Piper 3 Auto-pilot coupled to heading bug

[stapler101]

Excuse my lack of knowledge, but exactly what does the above mean?
My current AP will track the gps or vor.
I am not familiar with the piper 3 ap and I don't know what a heading bug is.

 

[Skip Miller]

Excuse my lack of knowledge, but exactly what does the above mean?
My current AP will track the gps or vor.
I am not familiar with the piper 3 ap and I don't know what a heading bug is.

A heading bug is a pointer on your DG, which can be set to any course by the pilot using a knob on the face of (or next to) the DG. It looks like the knob you use to set the DG to the mag compass heading, but on the other side.

An autopilot that follows the heading bug will steer any course you select on the DG.

Click on the link. In this case, the bug is yellow.

http://www.tghaviation.com/ProductDetails.asp?ProductCode=1U262-007-40


-Skip

 

[markb5900]

That is what we have in the rental's I fly. Basically it is a wing leveler. When flying IFR it can be REALLY nice to have. And as Skip stated, there is a heading bug on your DG and it will follow wherever you put it. (if it is working Properly)

Mark B

 

[flyingcheesehead]

Excuse my lack of knowledge, but exactly what does the above mean?
My current AP will track the gps or vor.
I am not familiar with the piper 3 ap and I don't know what a heading bug is.

A heading bug is a little arrow or similar shaped piece in the DG that can be adjusted. If you're flying a plane with an autopilot, you probably have one. If there are two knobs on the DG, one of them adjusts the card in the DG (to match the compass) and the other adjusts the heading bug. Then, when you adjust the heading bug to a new heading, the autopilot will turn to and fly that heading.

Pretty much any autopilot except for the simple wing-leveler variety will do that - And if you are flying an autopilot that tracks GPS or VOR, you should already have a heading bug.

 

[stapler101]

thanks for the replies.
My DG does not have a heading bug (only one knob to adjust the dg to the compass).
My autopilot is a wing leveler but it will track following my garmin 300 or it will track to a vor.
Is the heading bug above better than a gps linked autopilot?

 

[SCCutler]

Unusual to have an autopilot without a heading bug.

Does your autopilot controller include a rotary knob with "NAV OMNI HDG LOC-NORM and LOC-REV" settings?

In most installations, you'll find that the HDG ON switch (on th e right) will link up with either a nav source, or the heading bug, depending upon the position of the rotary selector referenced above.

If you want the autopilot to follow GPS steering commands (as opposed to simply holding a course to which you are navigating with the GPS), you'll need the ability to select heading mode with the autopilot... which the Autocontrol II can certainly do with ease.

 

[bbchien]

I have no idea what a piper 3AP is. If it's a Century III relabeled by Piper, the DG has been switched to a cheaper one w/o a heading bug and you do not have a useful position in the autopilot heading input to select the DG heading as the input.

Let's start out by finding out which system you are actually talking about....

 

[gismo]

I have no idea what a piper 3AP is. If it's a Century III relabeled by Piper, the DG has been switched to a cheaper one w/o a heading bug and you do not have a useful position in the autopilot heading input to select the DG heading as the input.

Let's start out by finding out which system you are actually talking about....

IIRC the Piper AutoControl III is indeed a rebadged C-III although I also have a vague recollection that Piper's III might be a C-II.

In any case the OP doesn't say he has a "Piper 3", he was just reading about it and wondered what a heading bug was.

 

[SCCutler]

I was presuming that it was an Autocontrol III, which is (of course) a Century II.

 

[ScottM]

I have no idea what a piper 3AP is. If it's a Century III relabeled by Piper, the DG has been switched to a cheaper one w/o a heading bug and you do not have a useful position in the autopilot heading input to select the DG heading as the input.

Let's start out by finding out which system you are actually talking about....

Bingo

I have this same AP and I also have a DG with a heading bug. It is surprisingly accurate and works off of a voltage generated by the CDI. I like the AP a lot. I like that it can also be selected to fly back courses during approaches so can be used to help you in not only straight forward nav situations. The heading bug feature is nice when you are given a vector to fly. Then you would take the AP out of NAV/VOR or GPS mode, dial in the heading and off you go.

