747/777 yaw damper lag?

[alex98 13]

As a matter of fact, the slip is not that bad. It is there but not that bothering. And the yaw dampers are catching up pretty well.

As I said (not an expert here...), it might be some FSX limitations...

But remember, it is a 90 bucks simulation, and a wonderful one, not a full professional simulator! And even there, it is not perfect... As far as I am concerned, nothing to prevent me enjoying this great product!

En-joy

Happy flying

[rondon9898 84]

John is clearly expert on the systems side of the 74', but my understanding was that turn coordination on the 747 was only available with flaps extended. Therefore, there will be some slip in turns when flaps retracted, but it is not very pronounced and generally it's not advised to use the rudders when not on takeoff/landing because if you overcook the correction, you throw the passengers' coffee all over them. In the cruise, the yaw dampers are there to prevent dutch roll, to which most swept-backed winged aircraft are prone, I believe. 

[achutchison 26]

I decided to upload a 1 min video showcasing this issue along with the ones immediately related to it: READ THE DESCRIPTION

 

[pete_auau 1,153]

14 hours ago, achutchison said:

Oh here we go with the flakey avsim insults. I'll just fly the 320

  looks like  your not  following  advice  you  were asked  to raise a  ticket   and  next  thing  you  come  back  with this  reply  good luck  with any other  help

[Mike777 163]

In the discussion accompanying your video on Youtube, you seem to assume that your increased angle of attack is due to the slow response of the yaw damper.  It seems to me that the increased angle of attack is due to the fairly steep bank angle, which reduces lift and requires more nose-up to maintain the same altitude -- particularly large nose-up because you are flying so slowly.  Also, it looks like you are losing some speed due to the increased angle of attack.  The loss of speed requires even higher angle of attack to maintain the same altitude, until the A/T compensates. 

Mike

 

[Captain_Al 66]

On 4/21/2017 at 1:07 PM, alex98 said:

As a matter of fact, the slip is not that bad. It is there but not that bothering. And the yaw dampers are catching up pretty well.

As I said (not an expert here...), it might be some FSX limitations...

But remember, it is a 90 bucks simulation, and a wonderful one, not a full professional simulator! And even there, it is not perfect... As far as I am concerned, nothing to prevent me enjoying this great product!

En-joy

Happy flying

I am in your camp alex98, for $90, this piece of software is amazing and I fly, teach, and check in the 747-400 and 747-8 where it costs hundreds or thousands of dollars for an hour of time. This is nothing, at least in the PMDG 747-400, I will have to try it in the 777, but I never noticed anything that I could not live with there either.

[Captain_Al 66]

On 4/21/2017 at 9:27 PM, achutchison said:

I decided to upload a 1 min video showcasing this issue along with the ones immediately related to it: READ THE DESCRIPTION

In my opinion, this is a little exaggerated from what the real airplane probably does in the 777, although I will not speak for the 777. In the 747, like my post said earlier, there is some slip induced when turning (like 1/4 deflection), which some pilots will or will not correct with a small amount of rudder.

What I will say is that this is not the airplane or a 35 million dollar simulator. When I do steep turns in the PMDG 747-400, it is no where close to the correct pitch and power for the given weight and conditions (280 knots, 10,000 feet, 45 degrees of bank, mid range weight) that you will find in the jet or a Level D simulator. Instead of 4.5 degrees of pitch, I am holding 10 degrees to hold altitude, instead of 75-76% N1, I am at 85% N1.

My point is that for less than $100 you are getting a pretty well designed accurate simulation of the jet, perfect...no, but pretty darn good. Can it be more accurate, yes, and is it flawless, no. But I am sure PMDG will decide what is worth fixing and what is not. I have found a lot of small things that are not accurate to the jet, does it detract from my enjoyment of the product, no. Have I let PMDG know about some of these items, yes. Will they fix these in time, maybe, up to them. If you really feel it is an issue, submit a ticket, they will listen...

 

[Qavion2 39]

Quote

 

John is clearly expert on the systems side of the 74',

 

I wish...

I wasn't aware there was any input from the flaps to the Yaw Damper System (but I stand to be corrected). My wiring diagrams and manuals don't show this.

Generally, the Yaw Damper System is designed to stop uncomfortable sideways accerations. The system does the following:

Supresses dutch roll (this can happen at any speed)

Coordinate turns (you would hope it would also do this at high speeds)

Suppress "structural modal oscillation" (the twisting of the fuselage about the wing area during turbulence). Again, you would hope it would happen at all speeds.

The YD System uses the IRUs and 4 dedicated accelerometers (two at each end of the fuselage). The system also uses Air Data Computer information. It has a maximum authority of 4 degrees of rudder (left or right), but the authority is reduced if the IRS or ADCs are faulty. As far as I know, it bypasses the Rudder Ratio system, so the YD system has to compute the effect of increasing airspeed on the rudder surfaces. I guess at higher speeds you normally wouldn't see much rudder movement due to the YD system..

The pilots will only feel the effect of the YD system through the seats of their pants (There is no feedback to the rudder pedals).

Cheers

JHW