Longhauler From Canada, joined Mar 2004, 4281 posts, RR: 36 Reply 1, posted (1 year 5 months 1 week 2 days 23 hours ago) and read 2686 times:
Quoting flyinTLow (Thread starter): When the spoilers are used as roll spoilers on the A320, spoilers 2-5 extend to a maximum of 35°. On the A319/321, spoilers 2,4 and 5 also extend to a maximum of 35°, but spoiler #3 is limited to 7°.
You are right, it is 35 degrees on the A320, but also the A319. It is only on the A321, that spoiler 3 has a maximum deflection of 7 degrees when used as a roll spoiler. When used as a speedbrake though, spoiler 3 can extend to 40 degrees on the A320, (25 degrees with the autopilot on), and 25 degrees for the A319/A321.
I read through FCOM 2 Flight Control chapter, and true to Airbus form, there is an elaborate explanation how everything works ... but not why! The only thing I can imagine is that the A321 wing, while the same size as the A319/320 is in fact quite different. Perhaps with the double slotted flaps only on the A321, there might be different aerodynamics that require the restriction of the roll spoilers.
Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
zeke From Hong Kong, joined Dec 2006, 7725 posts, RR: 73 Reply 2, posted (1 year 5 months 1 week 2 days 22 hours ago) and read 2630 times:
Spoilers are sized for a variety of reasons from emergency descent, rejected takeoffs, landing distance, and flight control etc, and also have to structurally fit in with other trailing edge devices and wing rib locations.
To meet the various parameters due to its increased lift and mass, the two inboard spoilers on the A321 are larger in area to meet various design parameters. For roll control the additional area is not fully required to meet the rates required by the FBW flight control system under normal and various failure conditions.
While the angles listed are maximum values for roll control, it is the FBW control system that will actually command the angle deflected depended on the commanded roll rate input.
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Thank you for correcting my mistake. I took the information from a CBT, which seems to be wrong. Absolutly correct, it's the A321 only.
The A321's spoilers are larger? That is new information for me. I always thought the A320's wings were identical apart from the double slotted flaps to supply the extra lft required in the low speed regime...
474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9 Reply 4, posted (1 year 5 months 1 week 2 days 1 hour ago) and read 2404 times:
I would say that limiting the angle (travel) of the #3 spoiler in the roll control mode was done because of the aerodynamic effect further deployment (higher angle/more travel) had on the horizontal stabilizer.
I know that was the case on the aircraft I worked on for over 30 years.
Pihero From France, joined Jan 2005, 3496 posts, RR: 72 Reply 5, posted (1 year 5 months 1 week 1 day 15 hours ago) and read 2317 times:
Something that's not known by many is that an A321 wing is bigger than a 320/319's, not by much as it is just about 7 cm at the yehudi,tapering to zero at the tip
The total IIRC is worth some .75 squre meter..