A. Short description
B. Detailed description
C. Own video studies of mentioned aspects
D. Third party videos for explanation
A. Short description:
Several aspects of the lateral dynamics deserve to be reengineered.
While touchdown, planes tend to bounce to the side rapidly and heavily.
During rollout, aircraft bank from side to side using rudder inputs.
Yaw movements are often not smooth and transitions are edgy.
At high speeds the rudder has very low effect, runway excursions on crosswind are inevitable.
The handling does not feel smooth, movement transitions are edgy.
All aspects mentioned above intensify with increase of crosswind.
B. Detailed description:
Here i want to elaborate various aspects of the lateral and yaw dynamics that need to be redone in my opinion. All these aspect are equally important and are connected with each other.
But here i am looking at every single aspect, trying to elaborate fundamental causes:
The wheels may have an unrealistic friction behavior (maybe too much friction and direction change when touching down).
Real aircraft tend to „slide a bit“ towards landing direction due to inertia before the friction of the wheels „kicks in“, even on dry runways.
See this example:
The 747 does not rapidly change direction on touchdown. Due to inertia it follows the recent flight path first, and the following direction changes are smooth.
Even without prior decrab the aircraft does not change the direction that fast.
Nose wheel behavior
The nose wheel changes the aircraft direction instantly on touchdown, making the aircraft veering and going into the „nose direction“. Best seen on the CRJ Landing in the research video in minute 1:08:
The change is not very smooth and occurs suddenly. Like the change of direction when you enter streetcar rails with the front wheel of your bicycle, as shown here:
Here is a footage of a real CRJ 900 landing. Note, that on nose wheel touchdown the aircraft does not cause a severe directional change: https://youtu.be/kDeGoKsHxy0?t=4
Severe bank on touchdown
Gear struts consist of a spring and a damper. In large aircraft gear struts the spring and damping function is provided by a cylinder filled with gasious nitrogen and oil. Technical details just for interest here:
It seems, that the rebound of the gear is exaggerated, leading to a severe banking movement on touchdown. Lets take a 320 crosswind landing as an example. One of the crosswind landing techniques is:
Touch down with the windward main wheel first, having the aircraft slightly banked into the wind.
Then touchdown with the other main wheel and bring down the nose wheel last.
this scenario can be seen in my research video in minute 4:16:
There it seems, that the touchdown of the right main wheel with „200fpm“ causes it to rebound with „400fpm“.
Due to the damping (dissipation of kinetic energy) and the 3rd law of Newton (actio=reactio)
the rebound of the touching gear can never be greater than the initial impact.
(At least without aileron input or gust…)
Also the other crosswind scenarios shown in this video show that behavior, preferably at asymmetric touchdown.
The laws of aerodynamics state, that forces are dependent on speed. Squared.
That means, that at high speed much rudder deflection has a great effect on an aircraft’s yaw movement. However, in IF even at the relatively high landing speeds the rudder seems to be very ineffective. In my research video these cases are very well shown at the following minutes:
2:12 and 2:55.
In both cases the rudder of the involved aircraft (747-8) is deflected fully to keep the aircraft on the runway, but in both cases a runway excursion could not be avoided.
Keep in mind that the aircraft is still at high speed at this moment and the rudder has almost no effect in the simulator. Furthermore, it seems that the yawing effect increases at lower speeds. But i am not sure if this is caused by the rudder or the wheel physics.
Even without decrab the rudder has to be way more effective when on runway.
This phenomenon occurs for all aircraft to some extent.
Banking on runway while rudder input
Especially for aircraft with narrow main gears this phenomenon occurs very easily.
Although it is understandable, that a narrow gear reinforces a potential tumbling behavior, in my opinion it is too much in Infinite Flight.
To see what i am describing, here again the part of the research video featuring a CRJ-900:
The next video shows the CRJ-900 landing in the real world again. As you can see: despite the rudder inputs by the pilot, the aircraft does not show excessive tumbling behavior. The wheels remain on ground and the wings are level.
Edgy, rough movement
Especially on the runway during the landing run, change of direction in my opinion is not smooth enough.
C. Own video studies:
Note: The video is only visible to people having this link, it can not be found on youtube search.
D. Third party videos for explanation
Let me try to give you a conclusion of what needs to be done in my opinion:
Finding a better compromise between controllability and inertia.
Hard to describe, but: These edgy, bouncy movements often give me the impression of controlling a „toy RC plane“ instead of a „real aircraft“.
The balance between „steering by rudder“ and „directional control by wheels“ is not right for some speeds.
The transition air to ground at crosswind scenarios is problematic.
I will be pleased to hear your thoughts on this, maybe you can provide some more constructive input on this matter!
Note that this is not a request to provide a seperate rudder/tiller system, but a rework of the physics involved. This is why i created a new topic apart from the existing request to seperate rudder and tiller steering.
Thank You for voting!