Mooney M20R - Change AP Altitude Reference Value

It’s s PITA to change the altitude reference value in flight through the virtual cockpit manipulators in the Mooney M20R Ovation.

I tried to assign controller switches to change the altitude reference values for the autopilot. But the usual controls ‘Decrease Altitude’ / ‘Increase Altitude’ that work in other GA aircraft (e.g. Skyhawk) seem to not work out as expected.

Does any of you fellow simmers know how to achieve this?

No !! I just wrote an email to Carenado to ask them to fix this ! There are some strange things with the trim which is working with switch OFF, all this makes the altitude capture with the Monney impossible.
Wait for the fix …

Well, I do not have a problem with the Mooney capturing the altitude. Once I get the altitude set in the Selector and armed it will perform the climb or descent properly and level off at the preset altitude.

It’s just the fiddling with the manipulators in the virtual cockpit what is an annoyance. Also the display of the digits in the KAS 297B selector gets unreadable when changing the value. I need to zoom out and in again to get a readable display.

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The most difficult (… impossible ?? ) is to set the altitude and VS …

and when you push VS and the plane starts to descent -500 fpm? I doubt that is the way the real plane do

I just wish there was a way to either change the default fpm value or preload it before hitting arm

Actually, the value of the preset for the vertical speed can be adjusted using the controls CTRL-PgUp and Ctrl-PgDown (or any other assigned controls). It’s only the value of the preset for the altitude that can’t be assigned.

According to the Bendix manual, there are two ways to engage VS mode.

First is ‘Vertical Speed Preselect’. Adjust the VS preselect value in the KAS 297B selector and press the ENG button while the value is displayed. Altitude Hold, if engaged, will be canceled and the system will capture the commanded vertical speed. If a change in vertical speed is desired, the vertical trim rocker switch (UP/DOWN) fom the AP control panel can be used.

Second is ‘Vertical Speed Sync’. By just pushing the ENG button while the KAS 297B is displaying the preset altitude, the system should maintain the current vertical speed. Upon enganging, the KAS 297B should display the vertical speed for 2 seconds.

I never used VS mode. So you should try this procedures yourself. Can you report which of the two methods work?

if display altitude doesn’t match with the actual alt, for example display 8000, real alt 6500, if you press VS the plane (Autopilot) will enter in a default -500 fpm. If the plane matches the display alt (8000) and the real alt (8000), if you press vs button the display will change to 0 fpm and now you can adjust it fine for climb or descent. The vs button is bugged. My recommendation is not no press it if you are not matching the alt in the display with the real one. Use in alt mode when the plane is stabilized and matching the desired alt with the real one. And it’s doesn’t matter what vs speed do you set before pressing VS. if you are not matching the altitude it will engage -500 by default

I’m not at home now. I will report more details later

OK, that’s certainly a bug in the implementation of the ENG button (I assume you mean the ENG button, because there is no VS button).

Just one more question. What is your attitude (pitch) or climb rate when you press the ENG button? Are you in level flight, in climb or in descent?

Yes, I mean the engage button.

By default, no matter the trim, the engage vs button is going to put you in a -500 fpm. (Readed in the display) , then you can rotate the knob and change but it will you put you in -500. No mather the last fpm settings. It’s the same to alt engage button. When you set a desired altitude and press engage alt it will put you in a +500 by default.

Regarding yo vs engage button, to get a 0 fpm by pressing it you need to first be matching the real alt and the display alt

I concur with the VS engage that it puts you in a descent, but I a disagree that the engage alt will put you in a climb. If I’m at cruise alt, and I select a new, lower altitude and then press eng alt, it will put the mooney in a - 500 descent.

Yeah sorry for the misunderstanding, it’s hard to explain quickly from a not native like me and not in front of the sim. I was trying to say that by default the plane put you in a +500 up or down when engaging it. The alt engage works well but the problem is the VS engage button that need to meet many requirements to not to put you in a -500 descent. If you simply want to climb at desired fpm without setting an alt is better to use the autopilot nose up reference than the vs engage button because it’s a bit bugged.

Start with altitude, and make sure it’s armed to capture. You might have to press the ARM/ALT button a couple of times. Press the lower button to get to Alt select mode, dial in your altitude, then press the same Arm/Alt button again to arm the desired altitude capture, then press the knob to engage vertical speed, and adjust as needed. It works sensibly in this way. I agree the other VS/ENG mode button acts a little weird but I haven’t really needed it.

And sometimes, everything is OK, your plane is flying perfectly well, and you push “pause” for any reason, and when you come back and push “start” the plane is diving immediatly and you buy the farm in a few seconds … Grrrrrrr

Hi! Did you managed to find event ids for AP Altitude adjustments? I’m struggling to find key bindings for them.

After a longer “pause” you have to start the engine again - somtimes

Yeah, active pause is bad news… Not a good idea to use when using the AP in any way… Use the escape key instead. Or did this happen after using the escape key?

Under active pause, the engine is effectively running the whole time. So it’s likely it ran out of fuel. There are other reasons it might have happened, too.