This is more a question to the development team. When TO with crosswind, the amount of rudder to apply depends on winds speed and direction. It also depends if the plane is heavy or not.
For a given airplane load in %, could we expect if the weight distribution to have any effect on plane behavior in IF. For instance, lets take 2 instances where Airplane load is 50%
In scenario A, we have lots of passengers but few fuel
In scenario B, we have fewer passengers but more fuel.
In both cases, the total load is the same. Is IF implemented in a way that the behavior will be the same for both scenario or does it take into consideration the load type and distribution ?
Edit: for anyone reading this, the discussion below is about the yaw inertia changing with the loading distribution. But in a later comment this was concluded to cause no change in the amount of rudder deflection needed for a given crosswind, because the rudder depends on the balance of external forces, not on the internal inertia variation.
So my conclusion in this post is wrong. The angular inertia only affects the sluggishness of the yaw response to an unmatched rudder deflection (which presumably is not modelled) End edit
It’s true that the amount of yaw torque (angular force) will be higher as mass gets distributed further from the center of mass (the rotation axis), to achieve a given value of angular acceleration (get it yawing).
The use of rudder at take off is to prevent yaw due to crosswind hitting the tail laterally.
So I think you’re correct that there will be a difference in rudder control input, because the moment of inertia (“angular mass”), changes with load distribution: more yaw acceleration tendency for a given crosswind when mass distribution is lower.
But, irl I question if the change in control response is easily detectable or not(?).
In other words, the percentage change of the range of moment of inertia change might be too small compared to the center value moment of inertia rudder application. Especially considering that the amount of rudder deflection we anticipate comes from the pilot guesstimating the actual crosswind effect from the wind arrow and speed.
If I were to bet money, it would be there is no rudder input difference for changes in load distribution in IF.
Do you have a solid method to know exactly the amount of rudder to apply depending on wind speed and dir and aircraft type, in a way to keep plane aligned with centerline once it lifts off ?
I don’t really know of a precise fix. I estimate how much rudder to be ready with based on having practised a lot and by looking at the relative wind angle and strength.
It helps to watch the official crosswind takeoff tutorial.
But other than that I would say what has worked the best is to go into solo mode, set a crosswind and just practice many takeoffs resetting each time with the takeoff position function.
Try starting with a very low crosswind and gradually work up to stronger.
Maybe mix up the aircraft you practice because the 757 for example has a very sensitive rudder. And for the 787 you may find you need to actively hold the nose down in the early part of the roll and simultaneously release the nose down force just as you apply rudder.