787 First Flight - Signs of Trouble Ahead?
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787 First Flight - Signs of Trouble Ahead?
While watching the 787 first flight yesterday I noticed that the outboard ailerons appeared to both be deflected negative to quite a noticeable extent.
Now it could just be an optical illusion because of the high deflection of the flaps, but is it possible that this is a load alleviation measure (shifting the lift distribution inboard to reduce wing root bending moment)? Am I being paranoid, or does that imply that the recent repairs haven't solved the wing root joint problems, and that they are having to keep the wing inboard loaded in order to satisfy the authorities?
I hate to be a conspiracy theorist (I really do) but given the recent problems and extensive delays already faced, I imagine there was huge pressure on Boeing to get it in the air before the end of the year, even if all the problems haven't been resolved.
My question is this - can anyone give me a more rational explanation for the aileron deflection at take-off? And if not, then do we really believe that Boeing will achieve a first delivery in 2010, especially given the extremely tight flight test programme?
For the sake of the industry I hope I am wrong....
Now it could just be an optical illusion because of the high deflection of the flaps, but is it possible that this is a load alleviation measure (shifting the lift distribution inboard to reduce wing root bending moment)? Am I being paranoid, or does that imply that the recent repairs haven't solved the wing root joint problems, and that they are having to keep the wing inboard loaded in order to satisfy the authorities?
I hate to be a conspiracy theorist (I really do) but given the recent problems and extensive delays already faced, I imagine there was huge pressure on Boeing to get it in the air before the end of the year, even if all the problems haven't been resolved.
My question is this - can anyone give me a more rational explanation for the aileron deflection at take-off? And if not, then do we really believe that Boeing will achieve a first delivery in 2010, especially given the extremely tight flight test programme?
For the sake of the industry I hope I am wrong....
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Must admit that to me the dihedral/ upsweep seemed quite large.
Especially for a very light aircraft. Might just have been the camera angle but to me it looked like the wings were really curved, almost as if they were a bit too flexible.
At max weight the tips would be getting intimate with each other at this rate!
Is there some film of it straight and level?
Especially for a very light aircraft. Might just have been the camera angle but to me it looked like the wings were really curved, almost as if they were a bit too flexible.
At max weight the tips would be getting intimate with each other at this rate!
Is there some film of it straight and level?
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Just checked various take-off videos and I suggest that ailerons were probably in neutral position.
I note that flight ~never exceeded 13000ft nor ~230kts. These limits could probably be achieved with gear down and without pressurisation.
That said, its always good to see an airplane where it belongs, in the air.
I note that flight ~never exceeded 13000ft nor ~230kts. These limits could probably be achieved with gear down and without pressurisation.
That said, its always good to see an airplane where it belongs, in the air.
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Especially for a very light aircraft. Might just have been the camera angle but to me it looked like the wings were really curved, almost as if they were a bit too flexible.
Just wait for the flight of the 747-8 when it comes to upward sweep.
FYI, high upward wing sweep has been used before with great success and superior efficiency!
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Upward Sweep Wing...
Upward Sweep Wing.... In 787 ,, And The Inward Bent Ailerons R Quite Prominently Visible But If U Look Closely The Root Joint Wing Problem Is Already Taken Care.... Example Of Upward Sweep / High Sweep Are Prominent From Examples Of Crtitcal Wing Like Tht Of The Challenger 650
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I noticed that the outboard ailerons appeared to both be deflected negative
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Both I/B and O/B ailerons are flaperons, they also deflect to the full up position with spoiler activation on touch down.
Photos: Boeing 787-8 Dreamliner Aircraft Pictures | Airliners.net
Photos: Boeing 787-8 Dreamliner Aircraft Pictures | Airliners.net
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You're onto something Rumour Merchant! I didn't notice this initially but its clear on the video. They must be really concerned about the wing root strength on that first aircraft to fly with ailerons up. Normally they are deflected down to give improved span loading and so improved L/D critical for low noise at Take-off...
Perhaps of greater concern – at least of interest at this early stage, is the apparent rapid activity of the elevators during the climb out.
This could have been auto stabilisation, if so then the system was working hard and might not aid the longevity of the control actuators.
If the rapid oscillatory motion (small amplitude) wasn’t stabilisation, then supposedly it was an interesting response to manual control input.
This could have been auto stabilisation, if so then the system was working hard and might not aid the longevity of the control actuators.
If the rapid oscillatory motion (small amplitude) wasn’t stabilisation, then supposedly it was an interesting response to manual control input.
