Compass trouble

On Thu, 17 Apr 2008 09:46:24 -0700 (PDT), Steve - KDMW
wrote:

On Apr 17, 9:15*am, Jay Somerset wrote:
On Thu, 17 Apr 2008 02:03:18 GMT, (Drew





Dalgleish) wrote:
On Wed, 16 Apr 2008 05:19:27 +0000 (UTC),
(Alan) wrote:

In article (Drew Dalgleish) writes:

My home airport has a compass rose and I use that. Taxiing aroud and
getting lined up on each heading takes me quite a bit longer than
that. Having a helper would speed things I'm sure but if we consider
man hours since the OP was about mechanics time then double your
15minutes.

*It is easier to shut down and just turn the plane from heading to
heading manually.

I was going to ask how do you know if it's an accurate land
compass but it occurs to me that a GPS would do the job and then you
could do it by yourself .

*How?

*A GPS knows where it is, not which way it is facing.

* * * *Alan
Do it while flying. The GPS know which way it's going.

You really don't seem to understand -- heading and track are two
different things. *They are only aligned if you are flying directly
into, or away from, the wind.

So your GPS is pretty well useless in flight for aligning a compass,
as you can never tell precisely the wind direction aloft. *Certainly
not within the +/- 3 degrees that you should be trying to calibrate
against.
--
Jay (remove dashes for legal email address)- Hide quoted text -

- Show quoted text -

Someone explained it pretty clearly earlier... use the GPS on the
ground. Taxi slowly to get your heading/track where you want it then
stop slowly and smoothly.

Yes, if you have a large enough ground area to do that at the 6
different directions (back and forth) that you need. Most GA airports
do not have anything like that amount of space. You would have to taxi
for at least 50-100 yards to have a reliable track.

But yes, in theory, this would work.
--
Jay (remove dashes for legal email address)