Nose Pitches Up Dramatically after A/P Disengaged FS9

[Martin Tochacek 958828]

I was wondering if there was some fix for this. I recently installed FS2004 and downloaded three planes from different developers. In all three cases, when I disengage the autopilot on finals, the nose pitches up severely and I almost lose control of the plane. Is there something in the aircrafts' .cfg files that may be attributing to this problem? I did not have this problem in FS2002 so it may be a FS2004 problem as well. Has anyone else seen this happen? Thanks in advance.

[George Anopov 895164]

I was wondering if there was some fix for this. I recently installed FS2004 and downloaded three planes from different developers. In all three cases, when I disengage the autopilot on finals, the nose pitches up severely and I almost lose control of the plane. Is there something in the aircrafts' .cfg files that may be attributing to this problem? I did not have this problem in FS2002 so it may be a FS2004 problem as well. Has anyone else seen this happen? Thanks in advance.

 

a)Check elevator trim settings

b)Check flap position

c)Check CG (Centre of Gravity)

d)Check the speed

[Martin Tochacek 958828]

Can you change the trim when in A/P? I thought that A/P controlled that as well. My speed on approach is always around 150kt in a B737 and I have full flaps before landing. For longer runways I usually have one less than full flaps.

[George Anopov 895164]

Can you change the trim when in A/P? I thought that A/P controlled that as well. My speed on approach is always around 150kt in a B737 and I have full flaps before landing. For longer runways I usually have one less than full flaps.

 

Well, you CAN change trim while AP is engaged, but it will be automatically setted back immediately

 

150 kt is ok, but my suggestion is to always calculate Vref speed and Flap speeds, just to be accurate in this dangerous phase of flight.

 

If trim is ok, the only thing left is CG. Check it (open Fuel and Payload menu by clicking ALT button on keyboard during the flight)

Each aircraft has it's own maximum boundaries of acceptable CG. I tend to think yours CG is back one, that's why aircraft is pitching up the nose

 

Hope this will help.

[Martin Tochacek 958828]

If trim is ok, the only thing left is CG. Check it (open Fuel and Payload menu by clicking ALT button on keyboard during the flight)

Each aircraft has it's own maximum boundaries of acceptable CG. I tend to think yours CG is back one, that's why aircraft is pitching up the nose

 

What is "CG"? Also, my tanks are usually at or below 50% full since I don't make very long flights (less than 2 hrs or so). Thanks for your suggestions.

[Michael Hodge Jr 961044]

CG = Center of Gravity

[Anibal Rivera 946565]

no no no ...I know what you are talking about....

Why would I need to check the flap or elevator trim settings??...see this scnerario...

The A/P is engaged with Altitude, heading. If I disengage the autopilot, it is supposed to NOT change the elevator trim settings, am I right? Everything is supposed to remain as it was before the disconnection. Then, why would the aircraft suddenly change only the nose pitch?...the only thing that this suggests is that A/P disengaging set the trims to another state other than the one just before the disconnection, see my point?

[Ben Zwebner 906832]

no no no ...I know what you are talking about....

Why would I need to check the flap or elevator trim settings??...see this scnerario...

The A/P is engaged with Altitude, heading. If I disengage the autopilot, it is supposed to NOT change the elevator trim settings, am I right? Everything is supposed to remain as it was before the disconnection. Then, why would the aircraft suddenly change only the nose pitch?...the only thing that this suggests is that A/P disengaging set the trims to another state other than the one just before the disconnection, see my point?

 

I see your point...

 

When the auto pilot is enganged, it over rides your joystick/ yoke. Most yokes and joysticks have an trim on them. If u used the trim wheel before take off, or during the manual phase of the flight and then engage the A/P, the computer will disregard your joysticks trim settings. however when you disengage the A/P, whatever settings are on your joystick come back to play.

 

this might not be the case with you, but it is the only thing that makes sense to me. make sure that your joysticks/ yokes, trim is centered before disengaging the A/P.

[George Anopov 895164]

Ben, you are wrong. When you engage the autopilot with particular trim setting say not suitable for maintaining constant vertical speed, autopilot will set trim to suitable position, BUT when you DISengage the autopilot, TRIM will remain as autopilot left it, NOT position YOU left BEFORE engaging the autopilot...

