Topic Author
Posts: 51
Joined: Tue Jul 20, 1999 11:13 pm

B-732 Wingtip's Steam

Thu Mar 15, 2001 10:41 am

Hi all !
Hey... yesterday i was at a known of mine, that is located under the final approach route for our RWY 06 at Carrasco Intl. in Uruguay.
Fortunately i could see two B-737-200 on arrival and it called my attention the following (hope to explain it clear in english for you): from the wingtips, something like steam/vapour was coming out... i know they land at more than 200 km/h, but the sky was clear, clouds were quite higher than the aircraft height... no clouds there... and i do not think they have any exhaust pipes near the wingtips... could somebody tell me what was that ? Both 732s did the same, and it was for about 150-200 mts no more...

ThanX !

Martín (Rombac111)
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: B-732 Wingtip's Steam

Thu Mar 15, 2001 11:14 am

As you can see from these photos, this is a common occurence when the amount of moisture in the air is high enough. You'll note that the aircraft in these photos linked below (757, DC10, DC11, 737) all share a common trait--the vapor starts where the outboard edge of the extended trailing edge flap(s) is next to the trailing edge of the wing.

I'm not an aerodynamic engineer, so I can't provide the textbook description, but my own understanding is that as the airflow above *and* below the wing come back together at the trailing edge, but that with flaps *extended* the trailing edges are now in two different places. It appears that the boundry between these two regions creates enough low pressure to the point where the moisture is visible in high humidity conditions, much like the visible vapor one sometimes sees on the *tops* of the wings in similar conditions during takeoffs.

Hope this helps...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
Posts: 129
Joined: Thu Dec 30, 1999 7:41 am

RE: B-732 Wingtip's Steam

Mon Mar 19, 2001 10:56 pm

it's condensation in the wing tip swirl and you see it nicely in humid air.
here's a beautiful picture:

Click for large version
Click here for full size photo!

Photo © PixAir

if you want to know why condensation takes place, please study the "Ranke-Hiltsch Effect". You'll find it on good search engines.
Ranke and Hiltsch had discovered that a swirl separates in cold (center) and warm (circumference) air.
good luck in trying to understand  Smile/happy/getting dizzy
Posts: 115
Joined: Sun Jan 07, 2001 6:35 pm

RE: B-732 Wingtip's Steam

Wed Mar 21, 2001 11:08 am

You even can see it on Formula 1 racecars...!!!
If it's an Airbus, I'll take the bus

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