Slaving autopilot to a VOR?

[Jay Honeck]

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"

[Dave Butler]

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!

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

Well, anyway, I think what you need is something like this MITCHELL RADIO
COUPLER FOR CENTURY III AUTOPILOT
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=26436&item=2479416829

....but (assuming all my assumptions above are true) I predict you won't like it.
If there's any unsteadiness at all in the VOR signal, the autopilot will
follow the swinging CDI. There's some damping built into the coupler, but
still... Even when the VOR signal is rock-steady, all (well, OK, 2) the
installations I've seen will "hunt" back and forth across the centerline of the
signal. There might be a sensitivity adjustment that will correct this.

When I had one, I nearly always used it in heading (not NAV) mode, except for
the occasional coupling with a localizer for instrument practice. Actually, I
always felt guilty using it on the localizer. It made the approach too easy.

Dave

[Jay Honeck]

> 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"

[Dave Butler]

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...

You're right. In common usage, wing-leveler plus heading mode equals a two-axis
autopilot. I've always rebelled against that usage. 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.

>
> 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?

Dave
Remove SHIRT to reply directly.

[Marc J. Zeitlin]

Jay Honeck writes:

> 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?

I have a single axis autopilot (Navaid) in my homebuilt. I have it
hooked up to my Garmin 195 GPS or to my Narco 122A NAV (via a switch).
Tracking the GPS is rock solid - no hunting whatsoever. Tracking the
VOR is a roller coaster. I watch the CDI needle, and it's always
jumping around a bit, and the AP tries to follow it, even when it goes a
dot to the left, and then two seconds later, a dot to the right.

The problem is in the VOR, not the AP - if your VOR CDI needle is
jumping around a bit, so will the AP when trying to track it. If your
VOR needle stays stuck (no clue if this jumping is a function of MY
receiver or of the inaccuracy of the basic system), then you'd probably
be OK tracking with the AP.

If I track an ILS/LOC, which never jumps around on my CDI, the AP is
solid, so I know it's not the VOR/AP combination.

At any rate, if it's easy to connect, give it a try. If not, don't
bother, especially if your needle is jumpy.

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

[Ray Andraka]

My STEC 20 is slaved can be slaved to my #1 VOR or to my Loran. It has front
panel selection of high and low sensitivity modes. Normally, for VOR's you'd
use the low sensitivity mode to minimize the manuevering to stay on a scalloped
signal. It flies a VOR radial just fine, no obvious hunting. It is a single
axis autopilot.

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 Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

[PaulaJay1]

In article <tossc.53968$gr.5228519@attbi_s52>, "Jay Honeck"
> writes:

>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

The Autocontrol III in my Archer has switches that allow it to track a VOR, the
LORAN, or the GPS. The LORAN and the GPS (Garmin 430) do a better job of
flying a heading and not wandering but I wouldn't say the the VOR is bad. If
you are tracking a VOR that is distant and the signal is weak, you might be
better to watch the needle and use the heading bug, but if you are close (30
miles) and have a good signal, there isn't much of a problem. Get a 430 though
and you will think that you are on rails!

Chuck

[Michelle P]

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

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!
>
>

--

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

[Aaron Coolidge]

Dave Butler > wrote:
: ...but (assuming all my assumptions above are true) I predict you won't like it.
: If there's any unsteadiness at all in the VOR signal, the autopilot will
: follow the swinging CDI. There's some damping built into the coupler, but
: still... Even when the VOR signal is rock-steady, all (well, OK, 2) the
: installations I've seen will "hunt" back and forth across the centerline of the
: signal. There might be a sensitivity adjustment that will correct this.

I also predict that Jay won't like it. I have an "Autoflite I" with the NAV
coupler. When coupled to the NAV (NAV1, FWIW), the needle stays dead centered.
But, look at the ground track on the GPS! It's moving all over! Who's flying
this thing?

Seriously, unless you're right on top of the VOR, or it's a Doppler VOR
(DVOR), the radials move around. A lot, in fact. The only steady one that
I routinely fly over is JFK.

When the autopilot is coupled up to the GPS following a radial, the VOR
needle moves around. The GPS guides the airplane where the radial is
supposed to be! This can get a bit nerve-wracking, especially if you're
flying, say, V3 in the gauntlet between ORL's "B" and Cape Canaveral's
restricted areas.

--
Aaron Coolidge

[BTIZ]

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

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.
>

[Marc J. Zeitlin]

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

[Jay Honeck]

> 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"

[Michelle P]

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

[Jeff]

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"

[Newps]

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"
>
>

[[email protected]]

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

[Tom Sixkiller]

"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!

[Dave Butler]

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.
>>

[TripFarmer]

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....:o) 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"
>
>

[Martin Kosina]

"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

[Kai Glaesner]

Martin,

> > 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 ;-)

But even it's possible technicaly, I guess nobody would let you do it, just
because the AvMap is a handheld unit (even if Jay straps it on his knee ;-)

Regards

Kai

[Martin Kosina]

"Kai Glaesner" > wrote in message >...
> Martin,
>
> > > How can I hook up my autopilot to my AvMap's outputs?
> > >
> > > Now THAT would be useful.
> >
Porcine Smart Coupler Info <snip>
>
> But even it's possible technicaly, I guess nobody would let you do it, just
> because the AvMap is a handheld unit (even if Jay straps it on his knee ;-)

Yeah, this is one of those things you probably don't want to ask
about, just install the box in a semi-portable way (quick-disconnect,
zip-tied) and be done with it. Remove before annual.

[Jay Honeck]

> > But even it's possible technicaly, I guess nobody would let you do it,
just
> > because the AvMap is a handheld unit (even if Jay straps it on his knee
;-)

It's now "semi-permanently" yoke-mounted.

I used such a strong, industrial-strength Velcro that I can't remove it from
the yoke mount!
;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"