 

Example. You have entered glideslope, you are descending with engaged autopilot in mode app, when you disengage the autopilot, everything will remain the same (trim i mean), if there is no wind you will even be able to descend down to DH with out single touching the yoke because trim has been setby the autopilot, NOT by you before engaged it...

[Ben Zwebner 906832]

Ben, you are wrong. When you engage the autopilot with particular trim setting say not suitable for maintaining constant vertical speed, autopilot will set trim to suitable position, BUT when you DISengage the autopilot, TRIM will remain as autopilot left it, NOT position YOU left BEFORE engaging the autopilot...

 

Example. You have entered glideslope, you are descending with engaged autopilot in mode app, when you disengage the autopilot, everything will remain the same (trim i mean), if there is no wind you will even be able to descend down to DH with out single touching the yoke because trim has been setby the autopilot, NOT by you before engaged it...

 

I am not reffering to the trim in the simulator. your game controller (ie flight yoke) in the most part, has a trim wheel, this trim wheel sends inputs to the simulator just like pushing in on the stick. while the A/P is on, the FS ignores game controller inputs such as this hardware trim wheel attached to your yoke. once you disengage the A/P the sim returns to recognizes the the HARDWARE trim wheel commanding it to pitch up or down. and this will show i the simulator.

 

try it.

I used to experiance the same problem that he is describing and the was the reson in my case.

[Owen Catherwood 903683]

Ben, it depends quite a bit on the hardware. My X45 Joystick's throttle input is not recognized until I give it a push after turning off the auto-throttle, same thing with the trim levers and flight controls.

[George Anopov 895164]

I am not reffering to the trim in the simulator. your game controller (ie flight yoke) in the most part, has a trim wheel, this trim wheel sends inputs to the simulator just like pushing in on the stick. while the A/P is on, the FS ignores game controller inputs such as this hardware trim wheel attached to your yoke. once you disengage the A/P the sim returns to recognizes the the HARDWARE trim wheel commanding it to pitch up or down. and this will show i the simulator.

 

try it.

I used to experiance the same problem that he is describing and the was the reson in my case.

 

ahh, i understand now what you mean Ben... Yes, in this case you are right.

I havn' got a trim whell, i have lot's of buttons, two of them i set to trim (up and down)

[Martin Tochacek 958828]

this might not be the case with you, but it is the only thing that makes sense to me. make sure that your joysticks/ yokes, trim is centered before disengaging the A/P.

 

I understand your point but how do you center the trim when you are on AP. Won't it just override whatever you try to do? I tried to disengage, center the trim, and re-engage the AP wihle starting my descent instead of on the glideslope but I still had nose pitch problems before landing.

[Jan Naslund]

Hi,

 

Perhaps you can make a short test. Fly the 737 manually and descend on the glideslope at lets say 150 kts in full landing configuration and when you are stable in the descent, note the trim setting.

 

Take off again fly level using the autopilot, perform an autopilot ILS approach, when stable on the glideslope at 150 kts in landing configuration, check the trim setting again and compare to what it was earlier.

 

To be accurate, try to check the setting at the same altitude.

 

Disengage the autopilot and see what happens.

[Craig Moulton]

The crux of the problem is going to be how you had your stick (or yoke) set when you connected the AP, and where that stick was positioned when you disconnecte the AP.

 

Very many aicraft will disable any and all stick inputs while the AP is engaged. Others, such as the Level-D 767 have options to let you control whether or not the stick is active while the AP is connected.

 

Bottom line is this. If you have your stick in a position that is not consistent with the current trim setting when you disconnect the AP, the plane will react by "centering" itself on how the stick is set.

 

Try a little forward pressure the next time you disconnect the AP and see if that doesn't help. By testing this several times you can find the setting that should best fit your situation.

[Richard Newton 976199]

I have found this happens with a Learjet 45.

[Dan Bergenholz 958090]

Use the arrow bottoms to set aircraft on straight level when on autopilot.In your case hold down the up arrow a bit and you will experience more control.Try also to fly with autopilot off and fly straight, that setting will be active when you again turns autopilot off.