rudder use while hand flying (jan?)

[mike10]

Hello,  I have a question about hand flying this lovely 733.. It is a joy to hand fly! Ok now for my question,   I have never flown a real jet aircraft and I always thought the Yaw damper on large jets like this handled the rudder for the pilot in turns. I noticed that this plane when hand flying I need to use quite a bit of rudder to keep my turns coordinated.  Not as much as I have to use IRL in gliders but similar to flying light powered aircraft. 

 

Is this normal?   

[Litjan]

Hi Mike,

in the real plane the roll spoilers help to overcome the adverse yaw you get when initiating the turn, and the general aerodynamic shape of the airplane and wing keep the turns coordinated (don´t ask me how, but I think the big size of the vertical stabilizer needed for engine-failures helps)... there is no rudder input needed when making turns in airliners.

The yaw damper is actually working against making a coordinated turn - it is a rate gyro that fights sudden "yaw onset". So when you initiate the turn, it will actually deflect the rudder opposite to stop the yaw. Once the turn is established (constant rate) the yaw damper input is washed out to zero.

We are already looking at turn coordination in our current model and XP11 - there are bound to be some more flight-model changes (as Austin hinted at) - and we are wary of tuning, retuning and then again tuning the model until he seems satisfied. For now the plane flies ok and according to real performance and unless that changes we are inclined to let Austin do his thing and then revisit when the dust settles...

Cheers, Jan

 

Edited July 30, 2017 by Litjan

[Morten]

That is correct. This is a  XP11 issue, we are looking into it.

 

[Litjan]

I just did some tests, and I came to the conclusion that everything works fine (both coordination in turns, and yaw damper).

Look at this first picture. It was taken when initiating the turn. The yaw-onset is to the left (in the direction of the turn) and you can see the yaw-damper COUNTER it (as designed) by applying opposite (to the right input):

Next picture shows the sustained turn at 220 kts - no rudder input. You can see that the ball is "almost" perfectly centered, the slip is about 0.4 degrees (its a bit hard to read):

And just to complete the test, here is another sustained turn at final approach configuration, slip is 0.6 degres:

These values are absolutely within what I would expect to see in the real plane.

Cheers, Jan

 

[mike10]

thanks for the fast response, Jan and Morten! and thank you for clearing this up.  

 

I think the problem is in my technique in turns.  I was trying to fly it like a small plane.   I am going go do a few patterns now and I will keep my feet away from the pedals LOL

Edited July 30, 2017 by mike10