Why The Hell... (random rant)

wrote:
On Apr 5, 5:37 am, "EridanMan" wrote:
On Apr 4, 5:23 am, "Steven P. McNicoll"
wrote:

"EridanMan" wrote in message
oups.com...
Why in gods name are VOR's Mag heading based?
Tradition.
Best answer I've heard yet

Isn't the difference between your compass heading and the radial you
are flying the drift? Knowing drift is pretty useful...

The correction angle maybe. You aren't drifting at all if you are
on the radial.

Mxsmanic wrote:
Ron Natalie writes:

No you are confused. Magnetic SOUTH is the exact opposite of magentic
north you fool. The fact that the MAGNETIC SOUTH POLE is not exactly
opposite the MAGNETIC NORTH POLE is a different issue.

I assumed that others would understand this, but I often get into trouble when
I assume others will understand things.

You expect others to understand things when you blither incorrect
concepts.

The fact that
the poles aren't aligned with the arbitrary "true" datum just means that
the variation equations aren't as simple as they might be.

They are more than just misaligned: they are not at opposite points in terms
of longitude and latitude, either. A line drawn between them does not
intersect the center of the Earth.

Correct, that was my point. It doesn't change anything. Magnetic
south and magnetic north are still opposite directions at any given
point on the earth.

Really, like what?

GPS and inertial reference platforms, VORs, NDBs, you name it.

GPS and INS use elaborate internal computation to determine it, yes.
Haven't ever seen an INS in anything smaller than a transport category.

NDB's chortle..you haven't a clue.
VORs not on your life, unless you're sitting on station.
You should learn something about navigation and geodessy before
you make these bogus statements.


Compasses are still damned reliable compared to
anything else. Cheap too. The only thing that presumes to do better
perhaps is GPS. And it's easier to program that to deal with the
magnetic measurements than to try to force everybody else the other
way.

So how often do you fly using just your magnetic compass alone?

Give me a chart and a compass and I'll do just fine VFR. Managed
to fly the Navion around just fine that way when I had all the
avionics and the gyros pulled out while I was redoing the panl.

Ron Natalie writes:

Correct, that was my point. It doesn't change anything. Magnetic
south and magnetic north are still opposite directions at any given
point on the earth.

They are close to opposite, but not exactly so.

Give me a chart and a compass and I'll do just fine VFR.

If you have a chart, you're not using your magnetic compass _alone_.

And even if you have a chart and a compass, how do you determine where you
are?

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Mxsmanic wrote:
writes:

A sensor to find true north in an airplane in flight doesn't exist.

GPS finds true north.

Nope, GPS finds a 3-d position based on the relative distances between
sets of satellites in geosynchronous orbit. It knows no more about
true north than magnetic without elaborate conversion between where
the satellites are at any given instant and where the earth is.

And, just incidentally, you can find true north by
looking at the sky. ANS will do that, and people can do it, too.

Funny, I'm looking at the sky today and all I see are clouds.
My compass still works.


The isogonic lines on a chart take care of all the problems of where
the actual north/south magnetic poles are.

Documenting them doesn't really eliminate them.

It gives you the tool, just like your beloved GPS knows how to find
the real north pole between the combination of the downloaded data
on where the satellites are and a substantial amount of information
on the shape of the earth inside it's internal database.


Unless the airplane is a glider, you have power.

You are clueless aren't you. The engine in just about every airplane
out there runs just freaking fine without any electrical power consumed
nor delivered to the rest of the aircraft.

One third correct: it requires power, but engines provide power. It doesn't
have to be set up against anything else to find true north. It doesn't need
to be constantly updated; the whole idea is to be fairly autonomous.


You are clueless. Your GPS is constantly updated or it won't work.
You put the thing in a box for a week or so or power it up in an
undisclosed location and it will DO NOTHING for you until it downloads
enough information to continue.

Mxsmanic wrote:
Tim writes:

Not all planes have GPSes. In fact, most don't.

That depends on what category of aircraft you're looking at.

Doesn't matter what category you are looking at. We've still
got transport aircraft with just steam gauges.


