fix: Crosswind issues

[donstim]

Summary of Changes

UPDATED This PR fixes two separate issues associated with crosswind effects on the A32NX:

1. It responds to comments made in the Development Discord channel on 20 January 2024 regarding the fidelity of A32NX landings in crosswinds. It appears that over time, including many MSFS and A32NX changes, the amount of rudder needed to counteract crosswinds during takeoff and landing has been reduced compared to what was intended and realistic.
2. It fixes an issue where the A32NX cannot turn against a crosswind at low taxi speed on the runway. If attempting a 180 degree turn on the runway in a strong crosswind (>~20 knots), the nose wheel will start to skid and the force of the crosswind will cause the airplane to weathervane into the wind even if the nose wheels are turned in the opposite direction.(See video below.)

This PR slightly increases the weathervaning tendency of the airplane and reduces the rudder effectiveness. It also removes the effect of crosswinds at speeds below about 6 knots and blends them in gradually thereafter until 100% crosswind at around 55 knots. (The latter change is what is needed to address the low speed taxi turn into a crosswind issue.)

Screenshots (if necessary)

References

Some references for the crosswind takeoff and landing techniques, amount of rudder needed during crosswind takeoffs and landings, and weathervaning include: https://www.youtube.com/watch?v=hFdu6DqnTnA https://www.youtube.com/watch?v=jtP48ZDhrBU and other references that cannot be included here

Additional context

Videos: 360 degree turn on runway with strong crosswind before PR: https://1drv.ms/v/s!Ajsy7Ey4_8uFgZFiV1s06rcFvcQH3g?e=KJmEvm 360 degree turn on runway with strong crosswind with PR fix (outside view): https://1drv.ms/v/s!Ajsy7Ey4_8uFgZFkCyh3V5z3AGVSZw?e=ttVXBj 360 degree turn on runway with strong crosswind with PR fix (cockpit view): https://1drv.ms/v/s!Ajsy7Ey4_8uFgZFjirCPP9STj-ZQCg?e=YL3aaw Landing with max Xwind (38 knots): https://1drv.ms/v/s!Ajsy7Ey4_8uFgZE7DiOTx8uYYhzfTg?e=MgJ1Gb Landing with 30 knot Xwind: https://1drv.ms/v/s!Ajsy7Ey4_8uFgZE8D6G49YXdFG50BQ?e=NG0Ewc Max Xwind (35 knots) takeoff: https://1drv.ms/v/s!Ajsy7Ey4_8uFgZE9iojwqNVqtsWR4g?e=qcbxh3

MSFS turbulence was set to low for the above videos and several wind layers were added to try to maintain a constant crosswind value. Delayed manual braking was used (except for the autoland) to better highlight the crosswind effects at high speeds.

These settings and tests were done with the following rudder sensitivity setting using CH Pro Pedals:

Discord username (if different from GitHub): donbikes

Testing instructions

Test taxi, takeoff, and landing on various runways in various crosswind conditions (up to the max crosswinds of 35 knots for takeoff, 38 for manual landing, and 20 for autoland. MSFS winds are input as m/s, so halve these values in knots when inputting them into the MSFS weather UI. Tests by our NEO pilots are required as well as other QA testers. Evaluate weathervaning tendency and amount of rudder needed to regain/maintain directional controllability after landing in different crosswind conditions.

To ensure stable winds at the desired crosswind during the approach or takeoff, you must set several MSFS wind layers covering the altitudes to be flown.

See the following video for an example of how to set up for a crosswind landing when starting in the air on final approach (i.e., by selecting only the destination runway in the MSFS UI to start (ignore the resetting of the FACs as that is no longer necessary): https://1drv.ms/v/s!Ajsy7Ey4_8uFgZBzpkPN-UDi3KGOfw?e=V7IFlD (The MSFS Simvar watcher was used to verify the crosswind value that existed throughout the test as the wind value on the ND drops out near the ground. The debug wheels window was used to see when wheel skids occurred.)

How to download the PR for QA

Every new commit to this PR will cause a new A32NX artifact to be created, built, and uploaded.

1. Make sure you are signed in to GitHub
2. Click on the Checks tab on the PR
3. On the left side, click on the bottom PR tab
4. Click on the A32NX download link at the bottom of the page

[2hwk]

QA Report

Testing:

• [x] Taxi,
• [x] Takeoff
• [x] Landing on various runways in various crosswind conditions (up to the max crosswinds of 35 knots for takeoff, 38 for manual landing, and 20 for autoland. MSFS winds are input as m/s, so halve these values in knots when inputting them into the MSFS weather UI. Tests by our NEO pilots are required as well as other QA testers.
• [x] ~~Evaluate weathervaning tendency and amount of rudder needed to regain/maintain directional controllability after landing in different crosswind conditions.~~ (Not a pilot but seems fine)
• [x] Rudder behavior elsewhere is as expected

Negatives:

• N/A

Results:

• Passed

Conclusions:

• LGTM
• Still needs pilot approval, this is mainly for testing regression

[pinatacolada]

Feels good to me from flight characteristics point of view.

This photo shows the average amount of rudder deflection required to keep the centerline in 37kts crosswind with a dry runway, shown is very slightly more as I was correcting towards the left.

For anyone else testing this, I suggest using the amount of rudder deflection as a comparison basis, as otherwise using the physical amount of force or deflection on the actual hardware rudder pedals would be affected by sensitivity settings and differences across different peripherals.

[danbw9]

Tests carried out at EKCH 22L. Wind from 300 degrees at varying velocities for testing purposes. Dry Runway. Circuits.

Done further testing regarding this and the changes work well. This time, matching the same rudder sensitivities at 50% to bring consistent results as were tested by others and donbikes. Multiple landings with varying crosswinds. Feels a lot more stable with regards to rudder input and squeezing rudder in the flare as opposed to the previous 'cessna-like' behaviour. Taxiing on ground with strong winds is a lot better, that was pretty crucial. 360 turns done and managed well.

Tests done with varying levels of X-wind, several circuits done. Take offs and landings

X-wind at 20kts without gusts X-wind at 20kts gusting 25 X-wind at 30kts gusting 38 X-wind at 38kts without gusts

The crosswind effect gone below 6 knots is a welcome change. It felt again like a less, stable smaller aircraft. Common MSFS issue.

From my side, I am happy with it. Much improved and needed changes.