GearDownPlease From Switzerland, joined May 2007, 43 posts, RR: 0 Posted (5 years 11 months 2 weeks 2 days 18 hours ago) and read 3437 times:
Hello,
Boeing large airliners traditionally feature an "inboard flaps, inboard aileron, outboard flaps AND outboard aileron" wing geometry, a feature shared in the Airbus range with the A300B4-200, B4-100, B2-200, B2-100 and probably B2-1.
While checking A310 photos on our favourite civil aviation photo database, I wondered why A310s and A300B4-600s do not feature outboard ailerons ? Is is due to the FBW (finer management, if A310s and A300B4-600s are ever equipped) ?
PGNCS From United States of America, joined Apr 2007, 2516 posts, RR: 45 Reply 1, posted (5 years 11 months 2 weeks 2 days 16 hours ago) and read 3370 times:
Quoting GearDownPlease (Thread starter): Is is due to the FBW (finer management, if A310s and A300B4-600s are ever equipped) ?
GearDownPlease From Switzerland, joined May 2007, 43 posts, RR: 0 Reply 2, posted (5 years 11 months 1 week 6 days ago) and read 3188 times:
Quoting PGNCS (Reply 1): Quoting GearDownPlease (Thread starter):
Is is due to the FBW (finer management, if A310s and A300B4-600s are ever equipped) ?
This has just been discussed in another thread.
The A-310 and A-300-600 are not FBW aircraft.
Thanks PGNCS but I was interested in knowing why A310s and A300B4-600s did not feature outboard ailerons (while other A300s featured them), more than if the are or not FBW-ed.
113312 From United States of America, joined Apr 2005, 537 posts, RR: 1 Reply 3, posted (5 years 11 months 1 week 5 days 23 hours ago) and read 3134 times:
AILERON CONTROL
Roll inputs are transmitted to the ailerons by dual cable
runs providing fail safe operation. Control column
inputs are transmitted to a differential unit. The differential
unit output is modified by:
• Artificial feel unit.
• Aileron droop actuator.
• Trim actuator (located on center console).
If one control jams, the interconnecting spring rod can
compress permitting operation of the control run to the
other wing. Pilot effort with a jammed control run is between
34 LB and 90 LB. Spoiler roll control is available
but degraded.
Artificial feel is a spring mechanism. It operates independently
of airspeed and provides:
• Artificial feel loads proportional to control
wheel deflection.
• A neutral centering mechanism.
To improve low speed aerodynamic characteristics,
Slat extension signals an aileron droop approximately
10°.
ROLL SPOILER CONTROL
The roll spoilers are electrically controlled by two identical
computers (EFCU-Electrical Flight Control Units)
which process signals from the control wheels position
transducers.
Four groups of spoilers are controlled and monitored
by both computers. Each spoiler group consists of one
or two pairs of symmetrical spoilers:
• A300: spoilers 3 & 2, spoilers 4 & 1, spoilers 5
& 7, spoilers 6).
• A310: spoilers 3 & 2, spoilers 4 & 1, spoilers 6
& 7, spoilers 5).
ROLL SPOILER (PANELS 3 - 7) LOGIC
Roll spoiler deployment starts at approximately 10° of
control wheel deflection.
Starlionblue From Hong Kong, joined Feb 2004, 15871 posts, RR: 66 Reply 5, posted (5 years 11 months 1 week 5 days 9 hours ago) and read 2993 times:
Quoting GearDownPlease (Reply 4): Well, thanks but I am still wondering why... lol !
Airbus felt there was no need for them. IIRC the ailerons are in fact FBW so quite fine control can be achieved.
Outer ailerons are not used at high speed on most aircraft that have both since the wing tends to bend so much it turns the plane the other way.
So we are left with low speed. Apparently the weight and cost savings from deleting the outer ailerons are great enough to justify the solution. Roll control is provided by spoilers and the inner ailerons.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
UAL747 From , joined Dec 1969, posts, RR: Reply 6, posted (5 years 11 months 1 week 4 days 21 hours ago) and read 2959 times:
I was the one who posted the earlier thread on this subject. I too, thought that neither aircraft had outboard ailerons, BUTTTTTTTTTT!!!!!!!!!...........
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 7, posted (5 years 11 months 1 week 4 days 13 hours ago) and read 2913 times:
Quoting Starlionblue (Reply 5): IIRC the ailerons are in fact FBW so quite fine control can be achieved.
The ailerons of the A310 and A300-600 are conventional. FBW might have been necessary if Airbus had deleted the inboard ailerons, leaving only the outboards, which might need to be variable gearing to reduce high speed control sensitivity. With only the inboards ("all speed ailerons" in Airbus terminology), there is no need for such finesse. In other words, a FBW system could reduce aileron sensitivity at high speed, but can't increase aileron control power at low speed.
As I recall, the rationale for deleting the outboard ailerons (called "low speed ailerons" by Airbus) was that there was sufficient roll control power at low speeds (i.e. with flaps extended) without them.
Quoting 113312 (Reply 3): ROLL SPOILER CONTROL
The roll spoilers are electrically controlled by two identical
computers (EFCU-Electrical Flight Control Units)
which process signals from the control wheels position
transducers.
This may be the roll FBW you were thinking of?
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Starlionblue From Hong Kong, joined Feb 2004, 15871 posts, RR: 66 Reply 8, posted (5 years 11 months 1 week 4 days 11 hours ago) and read 2900 times:
Good info on the FBW absence thx.
Quoting Jetlagged (Reply 7):
As I recall, the rationale for deleting the outboard ailerons (called "low speed ailerons" by Airbus) was that there was sufficient roll control power at low speeds (i.e. with flaps extended) without them.
That rationale works for me.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
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