justloveplanes
Topic Author
Posts: 867
Joined: Thu Jul 08, 2004 5:38 am

Difference 788/9 Wings And Wingbox

Fri Oct 21, 2011 2:05 am

The 789 notionally uses the 788 wing, though I heard it was reinforced. I am guessing this goes for the Wingbox as well. What will be the differences? The 789 is supposed to be on a better weight track and wondering what that is.
 
ferpe
Posts: 2651
Joined: Tue Nov 30, 2010 7:44 am

RE: Difference 788/9 Wings And Wingbox

Fri Oct 21, 2011 6:10 am

Quoting justloveplanes (Thread starter):
The 789 notionally uses the 788 wing, though I heard it was reinforced. I am guessing this goes for the Wingbox as well. What will be the differences?

The 789 has a 10,5% higher MTOW then the 788, i.e. the worst loading case of the wing and the aircraft as a whole would load the wing structure accordingly higher (unless they change the span-wise pressure distribution of the wing which I don't think they have done). I would believe the ultimate load case would be something like the frame passing a thunderstorm at cruise speed, i.e. the ultimate load case is an upward directed gust.

The load-taking structure is the wingbox (central + wings) it needs to be beefed up the 10,5%, the body joint needs to handle a heavier fuselage (compression) and fuselage (longer heavier tube: upper skins tension and lower compression, side shear loads increase) as well. The tail is not experiencing any higher loads most probably (moment arm is longer, i.e. lower forces needed on the tail surfaces) except the dimensioning for a higher risk for tail strikes perhaps. Further the FLG and MLG fitting points need to be beefed up as well (higher MLW).

[Edited 2011-10-21 00:12:18]
Non French in France
 
dynamicsguy
Posts: 442
Joined: Tue Jul 08, 2008 9:24 am

RE: Difference 788/9 Wings And Wingbox

Fri Oct 21, 2011 8:11 am

Pretty much all of the gauges (thicknesses) will have changed to meet the higher loads.

On the trailing edge we have a higher deployed angle for the flaps and higher approach speed, which then drives changes in the sizing of the flaps as well as greater loads going through the fixed trailing edge structure into the wing box.

I understand some more structure has changed from metallic to composite to meet the weight requirements, in spite of the extra cost involved for these parts.
 
TomB
Posts: 51
Joined: Sun Nov 12, 2006 10:17 pm

RE: Difference 788/9 Wings And Wingbox

Fri Oct 21, 2011 8:56 pm

To follow up DynamicsGuy, I have read elsewhere that the four wing ribs closest to fuselage on the B-787-9 wing will be changed from aluminum to composite.

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