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SASMD82
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The Evolution Of Flaps And Wings

Fri Apr 15, 2011 10:23 pm

Hi all,

Perhaps a strange question but today I was talking with a friend about aircraft and the flaps of aircraft. We noticed that a change has taken place in the last couple decades. In the 60s most aircraft (727, 737 and 747 e.g.) were fitted with triple-slotted flaps. Double-slotted flaps were fitted on the DC10, L1011, DC9, Fokker 28 and A300/310. Later, with the B767/777 (outdoor flaps) as well as the A330/340/380, only a single slotted flap was necessary.

Also a major change between Airbus and Boeing wings can be seen. Airbus wings are critical-designed, long and slim with a light angle. It has a single single-slotted flap. Boeing aircraft have larger, bigger wings with a big angle. Each wing has two flaps, an outer single-slotted flap and an inner double/triple-slotted flap.

What are the reasons for these designs, these evolutions and what are the major advantages/disadvantages of this design changes.

I look forward to seeing your replies! Thanks!  
 
aviopic
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RE: The Evolution Of Flaps And Wings

Sat Apr 16, 2011 2:07 pm

Quoting SASMD82 (Thread starter):
Airbus wings are critical-designed, long and slim with a light angle.

Can't imagine there is an airliner flying today without a super critical wing design.
Even the 60-ties F.28 you mentioned has them.
The truth lives in one’s mind, it doesn’t really exist
 
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dlednicer
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RE: The Evolution Of Flaps And Wings

Sat Apr 16, 2011 6:45 pm

Quoting Aviopic (Reply 1):
Can't imagine there is an airliner flying today without a super critical wing design.
Even the 60-ties F.28 you mentioned has them.

Not true - the first supercritical wing flew on a T-2 Buckeye in 1970.
http://books.google.com/books?id=8zl...%22%20supercritical%20wing&f=false
The F28 has a wing designed around NACA airfoils:
http://www.ae.illinois.edu/m-selig/ads/aircraft.html

In terms of flap design, the push in the last 20 years has been to simplify the designs, using fewer elements.
 
UAL747
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RE: The Evolution Of Flaps And Wings

Sat Apr 16, 2011 9:59 pm

Quoting Aviopic (Reply 1):
Can't imagine there is an airliner flying today without a super critical wing design.

747-400 does not have a super-critical wing. It didn't happen until the 747-8.

I think it just boils down to different philosophies with A vs. B wing design. But generally, newer made aircraft have less wing sweep than you see on the 747, DC-10, MD-11, L-1011's, however, the wings are longer for the mass of the aircraft.

UAL
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Pihero
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RE: The Evolution Of Flaps And Wings

Sat Apr 16, 2011 11:07 pm

Yes, there have been quite a few differences in the high-lift devices' desighn.
Let's just pose a valid concept : a long thin airfoil will have lots of lift more than a short square one. And the longer the wing, the less induced drag one would see.
Now let's compare the triple slotted flaps we could vind on the 727 or the 73è: they were only as efficient as the Fokker Triplane wing compared to a glider.
That's the sort of progress that has been achieved, and please note that the different 'Buses are closer to that ideal of a full span flap than the Boeings, which still have interruptions : engine exhaust gates, high /low speed ailerons etc...

Quoting SASMD82 (Thread starter):
Airbus wings are critical-designed, long and slim with a light angle.

You're quite right about the A300 being the first airliner equipped with a supercritical wing. The advantages brought by the supezrcritical airfoil were 1)delaying the Mach-induced effects : wave drag, disturbed airflow over the wing, bringing less drag... 2) lessening the need for high sweep angles (a gain of some 10 degrees 20 vs 30° ) ...3) as it is thicker, more fuel could be carried for the same wing surface ... 4) the wing structure is a lot lighter.
These wings were optimized for a .80Mach cruise...Competition has raised the desired cruise Mach to .85, hence the 3 to 4 ° extra sweep angle compared to the previous generation.

Quoting dlednicer (Reply 2):

In terms of flap design, the push in the last 20 years has been to simplify the designs, using fewer elements.

  

Quoting dlednicer (Reply 2):

Not true - the first supercritical wing flew on a T-2 Buckeye in 1970.

Wasn't it on a TF8 Crusader that it flew first?
Contrail designer
 
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dlednicer
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RE: The Evolution Of Flaps And Wings

Sun Apr 17, 2011 1:59 am

Quoting Pihero (Reply 4):
Wasn't it on a TF8 Crusader that it flew first?

No, the TF-8A SCW flew a year later.

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aviopic
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RE: The Evolution Of Flaps And Wings

Sun Apr 17, 2011 10:51 am

Quoting dlednicer (Reply 2):
Not true - the first supercritical wing flew on a T-2 Buckeye in 1970.

I'll must be wrong than   
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