Happy-flier
Posts: 286
Joined: Sat Dec 25, 1999 4:41 pm

Single-slotted Flaps On The 787

Sat Aug 13, 2011 3:40 pm

As a casual observer / enthusiast, I have been intrigued by Boeing's choice to go with single-slotted trailing edge flaps on the 787 wing. Even the inboards appear to be single-slotted. This is quite a directional change in design philosophy when compared to virtually every other large commercial jet, where the inboard trailing edge flaps have tended to consist of at least two sections (e.g. 767, 777) while the outboard flaps were single-piece Fowler types.

Could it be the composite materials that influenced the design decision? Or is it purely weight and / or aerodynamics?

Personally I like flaps that are mechanically less complex. Seems like they are less maintenance intensive, and obviously still able to get the job done at low speeds.

[Edited 2011-08-13 08:42:09]
May the wind be always at your back . . . except during takeoff & landing.
 
Pihero
Posts: 4196
Joined: Mon Jan 31, 2005 5:11 am

RE: Single-slotted Flaps On The 787

Sat Aug 13, 2011 5:42 pm

If you looked at all the Airbus FBW planes, with the evception of the A321, They all feature a single-slotted Fowler-type flap system.
It could have been part of the 75/767 planes but the high speed aileron was taking too much space so a double slotted solution for the inboard TED was necessary.
The progress is purely aerodynamics.
And, yes, it can do the job at low speeds as, at MLW, the A380 is the slowest airliner around.

See these :
Ther A380

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Photo © Pieter-Jan Van De Vijver



The A345

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Photo © Nigel Fenwick



The A332

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Photo © Darren Koch



The A320 compared to the A321 :

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Photo © Tomasz Janiak (EPGD Spotters)
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Photo © Alsatian D



[Edited 2011-08-13 11:09:32]
Contrail designer
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Single-slotted Flaps On The 787

Sat Aug 13, 2011 6:24 pm

Quoting happy-flier (Thread starter):
I have been intrigued by Boeing's choice to go with single-slotted trailing edge flaps on the 787 wing. Even the inboards appear to be single-slotted.

They're all single-slotted offset-hinge. No tracks.

Quoting happy-flier (Thread starter):
This is quite a directional change in design philosophy when compared to virtually every other large commercial jet

It's the same philosophy...the simplest/lightest flap system that will do that job. What's changed is technology (aerodynamics and FBW) so that you can accomplish the job with simpler, lighter flap systems.

Tom.
 
dynamicsguy
Posts: 442
Joined: Tue Jul 08, 2008 9:24 am

RE: Single-slotted Flaps On The 787

Sun Aug 14, 2011 7:24 am

Quoting happy-flier (Thread starter):
Could it be the composite materials that influenced the design decision? Or is it purely weight and / or aerodynamics?

As has been noted, improvements in aerodynamics have allowed Boeing to use a simpler configuration. One of the significant changes which enables this is the use of drooped spoilers, which reduces the need for a forward flap element by controlling the gap between the spoilers and flap.

The use of composites in the wing did apparently enable the configuration of flaps according to a Boeing configuration guy who I saw give a talk. It was related to the ability to meet structural requirements of the wingbox while at the same time allow the space for the high-lift components.

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