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If memory serves correctly, the MD-11 necessitated "drooped ailerons" to be able to appropriately spread the forces along the wing ... at least for takeoff ... and I don't recall about the remainder of the flight envelope. But, unfortunately, they didn't initially account for the additional lift/drag from the drooped ailerons and the resultant fuel burn ... and that led to other circumstances ... and so on.
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May be Both Aileron drop down by design to increase lift (Airbus use it on the A330 For Takeoff , not on all flap position BTW where is the VDO available I havent seen anything
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Was one of my first observations also, Boeing switched from their "old" flap philosophy to much smaller and less slotted ones (as Airbus does since A320), but does not compensate for the lower lift by aileron droop. Was a little strange to notice.
Load reduction may be one issue, the other one that came to my mind was lateral controlability. More negative ailerons give better lateral stability and higher aileron efficiency. I am still curious how the raked wingtips with no leading edge devices on a large portion of the outer wing will perform during low speed test.
Maybe it was a precautonary measure to keep a larger stall margin for the outer wing before all aerodynamic asumptions have been verified ?
I am quite convinced that later on we will see aileron droop on the 787.
Load reduction may be one issue, the other one that came to my mind was lateral controlability. More negative ailerons give better lateral stability and higher aileron efficiency. I am still curious how the raked wingtips with no leading edge devices on a large portion of the outer wing will perform during low speed test.
Maybe it was a precautonary measure to keep a larger stall margin for the outer wing before all aerodynamic asumptions have been verified ?
I am quite convinced that later on we will see aileron droop on the 787.
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The current B787 design includes aileron droop. All this speculation is amazing. Where do you guys come up this stuff?
One thing really interesting on the 787 is a system called Cruise flaps where it squeezes out a small undetected amount of trailing edege flaps and aileron droop to incrase the camber of the wing, thus enhancing performance. (Only in level cruise flight) Also another system called Auto Drag will assist the pilot when approaching the GS from above. Need flaps 25 or greater for it to work and it does this without pilot imput. Washes out at 500 AGL.
One thing really interesting on the 787 is a system called Cruise flaps where it squeezes out a small undetected amount of trailing edege flaps and aileron droop to incrase the camber of the wing, thus enhancing performance. (Only in level cruise flight) Also another system called Auto Drag will assist the pilot when approaching the GS from above. Need flaps 25 or greater for it to work and it does this without pilot imput. Washes out at 500 AGL.
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Surely the B787 design does include aileron droop, however as all the images clearly showed, it was deactivated for the first flight. In many pictures it even looked like "negative droop" was selected.
Only flight testing will show the optimum amount of aileron droop for each flap setting, and when the aircraft is delivered, it will for sure include this feature.
Only flight testing will show the optimum amount of aileron droop for each flap setting, and when the aircraft is delivered, it will for sure include this feature.
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Only flight testing will show the optimum amount of aileron droop for each flap setting, and when the aircraft is delivered, it will for sure include this feature.
As for rapid small movements of the tailplane I would think it unusual if a FBW design did not respond thus during flight even given zero pilot input - unless one was talking about absolute flat calm conditions.
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Can we get this straight? Are we talking about aileron 'droop' or 'upfloat'? Upfloat I can understand. But I do find it extraordinary that a correspondent thinks he has spotted design flaws from a company like Boeing on a maiden flight. Arrogance in misplaced self-confidence! He could have asked rather than approach the issue so negatively (and make a plonker of himself!).
Aileron upfloat would be expected on a very high aspect-ratio wing like this. The VC10 had it 45 years ago designed in, cutting in and out at 24,000' I remember, to alleviate mid span wing bending moment. I don't know if that was the first in a big jet. But Boeing are designing wings now optimised for high altitude, long range cruise, very long and slender and bendy! No wonder they bend so much. The 747-400 and 777 wings bend more than previous models like the 747 100-300, and even the 737-800/900 are very bendy. It's how they are now.
Aileron upfloat would be expected on a very high aspect-ratio wing like this. The VC10 had it 45 years ago designed in, cutting in and out at 24,000' I remember, to alleviate mid span wing bending moment. I don't know if that was the first in a big jet. But Boeing are designing wings now optimised for high altitude, long range cruise, very long and slender and bendy! No wonder they bend so much. The 747-400 and 777 wings bend more than previous models like the 747 100-300, and even the 737-800/900 are very bendy. It's how they are now.