Why is there a gap between the inner and the outer flaps on the 727? There's no engine on the wing that would make it necessary, so there must be another reason.
FlyASAGuy2005 From United States, joined Sep 2007, 2188 posts, RR: 1 Reply 3, posted (1 year 12 months 3 days 11 hours ago) and read 2250 times:
I always wondered why more airliners didn't pick up a flap design like the 727. The thing had GREAT performace on short runways. I saw a video once where they were retireing an 727 and it was being flown to its final airfield. The runway was very short and it seemed to be floating as it was coming itn, it was going so slow.
CAM2:"Lightning coming out of that one." CAM1: "What?"
Jetlagged From United Kingdom, joined Jan 2005, 2028 posts, RR: 14 Reply 4, posted (1 year 12 months 3 days 11 hours ago) and read 2248 times:
Quoting FlyASAGuy2005 (Reply 3): I always wondered why more airliners didn't pick up a flap design like the 727. The thing had GREAT performace on short runways. I saw a video once where they were retireing an 727 and it was being flown to its final airfield. The runway was very short and it seemed to be floating as it was coming itn, it was going so slow.
Because such complexity adds weight. You only need to install sufficient high lift devices for the runway performance required.
As for the last flight you mention I should imagine the aircraft was very light, which does wonders for any aircraft's runway performance.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Ebs757 From United States, joined Jul 2006, 751 posts, RR: 0 Reply 7, posted (1 year 12 months 2 days 1 hour ago) and read 2116 times:
Are you talking about this one? Sure is cool
Quoting FlyASAGuy2005 (Reply 3): I saw a video once where they were retireing an 727 and it was being flown to its final airfield. The runway was very short and it seemed to be floating as it was coming itn, it was going so slow.
Soon7x7 From United States, joined May 2006, 1219 posts, RR: 1 Reply 8, posted (1 year 12 months 1 day 5 hours ago) and read 2033 times:
747's,767's and 777's have them. They are HIGH SPEED AILERONS...at prescribed airspeeds relative to each model the outboard ailerons lockout and the inboards control rollrate at a less radical rate. By using ailerons on the outboard, the arm is much greater and the result of control input at high speed cruise would be too radical...The 727 inboard aileron also had trim tabs incorporated in them while the 47,67 and 77 do not.&27 inboards were all metal construction, while the others are alloy frame with honeycomb fiberglass skins. The 67 and 77 probably have carbon skins...not sure of that but they are composite.
2H4 From United States, joined Oct 2004, 8099 posts, RR: 65 Reply 9, posted (1 year 12 months 1 day 1 hour ago) and read 1993 times:
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Quoting Soon7x7 (Reply 8): By using ailerons on the outboard, the arm is much greater and the result of control input at high speed cruise would be too radical
I thought inboard ailerons were used to decrease the twisting moment on the wing, thus avoiding control reversal.
Transpac787 From United States, joined Jul 2007, 2046 posts, RR: 16 Reply 10, posted (1 year 12 months 1 day ago) and read 1987 times:
Quoting Soon7x7 (Reply 8): The 727 inboard aileron also had trim tabs incorporated in them
I thought those tabs were for the flight control manual reversion system on the 727?? The "cables and pulleys" so to speak. Just like on the MD80/DC9, there are those trim-like tabs on the elevator, of which are directly connected to the yoke in the cockpit, not the elevators themselves.
Starlionblue From Greenland, joined Feb 2004, 13570 posts, RR: 68 Reply 12, posted (1 year 12 months 22 hours ago) and read 1965 times:
Quoting FlyASAGuy2005 (Reply 3): . I saw a video once where they were retireing an 727 and it was being flown to its final airfield. The runway was very short and it seemed to be floating as it was coming itn, it was going so slow.
Neat video. Also reminds me why I stopped watching those local news posers years ago.
Quoting Soon7x7 (Reply 8): 747's,767's and 777's have them. They are HIGH SPEED AILERONS...at prescribed airspeeds relative to each model the outboard ailerons lockout and the inboards control rollrate at a less radical rate. By using ailerons on the outboard, the arm is much greater and the result of control input at high speed cruise would be too radical..
2H4 and Aeroweanie beat me to it. The outboards just bend the wing at high speeds, delivering the opposite effect to the intended.
