Flare law in the A320ceo vs neo
Thread Starter
Joined: Jan 2023
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From: I would tell you, but my GPS keeps getting jammed
Flare law in the A320ceo vs neo
Hi all,
I'm led to believe that the NEOs have a slightly different flare law vs the CEOs due to a ELAC update somewhere along the line. The THS on the A321neo freezes at 100ft and introduces a direct elevator-to-stick relation with some damping, correct? Does this exact same law apply with the A320neo too? Or does the A320neo's flare law also introduce some pitch down motion?
Thanks
I'm led to believe that the NEOs have a slightly different flare law vs the CEOs due to a ELAC update somewhere along the line. The THS on the A321neo freezes at 100ft and introduces a direct elevator-to-stick relation with some damping, correct? Does this exact same law apply with the A320neo too? Or does the A320neo's flare law also introduce some pitch down motion?
Thanks
Joined: Feb 2000
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From: 500 miles from Chaikhosi, Yogistan
Those guys in the orange jump suits who test these things told me that they do their best to ensure they handle as similarly as they can make it. Of course, different engines etc will mean different "laws" but the intent of that is so that you as the pilot can fly it as similarly as possibly. There is no intent that you second guess the laws and push/pull differently.
Joined: Jun 2007
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From: Wanderlust
In any aircraft the tail enters the ground effect first which causes a pitch down and flare prevents that, then when thrust is brought to idle the THR/WT couple causes further nose down and pilot controls it to touch down at appropriate rate of descent. In Airbus FBW normal/alternate law ELAC will oppose this to maintain flight path and any flare will be a g demand that will keep the aircraft pitching up unless stick is neutralised. So to get cosistant landings a flare mode was created in which stabiliser freezes at 50ft and ELAC causes a steady pitch down to make attitude to -2° in eight seconds. A321 being longer the arm from tail to center of pressure is longer causes early pitch down down at sufficient rate not requiring computer assistance. So the flare mode is made to start early at 100ft. freezing the stabilizer and let aerodynamics to take it's own course.
Thread Starter
Joined: Jan 2023
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From: I would tell you, but my GPS keeps getting jammed
Thank you all for your responses. So, A320ceo and A320neo have the same flare law. Cool
A321 has that slightly different flare law. I assume that it's the same both variants?
A321 has that slightly different flare law. I assume that it's the same both variants?
Joined: Jun 2004
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From: EU
A321ceo
When the aircraft passes 50 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. Flare mode is essentially a direct stick-to-elevator relationship (with some damping provided by the load factor and the pitch rate feedbacks).
The system memorizes the aircraft's attitude at 50 ft, and it becomes the initial reference for pitch attitude control.
As the aircraft descends through 30 ft, the system begins to reduce the pitch attitude to -2 °nose down over a period of 8 s. Consequently, to flare the aircraft, a gentle nose-up action by the pilot is required.
A321neo
When passing 100 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. The flare mode is a direct stick-to-elevator law without auto trim, with some damping provided by load factor and pitch rate feedback. The flare law provides full elevator authority. The flare law does not compensate the ground or thrust effect.
Joined: Jun 2001
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From: On the M25 mainly
Jeepers - some people do make things very difficult. Technically there are differences, but there are so many other variables day-to-day, are you really going to notice? As compressor stall said, the TPs at Airbus have done a great job in smoothing out the different control laws to make them all very similar. There are different laws in take off also between the Neo and Ceo but you'd never know. FWIW I fly most variants of the A320 from knackered old sheds to brand spanking new. The last thing on my mind at 50ft is whether the THS has been frozen by a control law on a particular variant. To the OP, yes there are differences between the Neo and the Ceo.
Joined: Jan 2004
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From: Here and there
Joined: Feb 2000
Posts: 4,704
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From: 500 miles from Chaikhosi, Yogistan
Joined: Jan 2004
Posts: 3,246
Likes: 202
From: Here and there
I don’t think the OP is interested in differences beyond FCOM though are they?
Thread Starter
Joined: Jan 2023
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From: I would tell you, but my GPS keeps getting jammed
A321 neo & ceo have very different flare laws :
A321ceo
When the aircraft passes 50 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. Flare mode is essentially a direct stick-to-elevator relationship (with some damping provided by the load factor and the pitch rate feedbacks).
The system memorizes the aircraft's attitude at 50 ft, and it becomes the initial reference for pitch attitude control.
As the aircraft descends through 30 ft, the system begins to reduce the pitch attitude to -2 °nose down over a period of 8 s. Consequently, to flare the aircraft, a gentle nose-up action by the pilot is required.
A321neo
When passing 100 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. The flare mode is a direct stick-to-elevator law without auto trim, with some damping provided by load factor and pitch rate feedback. The flare law provides full elevator authority. The flare law does not compensate the ground or thrust effect.
A321ceo
When the aircraft passes 50 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. Flare mode is essentially a direct stick-to-elevator relationship (with some damping provided by the load factor and the pitch rate feedbacks).
The system memorizes the aircraft's attitude at 50 ft, and it becomes the initial reference for pitch attitude control.
As the aircraft descends through 30 ft, the system begins to reduce the pitch attitude to -2 °nose down over a period of 8 s. Consequently, to flare the aircraft, a gentle nose-up action by the pilot is required.
A321neo
When passing 100 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. The flare mode is a direct stick-to-elevator law without auto trim, with some damping provided by load factor and pitch rate feedback. The flare law provides full elevator authority. The flare law does not compensate the ground or thrust effect.
Jeepers - some people do make things very difficult. Technically there are differences, but there are so many other variables day-to-day, are you really going to notice? As compressor stall said, the TPs at Airbus have done a great job in smoothing out the different control laws to make them all very similar. There are different laws in take off also between the Neo and Ceo but you'd never know. FWIW I fly most variants of the A320 from knackered old sheds to brand spanking new. The last thing on my mind at 50ft is whether the THS has been frozen by a control law on a particular variant. To the OP, yes there are differences between the Neo and the Ceo.
In some of the new FCOMs for the CEOs, I find that they're no longer mentioning the whole -2° in 8 seconds thing when they're explaining flare law, and that's why I asked here. I tried to do my own digging but came out even more confused. But it's good to see that they try to make the aircraft the feel the same throughout its evolution, although it's probably a regulatory requirement lol
