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-   -   Airbus sideslip crosswind (https://www.pprune.org/tech-log/635578-airbus-sideslip-crosswind.html)

mi68guel 17th Sep 2020 23:05

Airbus sideslip crosswind
 
https://cimg1.ibsrv.net/gimg/pprune....384af8aff7.jpg
What about the rudder pedals? Wind from the right and right rudder applied?? That doesn't look good to me. What do you think? This is A330 official type rating training

Vessbot 18th Sep 2020 00:20

Yes, wind from right needs left rudder. I don't think the pictures are all supposed to tell a consistent story. It' just "topic of the day is sideslips! So here's a picture of some rudder pedals, here's a picture of a crosswind..." (Or if they are supposed to be consistent, there were bigger fish to fry than thorough quality control on this slide, and it's a simple mistake.)

mi68guel 18th Sep 2020 11:04

A320 strong crosswind from the right-hand side. Decrab applying left rudder...if the side stick is in the neutral position, the airplane automatically applies some upwind bank angle (rolls to the right) to zero the roll rate induced by the yaw correction. Am I right?




vilas 18th Sep 2020 14:16


Originally Posted by mi68guel (Post 10887862)
A320 strong crosswind from the right-hand side. Decrab applying left rudder...if the side stick is in the neutral position, the airplane automatically applies some upwind bank angle (rolls to the right) to zero the roll rate induced by the yaw correction. Am I right?

Not by applying bank angle but by applying some ailron and may be spoilers it will prevent the roll from the yaw. Also the axis is ahead of C of G so the aircraft swings towards the wind.
​​

mi68guel 18th Sep 2020 14:33

https://cimg0.ibsrv.net/gimg/pprune....ca52967cdd.png
This is the correct picture. Sidestick neutral, when the right rudder is applied to align with the RWY the aircraft AUTOMATICALLY lowers the upwind wing (left one).

KingAir1978 18th Sep 2020 18:32

The only thing in this picture that's not necessarily correct it the A/C trajectory.

mi68guel 18th Sep 2020 21:08

After de crabbing the acft trajectory is aligned with the fuselage and the runway track so it looks good to me.

Tail-take-off 20th Sep 2020 06:37


Originally Posted by mi68guel (Post 10887964)
https://cimg0.ibsrv.net/gimg/pprune....ca52967cdd.png
This is the correct picture. Sidestick neutral, when the right rudder is applied to align with the RWY the aircraft AUTOMATICALLY lowers the upwind wing (left one).

The answer is in the text at the bottom of your picture: “the lateral controls attempt to zero the roll rate” which means that they try to maintain the current angle of bank. If you want to lower the upwind wing you’ll have to do it yourself. The lateral controls will then attempt to maintain that.

mi68guel 20th Sep 2020 09:03

The text says "sideslip is automatically performed" so with sidestick neutral and rudder applied the sideslip is done automatically by the aircraft applying bank angle opposite to the rudder deflection. Why don´t you try it the next time you go to the SIM?


fantom 20th Sep 2020 12:18

Applying steady rudder for a huge crosswind is a dead easy way to land the 320. I used it whenever necessary.

vilas 20th Sep 2020 13:53


Originally Posted by mi68guel (Post 10889019)
The text says "sideslip is automatically performed" so with sidestick neutral and rudder applied the sideslip is done automatically by the aircraft applying bank angle opposite to the rudder deflection. Why don´t you try it the next time you go to the SIM?

With side stick neutral the flight control laws maintain zero rate of roll. It will not bank but prevent the yaw from causing roll. FCTM below:
The recommended de-crab technique is to use all of the following:
‐ The rudder to align the aircraft with the runway heading during the flare
‐ The roll control, if needed, to maintain the aircraft on the runway centerline. Any tendency to drift downwind should be counteracted by an appropriate lateral (roll) input on the sidestick.
In the case of strong crosswind, in the de-crab phase, the PF should be prepared to add small bank angle into the wind in order to maintain the aircraft on the runway centerline. The aircraft may be landed with a partial de-crab (residual crab angle up to about 5 °) to prevent an excessive bank. This technique prevents wingtip/sharklet (or engine nacelle) strike caused by an excessive bank angle.
As a consequence, this may result in touching down with some bank angle into the wind (hence
with the upwind landing gear first).

sonicbum 20th Sep 2020 21:15

Just to add to all the wisdom already published a quick read by Airbus.