 

[stapler101]

thanks again
I do not have the ap in question, I saw it in an ad for a plane that I was considering.
My dg does not have a heading bug.

 

[poadeleted20]

I have no idea what a piper 3AP is. If it's a Century III relabeled by Piper,

Pretty much so. The Century II is a single-axis unit, while the C-III is basically a C-II plus pitch command and altitude hold. They are identical in operation in the roll modes.

the DG has been switched to a cheaper one w/o a heading bug and you do not have a useful position in the autopilot heading input to select the DG heading as the input.

In addition, the C-II/III will not accurately track a non-GPS nav system (i.e., VOR or LOC) without a heading bug. For GPS, it will still track if you have a roll steering (GPSS) module, but not if you don't. See the C-II/III manuals for more on these systems at www.centuryflight.com/manuals/CENTIII.pdf and www.centuryflight.com/manuals/CENTIIB.pdf.

 

[gismo]

Pretty much so. The Century II is a single-axis unit, while the C-III is basically a C-II plus pitch command and altitude hold. They are identical in operation in the roll modes.
In addition, the C-II/III will not accurately track a non-GPS nav system (i.e., VOR or LOC) without a heading bug. For GPS, it will still track if you have a roll steering (GPSS) module, but not if you don't..

AFaIK a C-II or III installation requires a heading source per the STC so any installation in a certified airplane without a heading bug on the DG (or a HSI) is probably not airworthy. That said, I would repeat that no such setup was suggested by the OP, he just read about a heading bug in an airplane listing and wondered what it was. His only experience with autopilots to date appears to be limited to wing levelers.

 

[poadeleted20]

AFaIK a C-II or III installation requires a heading source per the STC so any installation in a certified airplane without a heading bug on the DG (or a HSI) is probably not airworthy. That said, I would repeat that no such setup was suggested by the OP, he just read about a heading bug in an airplane listing and wondered what it was. His only experience with autopilots to date appears to be limited to wing levelers.

OK, I got confused between his plane and the one he is looking at.

In the case of the C-II/III, the heading bug is used both to command a heading to fly (in the HDG mode) and to establish a baseline course direction for non-GPSS nav tracking (NAV, OMNI, LOC, and LOC REV modes). It is out of the loop when using GPSS roll steering via a roll steering module (not included in the C-II/III itself).

 

[gismo]

OK, I got confused between his plane and the one he is looking at.

In the case of the C-II/III, the heading bug is used both to command a heading to fly (in the HDG mode) and to establish a baseline course direction for non-GPSS nav tracking (NAV, OMNI, LOC, and LOC REV modes). It is out of the loop when using GPSS roll steering via a roll steering module (not included in the C-II/III itself).

All correct. The C-II/III's "computer" is nothing more than a weighted summing node that combines the heading error (difference between the heading bug and the lubber line), nav error (analog signal that drives the nav head needle), and bank angle (from the AI) to produce a drive voltage to the roll servo motor proportional to the sum of the aformentioned signals.

 

[jstryker]

I located your post through google and am new to posting generally, but would appreciate some advice.
The electric turn coordinator on my 1979 Piper Cherokee Archer II is making a lot of noise and I have been told that it is on its way out. This t/c was new about 3 years ago, so it certainly didn’t last too long.

I have been told that the turn coordinator is powers my Piper Auto Control III auto pilot. However, I recently read your post where you say that this auto pilot is a Century C-II which is “a weighted summing node that combines the heading error (difference between the heading bug and the lubber line), nav error (analog signal that drives the nav head needle), and bank angle (from the AI) to produce a drive voltage to the roll servo motor proportional to the sum of the aformentioned signals”. If that is the case, it doesn’t sound like the turn coordinator is involved.

In any case, I think I should replace the t/c and am wondering if it would be better to replace it with a backup electrical Attitude Indicator or Artificial Horizon (are these the same?). If I do that is a inclinometer required with it? If I did that would it affect the operation of the AP? I would really appreciate your advice.