Autopilot - unable to preselect.

Bert Pieke

@eker said in Autopilot - unable to preselect.:

Thanks.
The engage button on KAP140 is really a troublemaker. Do not touch....
My new procedure:
Only select desired alt on ground. Scroll knob.
Lining up on runway - Set bug on rwy heading.
After TO - hit AP hdg button. AP instantly engage.
AP pitch mode is now set to actual pitch or vs . I am not sure which- but now you can adjust vs with up/down buttons.

Kind of... For me, it starts in PIT mode which is not what the RW unit does.. It starts up in VS mode. That matters because only VS mode can be adjusted via the up/down buttons..

MiRexer

Here's the workflow I've come up with. Set altitude for the autopilot on the ground. After takeoff get the plane trimmed for a normal climb then engage the autopilot and heading mode. It's now in pitch and Alt Arm mode and I can use the CWS button on the yoke to adjust the pitch attitude. Once it captures the target altitude then I can change the target altitude and hit alt to put it in VS and Alt Arm mode and use the up down to set the climb/descent rate.

I have sometimes been able to get it back into a pitch mode but I haven't yet figured out the magic combination to do so.

Here's the KAP140 manual - it does talk about a CWS button in it: https://www.bendixking.com/content/dam/bendixking/en/documents/document-lists/downloads-and-manuals/006-18034-0000-KAP-140-Pilots-Guide.pdf

Bert Pieke

A better way, I believe, is to get rid of Pitch mode entirely (as in the real unit).

A brute force hack is adding this to an interior model xml file, in an Update section:

(A:AUTOPILOT ATTITUDE HOLD, bool) if{ (>K:AP_PANEL_VS_SET) }

Hopefully Nick @Black-Square has a better way..

eker

@MiRexer said in Autopilot - unable to preselect.:

Here's the workflow I've come up with. Set altitude for the autopilot on the ground. After takeoff get the plane trimmed for a normal climb then engage the autopilot and heading mode. It's now in pitch and Alt Arm mode and I can use the CWS button on the yoke to adjust the pitch attitude. Once it captures the target altitude then I can change the target altitude and hit alt to put it in VS and Alt Arm mode and use the up down to set the climb/descent rate.

I have sometimes been able to get it back into a pitch mode but I haven't yet figured out the magic combination to do so.

Here's the KAP140 manual - it does talk about a CWS button in it: https://www.bendixking.com/content/dam/bendixking/en/documents/document-lists/downloads-and-manuals/006-18034-0000-KAP-140-Pilots-Guide.pdf
.

Seems to be similar to Learjet 35. Only way to adjust pitch - you have to map a toggle switch on stick.

MiRexer

@eker Exactly like the Learjet 35a - but I haven't found a reliable way to reengage it once VS mode has been enabled. I've occasionally hit on something that allowed it but haven't nailed it down yet.

Bert Pieke

Guys.. the KAP140 autopilot does not have Pitch mode.. end of story

lehbird

@Bert-Pieke said in Autopilot - unable to preselect.:

Guys.. the KAP140 autopilot does not have Pitch mode.. end of story

MiRexer

Well there is on this one - it even says "PIT" on the panel.

The only mention of the CWS button in the KAP 140 manual is this:

"2. “CHECK PITCH TRIM”- An
out of trim condition has existed
for 15 seconds.
a. Airplane Control Wheel
GRASP FIRMLY, press CWS
and check for an out of pitch trim
condition. Manually retrim as
required.
b. CWS button - RELEASE.
c. AUTOPILOT OPERATION
CONTINUE if satisfied that the
out of trim condition was tempo
rary. DISCONTINUE if evidence
indicates a failure of the auto trim
function."

So it looks like the only use of it IRL on the KAP140 is to check for an out of trim condition and correct it (so that the airplane doesn't "SNAP" when you turn the autopilot off - I've personally experienced this IRL on simple autopilots).

Black Square

To interject, I believe my rationale for the pitch mode back when I created this was that MSFS doesn't really have altitude arming like you think it does. This means that defaulting to VS mode can have some unexpected behavior depending on selected altitude. Of course, this was a decision probably made three years ago when I knew a lot less about how to reliably create workarounds for these things. I will look into it, what you're seeing now exists because it was a "safe" solution to a shortcoming in the simulator.

Bert Pieke

Thanks for agreeing to look into this.. I am sure a solution can be found.