meister808
Posts: 924
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Wing Antihedral On Falcon 2000

Fri Oct 17, 2003 2:44 am

So, in another thread about the Citation X, the fact that the Dassault Falcon 2000 has strange wings gets raised. It seems that, when on the ground, the wings are slanted down from the roots. I thought that such a configuration was really unstable, so why would they use it on a bizjet?


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-Meister
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manzoori
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RE: Wing Antihedral On Falcon 2000

Fri Oct 17, 2003 4:53 am

Personally I'd say that the wings are pretty level whilst on the ground.

Don't forget, when in flight the loads on the wing will give it a dihedral form.

Rez
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bio15
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RE: Wing Antihedral On Falcon 2000

Fri Oct 17, 2003 7:13 am

Manzoori is correct, the wings are usually seen bent down because of the fuel weight and their own weight. When in flight, the aircraft is literally lifted by the wings, so they can be seen bended upwards.

A fully loaded 747 shows its wings bent down while in the ground noticeably. This picture of a 747 just prior to t/o shows it a bit:

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And this one of the aircraft just after takeoff shows the upward bending:

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The same thing happens to the Falcon.

Hope it helps
-Alfredo
 
cancidas
Posts: 3985
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RE: Wing Antihedral On Falcon 2000

Fri Oct 17, 2003 12:34 pm

the falcon wings are actually designed with negative dihedral (antihedral). i can't remember the reason why though...
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L-188
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RE: Wing Antihedral On Falcon 2000

Fri Oct 17, 2003 12:43 pm

All other things being equal you should have more tendency to continue to roll with antihedral, that is why high wing transports use it, since their cargo is carried below the wing (C-5, AN-124) so it acts like a pendulum.




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cancidas
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RE: Wing Antihedral On Falcon 2000

Sat Oct 18, 2003 4:01 am

besides, it makes the plane look unique and sexy. Big grin
"...cannot the kingdom of salvation take me home."
 
Mr Spaceman
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RE: Wing Antihedral On Falcon 2000

Sat Oct 18, 2003 5:03 am

Hi guys.

Regarding commercial airliners, the Tupolev-154 is a good example of a low wing jet with antihedral wing angles.

As mentioned above, the Tu-154's wings also bend upwards when they're creating lift, although they don't appear to me to be as flexible as American & European built airliners.

The wing tips are lower than the roots (antihedral).


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The TU-154's wings before creating lift ........


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..... and bending up after creating lift.


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SkyGuy11
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RE: Wing Antihedral On Falcon 2000

Sat Oct 18, 2003 9:11 am

Both wing sweep and dihedral have an effect on lateral stability. Highly swept-back wings need less dihedreal to be stable.

You don't want extreme stability because the more stable an airplane is, the more difficult it is to change it's flight path.
.
 
Mr Spaceman
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RE: Wing Antihedral On Falcon 2000

Sun Oct 19, 2003 5:16 am

Hello Skyguy11.

You mentioned ...."Highly swept-back wings need less dihedral to be stable."

I believe your statement explains the "extra" dihedral angle on this Yak-40 airliner. It's wings aren't really swept back at all. They're very square looking.

I've never seen jet aircraft wings with so much dihedral angle before.  Wow! They look like they're damaged!

Check out this angle.
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There's not much sweep here.
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sovietjet
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RE: Wing Antihedral On Falcon 2000

Sun Oct 19, 2003 9:53 am

Actually the Tu-154 wing is one of the more flexible ones. The wing can be bent so that the tip is 14 meters from its original point before the wing breaks. Of course that doesn't happen in flight. The reason for flexibility is comfort because the flexible wing absorbs turbulence and also contributes to a very light touchdown. I'm guessing that the wing-mounted engines have something to do with the western aircrafts' wings bending more.
 
bio15
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RE: Wing Antihedral On Falcon 2000

Sun Oct 19, 2003 11:43 am

Actually the Tu-154 wing is one of the more flexible ones. The wing can be bent so that the tip is 14 meters from its original point before the wing breaks.

14 meters seems incorrect to me (an aircraft won't fly with vertical wings  Smile). That's probably close to the length of a single wing! 6, or 7 meters would be quite a lot!

That's just based on impression and common sense, I'm not knowledgeable on the subject, so I may be incorrect.


-Alfredo

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