WebMaximus

Trim down issue

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Noticed how I sometimes have a hard time trying to trim the a/c down.

I'm using the default HOME key and no matter how many times I press this key or if I hold it down the stab trim wheel doesn't move. Trim up on the other hand using the END key always works just fine.

Anyone else seen this?

 

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Check the keyboard assignments in your simulator.  Are you trying to fly with the keyboard?

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As mentioned in my first post I'm using the default assignment which is the HOME key. I have this mapped to a button on my yoke via FSUIPC.

When I noticed the issue on tonight's flight during short final I then tried using the key on the keyboard once I landed just to make sure it wasn't an issue with my yoke button assignment but the issue remained.

What is strange is I've seen this before and it's not consistent. Sometimes (mostly) it's working just fine but then all of a sudden the problem is back again.

Will do more testing trying to find how to reproduce the issue but figured I would ask in here as well if someone else seen this.

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The Home or Shift Num 7 key is the default trim nose down key, and using FSUIPC you are simply translating a controller button to a key command.  If the assignment in the platform is wrong or duplicated then even FSUIPC will have problems.  In P3D, since about v3.0, most all controllers that comply with DirectX are recognized by the platform and there is no need to translate the controller button with FSUIPC.  I simply assign my trim button to the trim action in the P3D keyboard controls set up.  The only reason i use FSUIPC is to translate controller buttons/switches to special keycommands to use the assignments in the PMDG FS Actions menus.

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Thanks for explaining to me what I'm doing and repeating what I said already in my first post and then tried to further explain in my second post 😉

I'm well aware of the HOME key being the default trim down key and that using FSUIPC in the way I mentioned simply will translate this key command.

The reason I've chosen this method over the method you're using is to be consistent in how I assign commands to the buttons on my yoke where I prefer to exclusively use default key mappings rather than a mix of that and direct assignments of the buttons on my yoke.

This isn't an assignment issue since it's working intermittently without changing any assignments and to repeat myself yet another time I even tried pressing the keyboard key instead of the button on my yoke just to make sure it wasn't the FSUIPC assignment that was the culprit.

So...for some reason the trim down function every now and then doesn't work and I need to figure out why that is.

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So I played around a bit more this time only sitting at the gate and this is what I found:

  • the green marking on the STAB TRIM wheel ranges from 3 units down -> 8 units up
  • using an assigned key/button to trim up you will reach about 15 units up on the band meaning long outside the green marking on the 'up' side
  • using an assigned key/button to trim down you will reach about 4 units down on the band meaning you're not even able to reach the end of the green marking (3 units) on the 'down' side
  • using the wheel and/or buttons on the mouse you can reach the full up and down positions on the scale with no issues

Not sure if this is related to the issue I experienced but will keep a close eye on the actual STAB TRIM value next time I see this happening.

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7 hours ago, WebMaximus said:

So I played around a bit more this time only sitting at the gate and this is what I found:

  • the green marking on the STAB TRIM wheel ranges from 3 units down -> 8 units up
  • using an assigned key/button to trim up you will reach about 15 units up on the band meaning long outside the green marking on the 'up' side
  • using an assigned key/button to trim down you will reach about 4 units down on the band meaning you're not even able to reach the end of the green marking (3 units) on the 'down' side
  • using the wheel and/or buttons on the mouse you can reach the full up and down positions on the scale with no issues

Not sure if this is related to the issue I experienced but will keep a close eye on the actual STAB TRIM value next time I see this happening.

This is correct, another example of the impressive depth of this sim. Electric trim limits are less than manual trim wheel inputs.The FCOM refers to additional trim movement being available using manual trim. If CG position is extreme fwd or aft you may need to use manual trim. If you extend flaps you will be able to use the electric trim switches to motor the trim to 0.05 units (aft limit isn't changed). The flaps retracted trim limit even varies according to which version of the NG you have selected.

See FCOM vol 2 pages 9.20.8/9 for full details.

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2 minutes ago, kevinh said:

This is correct, another example of the impressive depth of this sim. Electric trim limits are less than manual trim wheel inputs.The FCOM refers to additional trim movement being available using manual trim. If CG position is extreme fwd or aft you may need to use manual trim. If you extend flaps you will be able to use the electric trim switches to motor the trim to 0.05 units (aft limit isn't changed). The flaps retracted trim limit even varies according to which version of the NG you have selected.

See FCOM vol 2 pages 9.20.8/9 for full details.

Thanks for the information and can't agree more - so cool when you come across these small things where you realize how close to the real thing the NGX is!

One thing though I'm still wondering about is why the aircraft tend to pitch quite hard up when I disconnect the A/P on short final meaning I will always have to be prepared to apply quite an amount of forward pressure on the yoke to avoid "balooning".

I was under the assumption that the A/P would continuously adjust the trim to make sure it's in a trimmed condition by the time you disconnect the A/P?

Might be an issue with the config of my Brunner yoke and/or the software that drives it (CLS2Sim) rather than the NGX itself or otherwise I guess everyone would see the same behavior.

Will do more testing...

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9 minutes ago, WebMaximus said:

One thing though I'm still wondering about is why the aircraft tend to pitch quite hard up when I disconnect the A/P on short final meaning I will always have to be prepared to apply quite an amount of forward pressure on the yoke to avoid "balooning".

I've never experienced that. It's always in trim when I disconnect the AP. I use P3D calibration only for my controller.

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38 minutes ago, kevinh said:

I've never experienced that. It's always in trim when I disconnect the AP. I use P3D calibration only for my controller.

Thanks for confirming.

Guess it's related to the yoke so will ask about it over in Brunner's support forum.

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56 minutes ago, WebMaximus said:

Thanks for the information and can't agree more - so cool when you come across these small things where you realize how close to the real thing the NGX is!

One thing though I'm still wondering about is why the aircraft tend to pitch quite hard up when I disconnect the A/P on short final meaning I will always have to be prepared to apply quite an amount of forward pressure on the yoke to avoid "balooning".

I was under the assumption that the A/P would continuously adjust the trim to make sure it's in a trimmed condition by the time you disconnect the A/P?

Might be an issue with the config of my Brunner yoke and/or the software that drives it (CLS2Sim) rather than the NGX itself or otherwise I guess everyone would see the same behavior.

Will do more testing...

Also, If you have both APs on for the ILS, your autolanding will arm. This, according to FCOM, will trim nose up below 400' in preparations for the autolanding.

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2 minutes ago, leghorn said:

Also, If you have both APs on for the ILS, your autolanding will arm. This, according to FCOM, will trim nose up below 400' in preparations for the autolanding.

Good to know.

This must be something else though because I only had CMD A active and it happened already between 1000-1500 ft.

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Was able to fix the issue where the aircraft was pitching up when disconnecting the A/P.

As suspected it was caused by a setting in CLS2Sim (the software for the Brunner yoke) called 'Percent of way used by AP' where the default value is 100. I increased this value a bit to get more movement along the pitch axis with the autopilot engaged but apparently a side-effect was this pitching up behavior.

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If I'm understanding your issue correctly it really sounds like a yoke issue. If back pressure is being applied to the yoke they system will not let you trim forward and vice versa. It seems like your system is applying back pressure. 

 

I had had one time in the real plane where the switch that senses the yoke pressure went bad and though we were trying to apply back pressure so it locked out the forward trim via the yoke switches. We had to use the manual trim wheel for forward trim which was kind of a pain. 

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