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You can call it moment, I call it arm, both the same, you use inboards to decrease ARM,MOMENT,WING FLEX.
I never heard CONTROL REVERSAL used in this context, adverse yaw...I have, thats what the rudder is for...I fly sailplanes with 60 foot wingspans, wings bend like rubber, don,t need inboards for them...
Nope. I mean wing twist. At higher speeds, the outer aileron acts as a control tab, deflecting the entire outer section of wing. That outer section of wing then acts as a giant aileron, inducing roll opposite to that which is intended.
60-foot sailplane wings are a wonderful study in adverse yaw, but the loads they experience are quite different from that of swept-wings at high mach numbers and altitudes.
Boeing767mech From United States, joined Dec 2000, 757 posts, RR: 4 Reply 16, posted (1 year 12 months 15 hours ago) and read 1913 times:
Quoting Soon7x7 (Reply 8): 747's,767's and 777's have them. They are HIGH SPEED AILERONS
CV880/990's and A300-605R have only high speed ailerons. They use spoiler to help on roll axis, The older A300's B and B2 have outboard ailerons, The CV jets never had outboard ailerons.
Jetlagged From United Kingdom, joined Jan 2005, 2028 posts, RR: 14 Reply 17, posted (1 year 12 months 10 hours ago) and read 1878 times:
Quoting Transpac787 (Reply 10): I thought those tabs were for the flight control manual reversion system on the 727?? The "cables and pulleys" so to speak. Just like on the MD80/DC9, there are those trim-like tabs on the elevator, of which are directly connected to the yoke in the cockpit, not the elevators themselves.
IIRC in 727 and 737 manual reversion mode the controls cables do move the surfaces directly, the tabs move in the opposite sense to help reduce the hinge moment. So they aren't servo tabs like the DC-9.
On the DC-9/MD80, if you move the servo tab to full deflection further control movement then moves the control surface directly. In flight this never occurs but on ground with no airspeed it happens during the controls full and free movement check.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
AeroWeanie From United States, joined Dec 2004, 1527 posts, RR: 54 Reply 18, posted (1 year 12 months 8 hours ago) and read 1868 times:
Quoting Soon7x7 (Reply 13): You can call it moment, I call it arm, both the same, you use inboards to decrease ARM,MOMENT,WING FLEX.
I never heard CONTROL REVERSAL used in this context, adverse yaw...I have, thats what the rudder is for...I fly sailplanes with 60 foot wingspans, wings bend like rubber, don,t need inboards for them...
What happens on aircraft with torionally flexible wings is that the deflection of an aileron produces a torsional moment in the wing. This torque twists the wing in such a way that the airplane rolls the opposite direction from that intended. This is why its called control reversal. Control reversal was first observed on the Boeing B-47. On later aircraft (airliners and bombers mainly), inboard ailerons and/or roll spoilers were used to prevent this from happening, as they twist the wing much less.
Sailplanes usually don't experience control reversal, as despite their torsinally soft wings, they fly at lower airspeeds.
LTU932 From Germany, joined Jan 2006, 12172 posts, RR: 57 Reply 19, posted (1 year 12 months 2 hours ago) and read 1837 times:
Quoting Jetlagged (Reply 4): Because such complexity adds weight. You only need to install sufficient high lift devices for the runway performance required.
Besides, with the aerodynamical advances made since the 727, it's probably enough just to use single slotted or double slotted flaps nowadays.
Even when the 737, which had with triple slotted flaps all the way from the -100 until the -500, got its flaps re-designed by the time the 737NG was about to hit the market, and now has only double-slotted flaps. So now, only the 737 Originals and Classics have triple slotted flaps, while the 737NG has double slotted flaps (Pictures left to right to bottom: 737 Original, 737 Classic, 737 Next Generation).
Ah!...that makes sense...last month I flew on 777 and noticed through the climb out in weather the control inputs were very abrupt, but the strangest thing was the outboard and inboard were utilized simultaneously and I would literally see the wing tourqing...I have never seen that before and I've stared at many , many, wings in my years of flight...thnx...j
Yeh, I 'm aware of all that, still calculate my own wieght and balance the old fashioned way, just keeping the thread simple so all the scientists don't jump in..j
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