The vortices are due to the greater lift generated over the flap sections, not necessarily any greater angle of attack (the angle of attack of the wing is not affected by flap angle). It's analagous to the wing tip vortex, as you say yourself the flap is a separate aerofoil, so the flap edge is another wing tip with a vortex attached.While it's true the upper wing surface has slightly lower air pressure that isn't where the condensation starts. There is much lower pressure at the centre of the vortex itself, and that is why they become visible if there is moisture in the air. If you watch the water swirling out of a washbasin plug-hole you will see the centre of the vortex created is much lower than the surrounding water surface, indicating a water lower pressure in the centre.Kevin

Well this seems a bit pedantic. The flap is at a higher angle of attack in this case(or any case) and therefore ultimately does produce more lift than the wing/airfoil. I was speaking in terms of the pictured 737 the OP mentioned.The second part I can't argue with, but again I think my post summed it up reasonably well. :(

Well this seems a bit pedantic. The flap is at a higher angle of attack in this case(or any case) and therefore ultimately does produce more lift than the wing/airfoil. I was speaking in terms of the pictured 737 the OP mentioned.The second part I can't argue with, but again I think my post summed it up reasonably well. :(

It may be pedantic but if you use terms like angle of attack they should be used properly. Deflecting a TE flap increases wing camber (and so lift), it doesn't change AOA.The second part of your post mentioned Bernoulli (whose famous equation does not explain the acceleration of air over an aerofoil). You also talked about air reaching the dew point on the wing upper surface (it doesn't, except under extreme conditions behind a shock wave), and didn't explain why there's condensation in the vortex. Apart from that you did OK. :( Kevin

It may be pedantic but if you use terms like angle of attack they should be used properly. Deflecting a TE flap increases wing camber (and so lift), it doesn't change AOA.

Yes, the wings camber is increased. BUT when thinking of the flap as a separate airfoil (I mentioned that, didn't I?) it is at a higher angle of attack relative to the wing it is attached to. You're arguing nomenclature to a point where it confuses less knowledgeable people (the folks I was addressing).I'm not arguing your accuracy but rather that there's more than one way to explain the phenomenon.

Huh?The condensation is the result of reduced pressure over the top of the wing - nothing else! Same reason you get condensation in the fuselage when it undergoes rapid decompression - the air pressure drops, the air temperature drops (this is the actual mechanism) and the water can no longer be supported, so it condensates out and we see it as a white cloud. It soon dissipates back into the air, or falls as rain.It is related to AoA because as you increase the AoA, you are asking the wing to produce more lift, so there is a lower pressure over the top of the wing, and the effect is more likely (which is why it is most pronounced during takeoff and landing, but particularly landing).It has nothing to do with being only "extreme conditions behind a shock wave" or anything like it. The reason you get the white cloud behind the shockwave is the exact same reason - pressure drop that results in cooler air and the water condensates out.The flap is not a separate airfoil - it is part of the same airfoil - the wing! Extending flaps increases the wing area (not always), and the camber. It is camber that gives lift. When you extend the flaps the aircraft pitches down. I'll let you research why. Hint: center of pressure.Best regards,Robin.

The flap is not a separate airfoil - it is part of the same airfoil - the wing! Extending flaps increases the wing area (not always), and the camber. It is camber that gives lift. When you extend the flaps the aircraft pitches down. I'll let you research why. Hint: center of pressure.

"Huh?" :( We don't have to get rude here. But since you went there, I've taken 3 courses of aerodynamics. What you're saying is true. But you're too near sighted...Have you looked at a flap on modern airliners lately? It's technically an airfoil in itself in some cases. In particular this 737. I can assure you I know how flaps work. I digress.EDIT: No I don't. The cross sections speak for themselves. How do you think the flaps increase camber without severely separating air from the top of the airfoil? Think SLOTTED flaps: http://www.rcuniverse.com/forum/m_786417/anchors_786417/mpage_1/key_/anchor/tm.htm#786417 HINT: Note how the flaps and the slots between them form what looks like an airfoil(s)... :( "Coanda effect" (Just poking fun at the attitude of your post :( )*Condescending mode off*

I see George (Falcon999) has his official Beta Banner... I wonder :( :(

I see George (Falcon999) has his official Beta Banner... I wonder :( :(

I noticed that too! Lucky guy if it's true!

I see George (Falcon999) has his official Beta Banner... I wonder :( :(

I am hoping that's where production is at!!

I see George (Falcon999) has his official Beta Banner... I wonder :( :(

Look again... :(

Look again... :(

Are you teasing me George :( :(

I was wondering if this could be vapor from the fuel vent located under the wing. Looks like its coming from a point close to the vents position.

George your signature is amazing.

May I add some more controversy to this subject? :( VORTITRAILS TRIVIA------------------I challenge you guys to explain: a : Vortices are visible only for a short period of time while contrails last quite longer. b : Why contrails are not visible a low altitude.c : What is known as "distrail" d : Why vortices appear in turbofan engine inlets even at zero airspeed. e) Fuel being dumped from an airliner at high altitude will create: vortices, contrails, none, 3d pictures of my father riding a bicycle all over the sky, other?

George your signature is amazing.

The credit goes to one of the PMDG developers, Vin Scimone! :(

------------------I challenge you guys to explain

I thought we had already established that all such phenomena are caused by the illuminati's secret fleet of new world order chemical-spraying airliners? Don't you know the internet is never wrong?http://educate-yourself.org/ct/Sometimes comedy writes itself; here's just one quote from that website:'Chemtrail spraying seems to be heaviest and most constant over North America and most countries of western Europe. Some countries in Asia are being sprayed (Japan and Korea), but the greatest exception to any chemtrail activity whatsover is China. The Chinese are being spared completely because China is being groomed by the NWO to replace the United States as the leading nation of the world, both economically and militarily.On the brighter side, you should know that methods have been discovered to help neutralize chemtrails and return the sky to a normal blue with real clouds taking the place of the chemtrail soup and overcast which a host of disinformation peddlers are trying to convince you are just ordinary, "cirrus" clouds that "are formed from persistent contrails" (current disinformation spiel from government climatological web sites).'Well comrades, there you have it, so join the fight to have the clouds mended with proper ones and the sky to be returned to its proper blue colour!I'd like to think that the person who wrote that stuff is some sort of comedy genius who is merely winding people up with an elaborate spoof of a conspiracy theory website, but sadly, I suspect it's just a fruitcake who really believes all that stuff. Talk about cloud cuckoo land eh? And these people are allowed to vote, have kids, generally be allowed out without supervision etc, although fortunately it is doubtful any of them are PPLs since they would probably not want to get closer to the chemtrails, and tin foil hats set off the metal detectors at airports if trying to board a commercial flight, so at least you won't have to steer clear of them in the sky.Al

Thought I'd add these pictures to this thread.I was plane spotting today at KPHX, and saw a SWA737 with a relatively unusual (to me, anyway) vortex off its right wing.http://www.flickr.com/photos/russellmjohnston/5685623020/sizes/l/in/photostream/http://www.flickr.com/photos/russellmjohnston/5685053853/sizes/l/in/photostream/It was visible all the way from take off to as far as I could see.