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Still Slight Pitch Instablity with latest Service Pack

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I've been noticing slight pitch instabilities with the latest release.  For example during FLCH decents with autopilot and autothrottle engaged the nose with suddenly pitch down for no reason.  It will quickly recover but it is still annoying.  This also has happened on final approach when fully configured and trimmed for landing.  The nose will suddenly pitch down sometimes more than once.

 

I've also noticed that while hand flying on the intial climb out the aircraft will exhibit a very slight porpoising motion with flight director unstable and overcorrecting. Seems to me that if the aircraft is properly trimmed it should be rock solid.  Having said that I don't think this is a trim issue.  I feel that I have been able to trim this version pretty well by feel.

 

Any thoughts  would be appreciated.

Steve Giblin

 

Might be noise from joystick pitch axis

Bryan Richards

 

"People depend so much on automation that they forget how to get the automation to work." B.W.

  • Commercial Member

 

 


I've been noticing slight pitch instabilities with the latest release.  For example during FLCH decents with autopilot and autothrottle engaged the nose with suddenly pitch down for no reason.  It will quickly recover but it is still annoying.  This also has happened on final approach when fully configured and trimmed for landing.  The nose will suddenly pitch down sometimes more than once.

 

My guess - similar to Bryan's - is that you have noise in your joystick pitch axis.  Additionally, if you have a trim wheel/axis assigned and not just a trim up/down assignment, this can also cause what you describe.

 

 

 


I've also noticed that while hand flying on the intial climb out the aircraft will exhibit a very slight porpoising motion with flight director unstable and overcorrecting. Seems to me that if the aircraft is properly trimmed it should be rock solid.  Having said that I don't think this is a trim issue.  I feel that I have been able to trim this version pretty well by feel.

 

Could it be related to this?

http://forum.avsim.net/topic/444052-09jun14-pmdg-777-sp1-and-300er-updates/page-9#entry3007274

Kyle Rodgers

I have seen some porpoising with the AP engaged in both level flight, descend and climbs.

 

Short lived (a few seconds) so not enough to report it as a problem.

It could be OPUS real weather.....I do not know.

 

 

IF the problem is hardware related and if you have FSUIPC, then you could try if FSUIPC's "elevator spyke filter" helps!

Rob Robson

  • Author

I do run FSUIPC spike filter.  I have PFC controls with Hall sensors.  Not prone to spikes....

 

Been using AS Next...

Steve Giblin

 

I've also noticed that while hand flying on the intial climb out the aircraft will exhibit a very slight porpoising motion with flight director unstable and overcorrecting. Seems to me that if the aircraft is properly trimmed it should be rock solid.

Yep, me too.

 

I noticed the slight porpoising on my first test flight with SP1b. Noticed it on every flight since. Not extreme, but definitely there.

 

I doubt we all have joystick noise. Next time I see it, I'll disconnect my joystick and test.

  • Author

It's very subtle but there...

Steve Giblin

 

  • Commercial Member

 

 


I noticed the slight porpoising on my first test flight with SP1b. Noticed it on every flight since. Not extreme, but definitely there.

 

It's very subtle but there...

 

Yes i get it to

 

...did any of you happen to read the link I posted in post #3?

Kyle Rodgers

Don't think it's anything to do with it Kyle, unless you know different.

 

This is a protracted very slight porpoising.

 

Autopilot on.

 

Phugoid oscillation would only be apparent with the autopilot off I would imagine, and would eventually settle down. With autopilot on it would be in trim.

 

Unless I misunderstand.

  • Commercial Member

Don't think it's anything to do with it Kyle, unless you know different.

 

This is a protracted very slight porpoising.

 

Autopilot on.

 

Phugoid oscillation would only be apparent with the autopilot off I would imagine, and would eventually settle down. With autopilot on it would be in trim.

 

Unless I misunderstand.

 

Re-read the post you quoted.  It starts with:

"I've also noticed that while hand flying..."

Kyle Rodgers

Re-read the post you quoted. It starts with:

 

"I've also noticed that while hand flying..."

 

Why is that relevant? And since that post you asked if we had read the link. I answered you, and explained that I didn't think it was relevant, namely because the autopilot was on.

 

 

 

Thus, my issue I don't believe is related to your link. Thought that was clear.

 

Rob also said, with the AP on.

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