Many of the haldheld units fail.

How many? I've never seen one fail, although I'm sure it happens
occasionally. They don't even have any moving parts.

I've had them fail lots of times. All it takes is the battery to go doead.


The failure rate for compasses is quite low.

So is their accuracy, even when they are functioning perfectly.

Accurate enough. Reliable...never really have seen one fail.

Not really. It is unreliable. Its signals can be disrupted - rendering
them useless.

Magnetic bearings are constantly disrupted, everywhere on Earth.

Between your ears primarily.

You have an engine turning. That's power. And it can fail, just like
electrical power.

That power only propells the aircraft. There's no guarantee that it
provides electricity for avionics. I can tell you that I've been
in a number of aircraft where it did not, either by malfunction or
DESIGN.


Not in the real world. On a computer maybe...

Even in the real world. The purpose of INS is to have a way of navigating
without any external references; it's a very advanced and accurate
implementation of dead reckoning.

CHORTLE. Have you any experience with a real INS. A real INS can't
find squat without being told where it is starting from. This has
to be boostrapped from other navigational devices. It's long term
stability isn't any better than a compass. It needs additional
input.

It's useless for truth north unless you have a chart _and_ you know where you
are. Even for magnetic north, it can be substantially off. And just knowing
which way is north doesn't help you much, anyway.


Your GPS and INS are useless without a chart or their internal
electronic equivelent.

Mxsmanic wrote:
Nomen Nescio writes:

The category that has wings and goes up in the sky.

You mean like a 747-400? It has two GPS receivers, three IRUs, two VORs and
two ADFs. One rarely falls back upon the magnetic compass.

Once again you decide to generalize the entire realm of aviation
by your simplistic study of the simulation of one aircraft.

There are a great number of transport category aircraft with
neither INS nor GPS.

Mxsmanic wrote:
DR writes:

LOL! How do _you_ do that exactly?

I don't. I know the direction of true north at my location, and I don't go
anywhere else.

This is perhaps not only the truth, but the telling story of your
problem.

You don't go anywhere else.

Mxsmanic wrote:


That's one reason why I often like to fly big aircraft.

No you like to fly simulations of big aircraft.

Not all real airplanes have electrical systems.

True, and some are powered by rubber bands as well, but there's a lower
threshold below which I don't bother.

Yes, but you come here arguing that any outside your willingness
to simulate don't exist. This is makes you look pathetically
stupid and is the main reason that most people on this forum
are hostile to you.

wrote in message
oups.com...
On Apr 5, 5:33 pm, RomeoMike wrote:
DR wrote:

Declination in navigation is actually

something else but I'll let you googgle for it.

I'm not sure that's really true. In aviation we talk about variation,
but when I'm using 7.5' topo maps on the ground, declination is the term
used for the difference
between magnetic and true north. (See the bottom left of a US DOI
Geologic Survey 7.5' topo.)
Variation and declination are defined the same
If there's a more sophisticated use of the word declination in
navigation, I'm willing to be enlightened.

OK, it's celestial Nav. Stars are located by declination (angle from
the celestial equator) and RA. The geographical use of declination to
describe variation is the result of bad education propagating a
specilaized technical term into incorrect use IMHO. As I think about
it, how could a word derived from "decline" be related to horizontal
angle...?

Cheers MC

Declination also applies to the earth's magnetic field, and can be measured
and charted. However, its use generally involves an earth inductor compass.
(BTW, Lindberg apparently had one installed on the Spirit of St Louis; but I
don't know whether he ever commented on the ease of use in what obviously
qualified as a light aircraft.)

Peter

Ron Natalie writes:

CHORTLE. Have you any experience with a real INS. A real INS can't
find squat without being told where it is starting from. This has
to be boostrapped from other navigational devices. It's long term
stability isn't any better than a compass. It needs additional
input.

Not to find true north. It can find true north all on its own.

Your GPS and INS are useless without a chart or their internal
electronic equivelent.

I have a GPS with no chart and it's extremely useful.

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