787 First Flight - Signs of Trouble Ahead?

[Denti]

Do you mean the 150% limit load test? nope, the A380 didn't pass that the first time round either, however it did pass the tests until 148% on the first go unlike the 787 who delaminated below 120% load (and still hasn't been retested above that).

That said todays aircraft development certainly tries to design exactly on target and not one bit above it, which is good business sense but is walking a very very fine line. Still think the 787 is a beautiful aircraft and hope all goes well with the very ambitious flight test program. Too bad the delay is so large now that our whole order of that plane is under reconsideration now.

[barit1]

Assuming that by "negative deflection", RumorMonger means upward aileron deflection:

1) Yes, the structural effect is to move the center of lift inboard, reducing the bending moment on the center section; perhaps not uncommon for first flights, as a means of introducing extra conservatism.

2) Another effect is on handling qualities: raised outboard ailerons would help insure the wing root stalls first, so the ailerons remain effective throughout the stall.

Further, on a swept wing, keeping outboard lift available aft of the CG aids a nose-down pitching moment to aid stall recovery.

I wouldn't expect this to be a permanent feature of the production airplane, but merely "belt and suspenders" insurance during early flight test.

[violator]

barit1,

I don't think Boeing will rely on presumably a software function for aerodynamic stalling characteristics. During low speed, low loading I suspect the alleviation won't be active.

I also think that the 787 will use this load alleviation on production aircraft. It will provide a useful reduction in loads which you could take credit for in wing root design.

[ZAGORFLY]

B787 autoflaps

the only one Bugatti Plane had the similar system :
negative flaps on cruise to reduce drag and auto deployment of positive (down) flaps according the speed . Clever!

[deSitter]

Vince Weldon's concerns

What's the current thinking on Vince Weldon's "danger danger" alarms? He's anything but a crackpot - worked on the 727 flap system, Apollo CSM engine thrust structure, and Shuttle structures - IOW he knows structures! However Boeing fired him, and there is the possibility that he was just being old and cranky - however I have the utmost faith in engineers, and he's been a good one. What say ye?

-drl

[bearfoil]

Denti

Saw the limit load test with me own eyeballs, 152+ % There is a video.

bear

[Denti]

Of the 787? Interesting, boeing hasn't released that information yet.

[BarbiesBoyfriend]

Maybe the aileron deflection is due to 'gust alleviation', a la U-2?

[XPMorten]

Would make sense going all the way unofficially at this point
to see what max load the "fix" can take since this is new territory design.
No point in waiting another 6 months for the official test to find the "fix" didn't work.. .

[Denti]

Of course it makes sense to test the fix to the 150% mark, but i am somehow puzzled that they do not share that immediately like they did every little improvement in the past, after all it is a pretty big thing. Besides, it is of course something that has an impact on the stock market and sharing some unofficial information is somewhat puzzling at this point.

Anyway, i do hope the fix does work as intended and withstands the 150% load test, still hope to fly that plane myself at some point.

[Bullethead]

Maybe the outer ailerons were not deflected upwards, they just appeared to be as the TE flaps and inboard ailerons were all deflected downwards. The video clips I've seen are not clear enough to actually see the relative positon of the outer wing TE and the outer aileron to accurately say one way or the other .

Regards,
BH.

[vapilot2004]

What's the current thinking on Vince Weldon's "danger danger" alarms? He's anything but a crackpot - worked on the 727 flap system, Apollo CSM engine thrust structure, and Shuttle structures - IOW he knows structures! However Boeing fired him, and there is the possibility that he was just being old and cranky - however I have the utmost faith in engineers, and he's been a good one. What say ye?

Mr. Weldon Boeing's M. Jacquet? Oui? Non? Peut-etre?

[TURIN]

Point of Order-M'lud?

If you are referring to my comment that started this thread then I think it has been totally misinterpreted. My observation was a noticeable negative aileron deflection (clearly visible in the videos) and a question/theory as to why that might be the case.

and

Now maybe you can understand why my observation that negative aileron deflection (yes negative means up - thats the convention) may have been employed to inboard load the wing.

In what professional circles is the term "Negative Deflection" used when considering the rigging (or otherwise) position of flying controls?

I only ask as having worked in aircraft maintenance for the best part of 30 years it is not a term that I have seen commonly used. Maybe I'm missing something, but "Up/Down" or "Left/Right" have sufficed for now without causing any confusion.

Unlike the original post.

[XPMorten]

The FCOM doesnt mention any symetric "up" aileron as some claim to see.
So if it's the case, it probably is some testflight precaution as mentioned.

Only mention of aileron droop is;
1. With flap and flaperons at low speed
2. Cruise flap, they deflect very minor with flap, flaperons and spoilers to vary
camber and thereby reduce drag depending on weight, Alt, speed.

[RumourMerchant69]

In what professional circles is the term "Negative Deflection" used when considering the rigging (or otherwise) position of flying controls?

In Loads & Aero for aircraft design you normally use +ve for down deflections and -ve for up deflections of any control surface (at least in my experience - might be that different companies use different conventions?)

Either way, there will be a hinge-line axis system and either up or down will be defined as positive. Makes the maths a lot easier

[Kerosene Kraut]

Is this the 152% LL test mentioned above?
YouTube - The Boeing 787 Delay Liner Wing Load Test

This was the Dash 18 half span wingbox.

What is the highest load test the refurbished current wing did?

[SeenItAll]

Did it need to do a roll to satisfy the doubters?

I get the impression that some contributors to this board wouldn't have been satisfied with this first flight unless unless the Dreamliner demonstrated a full roll -- like was done by Tex Johnston on the 707 prototype's first appearance.

See: YouTube - Tex Johnston and Boeing 367-80 - Wikipedia, the free encyclopedia

[kijangnim]

Greetings evryone

I am currently visiting Boeing in Everett, and could see the B787 (in fact to day there is a flight at 0700 local time) and made a visit to the production lines.
Stop speculating the bird is magic, and Boeing has all the necessary knowhow to take all the challenges, everything is new in this airplane, NO BLEED (except for Anti Ice) the B787 is an AC/DC animal, no need for fuel tranfer in flight trailing edge will extand .5 to 1 degree during flight to move the c of g, expected fuel figure to be 15 to 20 % better than the B767! engine nacelle chevron design noise reducers give better than stage 4 EPNBs and so on and so on, the bird is magic.
Weither we like it or not While people are busy speculating, Boeing is busy working
Regards

[Willit Run]

From a Boeing Field service Rep:

It was very exciting yesterday and with minimal flight squawks reported. Boeing considers this first flight one of the best ever. And that's a huge accomplishment given all of the new systems designed into this airplane.

Take that for what its worth!

[411A]

Am surprised 411A hasn't joined the fray....the good old Tristar 500 had ailerons that I believe were offset upwards for take off?

411A doesn't know anything about the 787, other than the fact that it is a tad.....late.

-500 TriStar had active ailerons for climb/cruise gust load control.
Full time.
Very clever.