adults here.

In real life, ATC just wants you to fly from point A to point B in a
straight line. If you're being vectored in anything slower than 250
knots, ATC can't care less if you're flying a 180 degree track bearing
instead of holding a wobbling 185 heading in a 15 knots bumpy
crosswind. They eyeball your radar track after drinking half cup of
coffee, and turn you 10 degrees if need to.

On Sat, 25 Nov 2006 16:14:36 -0700, "Matt Barrow"
wrote:


"Mike Noel" wrote in message
...
ps Check out:

http://www.firstmarkaerospace.com/standbycompass.asp


Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html

I've had a vertical card compass for years. The Deb had one in it when
I go it so I'd hardly call it a new, let alone "totally new" concept.
Like a whisky compass it does not give the proper heading at all
times. You still have the lead and lag in turns and it won't set
still in turbulence, but it has far less movement than the whisky
compass in turbulence.

Swinging one is about the same. Just don't use runway headings unless
you know they are right. Ours are about 6 degrees plus so 360 is
really 006 and 060 is really 066. Hence the compass rose at some
airports and that set of tools in the instrument shop.





Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Sat, 25 Nov 2006 20:14:12 -0700, "Matt Barrow"
wrote:


"Stan Prevost" wrote in message
.. .

"Matt Barrow" wrote in message
...

Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html


Less prone to what kind of errors?
Turning, acceleration, deceleration...

I've been flying behind one for a long time and they suffer from the
same errors. You just don't see them tipping like the whisky compass.



Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

In article .com,
"M" wrote:

C'mon Roy, you've been around airplanes long enough to know the real
answer -- "Why that compass card has been in the airplane since I bought
it."

Same reaction here. Doesn't everyone here have at least two GPS's
onboard that show a ground track bearing 10 times better than the
compass?

Nope. not even one GPS. not even a handheld.

--
Bob Noel
Looking for a sig the
lawyers will hate

"Roger" wrote in message
...
On Sat, 25 Nov 2006 16:14:36 -0700, "Matt Barrow"
wrote:


"Mike Noel" wrote in message
m...
ps Check out:

http://www.firstmarkaerospace.com/standbycompass.asp


Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalo...rd_compass.php
and http://www.pai700.com/index.html

I've had a vertical card compass for years. The Deb had one in it when
I go it so I'd hardly call it a new, let alone "totally new" concept.
Like a whisky compass it does not give the proper heading at all
times. You still have the lead and lag in turns and it won't set
still in turbulence, but it has far less movement than the whisky
compass in turbulence.

I'd say about one-fourth the movement in any case. What surprised me was how
much less overshoot/undershoot there was during turns. I suspect it's from
being mounted in a jeweled gimbal (?) which dampens movement, instead of
floating in water

The only times (I think) that a whiskey compass is any good is on the ground
or in dead still air during 1.0G accell/decell.

How pilots used to navigate with them alone (wait for some cementhead to say
"they used watches and maps, too") is a testament to their skills.

"Bob Noel" wrote in message
...
In article .com,
"M" wrote:

C'mon Roy, you've been around airplanes long enough to know the real
answer -- "Why that compass card has been in the airplane since I
bought
it."

Same reaction here. Doesn't everyone here have at least two GPS's
onboard that show a ground track bearing 10 times better than the
compass?

Nope. not even one GPS. not even a handheld.


Infidel!!

Roy Smith wrote:
I've got AC 43.13-1B, which describes the procedure to swing a compass.
What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
and what paperwork follow-up is required (airframe logbook entry, or is
just making the new compass card sufficient?).


Recently the compass rose has come up office conversation and who,
when, how, and what type of compass survey should be accomplished. I
can assure everyone reading this not all airport have a surveyed
compass rose (calibrated). Many airports have compass roses that may
not be accurate due to underground pipes or other metal objects that
will affect the accuracy of the survey.

The FAA has published a document FAA No. 405, Standards for
Aeronautical Surveys and Related Products that explains why and how a
compass rose should be surveyed.

Next who can perform the calibration to your onboard compass installed
in your aircraft? Only a Repair station with the proper ratings with
the proper training, current manuals available, and proper tooling.
This is where it may get sticky for some. FAR 65 Subpart D for
Mechanics does NOT allow Airframe rated mechanic to calibrate
compasses. Only a repair station with the proper rating can perform
this task. FAR 65.81(a) excluded airframe mechanics form performing
maintenance, major repairs to, and major alterations of, propellers,
and any repair to, or alterations of instruments. FAR 1.1 under
maintenance explains calibrations are considered a repair. So this
just leaves repair stations to adjust your compass.

Needless to say a pilot cannot perform this task as it is not
considered preventive maintenance.

AC 43.13-1B does explain how to perform a compass swing and is
acceptable data however the compass rose has to be surveyed to make it
legal. The repair station will make an airframe record entry stated
what data the followed such as AC 43.13-1B, chapter 1, section 3. FAR
23.1327 explain the installed compass has to be accurate and all
compasses are classified as instruments.

Bottom line is the compass rose has to be surveyed (check with your
local airport) and a repair station has to perform the compass swing
and make a airframe record entry.

Stache