747 trim up works but trim down doesn't

[dukegamma]

Not sure if I'm doing something wrong. Trying to assign buttons and whether I'm assigning in P3D or FSUIPC the trim up works but trim down does not.

[dukegamma]

I see the bottun pressing on the yoke for trim up and trim down but the trim indicator doesn't move for trim down

[dukegamma]

Found the solution here:

Switched to USB 2.0 port and problem is fixed

 

[X_Man]

Trim Down works fine, it's just Trim Up that doesn't work - sounds exactly like a bug to me... (Morpheus voice) 😎

I unplugged the hub and reinserted it, fired up P3DV4  and it worked. Then I moved the engine reverse and the Trim Up only stopped working again. 

Surely there has to be another solution - My Joystick IDs will change for all the other games, remapping X-Plane 11, DCS & IL-2 BoX will be a nightmare. Dare I mention I have to buy new hardware because I don't have a USB 2.0 hub.

Can I get one of the developers to chime in here please?

Thanks

 

[Captain Kevin]

3 hours ago, X_Man said:

Trim Down works fine, it's just Trim Up that doesn't work - sounds exactly like a bug to me... (Morpheus voice) 😎

I unplugged the hub and reinserted it, fired up P3DV4  and it worked. Then I moved the engine reverse and the Trim Up only stopped working again. 

Surely there has to be another solution - My Joystick IDs will change for all the other games, remapping X-Plane 11, DCS & IL-2 BoX will be a nightmare. Dare I mention I have to buy new hardware because I don't have a USB 2.0 hub.

Can I get one of the developers to chime in here please?

Thanks

You'll need to submit a support ticket at support.precisionmanuals.com if you want to make sure they actually see it, as this is primarily a user to user forum.

[scandinavian13]

10 hours ago, X_Man said:

Can I get one of the developers to chime in here please?

If you want developers to chime in, you must use the support function - support.precisionmanuals.com

All the same, it is unlikely that this is a bug. If it were, there would be many more reports of this. More often than not, it is a conflicting hardware button, or hardware misconfiguration. Works fine here.

[cannonplug]

12 hours ago, X_Man said:

Trim Down works fine, it's just Trim Up that doesn't work

Make sure the elevators are in a neutral position when you actuate the trim. If the elevators are even slightly nose down, trim up will not work (and vice-versa).

[Ephedrin]

1 hour ago, wsmeier said:

Make sure the elevators are in a neutral position when you actuate the trim. If the elevators are even slightly nose down, trim up will not work (and vice-versa).

?? Were did you get THAT from?

the sense of trimming is to release pressure from the yoke... and pressure means your elevators are out of central position. 

[Jetlinker]

I have this happens sometimes in both the -8 and 400. I just shuffle the flight controls around a bit and it seems to correct itself. 

[X_Man]

Copy that! Thanks guys

[X_Man]

5 hours ago, Ephedrin said:

?? Were did you get THAT from?

the sense of trimming is to release pressure from the yoke... and pressure means your elevators are out of central position. 

Pulling back on the elevator does allow Trim Up. I have a old MS FFB 2 joystick and it droops when at rest, it doesn't center. So this was also part of my problem.

I guess I need a new joystick 

[Ephedrin]

12 hours ago, X_Man said:

Pulling back on the elevator does allow Trim Up

of course... You can move your trim (the whole stabalizer actually) in whatever position your elevator (or column) is.. it just doesn't necessarily make sense. But it is completely wrong to use it INSTEAD of the elevator.. I'm aware, that this is often been done when having thumb switches on the yoke to rather go for the switches than move the yoke to do small corrections... but that's still wrong. Moving the stabilizer in manual flight is only done to take forces off the controls, nothing else.

And if I'm not completely wrong even the autopilot works that way. It moves the stab trim if it is asked to hold a pitch attitude or a vertical speed but actually moves the elevator if it needs to change its attitude, for example to level off or to start a decent/climb. Then it moves the stab to hold this attitude while releasing the elevator to center position.. and THEN again, it keeps its pitch mainly with the stab trim. 

