A2A C172 Trainer autopilot does not work consistently

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David67
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A2A C172 Trainer autopilot does not work consistently

Post by David67 »

Hello, I'm not a pilot. I've read (pdf) the KAP140(?) autopilot manual, but seriously struggle to understand it. I've purchased the A2A Cherokee and use it successfully.

I've completed one successful GPS track flight with the C172, including adjusting height without issue. No idea how I managed that.

Now, all the plane wants to do is fly a continuous bank left, and either lose height or gain height.

Is there an easy to understand manual or explanation that does not require time and effort, as at my age I don't have the energy for it. It would be great to fly this plane on GPS tracks, as well as confidently use the heading mode, and easily adjust my height.

I doubt there is a refund or store credit, so hopefully I can at least acquire the basics of the autopilot.

Thanks for reading.

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Oracle427
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Re: A2A C172 Trainer autopilot does not work consistently

Post by Oracle427 »

Following GPS courses or any course for that matter can be done without the AP.

The autopilot behaves exactly like the real world unit so as long as you follow the real world steps, it will behave properly. I have used KAP140's in many aircraft I fly.

Firstly, to engage the autopilot, you must hold down the AP button for at least .25 seconds.

The AP baro setting must be adjusted to match the altimeter, everytime a new baro setting is used. This is done by pressing the Baro button and dialing in the new baro setting.

In order for the AP to get accurate course deviation information, the HSI must be maintained in alignment with the compass heading, you can do this manually using the VC knobs, or by pressing D. In real world flying I will align this on the ground prior to takeoff and then again every 30 minutes in the air.

The heading bug should be used even if not using the AP, but in order to use heading mode twist the VC knobs to set the bug where you want it. Then press the HDG button after engaging the autopilot using the AP button.

To follow a NAV signal, make sure the CDI Nav source is set to GPS or NAV depending on whether you are using a radio aid or the GPS. Then press NAV (assuming the AP is engaged).

Setting altitudes is a little more involved.

Always dial the altitude you will be flying at even when not using the AP. Good practice as it acts like a bug for you. The AP is always in a vertical and horizontal mode when engaged. It will hold the current rate of climb or descent when first engaged and will NOT level off at a preset altitude unless altitude capture is ARMed.

Pressing ALT alternates between ALT capture mode and VS mode. When the unit says VS, you can press the UP/DOWN buttons to specify the desired vertical speed. Pressing the ARM button will show ARM on the screen and indicate that the unit will capture the altitude dialed in. The screen will revert to show the selected altitude after a moment.

The GS button will allow you to capture and fly approaches with increased sensitivity to signal deviation. If flying an approach without vertical guidance, you can use the VS and ALT capture modes to set step down altitudes on your descent.

Practice makes perfect! This is a very faithful replica of the real world unit, so if you get the hang of it, you will be able to use the real one and many other autopilots for that matter. The stock FSX autopilots are extremely unrealistic in operation.
Flight Simmer since 1983. PP ASEL IR Tailwheel
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Nick - A2A
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Re: A2A C172 Trainer autopilot does not work consistently

Post by Nick - A2A »

Hello David - welcome to the A2A forums.

In addition to Oracle's great advice, there are a couple of other resources you may find helpful. One is this quick reference card for the KAP 140 autopilot which I came across a while back.

A short (5 page) PDF guide on the basics of operating the KAP 140 is available here too, if it helps.

The need to press the AP button for at least 0.25 secs to arm the AP as Oracle mentioned above is a safety feature of the real thing. It seems to catch quite a few people out.

Cheers,
Nick

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Lewis - A2A
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Re: A2A C172 Trainer autopilot does not work consistently

Post by Lewis - A2A »

Not sure how you are but for me personally videos can help a great deal so if you look at youtube you can find a great many videos from a great many authors to help you out, for example;

https://www.youtube.com/watch?v=HtWAebf0JkQ

https://www.youtube.com/watch?v=ok-mUQX7s7Y

hope this helps, thanks,
Lewis
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David67
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Joined: 04 Jan 2018, 15:08

Re: A2A C172 Trainer autopilot does not work consistently

Post by David67 »

Thanks for taking the time trying to assist. The reference PDF was a good idea, even though unsuccessful.

I've already spent a week watching those video's and trying to learn the system. Now after 1 flight and setting up a 2nd, I'm staring at a "NIL Value error message", and a non-functioning aircraft in FSX/A.

That's enough, thanks again.

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Oracle427
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Re: A2A C172 Trainer autopilot does not work consistently

Post by Oracle427 »

Have you downloaded and applies the updates?

http://a2asimulations.com/forum/viewtop ... 08&t=57819
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Lewis - A2A
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Re: A2A C172 Trainer autopilot does not work consistently

Post by Lewis - A2A »

Yes that does sound like you want to run the latest Updater to make sure you are all up to date

thanks,
Lewis
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David67
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Joined: 04 Jan 2018, 15:08

Re: A2A C172 Trainer autopilot does not work consistently

Post by David67 »

I had already applied the following updates before posting the issue:

1/17/17 update

10/12/17 update

flatH2Oav8r
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Re: A2A C172 Trainer autopilot does not work consistently

Post by flatH2Oav8r »

-- After some more trial and error I fixed the problem below by assigning AP buttons to hardware keys on my flight controls. For some reason using the mouse to push buttons on the screen was resulting in some wild behaviors --

Greetings, I'm brand new to A2A and downloaded the C172 for use with FSX to help get rid of some rust after not flying for six years. I'm using the AP and I've watched and read how it should function. When I set an altitude then press and hold the AP button in fairly level flight it drastically pitches up. When I look at VS it is set to 1,500 or more, not my current VS. I'm now also seeing issues where as I'm pushing the down button something else is automatically pushing the up button so I can't get it to work for me. Please let me know if you have any suggestions to figure out why it defaults to such a high VS and what could be working against me pushing the down button to reduce it. Thanks!

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