777 Rocking problem

[Mo45 32]

Not sure I am doing things right, but during the climb the front of the aircraft is moving up and down like a see saw.  Haven't had any problem with any other PMDG products.  Any help would be much appreciated.

 

Regards

Mo

[falcon999 24]

What weather are you using?

[Mo45 32]

Weather clear sky, fsx default (FSUIPC4).

[krisyyz 1]

Are you using VNAV? If so, try using FLCH or speed intervene via VNAV instead and see if the problem persists.

 

Just an idea.

 

Kristof

[Mo45 32]

Just using the LNAV + VS/FPA.

[Don t moderate me this way 882]

Max climb thrust or reduced?

[Mo45 32]

Thanks gents for your replies.  The problem started from the altitude above 10000 using LNAV and V/S FPA 1100 and the IAS speed  320.  This is when it starts having the pitch up/down motion.  I am not sure if there is anything I have to set on the FMC set up.

 

Will give it a try later and see what happens.

 

Thanks again.

 

Mo

[Don t moderate me this way 882]

It's not a left-to-right motion, but a pitch up/down thing. Looks like it oscillates because of only 1.100 fpm and a huge amount of surplus thrust.

 

Have you tried CLB-2 thrust?

[Mo45 32]

Yes, pitch up/down motion my mistake sorry. Yes tried CLB-2 still the same.

[Don t moderate me this way 882]

No problem. How are your frame rates when this happens?

[Mo45 32]

Would it be possible if you could try a short flight to see if you get the same problem.

 

1- Switch to FCTL so you can look at the STAB control counter.

2- Put V/S 1000

3- IAS 320 above 10000 altitude without using VNAV, just use the LNAV

If you look at the STAB control the numbers go up and down

I have tried it with the VNAV and LNAV it has no problem, it only happens when you use LNAV .

Usually when I am flying I only use the LNAV and VNAV up to 5000 altitude.  Then I switch to LNAV.

 

Regarding the frame rates, I have no problem with these.

 

Many thanks,

Mo

[Don t moderate me this way 882]

Yep, you're right: The oscillations become more and more over time. There's no inherent stability in that mode, it's dynamically unstable. Puzzling ...

[Paul Deemer 13]

Guys I have seen the Rocking Problem before in all of the PMDG planes with earlier versions of Activesky at one time or another. If you notice he mentioned he is using FSX Default Weather. It's the crazy FSX weather and turbulence that is causing the Plane to Rock back and forth like a Rocking Horse. Solution: Activesky 2012 and the latest version of FSUIPC.

[Mo45 32]

.

Yep, you're right: The oscillations become more and more over time. There's no inherent stability in that mode, it's dynamically unstable. Puzzling ...

 

Appreciated Oliver,

 

Regards,

Mo

[ajpongress 467]

Disable turbulence and thermals in the fsx weather options.