[gstreet]

1 hour ago, Ephedrin said:

of course... You can move your trim (the whole stabalizer actually) in whatever position your elevator (or column) is.. it just doesn't necessarily make sense. But it is completely wrong to use it INSTEAD of the elevator.. I'm aware, that this is often been done when having thumb switches on the yoke to rather go for the switches than move the yoke to do small corrections... but that's still wrong. Moving the stabilizer in manual flight is only done to take forces off the controls, nothing else.

And if I'm not completely wrong even the autopilot works that way. It moves the stab trim if it is asked to hold a pitch attitude or a vertical speed but actually moves the elevator if it needs to change its attitude, for example to level off or to start a decent/climb. Then it moves the stab to hold this attitude while releasing the elevator to center position.. and THEN again, it keeps its pitch mainly with the stab trim. 

I may be misunderstanding him but I think he is saying once he centers his control column the stabilizer trim works. I had this problem from walking around the aircraft on the ground with chaseplane using the arrow keys which moved my control column all the way down so I couldn’t trim up. As soon as I recentered it the trim worked. I assume this is the way the actual aircraft functions. 

[JRBarrett]

2 hours ago, Ephedrin said:

of course... You can move your trim (the whole stabalizer actually) in whatever position your elevator (or column) is.. it just doesn't necessarily make sense. But it is completely wrong to use it INSTEAD of the elevator.. I'm aware, that this is often been done when having thumb switches on the yoke to rather go for the switches than move the yoke to do small corrections... but that's still wrong. Moving the stabilizer in manual flight is only done to take forces off the controls, nothing else.

And if I'm not completely wrong even the autopilot works that way. It moves the stab trim if it is asked to hold a pitch attitude or a vertical speed but actually moves the elevator if it needs to change its attitude, for example to level off or to start a decent/climb. Then it moves the stab to hold this attitude while releasing the elevator to center position.. and THEN again, it keeps its pitch mainly with the stab trim. 

Yes. The autopilot works like a human pilot would when hand flying.

The human will initiate a pitch change with elevator and simultaneously trim to relieve the push or pull force being applied to the yoke. The end result is the the elevators end up faired in a neutral position, and the horizontal stab will be in a different position than it was before the pitch change.

In the case of the human pilot, the “feedback” as to how much trim is required comes from the muscles of the hands and arms that pushing/pulling the yoke.

In the case of an autopilot, the feedback comes from the electrical current required to drive the elevator pitch servo. The more the elevators deflect into the airstream, the harder the servo works, and the more servo current is required. The AP trims to reduce the servo current back to zero.

You can’t use the trim switch to initiate climbs or descents in a large aircraft. Any application of trim with the switch on the yoke will cause the autopilot to disconnect if it was engaged at the time.

It’s different in a small aircraft like a Cessna which has a fixed horizontal stabilizer, and the elevator position itself is trimmed. In a climb or descent the elevator will remain slightly deflected up or down when trimmed. Usually small aircraft are designed so that the elevator will be close to neutral when the aircraft is in level flight at its normal cruise airspeed.

In any case, I suspect that the OP has a hardware problem in his yoke/joystick that is causing the trim switch to malfunction in one particular direction. It could either be a switch failure, or something wrong with the USB interface in the yoke which translates yoke or switch position to serial data. 

I’ve never seen any problems with nose up or nose trim working properly with any PMDG aircraft in any part of the flight envelope using my TM Warthog joystick.

[cannonplug]

22 hours ago, Ephedrin said:

?? Were did you get THAT from?

From my own two eyes. Keep in mind that I'm referring to the airplane being on the ground without any aerodynamic forces. The few times I've seen the trim work in one direction but not the other, a quick shove or pull of the yoke has resolved the issue for me.