A-320 Flaps & Spoilers logic / mis-logic?
Thread Starter
Joined: Sep 2001
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From: "THAT" place??!!
A-320 Flaps & Spoilers logic / mis-logic?
This came about after discussing a few "why does it do THAT?!" issues with some Airbus drivers...
I'm more familiar with conventional aircraft, but even they were curious why on the Airbus A-320 it rolls slightly
with the deployment of speed-brakes while flaps are selected (and visa-versa: once flaps are selected and speed-brakes are selected).
This seems to be a consistent issue with the A-320 and not linked to one particular airframe so it's not a mis-rigging (unless the entire A-320 world-wide fleet is build mis-rigged!).
...anyone have a qualified guess on this?
I'm more familiar with conventional aircraft, but even they were curious why on the Airbus A-320 it rolls slightly
with the deployment of speed-brakes while flaps are selected (and visa-versa: once flaps are selected and speed-brakes are selected).This seems to be a consistent issue with the A-320 and not linked to one particular airframe so it's not a mis-rigging (unless the entire A-320 world-wide fleet is build mis-rigged!).
...anyone have a qualified guess on this?
Joined: Feb 2006
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From: On the dark side of the moon
What he's referring to is an issue with the A320 (all of them) when Flap 2 is selected with 1/2 speed brake extended. The aircraft does indeed have a momentary roll (left, then right I believe) as the flaps come to position. The bank angle is only a few degrees, and it's probably more noticeable to us pilots than it is to the SLF. In order to avoid it, I will back off on the speed brake lever if I can when the flaps are extending to Flap 2.
Thread Starter
Joined: Sep 2001
Posts: 253
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From: "THAT" place??!!
J.O. has it "bank" on! 
The QUESTION is... (not meaning to sound like this is being directed to J.O. as a result of his perfect explanation of what it is doing...) but for those engineering / aerodynamic-types out there... W H Y does it happen?! EVERY A-320 does this.
(And J.O.'s technique for avoiding it is "bank" on, too.)
Cheers,
R.D.
The QUESTION is... (not meaning to sound like this is being directed to J.O. as a result of his perfect explanation of what it is doing...) but for those engineering / aerodynamic-types out there... W H Y does it happen?! EVERY A-320 does this.
(And J.O.'s technique for avoiding it is "bank" on, too.)
Cheers,
R.D.
Joined: Feb 2006
Posts: 980
Likes: 11
From: On the dark side of the moon
Actually, it's Flaps 1 that's useless (the airplane setting, not you FlapsOne)! But Flap 2 with 1/2 speedbrake and about 170 kts on the clock (okay, speed tape) does a really nice job of re-stabilising an approach, whether it's was cocked up by the driver or by Fiumincino ATC! 
P.S. I've got a call in to one of my colleagues who's a bit of a whiz at this stuff, hopefully he can offer a logical
explanation.
P.S. I've got a call in to one of my colleagues who's a bit of a whiz at this stuff, hopefully he can offer a logical
explanation.
Joined: Jun 2001
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From: Blighty
It's mentioned in FCOM 3.03.18 p5 So I guess the answer is in the category of "because it does". It also suggests extending the landing gear to slow down instead of using speedbrakes.
Personally, I don't have a problem with it.
Personally, I don't have a problem with it.
Joined: Aug 2005
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From: fairly close to the colonial capitol
If this phenomenon were due to flight control design, it would have been fixed already. I wonder if it is not just another minor (yet interesting) FBW software/hardware interaction oddity.
I have not noticed this behaviour in the sims I have had sessions in. (Florida and Texas) Surely it must be modeled. Perhaps I had been too busy concentrating on tasks at hand to notice at the time. I will look for it. Anyone else?
I have not noticed this behaviour in the sims I have had sessions in. (Florida and Texas) Surely it must be modeled. Perhaps I had been too busy concentrating on tasks at hand to notice at the time. I will look for it. Anyone else?
Joined: Mar 2007
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From: berkshire
Was told (rumour code 3) by a nice man at TLS that it is because the SECS change the spoiler deployment limits when F2 selected and that the spoilers will then go to the new limit if they are 1/2 extended or more. This may happen with a slight assymetry.
Apparently.
Apparently.
