B777 folding wing
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B777 folding wing
I might have missed something but how does the composite build of the wing minimize drag (as per the linked video)? Or is this a reference to something different?
It would seem that this folding wing precludes any wing tips, which seem quite fashionable these days. Any performance disadvantages?
It would seem that this folding wing precludes any wing tips, which seem quite fashionable these days. Any performance disadvantages?
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The modern wing on Boeing wide body aircraft does not have winglets. These A/C (B787, B747-800) do have raked(?) wingtips which substitute the winglets. According to Boeing there is no performance disadvantage.
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Not after de-icing.
Looking forward to this. So are lamp posts and edges of buildings.
As said, the wing's perfect as it is - without winglets - not needed - it's just so damn big.
Looking forward to this. So are lamp posts and edges of buildings.
As said, the wing's perfect as it is - without winglets - not needed - it's just so damn big.
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The original 777 was planned to have folding wingtips ( circa 1992-93 ), but at that time for a variety of reasons, the folding tip was dropped. at about that same time, winglets for 737 buisness jet was aborning, mainly for" looks" to differentiate from ' commerical' 737. Sort of like executive perks like chrome hubcaps. The agreement was that as long as it did not degrade performance and looked neat, winglets would be an option. Internal battles with certain aerotypes who were pushing a new wing for 737 at a horrendous cost eventual¥ resulted in a series of flight tests with winglets. And the results were such that they eventually became ( long story short) an option for new commercial 737. meanwhile back at the ranch, raked wingtips were aborning. And for long range commecial routes, the raked tips were perhaps a bit better than the winglets. But apparantly a significant redesign of the metal 777 wing would be needed to accomodate the raked tips.
Along comes the all ( mostly) composite wing, and along with better control via layup and molds of wing contours and smoothness, the raked wingtip could be accomodated- and because of airport clearances, the folding tip became practical again.
Along comes the all ( mostly) composite wing, and along with better control via layup and molds of wing contours and smoothness, the raked wingtip could be accomodated- and because of airport clearances, the folding tip became practical again.
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Yes, I remember that option, but it was far more of the wing, 21 feet, that folded up. It was actually an option that no one purchased.
This folding wingtip seems like quite a bit of mechanism for the small portion that actually folds. One would think that this extra stiffness at the joint, at this part of the wing would not be helpful...
This folding wingtip seems like quite a bit of mechanism for the small portion that actually folds. One would think that this extra stiffness at the joint, at this part of the wing would not be helpful...
But apparantly a significant redesign of the metal 777 wing would be needed to accomodate the raked tips.
The folding wingtip offered on the original 777 was inboard of some of the movable aero surfaces - that caused major headaches. No moveable surfaces on the foldable surface on the 777X.
The Boeing Aero types claim the raked wing tip is more effective than winglets, but it necessarily increases the wing span - that would be bad news for the 737 for the gate size they often use, so they stayed with winglets to get the aero improvement with nearly the same span.
That was for trapping wave-lift at mach 3 while also addressing the transonic CP shift to reduce supersonic trim drag - doing what concord did by pumping fuel but addressing the fin area issue as well.
PDR
According to a book I read on the XB-70, the wave-lift was intentional "miss information". The primary reason was that drooping the wings dramatically improved directional stability at cruise Mach speeds (although I wouldn't be surprised if did provide wave-lift benefit - at least according to that book it wasn't the primary reason.)
According to a book I read on the XB-70, the wave-lift was intentional "miss information". The primary reason was that drooping the wings dramatically improved directional stability at cruise Mach speeds (although I wouldn't be surprised if did provide wave-lift benefit - at least according to that book it wasn't the primary reason.)
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Here's a comment on that video from someone who seems to know what he's talking about:
-Unknown to anyone, a wire in a junction box was accidentally pinched under the cover causing a short to ground.
-After takeoff, the landing gear was selected up but the hydraulics shut off because the shorted wire.
-When the hydraulic pump shut down the pressure was lost
and air loads on the unlocked gear caused it to drift rearwards into the door.
-the nose wheel tire was cut by the gear door.
-engineers on the ground gave instructions to the pilots where and how to jump a relay in the cockpit
to get the hydraulic pump started.
-Copilot use a paperclip and jumped terminals on a relay as instructed.
-Hydraulic pump started and pilot selected gear down, and the gear went back to down and locked.
-Aircraft landed normally but the anti skid system malfunctioned and locked some of the wheels
-After takeoff, the landing gear was selected up but the hydraulics shut off because the shorted wire.
-When the hydraulic pump shut down the pressure was lost
and air loads on the unlocked gear caused it to drift rearwards into the door.
-the nose wheel tire was cut by the gear door.
-engineers on the ground gave instructions to the pilots where and how to jump a relay in the cockpit
to get the hydraulic pump started.
-Copilot use a paperclip and jumped terminals on a relay as instructed.
-Hydraulic pump started and pilot selected gear down, and the gear went back to down and locked.
-Aircraft landed normally but the anti skid system malfunctioned and locked some of the wheels
