Slaving autopilot to a VOR?

BTIZ wrote:

lets see.. wing leveler and heading control... sounds close to roll
and
yaw..

"Dave Butler wrote:

To me an axis is
roll-pitch-yaw. Unless the autopilot controls two of those, it's a
one-axis
autopilot... but I'm swimming against the tide.

Dave is correct here. The # of axes in an autopilot refers to how many
axes of _controls_ it has feedback for - i.e. one for roll/ailerons (for
wing leveling and/or heading via roll), two for pitch/elevator (for
altitude and/or climb/descent rate) and three for rudder/yaw. Almost no
small GA autopilots are more than two axis, and many are only one axis.

With one axis, you can easily control heading - when you're at cruise
speed in most small GA aircraft, and you change direction with the
ailerons in anything less than a 30 degree roll, you hardly use the
rudders at all (I said MOST). Now consider that the autopilot generally
will roll no more than 5-10 degrees, and you can see that rudder control
is not required.

Pitch as a second axis, however, is nice to have.....

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004

if you are thinking about hooking up a VOR why not a GPS? The outputs
can be the same depending on the head configuration.

How can I hook up my autopilot to my AvMap's outputs?

Now THAT would be useful.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay,
There are so many possibilities that only a qualified avionics person
can answer if your GPS can be hooked up to your particular Autopilot.
I can tell you how the CRJ FMS works though ;-)
Michelle

Jay Honeck wrote:

if you are thinking about hooking up a VOR why not a GPS? The outputs
can be the same depending on the head configuration.



How can I hook up my autopilot to my AvMap's outputs?

Now THAT would be useful.



--

Michelle P ATP-ASEL, CP-AMEL, and AMT-A&P

"Elisabeth" a Maule M-7-235B (no two are alike)

Volunteer Pilot, Angel Flight Mid-Atlantic

Volunteer Builder, Habitat for Humanity

Do you have the Nav coupler ?
on your control panel for the AP, you dont have the switch to turn it to omni
or nav ?
if not thats the part you need.



Jay Honeck wrote:

My autopilot (2-axis, Piper) is hooked up to my DG, via a "heading bug."
Otherwise, it's just a wing leveler.

I've been told that this autopilot has the capability of being connected to
my VORs.

Can anyone outline what's involved with connecting the two?

Thanks!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

A one axis autopilot is a wing leveler. It may have features that allow it
to track a radial or GPS course or even to follow a heading bug or all
three. Even then it's a one axis autopilot. A two axis autopilot does that
plus holds altitude. A three axis autopilot will also control yaw. You see
these on a lot of V tail Bonanza's or any plane that is not that stable in
yaw. Some of these planes may have two separate autopilots. The first is a
typical two axis and a second totally separate autopilot to control yaw. A
buddy of mine has that setup on his Bo.



"Jay Honeck" wrote in message
news:tossc.53968$gr.5228519@attbi_s52...
I suspect what you have is something like a Piper Autocontrol? Two axis?
You
mean it has altitude-hold?

Hmm. I thought 3-axis was altitude-hold? Whatever, all mine does is
hold
the wings level, and follow the bug...

Thanks for the tips! I'd be interested to hear from folks who have these
things -- do they hunt all over, or can that be damped?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On 24-May-2004, "Jay Honeck" wrote:

I suspect what you have is something like a Piper Autocontrol? Two axis?
You mean it has altitude-hold?

Hmm. I thought 3-axis was altitude-hold? Whatever, all mine does is
hold the wings level, and follow the bug...

Thanks for the tips! I'd be interested to hear from folks who have these
things -- do they hunt all over, or can that be damped?
--


Jay,

My Arrow IV has the Autocontrol III (single axis) with nav coupling
(switchable between the 2 VHF Navs). There are actually four Nav modes that
can be selected. One is standard VOR. In this setting, the AP will "chase
the needle," resulting in gentle hunting in heading when the VOR signal is
not strong. A second nav mode also does VOR tracking, but with considerable
damping of the input signal. This results in much less hunting, and thus
this mode works best when the VOR signal is not very strong. There are also
LOC and LOC Backcourse (reversed sensing) modes that do a very good job of
intercepting and tracking the localizer during ILS approaches. In all
cases, the heading bug on the DG must be set to the intended course to give
the AP a datum for intercepting and tracking the nav signal.

Even IFR, I rarely use the VOR tracking feature of the AP. Instead, I use
heading hold and monitor the VOR needle. Actually, I primarily monitor the
moving map display of our non-IFR GPS (strictly for situational awareness,
of course) and adjust the heading bug to nail the exact course. I then
verify that he VOR needle is in agreement. So far, it always has been. If
there were ever a disagreement, I would have to rely on the VOR (after
verifying with the second Nav receiver, of course).

--
-Elliott Drucker

"Newps" wrote in message
...
A one axis autopilot is a wing leveler. It may have features that allow
it
to track a radial or GPS course or even to follow a heading bug or all
three. Even then it's a one axis autopilot. A two axis autopilot does
that
plus holds altitude. A three axis autopilot will also control yaw. You
see
these on a lot of V tail Bonanza's or any plane that is not that stable in
yaw. Some of these planes may have two separate autopilots. The first is
a
typical two axis and a second totally separate autopilot to control yaw.
A
buddy of mine has that setup on his Bo.



A yaw damper is a separate autopilot? Hmmm...I can see that!

BTIZ wrote:
lets see.. wing leveler and heading control... sounds close to roll and
yaw..

The ones I've seen have only one servo - the ailerons. They track heading by
controlling roll.


BT

"Dave Butler" wrote in message
...
To me an axis is

roll-pitch-yaw. Unless the autopilot controls two of those, it's a

one-axis

autopilot... but I'm swimming against the tide.

Jay,

We've got the same and ours is slaved to our VORs and LORAN (yes, LORAN).
Once you get it working it is nice for the price....) I'm not sure
what it takes to slave it, though.


Trip


In article iqrsc.53763$gr.5210911@attbi_s52, says...

My autopilot (2-axis, Piper) is hooked up to my DG, via a "heading bug."
Otherwise, it's just a wing leveler.

I've been told that this autopilot has the capability of being connected to
my VORs.

Can anyone outline what's involved with connecting the two?

Thanks!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message news:Esysc.1914$eT4.92@attbi_s54...
if you are thinking about hooking up a VOR why not a GPS? The outputs
can be the same depending on the head configuration.

How can I hook up my autopilot to my AvMap's outputs?

Now THAT would be useful.

If your autopilot supports nav coupling (ie has CDI L/R input pins and
some kind of a mode button to bring this into the control loop), you
can get a converter that generates the standard CDI voltages from an
NMEA RS-232 data stream, see the Smart Coupler on
http://www.porcine.com. Looks like it could be installed in a portable
manner via some panel jack, or get the "LE" model and hide it under
the panel good ;-)

I thought about doing this for the ARC 200A Fail-o-Matic in my
Cardinal, its not much of an autopilot, but it does work fairly well
in the VOR/LOC tracking mode, so the GPS input would make it slightly
more useful in the typical VFR GPS direct-to flying. I understand
people have done this with mixed results, however, the dampening
circuits in these units were designed for twitchy VHF nav, not the
ultra-steady GPS corrections. May need to use the "high-sens" mode for
that, if it has one (the ARC units have a button for that, used when
tracking a localizer).

Martin