Truth is no matter how knowledgeable you are, certain manoeuvres require a lot of practice to be mastered and need to be practiced regularly to avoid loosing the “grip”. Those Covid times possibly flying 1 - 2 times a month surely do not help.

Tail-take-off 21st Sep 2020 10:51


Originally Posted by mi68guel (Post 10889019)
The text says "sideslip is automatically performed" so with sidestick neutral and rudder applied the sideslip is done automatically by the aircraft applying bank angle opposite to the rudder deflection. Why don´t you try it the next time you go to the SIM?

Correct, with rudder applied but wings level the aircraft will be sideslipping. I teach the FCTM method in the sim as quoted by Vilas in his reply above.

vilas 21st Sep 2020 13:46


Originally Posted by mi68guel (Post 10889019)
The text says "sideslip is automatically performed" so with sidestick neutral and rudder applied the sideslip is done automatically by the aircraft applying bank angle opposite to the rudder deflection. Why don´t you try it the next time you go to the SIM?

Try in the sim autoland with 20kts crosswind. Keep the Flt Ctl page open and it will show you what it does.

mi68guel 22nd Sep 2020 07:47


Originally Posted by vilas (Post 10889187)
With side stick neutral the flight control laws maintain zero rate of roll. It will not bank but prevent the yaw from causing roll. FCTM below:
The recommended de-crab technique is to use all of the following:
‐ The rudder to align the aircraft with the runway heading during the flare
‐ The roll control, if needed, to maintain the aircraft on the runway centerline. Any tendency to drift downwind should be counteracted by an appropriate lateral (roll) input on the sidestick.
In the case of strong crosswind, in the de-crab phase, the PF should be prepared to add small bank angle into the wind in order to maintain the aircraft on the runway centerline. The aircraft may be landed with a partial de-crab (residual crab angle up to about 5 °) to prevent an excessive bank. This technique prevents wingtip/sharklet (or engine nacelle) strike caused by an excessive bank angle.
As a consequence, this may result in touching down with some bank angle into the wind (hence
with the upwind landing gear first).

I´ve got an FCTM too and I read it carefully!!

mi68guel 22nd Sep 2020 07:50

Try manual flight, crosswind and press the rudder and tell me were the bank angle goes (sidestick neutral)....

vilas 22nd Sep 2020 08:06


Originally Posted by mi68guel (Post 10890128)
Try manual flight, crosswind and press the rudder and tell me were the bank angle goes (sidestick neutral)....

With stick neutral for rudder application there is supposed to be no bank. The exercise in sim I mentioned is mentioned in Miami airbus Instructors meeting. When OEI demo is given with hands off it only banks 7° to 9° for same reason. It can't keep zero bank because yaw damper doesn't have that much authority.

mi68guel 22nd Sep 2020 13:01


Originally Posted by vilas (Post 10890134)
With stick neutral for rudder application there is supposed to be no bank. The exercise in sim I mentioned is mentioned in Miami airbus Instructors meeting. When OEI demo is given with hands off it only banks 7° to 9° for same reason. It can't keep zero bank because yaw damper doesn't have that much authority.

If you are a SIM instructor, can you try it there. With all the information I have, I disagree with you, sorry!!

mi68guel 22nd Sep 2020 13:09


Originally Posted by Tail-take-off (Post 10888951)
The answer is in the text at the bottom of your picture: “the lateral controls attempt to zero the roll rate” which means that they try to maintain the current angle of bank. If you want to lower the upwind wing you’ll have to do it yourself. The lateral controls will then attempt to maintain that.

I don´t understand the picture as you do! The only way to finish this topic is by trying it in the SIM or empty flight. Sidestick neutral , apply rudder and see where the bank angle goes. I say oppositte to the rudder deflection (sidesliping automatically).


mi68guel 22nd Sep 2020 13:15


Originally Posted by Tail-take-off (Post 10889601)
Correct, with rudder applied but wings level the aircraft will be sideslipping. I teach the FCTM method in the sim as quoted by Vilas in his reply above.

You are mentioning a condition "but wings level" ...This is not the case I´m talking about. What I´m saying is: fly wings level, A/P off, apply rudder, and see what happens (bank angle YES/NO which side??). I say R rudder bank angle to the left, L rudder bank angle to the right....


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